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* [PATCH] [gdb/mi] Don't treat references to compound values as "simple".
@ 2022-09-08  7:18 Gareth Rees
  2022-09-08 10:27 ` Andrew Burgess
  0 siblings, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-09-08  7:18 UTC (permalink / raw)
  To: gdb-patches

SUMMARY

The '--simple-values' argument to '-stack-list-arguments' and similar
GDB/MI commands does not take reference types into account, so that
references to arbitrarily large structures are considered "simple" and
printed. This means that the '--simple-values' argument cannot be used
by IDEs when tracing the stack due to the time taken to print large
structures passed by reference.

DETAILS

Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
'-stack-list-variables' and so on) take a PRINT-VALUES argument which
may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
In the '--simple-values' case, the command is supposed to print the
name, type, and value of variables with simple types, and print only the
name and type of variables with compound types.

The '--simple-values' argument ought to be suitable for IDEs that need
to update their user interface with the program's call stack every time
the program stops. However, it does not take C++ reference types into
account, and this makes the argument unsuitable for this purpose.

For example, consider the following C++ program:

    struct s {
        int v[10];
    };

    int
    sum(const struct s &s)
    {
        int total = 0;
        for (int i = 0; i < 10; ++i) total += s.v[i];
        return total;
    }

    int
    main(void)
    {
        struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
        return sum(s);
    }

If we start GDB in MI mode and continue to 'sum', the behaviour of
'-stack-list-arguments' is as follows:

    (gdb)
    -stack-list-arguments --simple-values
    ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]

Note that the value of the argument 's' was printed, even though 's' is
a reference to a structure, which is not a simple value.

See https://github.com/microsoft/MIEngine/pull/673 for a case where this
behaviour caused Microsoft to avoid the use of '--simple-values' in
their MIEngine debug adapter, because it caused Visual Studio Code to
take too long to refresh the call stack in the user interface.

SOLUTIONS

There are two ways we could fix this problem, depending on whether we
consider the current behaviour to be a bug.

1. If the current behaviour is a bug, then we can update the behaviour
   of '--simple-values' so that it takes reference types into account:
   that is, a value is simple if it is neither an array, struct, or
   union, nor a reference to an array, struct or union.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that it is safe to use the '--simple-values'
   argument when refreshing the call stack.

2. If the current behaviour is not a bug, then we can add a new option
   for the PRINT-VALUES argument, for example, '--simplest-values' (3),
   that would be suitable for use by IDEs.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that the '--simplest-values' argument is
   available for use when refreshing the call stack.

PATCH

This patch implements solution (1) as I think the current behaviour of
not printing structures, but printing references to structures, is
surprising. However, if you prefer solution (2) I would be happy to
implement that instead.
---
 gdb/NEWS                                     | 12 ++++++
 gdb/doc/gdb.texinfo                          |  7 ++++
 gdb/mi/mi-cmd-stack.c                        |  6 +--
 gdb/mi/mi-cmd-var.c                          | 22 ++++++----
 gdb/mi/mi-cmds.h                             |  5 +++
 gdb/mi/mi-main.c                             |  7 +---
 gdb/python/py-framefilter.c                  |  6 +--
 gdb/testsuite/gdb.mi/print-simple-values.cc  | 44 ++++++++++++++++++++
 gdb/testsuite/gdb.mi/print-simple-values.exp | 40 ++++++++++++++++++
 9 files changed, 126 insertions(+), 23 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.cc
 create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2ecd8..855f42a9549 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -114,6 +114,18 @@ maintenance info line-table
   entry corresponds to an address where a breakpoint should be placed
   to be at the first instruction past a function's prologue.
 
+* MI changes
+
+  ** The '--simple-values' argument to the '-stack-list-arguments',
+     '-stack-list-locals', '-stack-list-variables', and
+     '-var-list-children' commands takes reference types into account:
+     that is, a value is now considered simple if it is neither an
+     array, structure, or union, nor a reference to an array, structure,
+     or union. (Previously all references were considered simple.)
+     Support for this feature can be verified by using the
+     '-list-features' command, which should contain
+     "simple-values-ref-types".
+
 * New targets
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 238a49b027d..5ccf6609709 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -37295,6 +37295,13 @@ option (@pxref{GDB/MI Program Execution}).
 @item data-disassemble-a-option
 Indicates that the @code{-data-disassemble} command supports the @option{-a}
 option (@pxref{GDB/MI Data Manipulation}).
+@item simple-values-ref-types
+Indicates that the @code{--simple-values} argument to the
+@code{-stack-list-arguments}, @code{-stack-list-locals},
+@code{-stack-list-variables}, and @code{-var-list-children} commands
+takes reference types into account: that is, a value is considered
+simple if it neither an array, structure, or union, nor a reference to
+an array, structure, or union.
 @end ftable
 
 @subheading The @code{-list-target-features} Command
diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index 0fe204dbc66..f8f4ad266d0 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -571,7 +571,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
   const struct block *block;
   struct symbol *sym;
   struct block_iterator iter;
-  struct type *type;
   const char *name_of_result;
   struct ui_out *uiout = current_uiout;
 
@@ -650,10 +649,7 @@ list_args_or_locals (const frame_print_options &fp_opts,
 	      switch (values)
 		{
 		case PRINT_SIMPLE_VALUES:
-		  type = check_typedef (sym2->type ());
-		  if (type->code () != TYPE_CODE_ARRAY
-		      && type->code () != TYPE_CODE_STRUCT
-		      && type->code () != TYPE_CODE_UNION)
+                  if (mi_simple_values_type_p (sym2->type ()))
 		    {
 		case PRINT_ALL_VALUES:
 		  if (sym->is_argument ())
diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
index 3db09cf7815..f9d332d13a4 100644
--- a/gdb/mi/mi-cmd-var.c
+++ b/gdb/mi/mi-cmd-var.c
@@ -335,15 +335,21 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
   if (type == NULL)
     return 1;
   else
-    {
-      type = check_typedef (type);
+    return mi_simple_values_type_p (type);
+}
 
-      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
-	 and that type is not a compound type.  */
-      return (type->code () != TYPE_CODE_ARRAY
-	      && type->code () != TYPE_CODE_STRUCT
-	      && type->code () != TYPE_CODE_UNION);
-    }
+int
+mi_simple_values_type_p (struct type *type)
+{
+  type = check_typedef (type);
+
+  if (type->code () == TYPE_CODE_REF || type->code () == TYPE_CODE_RVALUE_REF)
+    type = TYPE_TARGET_TYPE (type);
+
+  return (type
+          && type->code () != TYPE_CODE_ARRAY
+          && type->code () != TYPE_CODE_STRUCT
+          && type->code () != TYPE_CODE_UNION);
 }
 
 void
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 9ffb11bf997..81a5578ca1c 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -226,4 +226,9 @@ using remove_mi_cmd_entries_ftype
   = gdb::function_view<bool (mi_command *)>;
 extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
 
+/* Return 1 if type is suitable for printing with PRINT_SIMPLE_VALUES, that is,
+   if type is neither a compound type nor a reference to a compound type. */
+
+extern int mi_simple_values_type_p (struct type *type);
+
 #endif /* MI_MI_CMDS_H */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b758f398e2a..dd1962fd0e2 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
       uiout->field_string (NULL, "undefined-command-error-code");
       uiout->field_string (NULL, "exec-run-start-option");
       uiout->field_string (NULL, "data-disassemble-a-option");
+      uiout->field_string (NULL, "simple-values-ref-types");
 
       if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
 	uiout->field_string (NULL, "python");
@@ -2462,7 +2463,6 @@ static void
 print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct value *val;
-  struct type *type;
   struct ui_out *uiout = current_uiout;
 
   string_file stb;
@@ -2482,12 +2482,9 @@ print_variable_or_computed (const char *expression, enum print_values values)
   switch (values)
     {
     case PRINT_SIMPLE_VALUES:
-      type = check_typedef (value_type (val));
       type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
-      if (type->code () != TYPE_CODE_ARRAY
-	  && type->code () != TYPE_CODE_STRUCT
-	  && type->code () != TYPE_CODE_UNION)
+      if (mi_simple_values_type_p (value_type (val)))
 	{
 	  struct value_print_options opts;
 
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 366f3745b9d..227a9ecb4f1 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -235,14 +235,10 @@ py_print_value (struct ui_out *out, struct value *val,
   if (args_type == MI_PRINT_SIMPLE_VALUES
       || args_type == MI_PRINT_ALL_VALUES)
     {
-      struct type *type = check_typedef (value_type (val));
-
       if (args_type == MI_PRINT_ALL_VALUES)
 	should_print = 1;
       else if (args_type == MI_PRINT_SIMPLE_VALUES
-	       && type->code () != TYPE_CODE_ARRAY
-	       && type->code () != TYPE_CODE_STRUCT
-	       && type->code () != TYPE_CODE_UNION)
+	       && mi_simple_values_type_p (value_type (val)))
 	should_print = 1;
     }
   else if (args_type != NO_VALUES)
diff --git a/gdb/testsuite/gdb.mi/print-simple-values.cc b/gdb/testsuite/gdb.mi/print-simple-values.cc
new file mode 100644
index 00000000000..15567c740a0
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-simple-values.cc
@@ -0,0 +1,44 @@
+/* This test case is part of GDB, the GNU debugger.
+
+   Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* PRINT_SIMPLE_VALUES test program.
+
+   Test that PRINT_SIMPLE_VALUES handles C++ reference types correctly.
+
+   In the function f(), arguments a, b, and c are either ints or references to
+   int, and their values should be printed by PRINT_SIMPLE_VALUES, but arguments
+   s, t, and u are structures or references to structures, and their values
+   should not be printed by PRINT_SIMPLE_VALUES. */
+
+struct s
+{
+    int v;
+};
+
+int
+f(int a, int &b, int &&c, struct s s, struct s &t, struct s &&u)
+{
+    return a + b + c + s.v + t.v + u.v;
+}
+
+int
+main(void)
+{
+    int a = 1, b = 2;
+    struct s s = { 4 }, t = { 5 };
+    return f(a, b, 3, s, t, (struct s){ 6 });
+}
diff --git a/gdb/testsuite/gdb.mi/print-simple-values.exp b/gdb/testsuite/gdb.mi/print-simple-values.exp
new file mode 100644
index 00000000000..c1b5a54ad3b
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-simple-values.exp
@@ -0,0 +1,40 @@
+# Copyright 2022 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+standard_testfile .cc
+
+if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+mi_clean_restart $binfile
+
+mi_runto_main
+
+mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
+
+mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
+
+mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} "run until breakpoint on f"
+
+mi_gdb_test "-stack-list-arguments 2" \
+    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"a\",type=\"int\",value=\"1\"\},\{name=\"b\",type=\"int &\",value=\"@0x\[0-9a-f\]+: 2\"\},\{name=\"c\",type=\"int &&\",value=\"@0x\[0-9a-f\]+: 3\"\},\{name=\"s\",type=\"s\"\},\{name=\"t\",type=\"s &\"\},\{name=\"u\",type=\"s &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
+    "stack list arguments, simple types: names, types and values, compound types: names and types"
+
+mi_gdb_exit
-- 
2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08  7:18 [PATCH] [gdb/mi] Don't treat references to compound values as "simple" Gareth Rees
@ 2022-09-08 10:27 ` Andrew Burgess
  2022-09-08 11:02   ` [PATCH v2] " Gareth Rees
  2022-09-08 11:09   ` [PATCH] " Gareth Rees
  0 siblings, 2 replies; 25+ messages in thread
From: Andrew Burgess @ 2022-09-08 10:27 UTC (permalink / raw)
  To: Gareth Rees, gdb-patches


Thanks for this patch.  I have a few notes, in line below.

Gareth Rees via Gdb-patches <gdb-patches@sourceware.org> writes:

> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug.
>
> 1. If the current behaviour is a bug, then we can update the behaviour
>    of '--simple-values' so that it takes reference types into account:
>    that is, a value is simple if it is neither an array, struct, or
>    union, nor a reference to an array, struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, then we can add a new option
>    for the PRINT-VALUES argument, for example, '--simplest-values' (3),
>    that would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--simplest-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (1) as I think the current behaviour of
> not printing structures, but printing references to structures, is
> surprising. However, if you prefer solution (2) I would be happy to
> implement that instead.

I'm agree that this feels like a bug, and that solution #1 seems like
the way to go.

> ---
>  gdb/NEWS                                     | 12 ++++++
>  gdb/doc/gdb.texinfo                          |  7 ++++
>  gdb/mi/mi-cmd-stack.c                        |  6 +--
>  gdb/mi/mi-cmd-var.c                          | 22 ++++++----
>  gdb/mi/mi-cmds.h                             |  5 +++
>  gdb/mi/mi-main.c                             |  7 +---
>  gdb/python/py-framefilter.c                  |  6 +--
>  gdb/testsuite/gdb.mi/print-simple-values.cc  | 44 ++++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-simple-values.exp | 40 ++++++++++++++++++
>  9 files changed, 126 insertions(+), 23 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..855f42a9549 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,18 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>  
> +* MI changes
> +
> +  ** The '--simple-values' argument to the '-stack-list-arguments',
> +     '-stack-list-locals', '-stack-list-variables', and
> +     '-var-list-children' commands takes reference types into account:
> +     that is, a value is now considered simple if it is neither an
> +     array, structure, or union, nor a reference to an array, structure,
> +     or union. (Previously all references were considered simple.)
> +     Support for this feature can be verified by using the
> +     '-list-features' command, which should contain
> +     "simple-values-ref-types".
> +
>  * New targets
>  
>  GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..5ccf6609709 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -37295,6 +37295,13 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item simple-values-ref-types
> +Indicates that the @code{--simple-values} argument to the
> +@code{-stack-list-arguments}, @code{-stack-list-locals},
> +@code{-stack-list-variables}, and @code{-var-list-children} commands
> +takes reference types into account: that is, a value is considered
> +simple if it neither an array, structure, or union, nor a reference to
> +an array, structure, or union.
>  @end ftable
>  
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..f8f4ad266d0 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -571,7 +571,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>  
> @@ -650,10 +649,7 @@ list_args_or_locals (const frame_print_options &fp_opts,
>  	      switch (values)
>  		{
>  		case PRINT_SIMPLE_VALUES:
> -		  type = check_typedef (sym2->type ());
> -		  if (type->code () != TYPE_CODE_ARRAY
> -		      && type->code () != TYPE_CODE_STRUCT
> -		      && type->code () != TYPE_CODE_UNION)
> +                  if (mi_simple_values_type_p (sym2->type ()))
>  		    {
>  		case PRINT_ALL_VALUES:
>  		  if (sym->is_argument ())
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..f9d332d13a4 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -335,15 +335,21 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    if (type == NULL)
>      return 1;
>    else
> -    {
> -      type = check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
>  
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -	 and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -	      && type->code () != TYPE_CODE_STRUCT
> -	      && type->code () != TYPE_CODE_UNION);
> -    }
> +int
> +mi_simple_values_type_p (struct type *type)

This new function should have a comment like:

  /* See mi-cmds.h.  */

And also, should be returning `bool`.

> +{
> +  type = check_typedef (type);
> +
> +  if (type->code () == TYPE_CODE_REF || type->code () == TYPE_CODE_RVALUE_REF)
> +    type = TYPE_TARGET_TYPE (type);
> +
> +  return (type

Checks for nullptr should be written as:

  type != nullptr

but, can you ever get nullptr here?  Certainly, if type is nullptr on
entry then an assert in check_typedef will trigger, I'd expect that
after calling check_typedef and TYPE_TARGET_TYPE you should still have a
valid type pointer ... but maybe there's some case you've seen where
this is not true?

Unless you know a case where type could be nullptr I would rather the
type check be moved into a separate:

  gdb_assert (type != nullptr);

before the return.

> +          && type->code () != TYPE_CODE_ARRAY
> +          && type->code () != TYPE_CODE_STRUCT
> +          && type->code () != TYPE_CODE_UNION);
>  }
>  
>  void
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..81a5578ca1c 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -226,4 +226,9 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>  
> +/* Return 1 if type is suitable for printing with PRINT_SIMPLE_VALUES, that is,
> +   if type is neither a compound type nor a reference to a compound type. */
> +
> +extern int mi_simple_values_type_p (struct type *type);

Update the comment to reflect an update of the return type to bool.

> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..dd1962fd0e2 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "simple-values-ref-types");
>  
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>  	uiout->field_string (NULL, "python");
> @@ -2462,7 +2463,6 @@ static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>  
>    string_file stb;
> @@ -2482,12 +2482,9 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -	  && type->code () != TYPE_CODE_STRUCT
> -	  && type->code () != TYPE_CODE_UNION)
> +      if (mi_simple_values_type_p (value_type (val)))
>  	{
>  	  struct value_print_options opts;
>  
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..227a9ecb4f1 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -235,14 +235,10 @@ py_print_value (struct ui_out *out, struct value *val,
>    if (args_type == MI_PRINT_SIMPLE_VALUES
>        || args_type == MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
>        if (args_type == MI_PRINT_ALL_VALUES)
>  	should_print = 1;
>        else if (args_type == MI_PRINT_SIMPLE_VALUES
> -	       && type->code () != TYPE_CODE_ARRAY
> -	       && type->code () != TYPE_CODE_STRUCT
> -	       && type->code () != TYPE_CODE_UNION)
> +	       && mi_simple_values_type_p (value_type (val)))
>  	should_print = 1;
>      }
>    else if (args_type != NO_VALUES)
> diff --git a/gdb/testsuite/gdb.mi/print-simple-values.cc b/gdb/testsuite/gdb.mi/print-simple-values.cc
> new file mode 100644
> index 00000000000..15567c740a0
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-simple-values.cc
> @@ -0,0 +1,44 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* PRINT_SIMPLE_VALUES test program.
> +
> +   Test that PRINT_SIMPLE_VALUES handles C++ reference types correctly.
> +
> +   In the function f(), arguments a, b, and c are either ints or references to
> +   int, and their values should be printed by PRINT_SIMPLE_VALUES, but arguments
> +   s, t, and u are structures or references to structures, and their values
> +   should not be printed by PRINT_SIMPLE_VALUES. */

Two spaces before '*/' to close this comment.

Test programs should follow GNU style unless specifically required not
to for some test reason.

> +
> +struct s
> +{
> +    int v;

It seems like everything is over indented in the test, 4 spaces instead
of 2.

> +};
> +
> +int
> +f(int a, int &b, int &&c, struct s s, struct s &t, struct s &&u)

Space after 'f'.

> +{
> +    return a + b + c + s.v + t.v + u.v;

Indentation.

> +}
> +
> +int
> +main(void)

Space after 'main'.

> +{
> +    int a = 1, b = 2;
> +    struct s s = { 4 }, t = { 5 };
> +    return f(a, b, 3, s, t, (struct s){ 6 });

Space after 'f' and after '(struct s)' (I think).

> +}
> diff --git a/gdb/testsuite/gdb.mi/print-simple-values.exp b/gdb/testsuite/gdb.mi/print-simple-values.exp
> new file mode 100644
> index 00000000000..c1b5a54ad3b
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-simple-values.exp
> @@ -0,0 +1,40 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +

Test scripts should have a brief summary here of what the test is
checking.  This will be similar to the comment you have in the source
file, so maybe you just want to move that here, but you can keep the
source comment and add an extra description here, whatever works.

> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} "run until breakpoint on f"

We still try to wrap lines to under 80 characters when possible, so
here, and maybe the previous line too should be wrapped.

> +
> +mi_gdb_test "-stack-list-arguments 2" \
> +    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"a\",type=\"int\",value=\"1\"\},\{name=\"b\",type=\"int &\",value=\"@0x\[0-9a-f\]+: 2\"\},\{name=\"c\",type=\"int &&\",value=\"@0x\[0-9a-f\]+: 3\"\},\{name=\"s\",type=\"s\"\},\{name=\"t\",type=\"s &\"\},\{name=\"u\",type=\"s &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
> +    "stack list arguments, simple types: names, types and values, compound types: names and types"

But lines like these can't easily be wrapped, so its fine for these to exist.

Thanks,
Andrew

> +
> +mi_gdb_exit
> -- 
> 2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 10:27 ` Andrew Burgess
@ 2022-09-08 11:02   ` Gareth Rees
  2022-09-08 13:30     ` Eli Zaretskii
  2022-09-08 11:09   ` [PATCH] " Gareth Rees
  1 sibling, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-09-08 11:02 UTC (permalink / raw)
  To: gdb-patches

SUMMARY

The '--simple-values' argument to '-stack-list-arguments' and similar
GDB/MI commands does not take reference types into account, so that
references to arbitrarily large structures are considered "simple" and
printed. This means that the '--simple-values' argument cannot be used
by IDEs when tracing the stack due to the time taken to print large
structures passed by reference.

DETAILS

Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
'-stack-list-variables' and so on) take a PRINT-VALUES argument which
may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
In the '--simple-values' case, the command is supposed to print the
name, type, and value of variables with simple types, and print only the
name and type of variables with compound types.

The '--simple-values' argument ought to be suitable for IDEs that need
to update their user interface with the program's call stack every time
the program stops. However, it does not take C++ reference types into
account, and this makes the argument unsuitable for this purpose.

For example, consider the following C++ program:

    struct s {
        int v[10];
    };

    int
    sum(const struct s &s)
    {
        int total = 0;
        for (int i = 0; i < 10; ++i) total += s.v[i];
        return total;
    }

    int
    main(void)
    {
        struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
        return sum(s);
    }

If we start GDB in MI mode and continue to 'sum', the behaviour of
'-stack-list-arguments' is as follows:

    (gdb)
    -stack-list-arguments --simple-values
    ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]

Note that the value of the argument 's' was printed, even though 's' is
a reference to a structure, which is not a simple value.

See https://github.com/microsoft/MIEngine/pull/673 for a case where this
behaviour caused Microsoft to avoid the use of '--simple-values' in
their MIEngine debug adapter, because it caused Visual Studio Code to
take too long to refresh the call stack in the user interface.

SOLUTIONS

There are two ways we could fix this problem, depending on whether we
consider the current behaviour to be a bug.

1. If the current behaviour is a bug, then we can update the behaviour
   of '--simple-values' so that it takes reference types into account:
   that is, a value is simple if it is neither an array, struct, or
   union, nor a reference to an array, struct or union.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that it is safe to use the '--simple-values'
   argument when refreshing the call stack.

2. If the current behaviour is not a bug, then we can add a new option
   for the PRINT-VALUES argument, for example, '--simplest-values' (3),
   that would be suitable for use by IDEs.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that the '--simplest-values' argument is
   available for use when refreshing the call stack.

PATCH

This patch implements solution (1) as I think the current behaviour of
not printing structures, but printing references to structures, is
contrary to reasonable expectation.
---
 gdb/NEWS                                     | 12 +++++
 gdb/doc/gdb.texinfo                          |  7 +++
 gdb/mi/mi-cmd-stack.c                        |  6 +--
 gdb/mi/mi-cmd-var.c                          | 24 +++++++---
 gdb/mi/mi-cmds.h                             |  6 +++
 gdb/mi/mi-main.c                             |  7 +--
 gdb/python/py-framefilter.c                  |  6 +--
 gdb/testsuite/gdb.mi/print-simple-values.cc  | 44 +++++++++++++++++
 gdb/testsuite/gdb.mi/print-simple-values.exp | 50 ++++++++++++++++++++
 9 files changed, 140 insertions(+), 22 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.cc
 create mode 100644 gdb/testsuite/gdb.mi/print-simple-values.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2ecd8..855f42a9549 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -114,6 +114,18 @@ maintenance info line-table
   entry corresponds to an address where a breakpoint should be placed
   to be at the first instruction past a function's prologue.
 
+* MI changes
+
+  ** The '--simple-values' argument to the '-stack-list-arguments',
+     '-stack-list-locals', '-stack-list-variables', and
+     '-var-list-children' commands takes reference types into account:
+     that is, a value is now considered simple if it is neither an
+     array, structure, or union, nor a reference to an array, structure,
+     or union. (Previously all references were considered simple.)
+     Support for this feature can be verified by using the
+     '-list-features' command, which should contain
+     "simple-values-ref-types".
+
 * New targets
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 238a49b027d..5ccf6609709 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -37295,6 +37295,13 @@ option (@pxref{GDB/MI Program Execution}).
 @item data-disassemble-a-option
 Indicates that the @code{-data-disassemble} command supports the @option{-a}
 option (@pxref{GDB/MI Data Manipulation}).
+@item simple-values-ref-types
+Indicates that the @code{--simple-values} argument to the
+@code{-stack-list-arguments}, @code{-stack-list-locals},
+@code{-stack-list-variables}, and @code{-var-list-children} commands
+takes reference types into account: that is, a value is considered
+simple if it neither an array, structure, or union, nor a reference to
+an array, structure, or union.
 @end ftable
 
 @subheading The @code{-list-target-features} Command
diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index 0fe204dbc66..f8f4ad266d0 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -571,7 +571,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
   const struct block *block;
   struct symbol *sym;
   struct block_iterator iter;
-  struct type *type;
   const char *name_of_result;
   struct ui_out *uiout = current_uiout;
 
@@ -650,10 +649,7 @@ list_args_or_locals (const frame_print_options &fp_opts,
 	      switch (values)
 		{
 		case PRINT_SIMPLE_VALUES:
-		  type = check_typedef (sym2->type ());
-		  if (type->code () != TYPE_CODE_ARRAY
-		      && type->code () != TYPE_CODE_STRUCT
-		      && type->code () != TYPE_CODE_UNION)
+                  if (mi_simple_values_type_p (sym2->type ()))
 		    {
 		case PRINT_ALL_VALUES:
 		  if (sym->is_argument ())
diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
index 3db09cf7815..a1c93f3a167 100644
--- a/gdb/mi/mi-cmd-var.c
+++ b/gdb/mi/mi-cmd-var.c
@@ -335,15 +335,25 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
   if (type == NULL)
     return 1;
   else
-    {
-      type = check_typedef (type);
+    return mi_simple_values_type_p (type);
+}
 
-      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
-	 and that type is not a compound type.  */
-      return (type->code () != TYPE_CODE_ARRAY
-	      && type->code () != TYPE_CODE_STRUCT
-	      && type->code () != TYPE_CODE_UNION);
+/* See mi-cmds.h.  */
+
+bool
+mi_simple_values_type_p (struct type *type)
+{
+  type = check_typedef (type);
+
+  if (type->code () == TYPE_CODE_REF || type->code () == TYPE_CODE_RVALUE_REF)
+    {
+      type = TYPE_TARGET_TYPE (type);
+      gdb_assert (type != nullptr);
     }
+
+  return (type->code () != TYPE_CODE_ARRAY
+          && type->code () != TYPE_CODE_STRUCT
+          && type->code () != TYPE_CODE_UNION);
 }
 
 void
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 9ffb11bf997..de39c7758d7 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -226,4 +226,10 @@ using remove_mi_cmd_entries_ftype
   = gdb::function_view<bool (mi_command *)>;
 extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
 
+/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
+   is, if type is neither a compound type, nor a reference to a compound
+   type.  */
+
+extern bool mi_simple_values_type_p (struct type *type);
+
 #endif /* MI_MI_CMDS_H */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b758f398e2a..dd1962fd0e2 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
       uiout->field_string (NULL, "undefined-command-error-code");
       uiout->field_string (NULL, "exec-run-start-option");
       uiout->field_string (NULL, "data-disassemble-a-option");
+      uiout->field_string (NULL, "simple-values-ref-types");
 
       if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
 	uiout->field_string (NULL, "python");
@@ -2462,7 +2463,6 @@ static void
 print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct value *val;
-  struct type *type;
   struct ui_out *uiout = current_uiout;
 
   string_file stb;
@@ -2482,12 +2482,9 @@ print_variable_or_computed (const char *expression, enum print_values values)
   switch (values)
     {
     case PRINT_SIMPLE_VALUES:
-      type = check_typedef (value_type (val));
       type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
-      if (type->code () != TYPE_CODE_ARRAY
-	  && type->code () != TYPE_CODE_STRUCT
-	  && type->code () != TYPE_CODE_UNION)
+      if (mi_simple_values_type_p (value_type (val)))
 	{
 	  struct value_print_options opts;
 
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 366f3745b9d..227a9ecb4f1 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -235,14 +235,10 @@ py_print_value (struct ui_out *out, struct value *val,
   if (args_type == MI_PRINT_SIMPLE_VALUES
       || args_type == MI_PRINT_ALL_VALUES)
     {
-      struct type *type = check_typedef (value_type (val));
-
       if (args_type == MI_PRINT_ALL_VALUES)
 	should_print = 1;
       else if (args_type == MI_PRINT_SIMPLE_VALUES
-	       && type->code () != TYPE_CODE_ARRAY
-	       && type->code () != TYPE_CODE_STRUCT
-	       && type->code () != TYPE_CODE_UNION)
+	       && mi_simple_values_type_p (value_type (val)))
 	should_print = 1;
     }
   else if (args_type != NO_VALUES)
diff --git a/gdb/testsuite/gdb.mi/print-simple-values.cc b/gdb/testsuite/gdb.mi/print-simple-values.cc
new file mode 100644
index 00000000000..3761b87f4cc
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-simple-values.cc
@@ -0,0 +1,44 @@
+/* This test case is part of GDB, the GNU debugger.
+
+   Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* PRINT_SIMPLE_VALUES test program.
+
+   Test that PRINT_SIMPLE_VALUES handles C++ reference types correctly.
+
+   In the function f(), arguments a, b, and c are either ints or references to
+   int, and their values should be printed by PRINT_SIMPLE_VALUES, but arguments
+   s, t, and u are structures or references to structures, and their values
+   should not be printed by PRINT_SIMPLE_VALUES.  */
+
+struct s
+{
+  int v;
+};
+
+int
+f (int a, int &b, int &&c, struct s s, struct s &t, struct s &&u)
+{
+  return a + b + c + s.v + t.v + u.v;
+}
+
+int
+main (void)
+{
+  int a = 1, b = 2;
+  struct s s = { 4 }, t = { 5 };
+  return f (a, b, 3, s, t, (struct s) { 6 });
+}
diff --git a/gdb/testsuite/gdb.mi/print-simple-values.exp b/gdb/testsuite/gdb.mi/print-simple-values.exp
new file mode 100644
index 00000000000..021ceb31ace
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-simple-values.exp
@@ -0,0 +1,50 @@
+# Copyright 2022 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# PRINT_SIMPLE_VALUES test.
+#
+# Test that PRINT_SIMPLE_VALUES handles C++ reference types correctly.
+#
+# In the function f() in the test program, arguments a, b, and c are either ints
+# or references to int, and their values should be printed by
+# PRINT_SIMPLE_VALUES, but arguments s, t, and u are structures or references to
+# structures, and their values should not be printed by PRINT_SIMPLE_VALUES. */
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+standard_testfile .cc
+
+if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+mi_clean_restart $binfile
+
+mi_runto_main
+
+mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
+
+mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
+
+mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
+    "run until breakpoint on f"
+
+mi_gdb_test "-stack-list-arguments --simple-values" \
+    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"a\",type=\"int\",value=\"1\"\},\{name=\"b\",type=\"int &\",value=\"@0x\[0-9a-f\]+: 2\"\},\{name=\"c\",type=\"int &&\",value=\"@0x\[0-9a-f\]+: 3\"\},\{name=\"s\",type=\"s\"\},\{name=\"t\",type=\"s &\"\},\{name=\"u\",type=\"s &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
+    "stack list arguments, simple types: names, types and values, compound types: names and types"
+
+mi_gdb_exit
-- 
2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 10:27 ` Andrew Burgess
  2022-09-08 11:02   ` [PATCH v2] " Gareth Rees
@ 2022-09-08 11:09   ` Gareth Rees
  1 sibling, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-08 11:09 UTC (permalink / raw)
  To: Andrew Burgess; +Cc: gdb-patches

Andrew Burgess <aburgess@redhat.com> wrote:
> Thanks for this patch.  I have a few notes, in line below.

Thank you for the detailed review. I believe I've addressed all your
comments in version 2 of the patch but let me know if there's anything
else I need to do.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 11:02   ` [PATCH v2] " Gareth Rees
@ 2022-09-08 13:30     ` Eli Zaretskii
  2022-09-08 13:58       ` Gareth Rees
                         ` (2 more replies)
  0 siblings, 3 replies; 25+ messages in thread
From: Eli Zaretskii @ 2022-09-08 13:30 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> Date: Thu,  8 Sep 2022 12:02:48 +0100
> From: Gareth Rees via Gdb-patches <gdb-patches@sourceware.org>
> 
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug.
> 
> 1. If the current behaviour is a bug, then we can update the behaviour
>    of '--simple-values' so that it takes reference types into account:
>    that is, a value is simple if it is neither an array, struct, or
>    union, nor a reference to an array, struct or union.
> 
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
> 
> 2. If the current behaviour is not a bug, then we can add a new option
>    for the PRINT-VALUES argument, for example, '--simplest-values' (3),
>    that would be suitable for use by IDEs.
> 
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--simplest-values' argument is
>    available for use when refreshing the call stack.
> 
> PATCH
> 
> This patch implements solution (1) as I think the current behaviour of
> not printing structures, but printing references to structures, is
> contrary to reasonable expectation.

Thanks.  FWIW, I think we should implement 2, not 1.

> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,18 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>  
> +* MI changes
> +
> +  ** The '--simple-values' argument to the '-stack-list-arguments',
> +     '-stack-list-locals', '-stack-list-variables', and
> +     '-var-list-children' commands takes reference types into account:
> +     that is, a value is now considered simple if it is neither an
> +     array, structure, or union, nor a reference to an array, structure,
> +     or union.

Isn't it easier to say "only if the value is a scalar"?

> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..5ccf6609709 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -37295,6 +37295,13 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item simple-values-ref-types
> +Indicates that the @code{--simple-values} argument to the
> +@code{-stack-list-arguments}, @code{-stack-list-locals},
> +@code{-stack-list-variables}, and @code{-var-list-children} commands
> +takes reference types into account: that is, a value is considered
> +simple if it neither an array, structure, or union, nor a reference to
> +an array, structure, or union.
>  @end ftable

Same here.

Other than that, the documentation parts are OK.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 13:30     ` Eli Zaretskii
@ 2022-09-08 13:58       ` Gareth Rees
  2022-09-08 14:07         ` Eli Zaretskii
  2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
  2022-09-09  8:04       ` [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple" Gareth Rees
  2 siblings, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-09-08 13:58 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: gdb-patches

Eli Zaretskii <eliz@gnu.org> wrote:
> > +* MI changes
> > +
> > +  ** The '--simple-values' argument to the '-stack-list-arguments',
> > +     '-stack-list-locals', '-stack-list-variables', and
> > +     '-var-list-children' commands takes reference types into account:
> > +     that is, a value is now considered simple if it is neither an
> > +     array, structure, or union, nor a reference to an array, structure,
> > +     or union.
>
> Isn't it easier to say "only if the value is a scalar"?

I deliberately echoed the wording used in the documentation for
'-stack-list-arguments' and similar commands, which uses the formula
"if it is 2 or --simple-values, print the name, type and value for
simple data types, and the name and type for arrays, structures and
unions."

But you are right that this concept corresponds to the 'scalars'
arguments to 'set print frame-arguments'. But then should I update the
documentation for '-stack-list-arguments' to match?

> Thanks.  FWIW, I think we should implement 2, not 1.

I note that 'set print frame-arguments scalars' already takes
reference types into account: see the function
'val_print_scalar_type_p' in gdb/valprint.c, which is implemented like
this:

    int
    val_print_scalar_type_p (struct type *type)
    {
      type = check_typedef (type);
      while (TYPE_IS_REFERENCE (type))
        {
          type = TYPE_TARGET_TYPE (type);
          type = check_typedef (type);
        }
      switch (type->code ())
        {
        case TYPE_CODE_ARRAY:
        case TYPE_CODE_STRUCT:
        case TYPE_CODE_UNION:
        case TYPE_CODE_SET:
        case TYPE_CODE_STRING:
          return 0;
        default:
          return 1;
        }
    }

Updating '--simple-values' to call 'val_print_scalar_type_p' is
probably a step too far because of the exclusion of strings, so if we
want the 'scalars' behaviour then we need solution (2) in which we
would add a PRINT-VALUES option '--scalar-values' which behaves the
same way as 'set print frame-arguments scalars'.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 13:58       ` Gareth Rees
@ 2022-09-08 14:07         ` Eli Zaretskii
  0 siblings, 0 replies; 25+ messages in thread
From: Eli Zaretskii @ 2022-09-08 14:07 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> From: Gareth Rees <grees@undo.io>
> Date: Thu, 8 Sep 2022 14:58:22 +0100
> Cc: gdb-patches@sourceware.org
> 
> > Isn't it easier to say "only if the value is a scalar"?
> 
> I deliberately echoed the wording used in the documentation for
> '-stack-list-arguments' and similar commands, which uses the formula
> "if it is 2 or --simple-values, print the name, type and value for
> simple data types, and the name and type for arrays, structures and
> unions."
> 
> But you are right that this concept corresponds to the 'scalars'
> arguments to 'set print frame-arguments'. But then should I update the
> documentation for '-stack-list-arguments' to match?

It would be nice, yes.  But you don't have to, it could be left for a
separate changeset.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-08 13:30     ` Eli Zaretskii
  2022-09-08 13:58       ` Gareth Rees
@ 2022-09-09  8:01       ` Gareth Rees
  2022-09-15  9:06         ` [PING] " Gareth Rees
                           ` (2 more replies)
  2022-09-09  8:04       ` [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple" Gareth Rees
  2 siblings, 3 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-09  8:01 UTC (permalink / raw)
  To: gdb-patches

SUMMARY

The '--simple-values' argument to '-stack-list-arguments' and similar
GDB/MI commands does not take reference types into account, so that
references to arbitrarily large structures are considered "simple" and
printed. This means that the '--simple-values' argument cannot be used
by IDEs when tracing the stack due to the time taken to print large
structures passed by reference.

DETAILS

Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
'-stack-list-variables' and so on) take a PRINT-VALUES argument which
may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
In the '--simple-values' case, the command is supposed to print the
name, type, and value of variables with simple types, and print only the
name and type of variables with compound types.

The '--simple-values' argument ought to be suitable for IDEs that need
to update their user interface with the program's call stack every time
the program stops. However, it does not take C++ reference types into
account, and this makes the argument unsuitable for this purpose.

For example, consider the following C++ program:

    struct s {
        int v[10];
    };

    int
    sum(const struct s &s)
    {
        int total = 0;
        for (int i = 0; i < 10; ++i) total += s.v[i];
        return total;
    }

    int
    main(void)
    {
        struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
        return sum(s);
    }

If we start GDB in MI mode and continue to 'sum', the behaviour of
'-stack-list-arguments' is as follows:

    (gdb)
    -stack-list-arguments --simple-values
    ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]

Note that the value of the argument 's' was printed, even though 's' is
a reference to a structure, which is not a simple value.

See https://github.com/microsoft/MIEngine/pull/673 for a case where this
behaviour caused Microsoft to avoid the use of '--simple-values' in
their MIEngine debug adapter, because it caused Visual Studio Code to
take too long to refresh the call stack in the user interface.

SOLUTIONS

There are two ways we could fix this problem, depending on whether we
consider the current behaviour to be a bug that can be fixed.

1. If the current behaviour is a bug that can be fixed, then we can
   update the behaviour of '--simple-values' so that it takes
   reference types into account: that is, a value is simple if it is
   neither an array, struct, or union, nor a reference to an array,
   struct or union.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that it is safe to use the '--simple-values'
   argument when refreshing the call stack.

2. If the current behaviour is not a bug, or cannot be changed due to
   backwards compatibility concerns, then we can add a new option for
   the PRINT-VALUES argument, for example, '--scalar-values' (3), that
   would be suitable for use by IDEs.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that the '--scalar-values' argument is
   available for use when refreshing the call stack.

PATCH

This patch implements solution (2), adding a '--scalar-values' option
for the PRINT-VALUES argument to '-stack-list-arguments' and similar
commands. This option prints the value only for scalars and so matches
the behaviour of the 'scalars' argument to the 'set print
frame-arguments' command. References to structures are not scalars,
and so the option is suitable for use by IDEs.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
---
 gdb/NEWS                                     |  9 +++
 gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
 gdb/extension.h                              |  3 +
 gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
 gdb/mi/mi-cmd-var.c                          | 26 ++++++---
 gdb/mi/mi-cmds.h                             |  8 ++-
 gdb/mi/mi-main.c                             | 54 ++++++++++--------
 gdb/mi/mi-parse.c                            |  8 ++-
 gdb/python/py-framefilter.c                  | 23 ++++----
 gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
 gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
 gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
 12 files changed, 272 insertions(+), 79 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
 create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2ecd8..57061f19719 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -114,6 +114,15 @@ maintenance info line-table
   entry corresponds to an address where a breakpoint should be placed
   to be at the first instruction past a function's prologue.
 
+* MI changes
+
+  ** The '-stack-list-arguments', '-stack-list-locals',
+     '-stack-list-variables', and '-var-list-children' commands
+     support the '--scalar-values' option, which requests the command
+     to print values only for scalar types. Support for this feature
+     can be verified by using the '-list-features' command, which
+     should contain "scalar-values".
+
 * New targets
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 238a49b027d..b2b53de1022 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
 @var{high-frame} may be larger than the actual number of frames, in
 which case only existing frames will be returned.
 
-If @var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+If @var{print-values} is 0 or @code{--no-values}, print only the names
+of the variables; if it is 1 or @code{--all-values}, print also their
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  If the option @code{--no-frame-filters} is supplied, then
+Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, arguments that
 are not available are not listed.  Partially available arguments
@@ -33549,13 +33551,15 @@ Show a single frame:
 Display the local variable names for the selected frame.  If
 @var{print-values} is 0 or @code{--no-values}, print only the names of
 the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  In this last case, a frontend can immediately
-display the value of simple data types and create variable objects for
-other data types when the user wishes to explore their values in
-more detail.  If the option @code{--no-frame-filters} is supplied, then
-Python frame filters will not be executed.
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  In the last two cases, a frontend can immediately display
+the value of simple or scalar data types and create variable objects
+for other data types when the user wishes to explore their values in
+more detail.  If the option @code{--no-frame-filters} is supplied,
+then Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 that are not available are not listed.  Partially available local
@@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
  -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
 @end smallexample
 
-Display the names of local variables and function arguments for the selected frame.  If
-@var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+Display the names of local variables and function arguments for the
+selected frame.  If @var{print-values} is 0 or @code{--no-values},
+print only the names of the variables; if it is 1 or
+@code{--all-values}, print also their values; if it is 2 or
+@code{--simple-values}, print the name, type and value for simple data
+types, and the name and type for arrays, structures and unions; and if
+it is 3 or @code{--scalar-values}, print the name, type and value for
+scalar data types, and the name and type otherwise.  If the option
+@code{--no-frame-filters} is supplied, then Python frame filters will
+not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 and arguments that are not available are not listed.  Partially
@@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
 a single argument or if @var{print-values} has a value of 0 or
 @code{--no-values}, print only the names of the variables; if
 @var{print-values} is 1 or @code{--all-values}, also print their
-values; and if it is 2 or @code{--simple-values} print the name and
-value for simple data types and just the name for arrays, structures
-and unions.
+values; if it is 2 or @code{--simple-values} print the name and value
+for simple data types and just the name for arrays, structures and
+unions; and if it is 3 or @code{--scalar-values}, print the name and
+value for scalar data types, and just the name otherwise.
 
 @var{from} and @var{to}, if specified, indicate the range of children
 to report.  If @var{from} or @var{to} is less than zero, the range is
@@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
 @item data-disassemble-a-option
 Indicates that the @code{-data-disassemble} command supports the @option{-a}
 option (@pxref{GDB/MI Data Manipulation}).
+@item scalar-values
+Indicates that the @code{-stack-list-arguments},
+@code{-stack-list-locals}, @code{-stack-list-variables}, and
+@code{-var-list-children} commands support the
+@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
 @end ftable
 
 @subheading The @code{-list-target-features} Command
diff --git a/gdb/extension.h b/gdb/extension.h
index 47839ea50be..16d12f00f41 100644
--- a/gdb/extension.h
+++ b/gdb/extension.h
@@ -121,6 +121,9 @@ enum ext_lang_frame_args
        arguments when invoked from the MI. */
     MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
 
+    /* Print only scalar values for arguments when invoked from the MI.  */
+    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
+
     /* Print only scalar values for arguments when invoked from the CLI. */
     CLI_SCALAR_VALUES,
 
diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index 0fe204dbc66..d3ae350f166 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
 	       && arg->error == NULL)
 	      || values == PRINT_SIMPLE_VALUES
+	      || values == PRINT_SCALAR_VALUES
 	      || (values == PRINT_ALL_VALUES
 		  && (arg->val != NULL || arg->error != NULL)));
   gdb_assert (arg->entry_kind == print_entry_values_no
@@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   if (what == all && arg->sym->is_argument ())
     uiout->field_signed ("arg", 1);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     {
       check_typedef (arg->sym->type ());
       type_print (arg->sym->type (), "", &stb, -1);
@@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
     }
 }
 
+/* Print SYM according to VALUES?  */
+
+static bool
+print_symbol_p (struct symbol *sym, enum print_values values)
+{
+  switch (values)
+    {
+    default:
+    case PRINT_NO_VALUES:
+      return false;
+    case PRINT_ALL_VALUES:
+      return true;
+    case PRINT_SIMPLE_VALUES:
+      return mi_simple_values_type_p (sym->type ());
+    case PRINT_SCALAR_VALUES:
+      return val_print_scalar_type_p (sym->type ());
+    }
+}
+
 /* Print a list of the objects for the frame FI in a certain form,
    which is determined by VALUES.  The objects can be locals,
    arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
@@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
   const struct block *block;
   struct symbol *sym;
   struct block_iterator iter;
-  struct type *type;
   const char *name_of_result;
   struct ui_out *uiout = current_uiout;
 
@@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
 	      entryarg.sym = sym2;
 	      entryarg.entry_kind = print_entry_values_no;
 
-	      switch (values)
+	      if (print_symbol_p (sym, values))
 		{
-		case PRINT_SIMPLE_VALUES:
-		  type = check_typedef (sym2->type ());
-		  if (type->code () != TYPE_CODE_ARRAY
-		      && type->code () != TYPE_CODE_STRUCT
-		      && type->code () != TYPE_CODE_UNION)
-		    {
-		case PRINT_ALL_VALUES:
 		  if (sym->is_argument ())
 		    read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
 		  else
 		    read_frame_local (sym2, fi, &arg);
-		    }
-		  break;
 		}
 
 	      if (arg.entry_kind != print_entry_values_only)
diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
index 3db09cf7815..064d13a3729 100644
--- a/gdb/mi/mi-cmd-var.c
+++ b/gdb/mi/mi-cmd-var.c
@@ -32,6 +32,7 @@
 #include "mi-parse.h"
 #include "gdbsupport/gdb_optional.h"
 #include "inferior.h"
+#include "valprint.h"
 
 static void varobj_update_one (struct varobj *var,
 			       enum print_values print_values,
@@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
   type = varobj_get_gdb_type (var);
   if (type == NULL)
     return 1;
+  else if (print_values == PRINT_SCALAR_VALUES)
+    return val_print_scalar_type_p (type);
   else
-    {
-      type = check_typedef (type);
+    return mi_simple_values_type_p (type);
+}
+
+/* See mi-cmds.h.  */
 
-      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
-	 and that type is not a compound type.  */
-      return (type->code () != TYPE_CODE_ARRAY
-	      && type->code () != TYPE_CODE_STRUCT
-	      && type->code () != TYPE_CODE_UNION);
+bool
+mi_simple_values_type_p (struct type *type)
+{
+  type = check_typedef (type);
+  switch (type->code ())
+    {
+    case TYPE_CODE_ARRAY:
+    case TYPE_CODE_STRUCT:
+    case TYPE_CODE_UNION:
+      return false;
+    default:
+      return true;
     }
 }
 
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 9ffb11bf997..56c3ccb8b8a 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -29,7 +29,8 @@
 enum print_values {
    PRINT_NO_VALUES,
    PRINT_ALL_VALUES,
-   PRINT_SIMPLE_VALUES
+   PRINT_SIMPLE_VALUES,
+   PRINT_SCALAR_VALUES
 };
 
 typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
@@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
   = gdb::function_view<bool (mi_command *)>;
 extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
 
+/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
+   is, if type is not an array, structure or union.  */
+
+extern bool mi_simple_values_type_p (struct type *type);
+
 #endif /* MI_MI_CMDS_H */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b758f398e2a..2e70bcde2da 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
       uiout->field_string (NULL, "undefined-command-error-code");
       uiout->field_string (NULL, "exec-run-start-option");
       uiout->field_string (NULL, "data-disassemble-a-option");
+      uiout->field_string (NULL, "scalar-values");
 
       if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
 	uiout->field_string (NULL, "python");
@@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
   print_ada_task_info (current_uiout, argv[0], current_inferior ());
 }
 
+/* Print VAL according to VALUES?  */
+
+static bool
+print_value_p (struct value *val, enum print_values values)
+{
+  switch (values)
+    {
+    default:
+    case PRINT_NO_VALUES:
+      return false;
+    case PRINT_ALL_VALUES:
+      return true;
+    case PRINT_SIMPLE_VALUES:
+      return mi_simple_values_type_p (value_type (val));
+    case PRINT_SCALAR_VALUES:
+      return val_print_scalar_type_p (value_type (val));
+    }
+}
+
 /* Print EXPRESSION according to VALUES.  */
 
 static void
 print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct value *val;
-  struct type *type;
   struct ui_out *uiout = current_uiout;
 
   string_file stb;
 
   expression_up expr = parse_expression (expression);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     val = evaluate_type (expr.get ());
   else
     val = evaluate_expression (expr.get ());
@@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
   switch (values)
     {
     case PRINT_SIMPLE_VALUES:
-      type = check_typedef (value_type (val));
+    case PRINT_SCALAR_VALUES:
       type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
-      if (type->code () != TYPE_CODE_ARRAY
-	  && type->code () != TYPE_CODE_STRUCT
-	  && type->code () != TYPE_CODE_UNION)
-	{
-	  struct value_print_options opts;
-
-	  get_no_prettyformat_print_options (&opts);
-	  opts.deref_ref = 1;
-	  common_val_print (val, &stb, 0, &opts, current_language);
-	  uiout->field_stream ("value", stb);
-	}
       break;
-    case PRINT_ALL_VALUES:
-      {
-	struct value_print_options opts;
+    }
 
-	get_no_prettyformat_print_options (&opts);
-	opts.deref_ref = 1;
-	common_val_print (val, &stb, 0, &opts, current_language);
-	uiout->field_stream ("value", stb);
-      }
-      break;
+  if (print_value_p (val, values))
+    {
+      struct value_print_options opts;
+      get_no_prettyformat_print_options (&opts);
+      opts.deref_ref = 1;
+      common_val_print (val, &stb, 0, &opts, current_language);
+      uiout->field_stream ("value", stb);
     }
 }
 
diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
index dfa7b462714..dd70e4648a1 100644
--- a/gdb/mi/mi-parse.c
+++ b/gdb/mi/mi-parse.c
@@ -29,6 +29,7 @@
 #include "language.h"
 
 static const char mi_no_values[] = "--no-values";
+static const char mi_scalar_values[] = "--scalar-values";
 static const char mi_simple_values[] = "--simple-values";
 static const char mi_all_values[] = "--all-values";
 
@@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
    else if (strcmp (name, "2") == 0
 	    || strcmp (name, mi_simple_values) == 0)
      return PRINT_SIMPLE_VALUES;
+   else if (strcmp (name, "3") == 0
+	    || strcmp (name, mi_scalar_values) == 0)
+     return PRINT_SCALAR_VALUES;
    else
      error (_("Unknown value for PRINT_VALUES: must be: \
-0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
-	    mi_no_values, mi_all_values, mi_simple_values);
+0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
+	    mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
 }
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 366f3745b9d..a746f309187 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
   /* MI does not print certain values, differentiated by type,
      depending on what ARGS_TYPE indicates.  Test type against option.
      For CLI print all values.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES
+  if (args_type == MI_PRINT_SCALAR_VALUES
+      || args_type == MI_PRINT_SIMPLE_VALUES
       || args_type == MI_PRINT_ALL_VALUES)
     {
-      struct type *type = check_typedef (value_type (val));
-
       if (args_type == MI_PRINT_ALL_VALUES)
 	should_print = 1;
+      else if (args_type == MI_PRINT_SCALAR_VALUES
+	       && val_print_scalar_type_p (value_type (val)))
+	should_print = 1;
       else if (args_type == MI_PRINT_SIMPLE_VALUES
-	       && type->code () != TYPE_CODE_ARRAY
-	       && type->code () != TYPE_CODE_STRUCT
-	       && type->code () != TYPE_CODE_UNION)
+	       && mi_simple_values_type_p (value_type (val)))
 	should_print = 1;
     }
   else if (args_type != NO_VALUES)
@@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
   if (print_args_field)
     out->field_signed ("arg", 1);
 
-  /* For MI print the type, but only for simple values.  This seems
-     weird, but this is how MI choose to format the various output
+  /* For MI print the type, but only for scalar and simple values. This
+     seems weird, but this is how MI chooses to format the various output
      types.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
+  if ((args_type == MI_PRINT_SCALAR_VALUES
+       || args_type == MI_PRINT_SIMPLE_VALUES)
+      && val != NULL)
     py_print_type (out, val);
 
   if (val != NULL)
@@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
       out->field_string ("name", sym_name.get ());
       out->text (" = ");
 
-      if (args_type == MI_PRINT_SIMPLE_VALUES)
+      if (args_type == MI_PRINT_SCALAR_VALUES
+          || args_type == MI_PRINT_SIMPLE_VALUES)
 	py_print_type (out, val);
 
       /* CLI always prints values for locals.  MI uses the
diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
index d04c8153c65..8aa4e2234ff 100644
--- a/gdb/testsuite/gdb.mi/mi-stack.exp
+++ b/gdb/testsuite/gdb.mi/mi-stack.exp
@@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
     # -stack-list-arguments 1 1 1
     # -stack-list-arguments 1 1 3
     # -stack-list-arguments 
+    # -stack-list-arguments 1 1 300
+    # -stack-list-arguments 2 1 1
+    # -stack-list-arguments 3 1 1
 
     mi_gdb_test "231-stack-list-arguments 0" \
 	"231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
@@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
     mi_gdb_test "235-stack-list-arguments 1 1 300" \
 	"235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
 	"stack args listing 1 1 300"
+
+    mi_gdb_test "236-stack-list-arguments 2 1 1" \
+	"236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
+	"stack args listing --simple-values 1 1"
+
+    mi_gdb_test "237-stack-list-arguments 3 1 1" \
+	"237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
+	"stack args listing --scalar-values 1 1"
 }
 
 proc test_stack_info_depth {} {
@@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
     # -stack-list-locals 0 (--no-values)
     # -stack-list-locals 1 (--all-values)
     # -stack-list-locals 2 (--simple-values)
-    # -stack-list-arguments 
+    # -stack-list-locals 3 (--scalar-values)
 
     mi_gdb_test "232-stack-list-locals 0" \
 	"232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
@@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
 	"232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
 	"stack locals listing, simple types: names and values, complex type: names and types"
 
+    mi_gdb_test "233-stack-list-locals --scalar-values" \
+	"233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
+	"stack locals listing, scalar types: names and values, otherwise: names and types"
+
     mi_gdb_test "234-stack-list-locals" \
 	"234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
 	"stack locals listing wrong"
diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
new file mode 100644
index 00000000000..fd9daf1d962
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
@@ -0,0 +1,58 @@
+/* This test case is part of GDB, the GNU debugger.
+
+   Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* PRINT_SCALAR_VALUES test program.
+
+   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
+   types, including C++ reference and rvalue reference types.
+
+   In the function f(), arguments i, ir, and irr are ints or references
+   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
+   but the other arguments are non-scalar, and so their values should
+   not be printed by PRINT_SCALAR_VALUES.  */
+
+struct s
+{
+  int v;
+};
+
+union u
+{
+  int v;
+};
+
+int
+f (int i, int &ir, int &&irr,
+   int a[1], int (&ar)[1], int (&&arr)[1],
+   struct s s, struct s &sr, struct s &&srr,
+   union u u, union u &ur, union u &&urr)
+{
+  return (i + ir + irr
+          + a[0] + ar[0] + arr[0]
+          + s.v + sr.v + srr.v
+          + u.v + ur.v + urr.v);
+}
+
+int
+main (void)
+{
+  int i = 1, j = 2;
+  int a[1] = { 4 }, b[1] = { 5 };
+  struct s s = { 7 }, t = { 8 };
+  union u u = { 10 }, v = { 11 };
+  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
+}
diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
new file mode 100644
index 00000000000..3398218c063
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
@@ -0,0 +1,51 @@
+# Copyright 2022 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# PRINT_SCALAR_VALUES test.
+#
+# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
+# types, including C++ reference and rvalue reference types.
+#
+# In the function f(), arguments i, ir, and irr are ints or references
+# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
+# but the other arguments are non-scalar, and so their values should not
+# be printed by PRINT_SCALAR_VALUES.
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+standard_testfile .cc
+
+if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+mi_clean_restart $binfile
+
+mi_runto_main
+
+mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
+
+mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
+
+mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
+    "run until breakpoint on f"
+
+mi_gdb_test "-stack-list-arguments --scalar-values" \
+    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
+    "stack list arguments, scalar types: names, types and values, compound types: names and types"
+
+mi_gdb_exit
-- 
2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple".
  2022-09-08 13:30     ` Eli Zaretskii
  2022-09-08 13:58       ` Gareth Rees
  2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
@ 2022-09-09  8:04       ` Gareth Rees
  2 siblings, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-09  8:04 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: gdb-patches

Eli Zaretskii <eliz@gnu.org> wrote:
> > There are two ways we could fix this problem, depending on whether we
> > consider the current behaviour to be a bug.
> >
> > 1. If the current behaviour is a bug, then we can update the behaviour
> >    of '--simple-values' so that it takes reference types into account:
> >    that is, a value is simple if it is neither an array, struct, or
> >    union, nor a reference to an array, struct or union.
> >
> >    In this case we must add a feature to the '-list-features' command so
> >    that IDEs can detect that it is safe to use the '--simple-values'
> >    argument when refreshing the call stack.
> >
> > 2. If the current behaviour is not a bug, then we can add a new option
> >    for the PRINT-VALUES argument, for example, '--simplest-values' (3),
> >    that would be suitable for use by IDEs.
> >
> >    In this case we must add a feature to the '-list-features' command so
> >    that IDEs can detect that the '--simplest-values' argument is
> >    available for use when refreshing the call stack.
>
> Thanks.  FWIW, I think we should implement 2, not 1.

I have prepared a new patch that implements solution (2), adding a
'--scalar-values' option for the PRINT-VALUES argument to
'-stack-list-arguments' and similar commands. This option prints the
value only for scalars and so matches the behaviour of the 'scalars'
argument to the 'set print frame-arguments' command. References to
structures are not scalars, and so the option is suitable for use by
IDEs.

See my e-mail with subject: "[PATCH v3] [PR mi/29554] New PRINT-VALUES
option '--scalar-values'."

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
@ 2022-09-15  9:06         ` Gareth Rees
  2022-09-25  8:15         ` Gareth Rees
  2022-09-26 12:46         ` [PATCH v4] " Gareth Rees
  2 siblings, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-15  9:06 UTC (permalink / raw)
  To: gdb-patches

Reminder to review. This patch adds a new '--scalar-values' option to
'-stack-list-arguments' and similar MI commands, making these commands
suitable for use by IDEs that need to refresh their stack trace
display each time the program stops.

(Note that in v1 and v2 of the patch I implemented a different
solution, modifying the behaviour of the existing '--simple-values'
option instead of adding a new option, but Eli Zaretskii requested
that I implement the solution given in v3.)

On Fri, 9 Sept 2022 at 09:01, Gareth Rees <grees@undo.io> wrote:
>
> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                     |  9 +++
>  gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
>  gdb/extension.h                              |  3 +
>  gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
>  gdb/mi/mi-cmd-var.c                          | 26 ++++++---
>  gdb/mi/mi-cmds.h                             |  8 ++-
>  gdb/mi/mi-main.c                             | 54 ++++++++++--------
>  gdb/mi/mi-parse.c                            |  8 ++-
>  gdb/python/py-framefilter.c                  | 23 ++++----
>  gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
>  gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
>  12 files changed, 272 insertions(+), 79 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..57061f19719 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types. Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     should contain "scalar-values".
> +
>  * New targets
>
>  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>
> -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
>  @end smallexample
>
> -Display the names of local variables and function arguments for the selected frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
>
> +    /* Print only scalar values for arguments when invoked from the MI.  */
> +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI. */
>      CLI_SCALAR_VALUES,
>
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..d3ae350f166 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
>                && arg->error == NULL)
>               || values == PRINT_SIMPLE_VALUES
> +             || values == PRINT_SCALAR_VALUES
>               || (values == PRINT_ALL_VALUES
>                   && (arg->val != NULL || arg->error != NULL)));
>    gdb_assert (arg->entry_kind == print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    if (what == all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>      }
>  }
>
> +/* Print SYM according to VALUES?  */
> +
> +static bool
> +print_symbol_p (struct symbol *sym, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (sym->type ());
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (sym->type ());
> +    }
> +}
> +
>  /* Print a list of the objects for the frame FI in a certain form,
>     which is determined by VALUES.  The objects can be locals,
>     arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
> @@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>
> @@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
>               entryarg.sym = sym2;
>               entryarg.entry_kind = print_entry_values_no;
>
> -             switch (values)
> +             if (print_symbol_p (sym, values))
>                 {
> -               case PRINT_SIMPLE_VALUES:
> -                 type = check_typedef (sym2->type ());
> -                 if (type->code () != TYPE_CODE_ARRAY
> -                     && type->code () != TYPE_CODE_STRUCT
> -                     && type->code () != TYPE_CODE_UNION)
> -                   {
> -               case PRINT_ALL_VALUES:
>                   if (sym->is_argument ())
>                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>                   else
>                     read_frame_local (sym2, fi, &arg);
> -                   }
> -                 break;
>                 }
>
>               if (arg.entry_kind != print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..064d13a3729 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>
>  static void varobj_update_one (struct varobj *var,
>                                enum print_values print_values,
> @@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    type = varobj_get_gdb_type (var);
>    if (type == NULL)
>      return 1;
> +  else if (print_values == PRINT_SCALAR_VALUES)
> +    return val_print_scalar_type_p (type);
>    else
> -    {
> -      type = check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
> +
> +/* See mi-cmds.h.  */
>
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -        and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -             && type->code () != TYPE_CODE_STRUCT
> -             && type->code () != TYPE_CODE_UNION);
> +bool
> +mi_simple_values_type_p (struct type *type)
> +{
> +  type = check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
>      }
>  }
>
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..56c3ccb8b8a 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> @@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>
> +/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
> +   is, if type is not an array, structure or union.  */
> +
> +extern bool mi_simple_values_type_p (struct type *type);
> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..2e70bcde2da 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>         uiout->field_string (NULL, "python");
> @@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
>    print_ada_task_info (current_uiout, argv[0], current_inferior ());
>  }
>
> +/* Print VAL according to VALUES?  */
> +
> +static bool
> +print_value_p (struct value *val, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (value_type (val));
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (value_type (val));
> +    }
> +}
> +
>  /* Print EXPRESSION according to VALUES.  */
>
>  static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>
>    string_file stb;
>
>    expression_up expr = parse_expression (expression);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      val = evaluate_type (expr.get ());
>    else
>      val = evaluate_expression (expr.get ());
> @@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -         && type->code () != TYPE_CODE_STRUCT
> -         && type->code () != TYPE_CODE_UNION)
> -       {
> -         struct value_print_options opts;
> -
> -         get_no_prettyformat_print_options (&opts);
> -         opts.deref_ref = 1;
> -         common_val_print (val, &stb, 0, &opts, current_language);
> -         uiout->field_stream ("value", stb);
> -       }
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -       struct value_print_options opts;
> +    }
>
> -       get_no_prettyformat_print_options (&opts);
> -       opts.deref_ref = 1;
> -       common_val_print (val, &stb, 0, &opts, current_language);
> -       uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (print_value_p (val, values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref = 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>
>  static const char mi_no_values[] = "--no-values";
> +static const char mi_scalar_values[] = "--scalar-values";
>  static const char mi_simple_values[] = "--simple-values";
>  static const char mi_all_values[] = "--all-values";
>
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") == 0
>             || strcmp (name, mi_simple_values) == 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") == 0
> +           || strcmp (name, mi_scalar_values) == 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -           mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..a746f309187 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES
> +  if (args_type == MI_PRINT_SCALAR_VALUES
> +      || args_type == MI_PRINT_SIMPLE_VALUES
>        || args_type == MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
>        if (args_type == MI_PRINT_ALL_VALUES)
>         should_print = 1;
> +      else if (args_type == MI_PRINT_SCALAR_VALUES
> +              && val_print_scalar_type_p (value_type (val)))
> +       should_print = 1;
>        else if (args_type == MI_PRINT_SIMPLE_VALUES
> -              && type->code () != TYPE_CODE_ARRAY
> -              && type->code () != TYPE_CODE_STRUCT
> -              && type->code () != TYPE_CODE_UNION)
> +              && mi_simple_values_type_p (value_type (val)))
>         should_print = 1;
>      }
>    else if (args_type != NO_VALUES)
> @@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for scalar and simple values. This
> +     seems weird, but this is how MI chooses to format the various output
>       types.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> +  if ((args_type == MI_PRINT_SCALAR_VALUES
> +       || args_type == MI_PRINT_SIMPLE_VALUES)
> +      && val != NULL)
>      py_print_type (out, val);
>
>    if (val != NULL)
> @@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" = ");
>
> -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> +      if (args_type == MI_PRINT_SCALAR_VALUES
> +          || args_type == MI_PRINT_SIMPLE_VALUES)
>         py_print_type (out, val);
>
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> index d04c8153c65..8aa4e2234ff 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments 3 1 1
>
>      mi_gdb_test "231-stack-list-arguments 0" \
>         "231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> @@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>         "235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
>         "stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +       "236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments 3 1 1" \
> +       "237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --scalar-values 1 1"
>  }
>
>  proc test_stack_info_depth {} {
> @@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments
> +    # -stack-list-locals 3 (--scalar-values)
>
>      mi_gdb_test "232-stack-list-locals 0" \
>         "232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> @@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
>         "232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
>         "stack locals listing, simple types: names and values, complex type: names and types"
>
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +       "233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
> +       "stack locals listing, scalar types: names and values, otherwise: names and types"
> +
>      mi_gdb_test "234-stack-list-locals" \
>         "234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
>         "stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> new file mode 100644
> index 00000000000..fd9daf1d962
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> @@ -0,0 +1,58 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* PRINT_SCALAR_VALUES test program.
> +
> +   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +   types, including C++ reference and rvalue reference types.
> +
> +   In the function f(), arguments i, ir, and irr are ints or references
> +   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +   but the other arguments are non-scalar, and so their values should
> +   not be printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i = 1, j = 2;
> +  int a[1] = { 4 }, b[1] = { 5 };
> +  struct s s = { 7 }, t = { 8 };
> +  union u u = { 10 }, v = { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> new file mode 100644
> index 00000000000..3398218c063
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> @@ -0,0 +1,51 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# PRINT_SCALAR_VALUES test.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +#
> +# In the function f(), arguments i, ir, and irr are ints or references
> +# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +# but the other arguments are non-scalar, and so their values should not
> +# be printed by PRINT_SCALAR_VALUES.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> +
> +mi_gdb_exit
> --
> 2.26.0
>

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
  2022-09-15  9:06         ` [PING] " Gareth Rees
@ 2022-09-25  8:15         ` Gareth Rees
  2022-09-25  8:25           ` Eli Zaretskii
  2022-09-25 10:16           ` Eli Zaretskii
  2022-09-26 12:46         ` [PATCH v4] " Gareth Rees
  2 siblings, 2 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-25  8:15 UTC (permalink / raw)
  To: gdb-patches

Reminder to review.

On Fri, 9 Sept 2022 at 09:01, Gareth Rees <grees@undo.io> wrote:
>
> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                     |  9 +++
>  gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
>  gdb/extension.h                              |  3 +
>  gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
>  gdb/mi/mi-cmd-var.c                          | 26 ++++++---
>  gdb/mi/mi-cmds.h                             |  8 ++-
>  gdb/mi/mi-main.c                             | 54 ++++++++++--------
>  gdb/mi/mi-parse.c                            |  8 ++-
>  gdb/python/py-framefilter.c                  | 23 ++++----
>  gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
>  gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
>  12 files changed, 272 insertions(+), 79 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..57061f19719 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types. Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     should contain "scalar-values".
> +
>  * New targets
>
>  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>
> -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
>  @end smallexample
>
> -Display the names of local variables and function arguments for the selected frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
>
> +    /* Print only scalar values for arguments when invoked from the MI.  */
> +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI. */
>      CLI_SCALAR_VALUES,
>
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..d3ae350f166 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
>                && arg->error == NULL)
>               || values == PRINT_SIMPLE_VALUES
> +             || values == PRINT_SCALAR_VALUES
>               || (values == PRINT_ALL_VALUES
>                   && (arg->val != NULL || arg->error != NULL)));
>    gdb_assert (arg->entry_kind == print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    if (what == all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>      }
>  }
>
> +/* Print SYM according to VALUES?  */
> +
> +static bool
> +print_symbol_p (struct symbol *sym, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (sym->type ());
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (sym->type ());
> +    }
> +}
> +
>  /* Print a list of the objects for the frame FI in a certain form,
>     which is determined by VALUES.  The objects can be locals,
>     arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
> @@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>
> @@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
>               entryarg.sym = sym2;
>               entryarg.entry_kind = print_entry_values_no;
>
> -             switch (values)
> +             if (print_symbol_p (sym, values))
>                 {
> -               case PRINT_SIMPLE_VALUES:
> -                 type = check_typedef (sym2->type ());
> -                 if (type->code () != TYPE_CODE_ARRAY
> -                     && type->code () != TYPE_CODE_STRUCT
> -                     && type->code () != TYPE_CODE_UNION)
> -                   {
> -               case PRINT_ALL_VALUES:
>                   if (sym->is_argument ())
>                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>                   else
>                     read_frame_local (sym2, fi, &arg);
> -                   }
> -                 break;
>                 }
>
>               if (arg.entry_kind != print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..064d13a3729 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>
>  static void varobj_update_one (struct varobj *var,
>                                enum print_values print_values,
> @@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    type = varobj_get_gdb_type (var);
>    if (type == NULL)
>      return 1;
> +  else if (print_values == PRINT_SCALAR_VALUES)
> +    return val_print_scalar_type_p (type);
>    else
> -    {
> -      type = check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
> +
> +/* See mi-cmds.h.  */
>
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -        and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -             && type->code () != TYPE_CODE_STRUCT
> -             && type->code () != TYPE_CODE_UNION);
> +bool
> +mi_simple_values_type_p (struct type *type)
> +{
> +  type = check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
>      }
>  }
>
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..56c3ccb8b8a 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> @@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>
> +/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
> +   is, if type is not an array, structure or union.  */
> +
> +extern bool mi_simple_values_type_p (struct type *type);
> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..2e70bcde2da 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>         uiout->field_string (NULL, "python");
> @@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
>    print_ada_task_info (current_uiout, argv[0], current_inferior ());
>  }
>
> +/* Print VAL according to VALUES?  */
> +
> +static bool
> +print_value_p (struct value *val, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (value_type (val));
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (value_type (val));
> +    }
> +}
> +
>  /* Print EXPRESSION according to VALUES.  */
>
>  static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>
>    string_file stb;
>
>    expression_up expr = parse_expression (expression);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      val = evaluate_type (expr.get ());
>    else
>      val = evaluate_expression (expr.get ());
> @@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -         && type->code () != TYPE_CODE_STRUCT
> -         && type->code () != TYPE_CODE_UNION)
> -       {
> -         struct value_print_options opts;
> -
> -         get_no_prettyformat_print_options (&opts);
> -         opts.deref_ref = 1;
> -         common_val_print (val, &stb, 0, &opts, current_language);
> -         uiout->field_stream ("value", stb);
> -       }
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -       struct value_print_options opts;
> +    }
>
> -       get_no_prettyformat_print_options (&opts);
> -       opts.deref_ref = 1;
> -       common_val_print (val, &stb, 0, &opts, current_language);
> -       uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (print_value_p (val, values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref = 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>
>  static const char mi_no_values[] = "--no-values";
> +static const char mi_scalar_values[] = "--scalar-values";
>  static const char mi_simple_values[] = "--simple-values";
>  static const char mi_all_values[] = "--all-values";
>
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") == 0
>             || strcmp (name, mi_simple_values) == 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") == 0
> +           || strcmp (name, mi_scalar_values) == 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -           mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..a746f309187 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES
> +  if (args_type == MI_PRINT_SCALAR_VALUES
> +      || args_type == MI_PRINT_SIMPLE_VALUES
>        || args_type == MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
>        if (args_type == MI_PRINT_ALL_VALUES)
>         should_print = 1;
> +      else if (args_type == MI_PRINT_SCALAR_VALUES
> +              && val_print_scalar_type_p (value_type (val)))
> +       should_print = 1;
>        else if (args_type == MI_PRINT_SIMPLE_VALUES
> -              && type->code () != TYPE_CODE_ARRAY
> -              && type->code () != TYPE_CODE_STRUCT
> -              && type->code () != TYPE_CODE_UNION)
> +              && mi_simple_values_type_p (value_type (val)))
>         should_print = 1;
>      }
>    else if (args_type != NO_VALUES)
> @@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for scalar and simple values. This
> +     seems weird, but this is how MI chooses to format the various output
>       types.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> +  if ((args_type == MI_PRINT_SCALAR_VALUES
> +       || args_type == MI_PRINT_SIMPLE_VALUES)
> +      && val != NULL)
>      py_print_type (out, val);
>
>    if (val != NULL)
> @@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" = ");
>
> -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> +      if (args_type == MI_PRINT_SCALAR_VALUES
> +          || args_type == MI_PRINT_SIMPLE_VALUES)
>         py_print_type (out, val);
>
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> index d04c8153c65..8aa4e2234ff 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments 3 1 1
>
>      mi_gdb_test "231-stack-list-arguments 0" \
>         "231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> @@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>         "235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
>         "stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +       "236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments 3 1 1" \
> +       "237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --scalar-values 1 1"
>  }
>
>  proc test_stack_info_depth {} {
> @@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments
> +    # -stack-list-locals 3 (--scalar-values)
>
>      mi_gdb_test "232-stack-list-locals 0" \
>         "232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> @@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
>         "232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
>         "stack locals listing, simple types: names and values, complex type: names and types"
>
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +       "233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
> +       "stack locals listing, scalar types: names and values, otherwise: names and types"
> +
>      mi_gdb_test "234-stack-list-locals" \
>         "234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
>         "stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> new file mode 100644
> index 00000000000..fd9daf1d962
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> @@ -0,0 +1,58 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* PRINT_SCALAR_VALUES test program.
> +
> +   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +   types, including C++ reference and rvalue reference types.
> +
> +   In the function f(), arguments i, ir, and irr are ints or references
> +   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +   but the other arguments are non-scalar, and so their values should
> +   not be printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i = 1, j = 2;
> +  int a[1] = { 4 }, b[1] = { 5 };
> +  struct s s = { 7 }, t = { 8 };
> +  union u u = { 10 }, v = { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> new file mode 100644
> index 00000000000..3398218c063
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> @@ -0,0 +1,51 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# PRINT_SCALAR_VALUES test.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +#
> +# In the function f(), arguments i, ir, and irr are ints or references
> +# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +# but the other arguments are non-scalar, and so their values should not
> +# be printed by PRINT_SCALAR_VALUES.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> +
> +mi_gdb_exit
> --
> 2.26.0
>

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-25  8:15         ` Gareth Rees
@ 2022-09-25  8:25           ` Eli Zaretskii
  2022-09-25  9:00             ` Gareth Rees
  2022-09-25 10:16           ` Eli Zaretskii
  1 sibling, 1 reply; 25+ messages in thread
From: Eli Zaretskii @ 2022-09-25  8:25 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> Date: Sun, 25 Sep 2022 09:15:49 +0100
> From: Gareth Rees via Gdb-patches <gdb-patches@sourceware.org>
> 
> Reminder to review.

I already reviewed the documentation parts, didn't I?

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-25  8:25           ` Eli Zaretskii
@ 2022-09-25  9:00             ` Gareth Rees
  2022-09-25 10:16               ` Eli Zaretskii
  0 siblings, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-09-25  9:00 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: gdb-patches

Eli Zaretskii <eliz@gnu.org> wrote:
> I already reviewed the documentation parts, didn't I?

You reviewed version 2 of the patch on 2022-09-08 (thanks!) requesting
that I add a new PRINT-VALUES option instead of modifying the
behaviour of the '--simple-values' option.

Accordingly, I made version 3 of the patch, which leaves the
'--simple-values' option unchanged and adds a new '--scalar-values'
option. This version of the patch still needs review.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-25  8:15         ` Gareth Rees
  2022-09-25  8:25           ` Eli Zaretskii
@ 2022-09-25 10:16           ` Eli Zaretskii
  1 sibling, 0 replies; 25+ messages in thread
From: Eli Zaretskii @ 2022-09-25 10:16 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> Date: Sun, 25 Sep 2022 09:15:49 +0100
> From: Gareth Rees via Gdb-patches <gdb-patches@sourceware.org>
> 
> > --- a/gdb/NEWS
> > +++ b/gdb/NEWS
> > @@ -114,6 +114,15 @@ maintenance info line-table
> >    entry corresponds to an address where a breakpoint should be placed
> >    to be at the first instruction past a function's prologue.
> >
> > +* MI changes
> > +
> > +  ** The '-stack-list-arguments', '-stack-list-locals',
> > +     '-stack-list-variables', and '-var-list-children' commands
> > +     support the '--scalar-values' option, which requests the command
> > +     to print values only for scalar types. Support for this feature
                                               ^^
Two spaces between sentences.

Otherwise, the documentation parts are OK, thanks.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-25  9:00             ` Gareth Rees
@ 2022-09-25 10:16               ` Eli Zaretskii
  2022-09-26 12:48                 ` Gareth Rees
  0 siblings, 1 reply; 25+ messages in thread
From: Eli Zaretskii @ 2022-09-25 10:16 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> From: Gareth Rees <grees@undo.io>
> Date: Sun, 25 Sep 2022 10:00:35 +0100
> Cc: gdb-patches@sourceware.org
> 
> Eli Zaretskii <eliz@gnu.org> wrote:
> > I already reviewed the documentation parts, didn't I?
> 
> You reviewed version 2 of the patch on 2022-09-08 (thanks!) requesting
> that I add a new PRINT-VALUES option instead of modifying the
> behaviour of the '--simple-values' option.
> 
> Accordingly, I made version 3 of the patch, which leaves the
> '--simple-values' option unchanged and adds a new '--scalar-values'
> option. This version of the patch still needs review.

Sorry for missing the original post.  I've reviewed it now.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH v4] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
  2022-09-15  9:06         ` [PING] " Gareth Rees
  2022-09-25  8:15         ` Gareth Rees
@ 2022-09-26 12:46         ` Gareth Rees
  2022-10-04  9:08           ` [PING] " Gareth Rees
  2022-10-12 16:38           ` Andrew Burgess
  2 siblings, 2 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-26 12:46 UTC (permalink / raw)
  To: gdb-patches

SUMMARY

The '--simple-values' argument to '-stack-list-arguments' and similar
GDB/MI commands does not take reference types into account, so that
references to arbitrarily large structures are considered "simple" and
printed. This means that the '--simple-values' argument cannot be used
by IDEs when tracing the stack due to the time taken to print large
structures passed by reference.

DETAILS

Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
'-stack-list-variables' and so on) take a PRINT-VALUES argument which
may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
In the '--simple-values' case, the command is supposed to print the
name, type, and value of variables with simple types, and print only the
name and type of variables with compound types.

The '--simple-values' argument ought to be suitable for IDEs that need
to update their user interface with the program's call stack every time
the program stops. However, it does not take C++ reference types into
account, and this makes the argument unsuitable for this purpose.

For example, consider the following C++ program:

    struct s {
        int v[10];
    };

    int
    sum(const struct s &s)
    {
        int total = 0;
        for (int i = 0; i < 10; ++i) total += s.v[i];
        return total;
    }

    int
    main(void)
    {
        struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
        return sum(s);
    }

If we start GDB in MI mode and continue to 'sum', the behaviour of
'-stack-list-arguments' is as follows:

    (gdb)
    -stack-list-arguments --simple-values
    ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]

Note that the value of the argument 's' was printed, even though 's' is
a reference to a structure, which is not a simple value.

See https://github.com/microsoft/MIEngine/pull/673 for a case where this
behaviour caused Microsoft to avoid the use of '--simple-values' in
their MIEngine debug adapter, because it caused Visual Studio Code to
take too long to refresh the call stack in the user interface.

SOLUTIONS

There are two ways we could fix this problem, depending on whether we
consider the current behaviour to be a bug that can be fixed.

1. If the current behaviour is a bug that can be fixed, then we can
   update the behaviour of '--simple-values' so that it takes
   reference types into account: that is, a value is simple if it is
   neither an array, struct, or union, nor a reference to an array,
   struct or union.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that it is safe to use the '--simple-values'
   argument when refreshing the call stack.

2. If the current behaviour is not a bug, or cannot be changed due to
   backwards compatibility concerns, then we can add a new option for
   the PRINT-VALUES argument, for example, '--scalar-values' (3), that
   would be suitable for use by IDEs.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that the '--scalar-values' argument is
   available for use when refreshing the call stack.

PATCH

This patch implements solution (2), adding a '--scalar-values' option
for the PRINT-VALUES argument to '-stack-list-arguments' and similar
commands. This option prints the value only for scalars and so matches
the behaviour of the 'scalars' argument to the 'set print
frame-arguments' command. References to structures are not scalars,
and so the option is suitable for use by IDEs.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
---
 gdb/NEWS                                     |  9 +++
 gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
 gdb/extension.h                              |  3 +
 gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
 gdb/mi/mi-cmd-var.c                          | 26 ++++++---
 gdb/mi/mi-cmds.h                             |  8 ++-
 gdb/mi/mi-main.c                             | 54 ++++++++++--------
 gdb/mi/mi-parse.c                            |  8 ++-
 gdb/python/py-framefilter.c                  | 23 ++++----
 gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
 gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
 gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
 12 files changed, 272 insertions(+), 79 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
 create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2ecd8..62b15094dee 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -114,6 +114,15 @@ maintenance info line-table
   entry corresponds to an address where a breakpoint should be placed
   to be at the first instruction past a function's prologue.
 
+* MI changes
+
+  ** The '-stack-list-arguments', '-stack-list-locals',
+     '-stack-list-variables', and '-var-list-children' commands
+     support the '--scalar-values' option, which requests the command
+     to print values only for scalar types.  Support for this feature
+     can be verified by using the '-list-features' command, which
+     should contain "scalar-values".
+
 * New targets
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 238a49b027d..b2b53de1022 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
 @var{high-frame} may be larger than the actual number of frames, in
 which case only existing frames will be returned.
 
-If @var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+If @var{print-values} is 0 or @code{--no-values}, print only the names
+of the variables; if it is 1 or @code{--all-values}, print also their
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  If the option @code{--no-frame-filters} is supplied, then
+Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, arguments that
 are not available are not listed.  Partially available arguments
@@ -33549,13 +33551,15 @@ Show a single frame:
 Display the local variable names for the selected frame.  If
 @var{print-values} is 0 or @code{--no-values}, print only the names of
 the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  In this last case, a frontend can immediately
-display the value of simple data types and create variable objects for
-other data types when the user wishes to explore their values in
-more detail.  If the option @code{--no-frame-filters} is supplied, then
-Python frame filters will not be executed.
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  In the last two cases, a frontend can immediately display
+the value of simple or scalar data types and create variable objects
+for other data types when the user wishes to explore their values in
+more detail.  If the option @code{--no-frame-filters} is supplied,
+then Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 that are not available are not listed.  Partially available local
@@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
  -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
 @end smallexample
 
-Display the names of local variables and function arguments for the selected frame.  If
-@var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+Display the names of local variables and function arguments for the
+selected frame.  If @var{print-values} is 0 or @code{--no-values},
+print only the names of the variables; if it is 1 or
+@code{--all-values}, print also their values; if it is 2 or
+@code{--simple-values}, print the name, type and value for simple data
+types, and the name and type for arrays, structures and unions; and if
+it is 3 or @code{--scalar-values}, print the name, type and value for
+scalar data types, and the name and type otherwise.  If the option
+@code{--no-frame-filters} is supplied, then Python frame filters will
+not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 and arguments that are not available are not listed.  Partially
@@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
 a single argument or if @var{print-values} has a value of 0 or
 @code{--no-values}, print only the names of the variables; if
 @var{print-values} is 1 or @code{--all-values}, also print their
-values; and if it is 2 or @code{--simple-values} print the name and
-value for simple data types and just the name for arrays, structures
-and unions.
+values; if it is 2 or @code{--simple-values} print the name and value
+for simple data types and just the name for arrays, structures and
+unions; and if it is 3 or @code{--scalar-values}, print the name and
+value for scalar data types, and just the name otherwise.
 
 @var{from} and @var{to}, if specified, indicate the range of children
 to report.  If @var{from} or @var{to} is less than zero, the range is
@@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
 @item data-disassemble-a-option
 Indicates that the @code{-data-disassemble} command supports the @option{-a}
 option (@pxref{GDB/MI Data Manipulation}).
+@item scalar-values
+Indicates that the @code{-stack-list-arguments},
+@code{-stack-list-locals}, @code{-stack-list-variables}, and
+@code{-var-list-children} commands support the
+@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
 @end ftable
 
 @subheading The @code{-list-target-features} Command
diff --git a/gdb/extension.h b/gdb/extension.h
index 47839ea50be..16d12f00f41 100644
--- a/gdb/extension.h
+++ b/gdb/extension.h
@@ -121,6 +121,9 @@ enum ext_lang_frame_args
        arguments when invoked from the MI. */
     MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
 
+    /* Print only scalar values for arguments when invoked from the MI.  */
+    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
+
     /* Print only scalar values for arguments when invoked from the CLI. */
     CLI_SCALAR_VALUES,
 
diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index 0fe204dbc66..d3ae350f166 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
 	       && arg->error == NULL)
 	      || values == PRINT_SIMPLE_VALUES
+	      || values == PRINT_SCALAR_VALUES
 	      || (values == PRINT_ALL_VALUES
 		  && (arg->val != NULL || arg->error != NULL)));
   gdb_assert (arg->entry_kind == print_entry_values_no
@@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   if (what == all && arg->sym->is_argument ())
     uiout->field_signed ("arg", 1);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     {
       check_typedef (arg->sym->type ());
       type_print (arg->sym->type (), "", &stb, -1);
@@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
     }
 }
 
+/* Print SYM according to VALUES?  */
+
+static bool
+print_symbol_p (struct symbol *sym, enum print_values values)
+{
+  switch (values)
+    {
+    default:
+    case PRINT_NO_VALUES:
+      return false;
+    case PRINT_ALL_VALUES:
+      return true;
+    case PRINT_SIMPLE_VALUES:
+      return mi_simple_values_type_p (sym->type ());
+    case PRINT_SCALAR_VALUES:
+      return val_print_scalar_type_p (sym->type ());
+    }
+}
+
 /* Print a list of the objects for the frame FI in a certain form,
    which is determined by VALUES.  The objects can be locals,
    arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
@@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
   const struct block *block;
   struct symbol *sym;
   struct block_iterator iter;
-  struct type *type;
   const char *name_of_result;
   struct ui_out *uiout = current_uiout;
 
@@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
 	      entryarg.sym = sym2;
 	      entryarg.entry_kind = print_entry_values_no;
 
-	      switch (values)
+	      if (print_symbol_p (sym, values))
 		{
-		case PRINT_SIMPLE_VALUES:
-		  type = check_typedef (sym2->type ());
-		  if (type->code () != TYPE_CODE_ARRAY
-		      && type->code () != TYPE_CODE_STRUCT
-		      && type->code () != TYPE_CODE_UNION)
-		    {
-		case PRINT_ALL_VALUES:
 		  if (sym->is_argument ())
 		    read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
 		  else
 		    read_frame_local (sym2, fi, &arg);
-		    }
-		  break;
 		}
 
 	      if (arg.entry_kind != print_entry_values_only)
diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
index 3db09cf7815..064d13a3729 100644
--- a/gdb/mi/mi-cmd-var.c
+++ b/gdb/mi/mi-cmd-var.c
@@ -32,6 +32,7 @@
 #include "mi-parse.h"
 #include "gdbsupport/gdb_optional.h"
 #include "inferior.h"
+#include "valprint.h"
 
 static void varobj_update_one (struct varobj *var,
 			       enum print_values print_values,
@@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
   type = varobj_get_gdb_type (var);
   if (type == NULL)
     return 1;
+  else if (print_values == PRINT_SCALAR_VALUES)
+    return val_print_scalar_type_p (type);
   else
-    {
-      type = check_typedef (type);
+    return mi_simple_values_type_p (type);
+}
+
+/* See mi-cmds.h.  */
 
-      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
-	 and that type is not a compound type.  */
-      return (type->code () != TYPE_CODE_ARRAY
-	      && type->code () != TYPE_CODE_STRUCT
-	      && type->code () != TYPE_CODE_UNION);
+bool
+mi_simple_values_type_p (struct type *type)
+{
+  type = check_typedef (type);
+  switch (type->code ())
+    {
+    case TYPE_CODE_ARRAY:
+    case TYPE_CODE_STRUCT:
+    case TYPE_CODE_UNION:
+      return false;
+    default:
+      return true;
     }
 }
 
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 9ffb11bf997..56c3ccb8b8a 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -29,7 +29,8 @@
 enum print_values {
    PRINT_NO_VALUES,
    PRINT_ALL_VALUES,
-   PRINT_SIMPLE_VALUES
+   PRINT_SIMPLE_VALUES,
+   PRINT_SCALAR_VALUES
 };
 
 typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
@@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
   = gdb::function_view<bool (mi_command *)>;
 extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
 
+/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
+   is, if type is not an array, structure or union.  */
+
+extern bool mi_simple_values_type_p (struct type *type);
+
 #endif /* MI_MI_CMDS_H */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b758f398e2a..2e70bcde2da 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
       uiout->field_string (NULL, "undefined-command-error-code");
       uiout->field_string (NULL, "exec-run-start-option");
       uiout->field_string (NULL, "data-disassemble-a-option");
+      uiout->field_string (NULL, "scalar-values");
 
       if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
 	uiout->field_string (NULL, "python");
@@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
   print_ada_task_info (current_uiout, argv[0], current_inferior ());
 }
 
+/* Print VAL according to VALUES?  */
+
+static bool
+print_value_p (struct value *val, enum print_values values)
+{
+  switch (values)
+    {
+    default:
+    case PRINT_NO_VALUES:
+      return false;
+    case PRINT_ALL_VALUES:
+      return true;
+    case PRINT_SIMPLE_VALUES:
+      return mi_simple_values_type_p (value_type (val));
+    case PRINT_SCALAR_VALUES:
+      return val_print_scalar_type_p (value_type (val));
+    }
+}
+
 /* Print EXPRESSION according to VALUES.  */
 
 static void
 print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct value *val;
-  struct type *type;
   struct ui_out *uiout = current_uiout;
 
   string_file stb;
 
   expression_up expr = parse_expression (expression);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     val = evaluate_type (expr.get ());
   else
     val = evaluate_expression (expr.get ());
@@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
   switch (values)
     {
     case PRINT_SIMPLE_VALUES:
-      type = check_typedef (value_type (val));
+    case PRINT_SCALAR_VALUES:
       type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
-      if (type->code () != TYPE_CODE_ARRAY
-	  && type->code () != TYPE_CODE_STRUCT
-	  && type->code () != TYPE_CODE_UNION)
-	{
-	  struct value_print_options opts;
-
-	  get_no_prettyformat_print_options (&opts);
-	  opts.deref_ref = 1;
-	  common_val_print (val, &stb, 0, &opts, current_language);
-	  uiout->field_stream ("value", stb);
-	}
       break;
-    case PRINT_ALL_VALUES:
-      {
-	struct value_print_options opts;
+    }
 
-	get_no_prettyformat_print_options (&opts);
-	opts.deref_ref = 1;
-	common_val_print (val, &stb, 0, &opts, current_language);
-	uiout->field_stream ("value", stb);
-      }
-      break;
+  if (print_value_p (val, values))
+    {
+      struct value_print_options opts;
+      get_no_prettyformat_print_options (&opts);
+      opts.deref_ref = 1;
+      common_val_print (val, &stb, 0, &opts, current_language);
+      uiout->field_stream ("value", stb);
     }
 }
 
diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
index dfa7b462714..dd70e4648a1 100644
--- a/gdb/mi/mi-parse.c
+++ b/gdb/mi/mi-parse.c
@@ -29,6 +29,7 @@
 #include "language.h"
 
 static const char mi_no_values[] = "--no-values";
+static const char mi_scalar_values[] = "--scalar-values";
 static const char mi_simple_values[] = "--simple-values";
 static const char mi_all_values[] = "--all-values";
 
@@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
    else if (strcmp (name, "2") == 0
 	    || strcmp (name, mi_simple_values) == 0)
      return PRINT_SIMPLE_VALUES;
+   else if (strcmp (name, "3") == 0
+	    || strcmp (name, mi_scalar_values) == 0)
+     return PRINT_SCALAR_VALUES;
    else
      error (_("Unknown value for PRINT_VALUES: must be: \
-0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
-	    mi_no_values, mi_all_values, mi_simple_values);
+0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
+	    mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
 }
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 366f3745b9d..a746f309187 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
   /* MI does not print certain values, differentiated by type,
      depending on what ARGS_TYPE indicates.  Test type against option.
      For CLI print all values.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES
+  if (args_type == MI_PRINT_SCALAR_VALUES
+      || args_type == MI_PRINT_SIMPLE_VALUES
       || args_type == MI_PRINT_ALL_VALUES)
     {
-      struct type *type = check_typedef (value_type (val));
-
       if (args_type == MI_PRINT_ALL_VALUES)
 	should_print = 1;
+      else if (args_type == MI_PRINT_SCALAR_VALUES
+	       && val_print_scalar_type_p (value_type (val)))
+	should_print = 1;
       else if (args_type == MI_PRINT_SIMPLE_VALUES
-	       && type->code () != TYPE_CODE_ARRAY
-	       && type->code () != TYPE_CODE_STRUCT
-	       && type->code () != TYPE_CODE_UNION)
+	       && mi_simple_values_type_p (value_type (val)))
 	should_print = 1;
     }
   else if (args_type != NO_VALUES)
@@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
   if (print_args_field)
     out->field_signed ("arg", 1);
 
-  /* For MI print the type, but only for simple values.  This seems
-     weird, but this is how MI choose to format the various output
+  /* For MI print the type, but only for scalar and simple values. This
+     seems weird, but this is how MI chooses to format the various output
      types.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
+  if ((args_type == MI_PRINT_SCALAR_VALUES
+       || args_type == MI_PRINT_SIMPLE_VALUES)
+      && val != NULL)
     py_print_type (out, val);
 
   if (val != NULL)
@@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
       out->field_string ("name", sym_name.get ());
       out->text (" = ");
 
-      if (args_type == MI_PRINT_SIMPLE_VALUES)
+      if (args_type == MI_PRINT_SCALAR_VALUES
+          || args_type == MI_PRINT_SIMPLE_VALUES)
 	py_print_type (out, val);
 
       /* CLI always prints values for locals.  MI uses the
diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
index d04c8153c65..8aa4e2234ff 100644
--- a/gdb/testsuite/gdb.mi/mi-stack.exp
+++ b/gdb/testsuite/gdb.mi/mi-stack.exp
@@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
     # -stack-list-arguments 1 1 1
     # -stack-list-arguments 1 1 3
     # -stack-list-arguments 
+    # -stack-list-arguments 1 1 300
+    # -stack-list-arguments 2 1 1
+    # -stack-list-arguments 3 1 1
 
     mi_gdb_test "231-stack-list-arguments 0" \
 	"231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
@@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
     mi_gdb_test "235-stack-list-arguments 1 1 300" \
 	"235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
 	"stack args listing 1 1 300"
+
+    mi_gdb_test "236-stack-list-arguments 2 1 1" \
+	"236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
+	"stack args listing --simple-values 1 1"
+
+    mi_gdb_test "237-stack-list-arguments 3 1 1" \
+	"237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
+	"stack args listing --scalar-values 1 1"
 }
 
 proc test_stack_info_depth {} {
@@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
     # -stack-list-locals 0 (--no-values)
     # -stack-list-locals 1 (--all-values)
     # -stack-list-locals 2 (--simple-values)
-    # -stack-list-arguments 
+    # -stack-list-locals 3 (--scalar-values)
 
     mi_gdb_test "232-stack-list-locals 0" \
 	"232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
@@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
 	"232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
 	"stack locals listing, simple types: names and values, complex type: names and types"
 
+    mi_gdb_test "233-stack-list-locals --scalar-values" \
+	"233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
+	"stack locals listing, scalar types: names and values, otherwise: names and types"
+
     mi_gdb_test "234-stack-list-locals" \
 	"234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
 	"stack locals listing wrong"
diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
new file mode 100644
index 00000000000..fd9daf1d962
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
@@ -0,0 +1,58 @@
+/* This test case is part of GDB, the GNU debugger.
+
+   Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* PRINT_SCALAR_VALUES test program.
+
+   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
+   types, including C++ reference and rvalue reference types.
+
+   In the function f(), arguments i, ir, and irr are ints or references
+   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
+   but the other arguments are non-scalar, and so their values should
+   not be printed by PRINT_SCALAR_VALUES.  */
+
+struct s
+{
+  int v;
+};
+
+union u
+{
+  int v;
+};
+
+int
+f (int i, int &ir, int &&irr,
+   int a[1], int (&ar)[1], int (&&arr)[1],
+   struct s s, struct s &sr, struct s &&srr,
+   union u u, union u &ur, union u &&urr)
+{
+  return (i + ir + irr
+          + a[0] + ar[0] + arr[0]
+          + s.v + sr.v + srr.v
+          + u.v + ur.v + urr.v);
+}
+
+int
+main (void)
+{
+  int i = 1, j = 2;
+  int a[1] = { 4 }, b[1] = { 5 };
+  struct s s = { 7 }, t = { 8 };
+  union u u = { 10 }, v = { 11 };
+  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
+}
diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
new file mode 100644
index 00000000000..3398218c063
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
@@ -0,0 +1,51 @@
+# Copyright 2022 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# PRINT_SCALAR_VALUES test.
+#
+# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
+# types, including C++ reference and rvalue reference types.
+#
+# In the function f(), arguments i, ir, and irr are ints or references
+# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
+# but the other arguments are non-scalar, and so their values should not
+# be printed by PRINT_SCALAR_VALUES.
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+standard_testfile .cc
+
+if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+mi_clean_restart $binfile
+
+mi_runto_main
+
+mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
+
+mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
+
+mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
+    "run until breakpoint on f"
+
+mi_gdb_test "-stack-list-arguments --scalar-values" \
+    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
+    "stack list arguments, scalar types: names, types and values, compound types: names and types"
+
+mi_gdb_exit
-- 
2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-25 10:16               ` Eli Zaretskii
@ 2022-09-26 12:48                 ` Gareth Rees
  0 siblings, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-09-26 12:48 UTC (permalink / raw)
  To: Eli Zaretskii; +Cc: gdb-patches

Eli Zaretskii wrote:
> Sorry for missing the original post.  I've reviewed it now.

Thanks for the review. I addressed your comment and posted v4 of the patch.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PING] [PATCH v4] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-26 12:46         ` [PATCH v4] " Gareth Rees
@ 2022-10-04  9:08           ` Gareth Rees
  2022-10-18 11:59             ` Gareth Rees
  2022-10-12 16:38           ` Andrew Burgess
  1 sibling, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-10-04  9:08 UTC (permalink / raw)
  To: gdb-patches

Thanks to Andrew Burgess and Eli Zaretskii for reviewing. I've
addressed all the comments, so let me know how I can help progress
this patch.

On Mon, 26 Sept 2022 at 13:46, Gareth Rees <grees@undo.io> wrote:
>
> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                     |  9 +++
>  gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
>  gdb/extension.h                              |  3 +
>  gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
>  gdb/mi/mi-cmd-var.c                          | 26 ++++++---
>  gdb/mi/mi-cmds.h                             |  8 ++-
>  gdb/mi/mi-main.c                             | 54 ++++++++++--------
>  gdb/mi/mi-parse.c                            |  8 ++-
>  gdb/python/py-framefilter.c                  | 23 ++++----
>  gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
>  gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
>  12 files changed, 272 insertions(+), 79 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..62b15094dee 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types.  Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     should contain "scalar-values".
> +
>  * New targets
>
>  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>
> -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
>  @end smallexample
>
> -Display the names of local variables and function arguments for the selected frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
>
> +    /* Print only scalar values for arguments when invoked from the MI.  */
> +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI. */
>      CLI_SCALAR_VALUES,
>
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..d3ae350f166 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
>                && arg->error == NULL)
>               || values == PRINT_SIMPLE_VALUES
> +             || values == PRINT_SCALAR_VALUES
>               || (values == PRINT_ALL_VALUES
>                   && (arg->val != NULL || arg->error != NULL)));
>    gdb_assert (arg->entry_kind == print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    if (what == all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>      }
>  }
>
> +/* Print SYM according to VALUES?  */
> +
> +static bool
> +print_symbol_p (struct symbol *sym, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (sym->type ());
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (sym->type ());
> +    }
> +}
> +
>  /* Print a list of the objects for the frame FI in a certain form,
>     which is determined by VALUES.  The objects can be locals,
>     arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
> @@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>
> @@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
>               entryarg.sym = sym2;
>               entryarg.entry_kind = print_entry_values_no;
>
> -             switch (values)
> +             if (print_symbol_p (sym, values))
>                 {
> -               case PRINT_SIMPLE_VALUES:
> -                 type = check_typedef (sym2->type ());
> -                 if (type->code () != TYPE_CODE_ARRAY
> -                     && type->code () != TYPE_CODE_STRUCT
> -                     && type->code () != TYPE_CODE_UNION)
> -                   {
> -               case PRINT_ALL_VALUES:
>                   if (sym->is_argument ())
>                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>                   else
>                     read_frame_local (sym2, fi, &arg);
> -                   }
> -                 break;
>                 }
>
>               if (arg.entry_kind != print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..064d13a3729 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>
>  static void varobj_update_one (struct varobj *var,
>                                enum print_values print_values,
> @@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    type = varobj_get_gdb_type (var);
>    if (type == NULL)
>      return 1;
> +  else if (print_values == PRINT_SCALAR_VALUES)
> +    return val_print_scalar_type_p (type);
>    else
> -    {
> -      type = check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
> +
> +/* See mi-cmds.h.  */
>
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -        and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -             && type->code () != TYPE_CODE_STRUCT
> -             && type->code () != TYPE_CODE_UNION);
> +bool
> +mi_simple_values_type_p (struct type *type)
> +{
> +  type = check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
>      }
>  }
>
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..56c3ccb8b8a 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> @@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>
> +/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
> +   is, if type is not an array, structure or union.  */
> +
> +extern bool mi_simple_values_type_p (struct type *type);
> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..2e70bcde2da 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>         uiout->field_string (NULL, "python");
> @@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
>    print_ada_task_info (current_uiout, argv[0], current_inferior ());
>  }
>
> +/* Print VAL according to VALUES?  */
> +
> +static bool
> +print_value_p (struct value *val, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (value_type (val));
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (value_type (val));
> +    }
> +}
> +
>  /* Print EXPRESSION according to VALUES.  */
>
>  static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>
>    string_file stb;
>
>    expression_up expr = parse_expression (expression);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      val = evaluate_type (expr.get ());
>    else
>      val = evaluate_expression (expr.get ());
> @@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -         && type->code () != TYPE_CODE_STRUCT
> -         && type->code () != TYPE_CODE_UNION)
> -       {
> -         struct value_print_options opts;
> -
> -         get_no_prettyformat_print_options (&opts);
> -         opts.deref_ref = 1;
> -         common_val_print (val, &stb, 0, &opts, current_language);
> -         uiout->field_stream ("value", stb);
> -       }
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -       struct value_print_options opts;
> +    }
>
> -       get_no_prettyformat_print_options (&opts);
> -       opts.deref_ref = 1;
> -       common_val_print (val, &stb, 0, &opts, current_language);
> -       uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (print_value_p (val, values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref = 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>
>  static const char mi_no_values[] = "--no-values";
> +static const char mi_scalar_values[] = "--scalar-values";
>  static const char mi_simple_values[] = "--simple-values";
>  static const char mi_all_values[] = "--all-values";
>
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") == 0
>             || strcmp (name, mi_simple_values) == 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") == 0
> +           || strcmp (name, mi_scalar_values) == 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -           mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..a746f309187 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES
> +  if (args_type == MI_PRINT_SCALAR_VALUES
> +      || args_type == MI_PRINT_SIMPLE_VALUES
>        || args_type == MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
>        if (args_type == MI_PRINT_ALL_VALUES)
>         should_print = 1;
> +      else if (args_type == MI_PRINT_SCALAR_VALUES
> +              && val_print_scalar_type_p (value_type (val)))
> +       should_print = 1;
>        else if (args_type == MI_PRINT_SIMPLE_VALUES
> -              && type->code () != TYPE_CODE_ARRAY
> -              && type->code () != TYPE_CODE_STRUCT
> -              && type->code () != TYPE_CODE_UNION)
> +              && mi_simple_values_type_p (value_type (val)))
>         should_print = 1;
>      }
>    else if (args_type != NO_VALUES)
> @@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for scalar and simple values. This
> +     seems weird, but this is how MI chooses to format the various output
>       types.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> +  if ((args_type == MI_PRINT_SCALAR_VALUES
> +       || args_type == MI_PRINT_SIMPLE_VALUES)
> +      && val != NULL)
>      py_print_type (out, val);
>
>    if (val != NULL)
> @@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" = ");
>
> -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> +      if (args_type == MI_PRINT_SCALAR_VALUES
> +          || args_type == MI_PRINT_SIMPLE_VALUES)
>         py_print_type (out, val);
>
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> index d04c8153c65..8aa4e2234ff 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments 3 1 1
>
>      mi_gdb_test "231-stack-list-arguments 0" \
>         "231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> @@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>         "235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
>         "stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +       "236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments 3 1 1" \
> +       "237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --scalar-values 1 1"
>  }
>
>  proc test_stack_info_depth {} {
> @@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments
> +    # -stack-list-locals 3 (--scalar-values)
>
>      mi_gdb_test "232-stack-list-locals 0" \
>         "232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> @@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
>         "232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
>         "stack locals listing, simple types: names and values, complex type: names and types"
>
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +       "233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
> +       "stack locals listing, scalar types: names and values, otherwise: names and types"
> +
>      mi_gdb_test "234-stack-list-locals" \
>         "234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
>         "stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> new file mode 100644
> index 00000000000..fd9daf1d962
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> @@ -0,0 +1,58 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* PRINT_SCALAR_VALUES test program.
> +
> +   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +   types, including C++ reference and rvalue reference types.
> +
> +   In the function f(), arguments i, ir, and irr are ints or references
> +   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +   but the other arguments are non-scalar, and so their values should
> +   not be printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i = 1, j = 2;
> +  int a[1] = { 4 }, b[1] = { 5 };
> +  struct s s = { 7 }, t = { 8 };
> +  union u u = { 10 }, v = { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> new file mode 100644
> index 00000000000..3398218c063
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> @@ -0,0 +1,51 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# PRINT_SCALAR_VALUES test.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +#
> +# In the function f(), arguments i, ir, and irr are ints or references
> +# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +# but the other arguments are non-scalar, and so their values should not
> +# be printed by PRINT_SCALAR_VALUES.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> +
> +mi_gdb_exit
> --
> 2.26.0
>

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v4] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-09-26 12:46         ` [PATCH v4] " Gareth Rees
  2022-10-04  9:08           ` [PING] " Gareth Rees
@ 2022-10-12 16:38           ` Andrew Burgess
  2022-10-20 17:47             ` [PATCH v5] " Gareth Rees
  2022-10-20 17:58             ` [PATCH v4] " Gareth Rees
  1 sibling, 2 replies; 25+ messages in thread
From: Andrew Burgess @ 2022-10-12 16:38 UTC (permalink / raw)
  To: Gareth Rees, gdb-patches

Gareth Rees via Gdb-patches <gdb-patches@sourceware.org> writes:

> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                     |  9 +++
>  gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
>  gdb/extension.h                              |  3 +
>  gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
>  gdb/mi/mi-cmd-var.c                          | 26 ++++++---
>  gdb/mi/mi-cmds.h                             |  8 ++-
>  gdb/mi/mi-main.c                             | 54 ++++++++++--------
>  gdb/mi/mi-parse.c                            |  8 ++-
>  gdb/python/py-framefilter.c                  | 23 ++++----
>  gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
>  gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
>  12 files changed, 272 insertions(+), 79 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..62b15094dee 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>  
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types.  Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     should contain "scalar-values".

I think:

  can be verified by using the '-list-features' command, which
  now includes "scalar-values".

Using "should" seems to indicate some doubt as to whether the value is
there or not.

I prefer "includes" to "contains", for former is, I think, clearer that
"scalar-values" is just one of many values.

> +
>  * New targets
>  
>  GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>  
> -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>  
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>  
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
>  @end smallexample
>  
> -Display the names of local variables and function arguments for the selected frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>  
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>  
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>  
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
>  
> +    /* Print only scalar values for arguments when invoked from the MI.  */
> +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI. */
>      CLI_SCALAR_VALUES,
>  
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..d3ae350f166 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
>  	       && arg->error == NULL)
>  	      || values == PRINT_SIMPLE_VALUES
> +	      || values == PRINT_SCALAR_VALUES
>  	      || (values == PRINT_ALL_VALUES
>  		  && (arg->val != NULL || arg->error != NULL)));
>    gdb_assert (arg->entry_kind == print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    if (what == all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>  
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>      }
>  }
>  
> +/* Print SYM according to VALUES?  */
> +
> +static bool
> +print_symbol_p (struct symbol *sym, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (sym->type ());
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (sym->type ());
> +    }
> +}
> +
>  /* Print a list of the objects for the frame FI in a certain form,
>     which is determined by VALUES.  The objects can be locals,
>     arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
> @@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>  
> @@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
>  	      entryarg.sym = sym2;
>  	      entryarg.entry_kind = print_entry_values_no;
>  
> -	      switch (values)
> +	      if (print_symbol_p (sym, values))
>  		{
> -		case PRINT_SIMPLE_VALUES:
> -		  type = check_typedef (sym2->type ());
> -		  if (type->code () != TYPE_CODE_ARRAY
> -		      && type->code () != TYPE_CODE_STRUCT
> -		      && type->code () != TYPE_CODE_UNION)
> -		    {
> -		case PRINT_ALL_VALUES:
>  		  if (sym->is_argument ())
>  		    read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>  		  else
>  		    read_frame_local (sym2, fi, &arg);
> -		    }
> -		  break;
>  		}
>  
>  	      if (arg.entry_kind != print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..064d13a3729 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>  
>  static void varobj_update_one (struct varobj *var,
>  			       enum print_values print_values,
> @@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    type = varobj_get_gdb_type (var);
>    if (type == NULL)
>      return 1;
> +  else if (print_values == PRINT_SCALAR_VALUES)
> +    return val_print_scalar_type_p (type);
>    else
> -    {
> -      type = check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
> +
> +/* See mi-cmds.h.  */
>  
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -	 and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -	      && type->code () != TYPE_CODE_STRUCT
> -	      && type->code () != TYPE_CODE_UNION);
> +bool
> +mi_simple_values_type_p (struct type *type)
> +{
> +  type = check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
>      }
>  }
>  
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..56c3ccb8b8a 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>  
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> @@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>  
> +/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES: that
> +   is, if type is not an array, structure or union.  */
> +
> +extern bool mi_simple_values_type_p (struct type *type);

I think this should be renamed to just 'mi_simple_type_p', I don't think
the values part is useful.

Instances of 'type' in the comment should be upper case.

I also think it is worth drawing attention to the issues that triggered
this patch in the first place, that is, I think you should include some
text that says that references are always considered simple, even if the
type they refer to is not simple, and that this behaviour needs to be
maintained for backward compatibility.

This will prevent someone helpfully "fixing" the simple type mechanism
in the future.

> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..2e70bcde2da 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>  
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>  	uiout->field_string (NULL, "python");
> @@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char **argv, int argc)
>    print_ada_task_info (current_uiout, argv[0], current_inferior ());
>  }
>  
> +/* Print VAL according to VALUES?  */
> +
> +static bool
> +print_value_p (struct value *val, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (value_type (val));
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (value_type (val));
> +    }
> +}

I think you should probably fold together this print_value_p and
print_symbol_p in mi-cmd-stack.c.  Maybe create an mi_print_type_p
somewhere, which can contain the core switch table?

> +
>  /* Print EXPRESSION according to VALUES.  */
>  
>  static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>  
>    string_file stb;
>  
>    expression_up expr = parse_expression (expression);
>  
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      val = evaluate_type (expr.get ());
>    else
>      val = evaluate_expression (expr.get ());
> @@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -	  && type->code () != TYPE_CODE_STRUCT
> -	  && type->code () != TYPE_CODE_UNION)
> -	{
> -	  struct value_print_options opts;
> -
> -	  get_no_prettyformat_print_options (&opts);
> -	  opts.deref_ref = 1;
> -	  common_val_print (val, &stb, 0, &opts, current_language);
> -	  uiout->field_stream ("value", stb);
> -	}
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -	struct value_print_options opts;
> +    }
>  
> -	get_no_prettyformat_print_options (&opts);
> -	opts.deref_ref = 1;
> -	common_val_print (val, &stb, 0, &opts, current_language);
> -	uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (print_value_p (val, values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref = 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>  
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>  
>  static const char mi_no_values[] = "--no-values";
> +static const char mi_scalar_values[] = "--scalar-values";
>  static const char mi_simple_values[] = "--simple-values";
>  static const char mi_all_values[] = "--all-values";
>  
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") == 0
>  	    || strcmp (name, mi_simple_values) == 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") == 0
> +	    || strcmp (name, mi_scalar_values) == 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -	    mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +	    mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..a746f309187 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *val,
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES
> +  if (args_type == MI_PRINT_SCALAR_VALUES
> +      || args_type == MI_PRINT_SIMPLE_VALUES
>        || args_type == MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
>        if (args_type == MI_PRINT_ALL_VALUES)
>  	should_print = 1;
> +      else if (args_type == MI_PRINT_SCALAR_VALUES
> +	       && val_print_scalar_type_p (value_type (val)))
> +	should_print = 1;
>        else if (args_type == MI_PRINT_SIMPLE_VALUES
> -	       && type->code () != TYPE_CODE_ARRAY
> -	       && type->code () != TYPE_CODE_STRUCT
> -	       && type->code () != TYPE_CODE_UNION)
> +	       && mi_simple_values_type_p (value_type (val)))
>  	should_print = 1;
>      }
>    else if (args_type != NO_VALUES)
> @@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>  
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for scalar and simple values. This
> +     seems weird, but this is how MI chooses to format the various output
>       types.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> +  if ((args_type == MI_PRINT_SCALAR_VALUES
> +       || args_type == MI_PRINT_SIMPLE_VALUES)
> +      && val != NULL)
>      py_print_type (out, val);
>  
>    if (val != NULL)
> @@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" = ");
>  
> -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> +      if (args_type == MI_PRINT_SCALAR_VALUES
> +          || args_type == MI_PRINT_SIMPLE_VALUES)
>  	py_print_type (out, val);
>  
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> index d04c8153c65..8aa4e2234ff 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments 
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments 3 1 1
>  
>      mi_gdb_test "231-stack-list-arguments 0" \
>  	"231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> @@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>  	"235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
>  	"stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +	"236\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +	"stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments 3 1 1" \
> +	"237\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\}\\\]" \
> +	"stack args listing --scalar-values 1 1"

I think these tests should be repeated using the string version of the
control parameter, i.e. --simple-values and --scalar-values.

>  }
>  
>  proc test_stack_info_depth {} {
> @@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments 
> +    # -stack-list-locals 3 (--scalar-values)
>  
>      mi_gdb_test "232-stack-list-locals 0" \
>  	"232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> @@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
>  	"232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
>  	"stack locals listing, simple types: names and values, complex type: names and types"
>  
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +	"233\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
> +	"stack locals listing, scalar types: names and values, otherwise: names and types"
> +

And this test should be repeated using the numerical version of the
control parameter, i.e. 3.

>      mi_gdb_test "234-stack-list-locals" \
>  	"234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
>  	"stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> new file mode 100644
> index 00000000000..fd9daf1d962
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> @@ -0,0 +1,58 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* PRINT_SCALAR_VALUES test program.
> +
> +   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +   types, including C++ reference and rvalue reference types.
> +
> +   In the function f(), arguments i, ir, and irr are ints or references
> +   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +   but the other arguments are non-scalar, and so their values should
> +   not be printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i = 1, j = 2;
> +  int a[1] = { 4 }, b[1] = { 5 };
> +  struct s s = { 7 }, t = { 8 };
> +  union u u = { 10 }, v = { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> new file mode 100644
> index 00000000000..3398218c063
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> @@ -0,0 +1,51 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# PRINT_SCALAR_VALUES test.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +#
> +# In the function f(), arguments i, ir, and irr are ints or references
> +# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +# but the other arguments are non-scalar, and so their values should not
> +# be printed by PRINT_SCALAR_VALUES.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\{name=\"i\",type=\"int\",value=\"1\"\},\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\},\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\},\{name=\"a\",type=\"int \\*\",value=\"$hex\"\},\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\},\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\},\{name=\"s\",type=\"s\"\},\{name=\"sr\",type=\"s &\"\},\{name=\"srr\",type=\"s &&\"\},\{name=\"u\",type=\"u\"\},\{name=\"ur\",type=\"u &\"\},\{name=\"urr\",type=\"u &&\"\}\\\]\},frame=\{level=\"1\",args=\\\[\\\]\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> +

I think this test should be repeated using '3' as the control variable.

More importantly, I think this would be the perfect place to test
--simple-values too.

I'm pretty sure we don't have an existing test that checks that
--simple-values _does_ print the target of a reference, if we had ever
tried to write such a test then I think --simple-values would have been
"fixed" long ago.

So, given we have decided to preserve its current behaviour, which is
fine, we should be adding tests for that behaviour, and here seems like
the perfect place.  I think it's probably only a couple of extra
mi_gdb_test calls.

Other than the above minor issues, I think the patch is looking pretty
good.  Thanks for all your work so far.

Thanks,
Andrew



> +mi_gdb_exit
> -- 
> 2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PING] [PATCH v4] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-10-04  9:08           ` [PING] " Gareth Rees
@ 2022-10-18 11:59             ` Gareth Rees
  0 siblings, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-10-18 11:59 UTC (permalink / raw)
  To: gdb-patches

Thanks to Andrew Burgess and Eli Zaretskii for reviewing. I've
addressed all the comments, so let me know how I can help progress
this patch.

On Mon, 26 Sept 2022 at 13:46, Gareth Rees <grees@undo.io> wrote:
>
> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total =3D 0;
>         for (int i =3D 0; i < 10; ++i) total +=3D s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s =3D { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=3D[frame=3D{level=3D"0",args=3D[{name=3D"s",type=3D"=
const s &",value=3D"@0x7fffffffe310: {v =3D {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}=
}"}]},frame=3D{level=3D"1",args=3D[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=3D29554
> ---
>  gdb/NEWS                                     |  9 +++
>  gdb/doc/gdb.texinfo                          | 59 ++++++++++++--------
>  gdb/extension.h                              |  3 +
>  gdb/mi/mi-cmd-stack.c                        | 35 ++++++++----
>  gdb/mi/mi-cmd-var.c                          | 26 ++++++---
>  gdb/mi/mi-cmds.h                             |  8 ++-
>  gdb/mi/mi-main.c                             | 54 ++++++++++--------
>  gdb/mi/mi-parse.c                            |  8 ++-
>  gdb/python/py-framefilter.c                  | 23 ++++----
>  gdb/testsuite/gdb.mi/mi-stack.exp            | 17 +++++-
>  gdb/testsuite/gdb.mi/print-scalar-values.cc  | 58 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-scalar-values.exp | 51 +++++++++++++++++
>  12 files changed, 272 insertions(+), 79 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-scalar-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..62b15094dee 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types.  Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     should contain "scalar-values".
> +
>  * New targets
>
>  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On th=
e other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>
> -If @var{print-values} is 0 or @code{--no-values}, print only the names o=
f
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @va=
r{print-values}
>  @end smallexample
>
> -Display the names of local variables and function arguments for the sele=
cted frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not=
 already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option=
{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES =3D PRINT_SIMPLE_VALUES,
>
> +    /* Print only scalar values for arguments when invoked from the MI. =
 */
> +    MI_PRINT_SCALAR_VALUES =3D PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI.=
 */
>      CLI_SCALAR_VALUES,
>
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..d3ae350f166 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum =
what_to_list what,
>    gdb_assert ((values =3D=3D PRINT_NO_VALUES && arg->val =3D=3D NULL
>                && arg->error =3D=3D NULL)
>               || values =3D=3D PRINT_SIMPLE_VALUES
> +             || values =3D=3D PRINT_SCALAR_VALUES
>               || (values =3D=3D PRINT_ALL_VALUES
>                   && (arg->val !=3D NULL || arg->error !=3D NULL)));
>    gdb_assert (arg->entry_kind =3D=3D print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum =
what_to_list what,
>    if (what =3D=3D all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>
> -  if (values =3D=3D PRINT_SIMPLE_VALUES)
> +  if (values =3D=3D PRINT_SIMPLE_VALUES
> +      || values =3D=3D PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -557,6 +559,25 @@ list_arg_or_local (const struct frame_arg *arg, enum=
 what_to_list what,
>      }
>  }
>
> +/* Print SYM according to VALUES?  */
> +
> +static bool
> +print_symbol_p (struct symbol *sym, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (sym->type ());
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (sym->type ());
> +    }
> +}
> +
>  /* Print a list of the objects for the frame FI in a certain form,
>     which is determined by VALUES.  The objects can be locals,
>     arguments or both, which is determined by WHAT.  If SKIP_UNAVAILABLE
> @@ -571,7 +592,6 @@ list_args_or_locals (const frame_print_options &fp_op=
ts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout =3D current_uiout;
>
> @@ -647,21 +667,12 @@ list_args_or_locals (const frame_print_options &fp_=
opts,
>               entryarg.sym =3D sym2;
>               entryarg.entry_kind =3D print_entry_values_no;
>
> -             switch (values)
> +             if (print_symbol_p (sym, values))
>                 {
> -               case PRINT_SIMPLE_VALUES:
> -                 type =3D check_typedef (sym2->type ());
> -                 if (type->code () !=3D TYPE_CODE_ARRAY
> -                     && type->code () !=3D TYPE_CODE_STRUCT
> -                     && type->code () !=3D TYPE_CODE_UNION)
> -                   {
> -               case PRINT_ALL_VALUES:
>                   if (sym->is_argument ())
>                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>                   else
>                     read_frame_local (sym2, fi, &arg);
> -                   }
> -                 break;
>                 }
>
>               if (arg.entry_kind !=3D print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..064d13a3729 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>
>  static void varobj_update_one (struct varobj *var,
>                                enum print_values print_values,
> @@ -334,15 +335,26 @@ mi_print_value_p (struct varobj *var, enum print_va=
lues print_values)
>    type =3D varobj_get_gdb_type (var);
>    if (type =3D=3D NULL)
>      return 1;
> +  else if (print_values =3D=3D PRINT_SCALAR_VALUES)
> +    return val_print_scalar_type_p (type);
>    else
> -    {
> -      type =3D check_typedef (type);
> +    return mi_simple_values_type_p (type);
> +}
> +
> +/* See mi-cmds.h.  */
>
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -        and that type is not a compound type.  */
> -      return (type->code () !=3D TYPE_CODE_ARRAY
> -             && type->code () !=3D TYPE_CODE_STRUCT
> -             && type->code () !=3D TYPE_CODE_UNION);
> +bool
> +mi_simple_values_type_p (struct type *type)
> +{
> +  type =3D check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
>      }
>  }
>
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..56c3ccb8b8a 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int =
argc);
> @@ -226,4 +227,9 @@ using remove_mi_cmd_entries_ftype
>    =3D gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback)=
;
>
> +/* Return true if type is suitable for printing with PRINT_SIMPLE_VALUES=
: that
> +   is, if type is not an array, structure or union.  */
> +
> +extern bool mi_simple_values_type_p (struct type *type);
> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..2e70bcde2da 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **a=
rgv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>         uiout->field_string (NULL, "python");
> @@ -2456,20 +2457,39 @@ mi_cmd_ada_task_info (const char *command, char *=
*argv, int argc)
>    print_ada_task_info (current_uiout, argv[0], current_inferior ());
>  }
>
> +/* Print VAL according to VALUES?  */
> +
> +static bool
> +print_value_p (struct value *val, enum print_values values)
> +{
> +  switch (values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_values_type_p (value_type (val));
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (value_type (val));
> +    }
> +}
> +
>  /* Print EXPRESSION according to VALUES.  */
>
>  static void
>  print_variable_or_computed (const char *expression, enum print_values va=
lues)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout =3D current_uiout;
>
>    string_file stb;
>
>    expression_up expr =3D parse_expression (expression);
>
> -  if (values =3D=3D PRINT_SIMPLE_VALUES)
> +  if (values =3D=3D PRINT_SIMPLE_VALUES
> +      || values =3D=3D PRINT_SCALAR_VALUES)
>      val =3D evaluate_type (expr.get ());
>    else
>      val =3D evaluate_expression (expr.get ());
> @@ -2482,31 +2502,19 @@ print_variable_or_computed (const char *expressio=
n, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type =3D check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () !=3D TYPE_CODE_ARRAY
> -         && type->code () !=3D TYPE_CODE_STRUCT
> -         && type->code () !=3D TYPE_CODE_UNION)
> -       {
> -         struct value_print_options opts;
> -
> -         get_no_prettyformat_print_options (&opts);
> -         opts.deref_ref =3D 1;
> -         common_val_print (val, &stb, 0, &opts, current_language);
> -         uiout->field_stream ("value", stb);
> -       }
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -       struct value_print_options opts;
> +    }
>
> -       get_no_prettyformat_print_options (&opts);
> -       opts.deref_ref =3D 1;
> -       common_val_print (val, &stb, 0, &opts, current_language);
> -       uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (print_value_p (val, values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref =3D 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>
>  static const char mi_no_values[] =3D "--no-values";
> +static const char mi_scalar_values[] =3D "--scalar-values";
>  static const char mi_simple_values[] =3D "--simple-values";
>  static const char mi_all_values[] =3D "--all-values";
>
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") =3D=3D 0
>             || strcmp (name, mi_simple_values) =3D=3D 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") =3D=3D 0
> +           || strcmp (name, mi_scalar_values) =3D=3D 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -           mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_valu=
es);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..a746f309187 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -232,17 +232,17 @@ py_print_value (struct ui_out *out, struct value *v=
al,
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type =3D=3D MI_PRINT_SIMPLE_VALUES
> +  if (args_type =3D=3D MI_PRINT_SCALAR_VALUES
> +      || args_type =3D=3D MI_PRINT_SIMPLE_VALUES
>        || args_type =3D=3D MI_PRINT_ALL_VALUES)
>      {
> -      struct type *type =3D check_typedef (value_type (val));
> -
>        if (args_type =3D=3D MI_PRINT_ALL_VALUES)
>         should_print =3D 1;
> +      else if (args_type =3D=3D MI_PRINT_SCALAR_VALUES
> +              && val_print_scalar_type_p (value_type (val)))
> +       should_print =3D 1;
>        else if (args_type =3D=3D MI_PRINT_SIMPLE_VALUES
> -              && type->code () !=3D TYPE_CODE_ARRAY
> -              && type->code () !=3D TYPE_CODE_STRUCT
> -              && type->code () !=3D TYPE_CODE_UNION)
> +              && mi_simple_values_type_p (value_type (val)))
>         should_print =3D 1;
>      }
>    else if (args_type !=3D NO_VALUES)
> @@ -371,10 +371,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for scalar and simple values. This
> +     seems weird, but this is how MI chooses to format the various outpu=
t
>       types.  */
> -  if (args_type =3D=3D MI_PRINT_SIMPLE_VALUES && val !=3D NULL)
> +  if ((args_type =3D=3D MI_PRINT_SCALAR_VALUES
> +       || args_type =3D=3D MI_PRINT_SIMPLE_VALUES)
> +      && val !=3D NULL)
>      py_print_type (out, val);
>
>    if (val !=3D NULL)
> @@ -603,7 +605,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" =3D ");
>
> -      if (args_type =3D=3D MI_PRINT_SIMPLE_VALUES)
> +      if (args_type =3D=3D MI_PRINT_SCALAR_VALUES
> +          || args_type =3D=3D MI_PRINT_SIMPLE_VALUES)
>         py_print_type (out, val);
>
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-=
stack.exp
> index d04c8153c65..8aa4e2234ff 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,9 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments 3 1 1
>
>      mi_gdb_test "231-stack-list-arguments 0" \
>         "231\\^done,stack-args=3D\\\[frame=3D\{level=3D\"0\",args=3D\\\[\=
\\]\},frame=3D\{level=3D\"1\",args=3D\\\[name=3D\"strarg\"\\\]\},frame=3D\{=
level=3D\"2\",args=3D\\\[name=3D\"intarg\",name=3D\"strarg\"\\\]\},frame=3D=
\{level=3D\"3\",args=3D\\\[name=3D\"intarg\",name=3D\"strarg\",name=3D\"flt=
arg\"\\\]\},frame=3D\{level=3D\"4\",args=3D\\\[\\\]\}\\\]" \
> @@ -125,6 +128,14 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>         "235\\^done,stack-args=3D\\\[frame=3D\{level=3D\"1\",args=3D\\\[\=
{name=3D\"strarg\",value=3D\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},=
frame=3D\{level=3D\"2\",args=3D\\\[\{name=3D\"intarg\",value=3D\"2\"\},\{na=
me=3D\"strarg\",value=3D\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},fra=
me=3D\{level=3D\"3\",args=3D\\\[\{name=3D\"intarg\",value=3D\"2\"\},\{name=
=3D\"strarg\",value=3D\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=3D\"=
fltarg\",value=3D\"3.5\"\}\\\]\},frame=3D\{level=3D\"4\",args=3D\\\[\\\]\}\=
\\]" \
>         "stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +       "236\\^done,stack-args=3D\\\[frame=3D\{level=3D\"1\",args=3D\\\[\=
{name=3D\"strarg\",type=3D\"char \\*\",value=3D\"$hex \\\\\"A string argume=
nt.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments 3 1 1" \
> +       "237\\^done,stack-args=3D\\\[frame=3D\{level=3D\"1\",args=3D\\\[\=
{name=3D\"strarg\",type=3D\"char \\*\",value=3D\"$hex \\\\\"A string argume=
nt.\\\\\"\"\}\\\]\}\\\]" \
> +       "stack args listing --scalar-values 1 1"
>  }
>
>  proc test_stack_info_depth {} {
> @@ -163,7 +174,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments
> +    # -stack-list-locals 3 (--scalar-values)
>
>      mi_gdb_test "232-stack-list-locals 0" \
>         "232\\^done,locals=3D\\\[name=3D\"A\",name=3D\"B\",name=3D\"C\",n=
ame=3D\"D\"\\\]" \
> @@ -183,6 +194,10 @@ proc test_stack_locals_listing {} {
>         "232\\^done,locals=3D\\\[\{name=3D\"A\",type=3D\"int\",value=3D\"=
1\"\},\{name=3D\"B\",type=3D\"int\",value=3D\"2\"\},\{name=3D\"C\",type=3D\=
"int\",value=3D\"3\"\},\{name=3D\"D\",type=3D\"int \\\[3\\\]\"\}\\\]" \
>         "stack locals listing, simple types: names and values, complex ty=
pe: names and types"
>
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +       "233\\^done,locals=3D\\\[\{name=3D\"A\",type=3D\"int\",value=3D\"=
1\"\},\{name=3D\"B\",type=3D\"int\",value=3D\"2\"\},\{name=3D\"C\",type=3D\=
"int\",value=3D\"3\"\},\{name=3D\"D\",type=3D\"int \\\[3\\\]\"\}\\\]" \
> +       "stack locals listing, scalar types: names and values, otherwise:=
 names and types"
> +
>      mi_gdb_test "234-stack-list-locals" \
>         "234\\^error,msg=3D\"-stack-list-locals: Usage.*PRINT_VALUES.*\""=
 \
>         "stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.cc b/gdb/testsuite/=
gdb.mi/print-scalar-values.cc
> new file mode 100644
> index 00000000000..fd9daf1d962
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.cc
> @@ -0,0 +1,58 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.=
  */
> +
> +/* PRINT_SCALAR_VALUES test program.
> +
> +   Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +   types, including C++ reference and rvalue reference types.
> +
> +   In the function f(), arguments i, ir, and irr are ints or references
> +   to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +   but the other arguments are non-scalar, and so their values should
> +   not be printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i =3D 1, j =3D 2;
> +  int a[1] =3D { 4 }, b[1] =3D { 5 };
> +  struct s s =3D { 7 }, t =3D { 8 };
> +  union u u =3D { 10 }, v =3D { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-scalar-values.exp b/gdb/testsuite=
/gdb.mi/print-scalar-values.exp
> new file mode 100644
> index 00000000000..3398218c063
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-scalar-values.exp
> @@ -0,0 +1,51 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# PRINT_SCALAR_VALUES test.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +#
> +# In the function f(), arguments i, ir, and irr are ints or references
> +# to ints, and their values should be printed by PRINT_SCALAR_VALUES;
> +# but the other arguments are non-scalar, and so their values should not
> +# be printed by PRINT_SCALAR_VALUES.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug =
c++}] !=3D "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on=
 f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp=3D"keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=3D\\\[frame=3D\{level=3D\"0\",args=3D\\\[\{name=
=3D\"i\",type=3D\"int\",value=3D\"1\"\},\{name=3D\"ir\",type=3D\"int &\",va=
lue=3D\"@$hex: 2\"\},\{name=3D\"irr\",type=3D\"int &&\",value=3D\"@$hex: 3\=
"\},\{name=3D\"a\",type=3D\"int \\*\",value=3D\"$hex\"\},\{name=3D\"ar\",ty=
pe=3D\"int \\(&\\)\\\[1\\\]\"\},\{name=3D\"arr\",type=3D\"int \\(&&\\)\\\[1=
\\\]\"\},\{name=3D\"s\",type=3D\"s\"\},\{name=3D\"sr\",type=3D\"s &\"\},\{n=
ame=3D\"srr\",type=3D\"s &&\"\},\{name=3D\"u\",type=3D\"u\"\},\{name=3D\"ur=
\",type=3D\"u &\"\},\{name=3D\"urr\",type=3D\"u &&\"\}\\\]\},frame=3D\{leve=
l=3D\"1\",args=3D\\\[\\\]\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compou=
nd types: names and types"
> +
> +mi_gdb_exit
> --
> 2.26.0
>

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH v5] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-10-12 16:38           ` Andrew Burgess
@ 2022-10-20 17:47             ` Gareth Rees
  2022-10-20 18:00               ` Eli Zaretskii
  2022-11-03 16:20               ` [PING] " Gareth Rees
  2022-10-20 17:58             ` [PATCH v4] " Gareth Rees
  1 sibling, 2 replies; 25+ messages in thread
From: Gareth Rees @ 2022-10-20 17:47 UTC (permalink / raw)
  To: gdb-patches

SUMMARY

The '--simple-values' argument to '-stack-list-arguments' and similar
GDB/MI commands does not take reference types into account, so that
references to arbitrarily large structures are considered "simple" and
printed. This means that the '--simple-values' argument cannot be used
by IDEs when tracing the stack due to the time taken to print large
structures passed by reference.

DETAILS

Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
'-stack-list-variables' and so on) take a PRINT-VALUES argument which
may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
In the '--simple-values' case, the command is supposed to print the
name, type, and value of variables with simple types, and print only the
name and type of variables with compound types.

The '--simple-values' argument ought to be suitable for IDEs that need
to update their user interface with the program's call stack every time
the program stops. However, it does not take C++ reference types into
account, and this makes the argument unsuitable for this purpose.

For example, consider the following C++ program:

    struct s {
        int v[10];
    };

    int
    sum(const struct s &s)
    {
        int total = 0;
        for (int i = 0; i < 10; ++i) total += s.v[i];
        return total;
    }

    int
    main(void)
    {
        struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
        return sum(s);
    }

If we start GDB in MI mode and continue to 'sum', the behaviour of
'-stack-list-arguments' is as follows:

    (gdb)
    -stack-list-arguments --simple-values
    ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]

Note that the value of the argument 's' was printed, even though 's' is
a reference to a structure, which is not a simple value.

See https://github.com/microsoft/MIEngine/pull/673 for a case where this
behaviour caused Microsoft to avoid the use of '--simple-values' in
their MIEngine debug adapter, because it caused Visual Studio Code to
take too long to refresh the call stack in the user interface.

SOLUTIONS

There are two ways we could fix this problem, depending on whether we
consider the current behaviour to be a bug that can be fixed.

1. If the current behaviour is a bug that can be fixed, then we can
   update the behaviour of '--simple-values' so that it takes
   reference types into account: that is, a value is simple if it is
   neither an array, struct, or union, nor a reference to an array,
   struct or union.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that it is safe to use the '--simple-values'
   argument when refreshing the call stack.

2. If the current behaviour is not a bug, or cannot be changed due to
   backwards compatibility concerns, then we can add a new option for
   the PRINT-VALUES argument, for example, '--scalar-values' (3), that
   would be suitable for use by IDEs.

   In this case we must add a feature to the '-list-features' command so
   that IDEs can detect that the '--scalar-values' argument is
   available for use when refreshing the call stack.

PATCH

This patch implements solution (2), adding a '--scalar-values' option
for the PRINT-VALUES argument to '-stack-list-arguments' and similar
commands. This option prints the value only for scalars and so matches
the behaviour of the 'scalars' argument to the 'set print
frame-arguments' command. References to structures are not scalars,
and so the option is suitable for use by IDEs.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
---
 gdb/NEWS                                      |  9 +++
 gdb/doc/gdb.texinfo                           | 59 ++++++++++-------
 gdb/extension.h                               |  3 +
 gdb/mi/mi-cmd-stack.c                         | 16 ++---
 gdb/mi/mi-cmd-var.c                           | 45 ++++++++++---
 gdb/mi/mi-cmds.h                              | 17 ++++-
 gdb/mi/mi-main.c                              | 35 ++++-------
 gdb/mi/mi-parse.c                             |  8 ++-
 gdb/python/py-framefilter.c                   | 40 ++++++------
 gdb/testsuite/gdb.mi/mi-stack.exp             | 37 ++++++++++-
 gdb/testsuite/gdb.mi/print-values.cc          | 63 +++++++++++++++++++
 gdb/testsuite/gdb.mi/print-values.exp         | 53 ++++++++++++++++
 .../gdb.python/py-framefilter-mi.exp          | 28 +++++++++
 13 files changed, 323 insertions(+), 90 deletions(-)
 create mode 100644 gdb/testsuite/gdb.mi/print-values.cc
 create mode 100644 gdb/testsuite/gdb.mi/print-values.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2ecd8..9ad441691ea 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -114,6 +114,15 @@ maintenance info line-table
   entry corresponds to an address where a breakpoint should be placed
   to be at the first instruction past a function's prologue.
 
+* MI changes
+
+  ** The '-stack-list-arguments', '-stack-list-locals',
+     '-stack-list-variables', and '-var-list-children' commands
+     support the '--scalar-values' option, which requests the command
+     to print values only for scalar types.  Support for this feature
+     can be verified by using the '-list-features' command, which
+     now includes "scalar-values".
+
 * New targets
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 238a49b027d..b2b53de1022 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
 @var{high-frame} may be larger than the actual number of frames, in
 which case only existing frames will be returned.
 
-If @var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+If @var{print-values} is 0 or @code{--no-values}, print only the names
+of the variables; if it is 1 or @code{--all-values}, print also their
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  If the option @code{--no-frame-filters} is supplied, then
+Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, arguments that
 are not available are not listed.  Partially available arguments
@@ -33549,13 +33551,15 @@ Show a single frame:
 Display the local variable names for the selected frame.  If
 @var{print-values} is 0 or @code{--no-values}, print only the names of
 the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  In this last case, a frontend can immediately
-display the value of simple data types and create variable objects for
-other data types when the user wishes to explore their values in
-more detail.  If the option @code{--no-frame-filters} is supplied, then
-Python frame filters will not be executed.
+values; if it is 2 or @code{--simple-values}, print the name, type and
+value for simple data types, and the name and type for arrays,
+structures and unions; and if it is 3 or @code{--scalar-values}, print
+the name, type and value for scalar data types, and the name and type
+otherwise.  In the last two cases, a frontend can immediately display
+the value of simple or scalar data types and create variable objects
+for other data types when the user wishes to explore their values in
+more detail.  If the option @code{--no-frame-filters} is supplied,
+then Python frame filters will not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 that are not available are not listed.  Partially available local
@@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
  -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
 @end smallexample
 
-Display the names of local variables and function arguments for the selected frame.  If
-@var{print-values} is 0 or @code{--no-values}, print only the names of
-the variables; if it is 1 or @code{--all-values}, print also their
-values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types, and the name and type for arrays,
-structures and unions.  If the option @code{--no-frame-filters} is
-supplied, then Python frame filters will not be executed.
+Display the names of local variables and function arguments for the
+selected frame.  If @var{print-values} is 0 or @code{--no-values},
+print only the names of the variables; if it is 1 or
+@code{--all-values}, print also their values; if it is 2 or
+@code{--simple-values}, print the name, type and value for simple data
+types, and the name and type for arrays, structures and unions; and if
+it is 3 or @code{--scalar-values}, print the name, type and value for
+scalar data types, and the name and type otherwise.  If the option
+@code{--no-frame-filters} is supplied, then Python frame filters will
+not be executed.
 
 If the @code{--skip-unavailable} option is specified, local variables
 and arguments that are not available are not listed.  Partially
@@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
 a single argument or if @var{print-values} has a value of 0 or
 @code{--no-values}, print only the names of the variables; if
 @var{print-values} is 1 or @code{--all-values}, also print their
-values; and if it is 2 or @code{--simple-values} print the name and
-value for simple data types and just the name for arrays, structures
-and unions.
+values; if it is 2 or @code{--simple-values} print the name and value
+for simple data types and just the name for arrays, structures and
+unions; and if it is 3 or @code{--scalar-values}, print the name and
+value for scalar data types, and just the name otherwise.
 
 @var{from} and @var{to}, if specified, indicate the range of children
 to report.  If @var{from} or @var{to} is less than zero, the range is
@@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
 @item data-disassemble-a-option
 Indicates that the @code{-data-disassemble} command supports the @option{-a}
 option (@pxref{GDB/MI Data Manipulation}).
+@item scalar-values
+Indicates that the @code{-stack-list-arguments},
+@code{-stack-list-locals}, @code{-stack-list-variables}, and
+@code{-var-list-children} commands support the
+@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
 @end ftable
 
 @subheading The @code{-list-target-features} Command
diff --git a/gdb/extension.h b/gdb/extension.h
index 47839ea50be..16d12f00f41 100644
--- a/gdb/extension.h
+++ b/gdb/extension.h
@@ -121,6 +121,9 @@ enum ext_lang_frame_args
        arguments when invoked from the MI. */
     MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
 
+    /* Print only scalar values for arguments when invoked from the MI.  */
+    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
+
     /* Print only scalar values for arguments when invoked from the CLI. */
     CLI_SCALAR_VALUES,
 
diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index 0fe204dbc66..43eea32e460 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
 	       && arg->error == NULL)
 	      || values == PRINT_SIMPLE_VALUES
+	      || values == PRINT_SCALAR_VALUES
 	      || (values == PRINT_ALL_VALUES
 		  && (arg->val != NULL || arg->error != NULL)));
   gdb_assert (arg->entry_kind == print_entry_values_no
@@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   if (what == all && arg->sym->is_argument ())
     uiout->field_signed ("arg", 1);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     {
       check_typedef (arg->sym->type ());
       type_print (arg->sym->type (), "", &stb, -1);
@@ -571,7 +573,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
   const struct block *block;
   struct symbol *sym;
   struct block_iterator iter;
-  struct type *type;
   const char *name_of_result;
   struct ui_out *uiout = current_uiout;
 
@@ -647,21 +648,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
 	      entryarg.sym = sym2;
 	      entryarg.entry_kind = print_entry_values_no;
 
-	      switch (values)
+	      if (mi_print_type_p (sym->type (), values))
 		{
-		case PRINT_SIMPLE_VALUES:
-		  type = check_typedef (sym2->type ());
-		  if (type->code () != TYPE_CODE_ARRAY
-		      && type->code () != TYPE_CODE_STRUCT
-		      && type->code () != TYPE_CODE_UNION)
-		    {
-		case PRINT_ALL_VALUES:
 		  if (sym->is_argument ())
 		    read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
 		  else
 		    read_frame_local (sym2, fi, &arg);
-		    }
-		  break;
 		}
 
 	      if (arg.entry_kind != print_entry_values_only)
diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
index 3db09cf7815..1d4d3ec8534 100644
--- a/gdb/mi/mi-cmd-var.c
+++ b/gdb/mi/mi-cmd-var.c
@@ -32,6 +32,7 @@
 #include "mi-parse.h"
 #include "gdbsupport/gdb_optional.h"
 #include "inferior.h"
+#include "valprint.h"
 
 static void varobj_update_one (struct varobj *var,
 			       enum print_values print_values,
@@ -314,6 +315,40 @@ mi_cmd_var_info_num_children (const char *command, char **argv, int argc)
   uiout->field_signed ("numchild", varobj_get_num_children (var));
 }
 
+/* See mi-cmds.h.  */
+
+bool
+mi_simple_type_p (struct type *type)
+{
+  type = check_typedef (type);
+  switch (type->code ())
+    {
+    case TYPE_CODE_ARRAY:
+    case TYPE_CODE_STRUCT:
+    case TYPE_CODE_UNION:
+      return false;
+    default:
+      return true;
+    }
+}
+
+bool
+mi_print_type_p (struct type *type, enum print_values print_values)
+{
+  switch (print_values)
+    {
+    default:
+    case PRINT_NO_VALUES:
+      return false;
+    case PRINT_ALL_VALUES:
+      return true;
+    case PRINT_SIMPLE_VALUES:
+      return mi_simple_type_p (type);
+    case PRINT_SCALAR_VALUES:
+      return val_print_scalar_type_p (type);
+    }
+}
+
 /* Return 1 if given the argument PRINT_VALUES we should display
    the varobj VAR.  */
 
@@ -335,15 +370,7 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
   if (type == NULL)
     return 1;
   else
-    {
-      type = check_typedef (type);
-
-      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
-	 and that type is not a compound type.  */
-      return (type->code () != TYPE_CODE_ARRAY
-	      && type->code () != TYPE_CODE_STRUCT
-	      && type->code () != TYPE_CODE_UNION);
-    }
+    return mi_print_type_p (type, print_values);
 }
 
 void
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 9ffb11bf997..3a5b6b72be9 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -29,7 +29,8 @@
 enum print_values {
    PRINT_NO_VALUES,
    PRINT_ALL_VALUES,
-   PRINT_SIMPLE_VALUES
+   PRINT_SIMPLE_VALUES,
+   PRINT_SCALAR_VALUES
 };
 
 typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
@@ -226,4 +227,18 @@ using remove_mi_cmd_entries_ftype
   = gdb::function_view<bool (mi_command *)>;
 extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
 
+/* Return true if TYPE is suitable for printing with PRINT_SIMPLE_VALUES: that
+   is, if TYPE is not an array, structure or union.
+
+   Note that reference types are always considered simple by this function, even
+   if the referenced type is non-scalar.  This behaviour is retained for backwards
+   compatibility, and PRINT_SCALAR_VALUES may be used instead to avoid printing
+   references to non-scalar values.  */
+
+extern bool mi_simple_type_p (struct type *type);
+
+/* Return true if TYPE is suitable for printing with PRINT_VALUES.  */
+
+extern bool mi_print_type_p (struct type *type, enum print_values values);
+
 #endif /* MI_MI_CMDS_H */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index b758f398e2a..9bb00390370 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
       uiout->field_string (NULL, "undefined-command-error-code");
       uiout->field_string (NULL, "exec-run-start-option");
       uiout->field_string (NULL, "data-disassemble-a-option");
+      uiout->field_string (NULL, "scalar-values");
 
       if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
 	uiout->field_string (NULL, "python");
@@ -2462,14 +2463,14 @@ static void
 print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct value *val;
-  struct type *type;
   struct ui_out *uiout = current_uiout;
 
   string_file stb;
 
   expression_up expr = parse_expression (expression);
 
-  if (values == PRINT_SIMPLE_VALUES)
+  if (values == PRINT_SIMPLE_VALUES
+      || values == PRINT_SCALAR_VALUES)
     val = evaluate_type (expr.get ());
   else
     val = evaluate_expression (expr.get ());
@@ -2482,31 +2483,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
   switch (values)
     {
     case PRINT_SIMPLE_VALUES:
-      type = check_typedef (value_type (val));
+    case PRINT_SCALAR_VALUES:
       type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
-      if (type->code () != TYPE_CODE_ARRAY
-	  && type->code () != TYPE_CODE_STRUCT
-	  && type->code () != TYPE_CODE_UNION)
-	{
-	  struct value_print_options opts;
-
-	  get_no_prettyformat_print_options (&opts);
-	  opts.deref_ref = 1;
-	  common_val_print (val, &stb, 0, &opts, current_language);
-	  uiout->field_stream ("value", stb);
-	}
       break;
-    case PRINT_ALL_VALUES:
-      {
-	struct value_print_options opts;
+    }
 
-	get_no_prettyformat_print_options (&opts);
-	opts.deref_ref = 1;
-	common_val_print (val, &stb, 0, &opts, current_language);
-	uiout->field_stream ("value", stb);
-      }
-      break;
+  if (mi_print_type_p (value_type (val), values))
+    {
+      struct value_print_options opts;
+      get_no_prettyformat_print_options (&opts);
+      opts.deref_ref = 1;
+      common_val_print (val, &stb, 0, &opts, current_language);
+      uiout->field_stream ("value", stb);
     }
 }
 
diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
index dfa7b462714..dd70e4648a1 100644
--- a/gdb/mi/mi-parse.c
+++ b/gdb/mi/mi-parse.c
@@ -29,6 +29,7 @@
 #include "language.h"
 
 static const char mi_no_values[] = "--no-values";
+static const char mi_scalar_values[] = "--scalar-values";
 static const char mi_simple_values[] = "--simple-values";
 static const char mi_all_values[] = "--all-values";
 
@@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
    else if (strcmp (name, "2") == 0
 	    || strcmp (name, mi_simple_values) == 0)
      return PRINT_SIMPLE_VALUES;
+   else if (strcmp (name, "3") == 0
+	    || strcmp (name, mi_scalar_values) == 0)
+     return PRINT_SCALAR_VALUES;
    else
      error (_("Unknown value for PRINT_VALUES: must be: \
-0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
-	    mi_no_values, mi_all_values, mi_simple_values);
+0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
+	    mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
 }
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 366f3745b9d..e295036f46e 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -227,26 +227,27 @@ py_print_value (struct ui_out *out, struct value *val,
 		enum ext_lang_frame_args args_type,
 		const struct language_defn *language)
 {
-  int should_print = 0;
+  int should_print;
 
   /* MI does not print certain values, differentiated by type,
      depending on what ARGS_TYPE indicates.  Test type against option.
      For CLI print all values.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES
-      || args_type == MI_PRINT_ALL_VALUES)
+  switch (args_type)
     {
-      struct type *type = check_typedef (value_type (val));
-
-      if (args_type == MI_PRINT_ALL_VALUES)
-	should_print = 1;
-      else if (args_type == MI_PRINT_SIMPLE_VALUES
-	       && type->code () != TYPE_CODE_ARRAY
-	       && type->code () != TYPE_CODE_STRUCT
-	       && type->code () != TYPE_CODE_UNION)
-	should_print = 1;
+    case NO_VALUES:
+      should_print = 0;
+      break;
+    default:
+    case MI_PRINT_ALL_VALUES:
+      should_print = 1;
+      break;
+    case MI_PRINT_SIMPLE_VALUES:
+      should_print = mi_print_type_p (value_type (val), PRINT_SIMPLE_VALUES);
+      break;
+    case MI_PRINT_SCALAR_VALUES:
+      should_print = mi_print_type_p (value_type (val), PRINT_SCALAR_VALUES);
+      break;
     }
-  else if (args_type != NO_VALUES)
-    should_print = 1;
 
   if (should_print)
     {
@@ -371,10 +372,12 @@ py_print_single_arg (struct ui_out *out,
   if (print_args_field)
     out->field_signed ("arg", 1);
 
-  /* For MI print the type, but only for simple values.  This seems
-     weird, but this is how MI choose to format the various output
+  /* For MI print the type, but only for simple and scalar values. This
+     seems weird, but this is how MI chooses to format the various output
      types.  */
-  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
+  if ((args_type == MI_PRINT_SIMPLE_VALUES
+       || args_type == MI_PRINT_SCALAR_VALUES)
+      && val != NULL)
     py_print_type (out, val);
 
   if (val != NULL)
@@ -603,7 +606,8 @@ enumerate_locals (PyObject *iter,
       out->field_string ("name", sym_name.get ());
       out->text (" = ");
 
-      if (args_type == MI_PRINT_SIMPLE_VALUES)
+      if (args_type == MI_PRINT_SIMPLE_VALUES
+          || args_type == MI_PRINT_SCALAR_VALUES)
 	py_print_type (out, val);
 
       /* CLI always prints values for locals.  MI uses the
diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
index d04c8153c65..2c74da00c18 100644
--- a/gdb/testsuite/gdb.mi/mi-stack.exp
+++ b/gdb/testsuite/gdb.mi/mi-stack.exp
@@ -93,6 +93,11 @@ proc test_stack_args_listing {} {
     # -stack-list-arguments 1 1 1
     # -stack-list-arguments 1 1 3
     # -stack-list-arguments 
+    # -stack-list-arguments 1 1 300
+    # -stack-list-arguments 2 1 1
+    # -stack-list-arguments --simple-values 1 1
+    # -stack-list-arguments 3 1 1
+    # -stack-list-arguments --scalar-values 1 1
 
     mi_gdb_test "231-stack-list-arguments 0" \
 	"231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
@@ -125,6 +130,22 @@ proc test_stack_args_listing {} {
     mi_gdb_test "235-stack-list-arguments 1 1 300" \
 	"235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
 	"stack args listing 1 1 300"
+
+    mi_gdb_test "236-stack-list-arguments 2 1 1" \
+	"236\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
+	"stack args listing 2 1 1"
+
+    mi_gdb_test "237-stack-list-arguments --simple-values 1 1" \
+	"237\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
+	"stack args listing --simple-values 1 1"
+
+    mi_gdb_test "238-stack-list-arguments 3 1 1" \
+	"238\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
+	"stack args listing 3 1 1"
+
+    mi_gdb_test "239-stack-list-arguments --scalar-values 1 1" \
+	"239\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
+	"stack args listing --scalar-values 1 1"
 }
 
 proc test_stack_info_depth {} {
@@ -163,7 +184,7 @@ proc test_stack_locals_listing {} {
     # -stack-list-locals 0 (--no-values)
     # -stack-list-locals 1 (--all-values)
     # -stack-list-locals 2 (--simple-values)
-    # -stack-list-arguments 
+    # -stack-list-locals 3 (--scalar-values)
 
     mi_gdb_test "232-stack-list-locals 0" \
 	"232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
@@ -179,10 +200,22 @@ proc test_stack_locals_listing {} {
 	"232\\^done,locals=\\\[\{name=\"A\",value=\"1\"\},\{name=\"B\",value=\"2\"\},\{name=\"C\",value=\"3\"\},\{name=\"D\",value=\"\\{0, 1, 2\\}\"\}\\\]" \
 	"stack locals listing of names and values"
 
-    mi_gdb_test "232-stack-list-locals --simple-values" \
+    mi_gdb_test "232-stack-list-locals 2" \
 	"232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
 	"stack locals listing, simple types: names and values, complex type: names and types"
 
+    mi_gdb_test "232-stack-list-locals --simple-values" \
+	"232\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
+	"stack locals listing with --simple-values"
+
+    mi_gdb_test "233-stack-list-locals 3" \
+	"233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
+	"stack locals listing, scalar types: names and values, otherwise: names and types"
+
+    mi_gdb_test "233-stack-list-locals --scalar-values" \
+	"233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
+	"stack locals listing with --scalar-values"
+
     mi_gdb_test "234-stack-list-locals" \
 	"234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
 	"stack locals listing wrong"
diff --git a/gdb/testsuite/gdb.mi/print-values.cc b/gdb/testsuite/gdb.mi/print-values.cc
new file mode 100644
index 00000000000..b52683d1537
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-values.cc
@@ -0,0 +1,63 @@
+/* This test case is part of GDB, the GNU debugger.
+
+   Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Test program for PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
+
+   In the function f:
+
+   * The arguments i, ir, and irr are ints or references to ints,
+     which must be printed by both PRINT_SIMPLE_VALUES and
+     PRINT_SCALAR_VALUES.
+
+   * The arguments a, s, and u are non-scalar values, which must not
+     be printed by either PRINT_SIMPLE_VALUES or PRINT_SCALAR_VALUES.
+
+   * The arguments ar, arr, sr, srr, ur, and urr are references to
+     non-scalar values, which must be printed by PRINT_SIMPLE_VALUES
+     but not printed by PRINT_SCALAR_VALUES.  */
+
+struct s
+{
+  int v;
+};
+
+union u
+{
+  int v;
+};
+
+int
+f (int i, int &ir, int &&irr,
+   int a[1], int (&ar)[1], int (&&arr)[1],
+   struct s s, struct s &sr, struct s &&srr,
+   union u u, union u &ur, union u &&urr)
+{
+  return (i + ir + irr
+          + a[0] + ar[0] + arr[0]
+          + s.v + sr.v + srr.v
+          + u.v + ur.v + urr.v);
+}
+
+int
+main (void)
+{
+  int i = 1, j = 2;
+  int a[1] = { 4 }, b[1] = { 5 };
+  struct s s = { 7 }, t = { 8 };
+  union u u = { 10 }, v = { 11 };
+  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
+}
diff --git a/gdb/testsuite/gdb.mi/print-values.exp b/gdb/testsuite/gdb.mi/print-values.exp
new file mode 100644
index 00000000000..7896d773119
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/print-values.exp
@@ -0,0 +1,53 @@
+# Copyright 2022 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test of PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
+#
+# Test that PRINT_SIMPLE_VALUES distinguishes scalar and non-scalar
+# types, except for C++ reference and rvalue reference types.
+#
+# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
+# types, including C++ reference and rvalue reference types.
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+standard_testfile .cc
+
+if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+mi_clean_restart $binfile
+
+mi_runto_main
+
+mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
+
+mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
+
+mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
+    "run until breakpoint on f"
+
+mi_gdb_test "-stack-list-arguments --simple-values" \
+    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\",value=\"@$hex: \\{5\\}\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\",value=\"@$hex: \\{6\\}\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\",value=\"@$hex: \\{v = 8\\}\"\\},\\{name=\"srr\",type=\"s &&\",value=\"@$hex: \\{v = 9\\}\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\",value=\"@$hex: \\{v = 11\\}\"\\},\\{name=\"urr\",type=\"u &&\",value=\"@$hex: \\{v = 12\\}\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
+    "stack list arguments, simple types: names, types and values, otherwise: names and types"
+
+mi_gdb_test "-stack-list-arguments --scalar-values" \
+    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\"\\},\\{name=\"srr\",type=\"s &&\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\"\\},\\{name=\"urr\",type=\"u &&\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
+    "stack list arguments, scalar types: names, types and values, compound types: names and types"
+
+mi_gdb_exit
diff --git a/gdb/testsuite/gdb.python/py-framefilter-mi.exp b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
index 344067fe4a7..fa4e559e343 100644
--- a/gdb/testsuite/gdb.python/py-framefilter-mi.exp
+++ b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
@@ -120,6 +120,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2" \
     "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
     "stack-list-arguments --no-frame-filters 2"
 
+mi_gdb_test "-stack-list-arguments 3" \
+    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"\}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
+    "stack-list-arguments 3"
+
+mi_gdb_test "-stack-list-arguments --no-frame-filters 3" \
+    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
+    "stack-list-arguments --no-frame-filters 3"
+
 
 mi_gdb_test "-stack-list-arguments 2 0 3" \
     "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},frame={level=\"3\",args=\\\[\\\]}\\\]" \
@@ -133,6 +141,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2 22 27" \
     "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
     "stack-list-arguments --no-frame-filters 2 22 27"
 
+mi_gdb_test "-stack-list-arguments 3 22 27" \
+    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
+    "stack-list-arguments 3 22 27"
+
+mi_gdb_test "-stack-list-arguments --no-frame-filters 3 22 27" \
+    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
+    "stack-list-arguments --no-frame-filters 3 22 27"
+
 #stack-list-locals
 mi_gdb_test "-stack-list-locals --no-frame-filters 0" \
     "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
@@ -146,6 +162,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters 2" \
     "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
     "stack-list-locals --no-frame-filters 2"
 
+mi_gdb_test "-stack-list-locals --no-frame-filters 3" \
+    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
+    "stack-list-locals --no-frame-filters 3"
+
 mi_gdb_test "-stack-list-locals --no-frame-filters --no-values" \
     "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
     "stack-list-locals --no-frame-filters --no-values"
@@ -158,6 +178,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters --simple-values" \
     "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
     "stack-list-locals --no-frame-filters --simple-values"
 
+mi_gdb_test "-stack-list-locals --no-frame-filters --scalar-values" \
+    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
+    "stack-list-locals --no-frame-filters --scalar-values"
+
 mi_gdb_test "-stack-list-locals 0" \
     "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
     "stack-list-locals 0"
@@ -170,6 +194,10 @@ mi_gdb_test "-stack-list-locals 2" \
     "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
     "stack-list-locals 2"
 
+mi_gdb_test "-stack-list-locals 3" \
+    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
+    "stack-list-locals 3"
+
 # stack-list-variables
 mi_gdb_test "-stack-list-variables --no-frame-filters 0" \
     "\\^done,variables=\\\[{name=\"foo\",arg=\"1\"},{name=\"bar\",arg=\"1\"},{name=\"fb\",arg=\"1\"},{name=\"bf\",arg=\"1\"},{name=\"str\"},{name=\"st2\"},{name=\"b\"},{name=\"c\"}\\\]" \
-- 
2.26.0


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v4] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-10-12 16:38           ` Andrew Burgess
  2022-10-20 17:47             ` [PATCH v5] " Gareth Rees
@ 2022-10-20 17:58             ` Gareth Rees
  1 sibling, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-10-20 17:58 UTC (permalink / raw)
  To: Andrew Burgess; +Cc: gdb-patches

Thank you for the thorough review. I implemented all your suggestions,
and have attempted to add tests covering all the behaviour of the new
'--scalar-values' option. The revised patch is v5, posted separately.

Andrew Burgess wrote:
> > +/* Print VAL according to VALUES?  */
> > +
> > +static bool
> > +print_value_p (struct value *val, enum print_values values)
> > +{
> > +  switch (values)
> > +    {
> > +    default:
> > +    case PRINT_NO_VALUES:
> > +      return false;
> > +    case PRINT_ALL_VALUES:
> > +      return true;
> > +    case PRINT_SIMPLE_VALUES:
> > +      return mi_simple_values_type_p (value_type (val));
> > +    case PRINT_SCALAR_VALUES:
> > +      return val_print_scalar_type_p (value_type (val));
> > +    }
> > +}
>
> I think you should probably fold together this print_value_p and
> print_symbol_p in mi-cmd-stack.c.  Maybe create an mi_print_type_p
> somewhere, which can contain the core switch table?

I have implemented this suggestion. Note that a consequence is that in
the PRINT_NO_VALUES and PRINT_ALL_VALUES cases, we now incur a call to
value_type(val) or sym->type() when previously we just returned false
or true respectively. I think this is probably worth it, in order to
reduce the amount of duplicated code, but just want to highlight the
small change in behaviour here.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH v5] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-10-20 17:47             ` [PATCH v5] " Gareth Rees
@ 2022-10-20 18:00               ` Eli Zaretskii
  2022-11-03 16:20               ` [PING] " Gareth Rees
  1 sibling, 0 replies; 25+ messages in thread
From: Eli Zaretskii @ 2022-10-20 18:00 UTC (permalink / raw)
  To: Gareth Rees; +Cc: gdb-patches

> Date: Thu, 20 Oct 2022 18:47:02 +0100
> From: Gareth Rees via Gdb-patches <gdb-patches@sourceware.org>
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                      |  9 +++
>  gdb/doc/gdb.texinfo                           | 59 ++++++++++-------
>  gdb/extension.h                               |  3 +
>  gdb/mi/mi-cmd-stack.c                         | 16 ++---
>  gdb/mi/mi-cmd-var.c                           | 45 ++++++++++---
>  gdb/mi/mi-cmds.h                              | 17 ++++-
>  gdb/mi/mi-main.c                              | 35 ++++-------
>  gdb/mi/mi-parse.c                             |  8 ++-
>  gdb/python/py-framefilter.c                   | 40 ++++++------
>  gdb/testsuite/gdb.mi/mi-stack.exp             | 37 ++++++++++-
>  gdb/testsuite/gdb.mi/print-values.cc          | 63 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-values.exp         | 53 ++++++++++++++++
>  .../gdb.python/py-framefilter-mi.exp          | 28 +++++++++
>  13 files changed, 323 insertions(+), 90 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-values.exp

Thanks, the documentation parts are OK.

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PING] [PATCH v5] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-10-20 17:47             ` [PATCH v5] " Gareth Rees
  2022-10-20 18:00               ` Eli Zaretskii
@ 2022-11-03 16:20               ` Gareth Rees
  2022-11-14  9:25                 ` Gareth Rees
  1 sibling, 1 reply; 25+ messages in thread
From: Gareth Rees @ 2022-11-03 16:20 UTC (permalink / raw)
  To: gdb-patches

After four rounds of review, this must be getting close to being
mergeable! But do let me know if there's anything else that I need to
improve here.


On Thu, 20 Oct 2022 at 18:47, Gareth Rees <grees@undo.io> wrote:
>
> SUMMARY
>
> The '--simple-values' argument to '-stack-list-arguments' and similar
> GDB/MI commands does not take reference types into account, so that
> references to arbitrarily large structures are considered "simple" and
> printed. This means that the '--simple-values' argument cannot be used
> by IDEs when tracing the stack due to the time taken to print large
> structures passed by reference.
>
> DETAILS
>
> Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> In the '--simple-values' case, the command is supposed to print the
> name, type, and value of variables with simple types, and print only the
> name and type of variables with compound types.
>
> The '--simple-values' argument ought to be suitable for IDEs that need
> to update their user interface with the program's call stack every time
> the program stops. However, it does not take C++ reference types into
> account, and this makes the argument unsuitable for this purpose.
>
> For example, consider the following C++ program:
>
>     struct s {
>         int v[10];
>     };
>
>     int
>     sum(const struct s &s)
>     {
>         int total = 0;
>         for (int i = 0; i < 10; ++i) total += s.v[i];
>         return total;
>     }
>
>     int
>     main(void)
>     {
>         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
>         return sum(s);
>     }
>
> If we start GDB in MI mode and continue to 'sum', the behaviour of
> '-stack-list-arguments' is as follows:
>
>     (gdb)
>     -stack-list-arguments --simple-values
>     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
>
> Note that the value of the argument 's' was printed, even though 's' is
> a reference to a structure, which is not a simple value.
>
> See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> behaviour caused Microsoft to avoid the use of '--simple-values' in
> their MIEngine debug adapter, because it caused Visual Studio Code to
> take too long to refresh the call stack in the user interface.
>
> SOLUTIONS
>
> There are two ways we could fix this problem, depending on whether we
> consider the current behaviour to be a bug that can be fixed.
>
> 1. If the current behaviour is a bug that can be fixed, then we can
>    update the behaviour of '--simple-values' so that it takes
>    reference types into account: that is, a value is simple if it is
>    neither an array, struct, or union, nor a reference to an array,
>    struct or union.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that it is safe to use the '--simple-values'
>    argument when refreshing the call stack.
>
> 2. If the current behaviour is not a bug, or cannot be changed due to
>    backwards compatibility concerns, then we can add a new option for
>    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
>    would be suitable for use by IDEs.
>
>    In this case we must add a feature to the '-list-features' command so
>    that IDEs can detect that the '--scalar-values' argument is
>    available for use when refreshing the call stack.
>
> PATCH
>
> This patch implements solution (2), adding a '--scalar-values' option
> for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> commands. This option prints the value only for scalars and so matches
> the behaviour of the 'scalars' argument to the 'set print
> frame-arguments' command. References to structures are not scalars,
> and so the option is suitable for use by IDEs.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> ---
>  gdb/NEWS                                      |  9 +++
>  gdb/doc/gdb.texinfo                           | 59 ++++++++++-------
>  gdb/extension.h                               |  3 +
>  gdb/mi/mi-cmd-stack.c                         | 16 ++---
>  gdb/mi/mi-cmd-var.c                           | 45 ++++++++++---
>  gdb/mi/mi-cmds.h                              | 17 ++++-
>  gdb/mi/mi-main.c                              | 35 ++++-------
>  gdb/mi/mi-parse.c                             |  8 ++-
>  gdb/python/py-framefilter.c                   | 40 ++++++------
>  gdb/testsuite/gdb.mi/mi-stack.exp             | 37 ++++++++++-
>  gdb/testsuite/gdb.mi/print-values.cc          | 63 +++++++++++++++++++
>  gdb/testsuite/gdb.mi/print-values.exp         | 53 ++++++++++++++++
>  .../gdb.python/py-framefilter-mi.exp          | 28 +++++++++
>  13 files changed, 323 insertions(+), 90 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.mi/print-values.cc
>  create mode 100644 gdb/testsuite/gdb.mi/print-values.exp
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index dee0ac2ecd8..9ad441691ea 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -114,6 +114,15 @@ maintenance info line-table
>    entry corresponds to an address where a breakpoint should be placed
>    to be at the first instruction past a function's prologue.
>
> +* MI changes
> +
> +  ** The '-stack-list-arguments', '-stack-list-locals',
> +     '-stack-list-variables', and '-var-list-children' commands
> +     support the '--scalar-values' option, which requests the command
> +     to print values only for scalar types.  Support for this feature
> +     can be verified by using the '-list-features' command, which
> +     now includes "scalar-values".
> +
>  * New targets
>
>  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 238a49b027d..b2b53de1022 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
>  @var{high-frame} may be larger than the actual number of frames, in
>  which case only existing frames will be returned.
>
> -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +If @var{print-values} is 0 or @code{--no-values}, print only the names
> +of the variables; if it is 1 or @code{--all-values}, print also their
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> +Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, arguments that
>  are not available are not listed.  Partially available arguments
> @@ -33549,13 +33551,15 @@ Show a single frame:
>  Display the local variable names for the selected frame.  If
>  @var{print-values} is 0 or @code{--no-values}, print only the names of
>  the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  In this last case, a frontend can immediately
> -display the value of simple data types and create variable objects for
> -other data types when the user wishes to explore their values in
> -more detail.  If the option @code{--no-frame-filters} is supplied, then
> -Python frame filters will not be executed.
> +values; if it is 2 or @code{--simple-values}, print the name, type and
> +value for simple data types, and the name and type for arrays,
> +structures and unions; and if it is 3 or @code{--scalar-values}, print
> +the name, type and value for scalar data types, and the name and type
> +otherwise.  In the last two cases, a frontend can immediately display
> +the value of simple or scalar data types and create variable objects
> +for other data types when the user wishes to explore their values in
> +more detail.  If the option @code{--no-frame-filters} is supplied,
> +then Python frame filters will not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  that are not available are not listed.  Partially available local
> @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
>   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
>  @end smallexample
>
> -Display the names of local variables and function arguments for the selected frame.  If
> -@var{print-values} is 0 or @code{--no-values}, print only the names of
> -the variables; if it is 1 or @code{--all-values}, print also their
> -values; and if it is 2 or @code{--simple-values}, print the name,
> -type and value for simple data types, and the name and type for arrays,
> -structures and unions.  If the option @code{--no-frame-filters} is
> -supplied, then Python frame filters will not be executed.
> +Display the names of local variables and function arguments for the
> +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> +print only the names of the variables; if it is 1 or
> +@code{--all-values}, print also their values; if it is 2 or
> +@code{--simple-values}, print the name, type and value for simple data
> +types, and the name and type for arrays, structures and unions; and if
> +it is 3 or @code{--scalar-values}, print the name, type and value for
> +scalar data types, and the name and type otherwise.  If the option
> +@code{--no-frame-filters} is supplied, then Python frame filters will
> +not be executed.
>
>  If the @code{--skip-unavailable} option is specified, local variables
>  and arguments that are not available are not listed.  Partially
> @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
>  a single argument or if @var{print-values} has a value of 0 or
>  @code{--no-values}, print only the names of the variables; if
>  @var{print-values} is 1 or @code{--all-values}, also print their
> -values; and if it is 2 or @code{--simple-values} print the name and
> -value for simple data types and just the name for arrays, structures
> -and unions.
> +values; if it is 2 or @code{--simple-values} print the name and value
> +for simple data types and just the name for arrays, structures and
> +unions; and if it is 3 or @code{--scalar-values}, print the name and
> +value for scalar data types, and just the name otherwise.
>
>  @var{from} and @var{to}, if specified, indicate the range of children
>  to report.  If @var{from} or @var{to} is less than zero, the range is
> @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
>  @item data-disassemble-a-option
>  Indicates that the @code{-data-disassemble} command supports the @option{-a}
>  option (@pxref{GDB/MI Data Manipulation}).
> +@item scalar-values
> +Indicates that the @code{-stack-list-arguments},
> +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> +@code{-var-list-children} commands support the
> +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
>  @end ftable
>
>  @subheading The @code{-list-target-features} Command
> diff --git a/gdb/extension.h b/gdb/extension.h
> index 47839ea50be..16d12f00f41 100644
> --- a/gdb/extension.h
> +++ b/gdb/extension.h
> @@ -121,6 +121,9 @@ enum ext_lang_frame_args
>         arguments when invoked from the MI. */
>      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
>
> +    /* Print only scalar values for arguments when invoked from the MI.  */
> +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> +
>      /* Print only scalar values for arguments when invoked from the CLI. */
>      CLI_SCALAR_VALUES,
>
> diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> index 0fe204dbc66..43eea32e460 100644
> --- a/gdb/mi/mi-cmd-stack.c
> +++ b/gdb/mi/mi-cmd-stack.c
> @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
>                && arg->error == NULL)
>               || values == PRINT_SIMPLE_VALUES
> +             || values == PRINT_SCALAR_VALUES
>               || (values == PRINT_ALL_VALUES
>                   && (arg->val != NULL || arg->error != NULL)));
>    gdb_assert (arg->entry_kind == print_entry_values_no
> @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
>    if (what == all && arg->sym->is_argument ())
>      uiout->field_signed ("arg", 1);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      {
>        check_typedef (arg->sym->type ());
>        type_print (arg->sym->type (), "", &stb, -1);
> @@ -571,7 +573,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
>    const struct block *block;
>    struct symbol *sym;
>    struct block_iterator iter;
> -  struct type *type;
>    const char *name_of_result;
>    struct ui_out *uiout = current_uiout;
>
> @@ -647,21 +648,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
>               entryarg.sym = sym2;
>               entryarg.entry_kind = print_entry_values_no;
>
> -             switch (values)
> +             if (mi_print_type_p (sym->type (), values))
>                 {
> -               case PRINT_SIMPLE_VALUES:
> -                 type = check_typedef (sym2->type ());
> -                 if (type->code () != TYPE_CODE_ARRAY
> -                     && type->code () != TYPE_CODE_STRUCT
> -                     && type->code () != TYPE_CODE_UNION)
> -                   {
> -               case PRINT_ALL_VALUES:
>                   if (sym->is_argument ())
>                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
>                   else
>                     read_frame_local (sym2, fi, &arg);
> -                   }
> -                 break;
>                 }
>
>               if (arg.entry_kind != print_entry_values_only)
> diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> index 3db09cf7815..1d4d3ec8534 100644
> --- a/gdb/mi/mi-cmd-var.c
> +++ b/gdb/mi/mi-cmd-var.c
> @@ -32,6 +32,7 @@
>  #include "mi-parse.h"
>  #include "gdbsupport/gdb_optional.h"
>  #include "inferior.h"
> +#include "valprint.h"
>
>  static void varobj_update_one (struct varobj *var,
>                                enum print_values print_values,
> @@ -314,6 +315,40 @@ mi_cmd_var_info_num_children (const char *command, char **argv, int argc)
>    uiout->field_signed ("numchild", varobj_get_num_children (var));
>  }
>
> +/* See mi-cmds.h.  */
> +
> +bool
> +mi_simple_type_p (struct type *type)
> +{
> +  type = check_typedef (type);
> +  switch (type->code ())
> +    {
> +    case TYPE_CODE_ARRAY:
> +    case TYPE_CODE_STRUCT:
> +    case TYPE_CODE_UNION:
> +      return false;
> +    default:
> +      return true;
> +    }
> +}
> +
> +bool
> +mi_print_type_p (struct type *type, enum print_values print_values)
> +{
> +  switch (print_values)
> +    {
> +    default:
> +    case PRINT_NO_VALUES:
> +      return false;
> +    case PRINT_ALL_VALUES:
> +      return true;
> +    case PRINT_SIMPLE_VALUES:
> +      return mi_simple_type_p (type);
> +    case PRINT_SCALAR_VALUES:
> +      return val_print_scalar_type_p (type);
> +    }
> +}
> +
>  /* Return 1 if given the argument PRINT_VALUES we should display
>     the varobj VAR.  */
>
> @@ -335,15 +370,7 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
>    if (type == NULL)
>      return 1;
>    else
> -    {
> -      type = check_typedef (type);
> -
> -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> -        and that type is not a compound type.  */
> -      return (type->code () != TYPE_CODE_ARRAY
> -             && type->code () != TYPE_CODE_STRUCT
> -             && type->code () != TYPE_CODE_UNION);
> -    }
> +    return mi_print_type_p (type, print_values);
>  }
>
>  void
> diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> index 9ffb11bf997..3a5b6b72be9 100644
> --- a/gdb/mi/mi-cmds.h
> +++ b/gdb/mi/mi-cmds.h
> @@ -29,7 +29,8 @@
>  enum print_values {
>     PRINT_NO_VALUES,
>     PRINT_ALL_VALUES,
> -   PRINT_SIMPLE_VALUES
> +   PRINT_SIMPLE_VALUES,
> +   PRINT_SCALAR_VALUES
>  };
>
>  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> @@ -226,4 +227,18 @@ using remove_mi_cmd_entries_ftype
>    = gdb::function_view<bool (mi_command *)>;
>  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
>
> +/* Return true if TYPE is suitable for printing with PRINT_SIMPLE_VALUES: that
> +   is, if TYPE is not an array, structure or union.
> +
> +   Note that reference types are always considered simple by this function, even
> +   if the referenced type is non-scalar.  This behaviour is retained for backwards
> +   compatibility, and PRINT_SCALAR_VALUES may be used instead to avoid printing
> +   references to non-scalar values.  */
> +
> +extern bool mi_simple_type_p (struct type *type);
> +
> +/* Return true if TYPE is suitable for printing with PRINT_VALUES.  */
> +
> +extern bool mi_print_type_p (struct type *type, enum print_values values);
> +
>  #endif /* MI_MI_CMDS_H */
> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index b758f398e2a..9bb00390370 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
>        uiout->field_string (NULL, "undefined-command-error-code");
>        uiout->field_string (NULL, "exec-run-start-option");
>        uiout->field_string (NULL, "data-disassemble-a-option");
> +      uiout->field_string (NULL, "scalar-values");
>
>        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
>         uiout->field_string (NULL, "python");
> @@ -2462,14 +2463,14 @@ static void
>  print_variable_or_computed (const char *expression, enum print_values values)
>  {
>    struct value *val;
> -  struct type *type;
>    struct ui_out *uiout = current_uiout;
>
>    string_file stb;
>
>    expression_up expr = parse_expression (expression);
>
> -  if (values == PRINT_SIMPLE_VALUES)
> +  if (values == PRINT_SIMPLE_VALUES
> +      || values == PRINT_SCALAR_VALUES)
>      val = evaluate_type (expr.get ());
>    else
>      val = evaluate_expression (expr.get ());
> @@ -2482,31 +2483,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
>    switch (values)
>      {
>      case PRINT_SIMPLE_VALUES:
> -      type = check_typedef (value_type (val));
> +    case PRINT_SCALAR_VALUES:
>        type_print (value_type (val), "", &stb, -1);
>        uiout->field_stream ("type", stb);
> -      if (type->code () != TYPE_CODE_ARRAY
> -         && type->code () != TYPE_CODE_STRUCT
> -         && type->code () != TYPE_CODE_UNION)
> -       {
> -         struct value_print_options opts;
> -
> -         get_no_prettyformat_print_options (&opts);
> -         opts.deref_ref = 1;
> -         common_val_print (val, &stb, 0, &opts, current_language);
> -         uiout->field_stream ("value", stb);
> -       }
>        break;
> -    case PRINT_ALL_VALUES:
> -      {
> -       struct value_print_options opts;
> +    }
>
> -       get_no_prettyformat_print_options (&opts);
> -       opts.deref_ref = 1;
> -       common_val_print (val, &stb, 0, &opts, current_language);
> -       uiout->field_stream ("value", stb);
> -      }
> -      break;
> +  if (mi_print_type_p (value_type (val), values))
> +    {
> +      struct value_print_options opts;
> +      get_no_prettyformat_print_options (&opts);
> +      opts.deref_ref = 1;
> +      common_val_print (val, &stb, 0, &opts, current_language);
> +      uiout->field_stream ("value", stb);
>      }
>  }
>
> diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> index dfa7b462714..dd70e4648a1 100644
> --- a/gdb/mi/mi-parse.c
> +++ b/gdb/mi/mi-parse.c
> @@ -29,6 +29,7 @@
>  #include "language.h"
>
>  static const char mi_no_values[] = "--no-values";
> +static const char mi_scalar_values[] = "--scalar-values";
>  static const char mi_simple_values[] = "--simple-values";
>  static const char mi_all_values[] = "--all-values";
>
> @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
>     else if (strcmp (name, "2") == 0
>             || strcmp (name, mi_simple_values) == 0)
>       return PRINT_SIMPLE_VALUES;
> +   else if (strcmp (name, "3") == 0
> +           || strcmp (name, mi_scalar_values) == 0)
> +     return PRINT_SCALAR_VALUES;
>     else
>       error (_("Unknown value for PRINT_VALUES: must be: \
> -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> -           mi_no_values, mi_all_values, mi_simple_values);
> +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
>  }
> diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> index 366f3745b9d..e295036f46e 100644
> --- a/gdb/python/py-framefilter.c
> +++ b/gdb/python/py-framefilter.c
> @@ -227,26 +227,27 @@ py_print_value (struct ui_out *out, struct value *val,
>                 enum ext_lang_frame_args args_type,
>                 const struct language_defn *language)
>  {
> -  int should_print = 0;
> +  int should_print;
>
>    /* MI does not print certain values, differentiated by type,
>       depending on what ARGS_TYPE indicates.  Test type against option.
>       For CLI print all values.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES
> -      || args_type == MI_PRINT_ALL_VALUES)
> +  switch (args_type)
>      {
> -      struct type *type = check_typedef (value_type (val));
> -
> -      if (args_type == MI_PRINT_ALL_VALUES)
> -       should_print = 1;
> -      else if (args_type == MI_PRINT_SIMPLE_VALUES
> -              && type->code () != TYPE_CODE_ARRAY
> -              && type->code () != TYPE_CODE_STRUCT
> -              && type->code () != TYPE_CODE_UNION)
> -       should_print = 1;
> +    case NO_VALUES:
> +      should_print = 0;
> +      break;
> +    default:
> +    case MI_PRINT_ALL_VALUES:
> +      should_print = 1;
> +      break;
> +    case MI_PRINT_SIMPLE_VALUES:
> +      should_print = mi_print_type_p (value_type (val), PRINT_SIMPLE_VALUES);
> +      break;
> +    case MI_PRINT_SCALAR_VALUES:
> +      should_print = mi_print_type_p (value_type (val), PRINT_SCALAR_VALUES);
> +      break;
>      }
> -  else if (args_type != NO_VALUES)
> -    should_print = 1;
>
>    if (should_print)
>      {
> @@ -371,10 +372,12 @@ py_print_single_arg (struct ui_out *out,
>    if (print_args_field)
>      out->field_signed ("arg", 1);
>
> -  /* For MI print the type, but only for simple values.  This seems
> -     weird, but this is how MI choose to format the various output
> +  /* For MI print the type, but only for simple and scalar values. This
> +     seems weird, but this is how MI chooses to format the various output
>       types.  */
> -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> +  if ((args_type == MI_PRINT_SIMPLE_VALUES
> +       || args_type == MI_PRINT_SCALAR_VALUES)
> +      && val != NULL)
>      py_print_type (out, val);
>
>    if (val != NULL)
> @@ -603,7 +606,8 @@ enumerate_locals (PyObject *iter,
>        out->field_string ("name", sym_name.get ());
>        out->text (" = ");
>
> -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> +      if (args_type == MI_PRINT_SIMPLE_VALUES
> +          || args_type == MI_PRINT_SCALAR_VALUES)
>         py_print_type (out, val);
>
>        /* CLI always prints values for locals.  MI uses the
> diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> index d04c8153c65..2c74da00c18 100644
> --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> @@ -93,6 +93,11 @@ proc test_stack_args_listing {} {
>      # -stack-list-arguments 1 1 1
>      # -stack-list-arguments 1 1 3
>      # -stack-list-arguments
> +    # -stack-list-arguments 1 1 300
> +    # -stack-list-arguments 2 1 1
> +    # -stack-list-arguments --simple-values 1 1
> +    # -stack-list-arguments 3 1 1
> +    # -stack-list-arguments --scalar-values 1 1
>
>      mi_gdb_test "231-stack-list-arguments 0" \
>         "231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> @@ -125,6 +130,22 @@ proc test_stack_args_listing {} {
>      mi_gdb_test "235-stack-list-arguments 1 1 300" \
>         "235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
>         "stack args listing 1 1 300"
> +
> +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> +       "236\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> +       "stack args listing 2 1 1"
> +
> +    mi_gdb_test "237-stack-list-arguments --simple-values 1 1" \
> +       "237\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> +       "stack args listing --simple-values 1 1"
> +
> +    mi_gdb_test "238-stack-list-arguments 3 1 1" \
> +       "238\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> +       "stack args listing 3 1 1"
> +
> +    mi_gdb_test "239-stack-list-arguments --scalar-values 1 1" \
> +       "239\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> +       "stack args listing --scalar-values 1 1"
>  }
>
>  proc test_stack_info_depth {} {
> @@ -163,7 +184,7 @@ proc test_stack_locals_listing {} {
>      # -stack-list-locals 0 (--no-values)
>      # -stack-list-locals 1 (--all-values)
>      # -stack-list-locals 2 (--simple-values)
> -    # -stack-list-arguments
> +    # -stack-list-locals 3 (--scalar-values)
>
>      mi_gdb_test "232-stack-list-locals 0" \
>         "232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> @@ -179,10 +200,22 @@ proc test_stack_locals_listing {} {
>         "232\\^done,locals=\\\[\{name=\"A\",value=\"1\"\},\{name=\"B\",value=\"2\"\},\{name=\"C\",value=\"3\"\},\{name=\"D\",value=\"\\{0, 1, 2\\}\"\}\\\]" \
>         "stack locals listing of names and values"
>
> -    mi_gdb_test "232-stack-list-locals --simple-values" \
> +    mi_gdb_test "232-stack-list-locals 2" \
>         "232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
>         "stack locals listing, simple types: names and values, complex type: names and types"
>
> +    mi_gdb_test "232-stack-list-locals --simple-values" \
> +       "232\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> +       "stack locals listing with --simple-values"
> +
> +    mi_gdb_test "233-stack-list-locals 3" \
> +       "233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> +       "stack locals listing, scalar types: names and values, otherwise: names and types"
> +
> +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> +       "233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> +       "stack locals listing with --scalar-values"
> +
>      mi_gdb_test "234-stack-list-locals" \
>         "234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
>         "stack locals listing wrong"
> diff --git a/gdb/testsuite/gdb.mi/print-values.cc b/gdb/testsuite/gdb.mi/print-values.cc
> new file mode 100644
> index 00000000000..b52683d1537
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-values.cc
> @@ -0,0 +1,63 @@
> +/* This test case is part of GDB, the GNU debugger.
> +
> +   Copyright 2022 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* Test program for PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
> +
> +   In the function f:
> +
> +   * The arguments i, ir, and irr are ints or references to ints,
> +     which must be printed by both PRINT_SIMPLE_VALUES and
> +     PRINT_SCALAR_VALUES.
> +
> +   * The arguments a, s, and u are non-scalar values, which must not
> +     be printed by either PRINT_SIMPLE_VALUES or PRINT_SCALAR_VALUES.
> +
> +   * The arguments ar, arr, sr, srr, ur, and urr are references to
> +     non-scalar values, which must be printed by PRINT_SIMPLE_VALUES
> +     but not printed by PRINT_SCALAR_VALUES.  */
> +
> +struct s
> +{
> +  int v;
> +};
> +
> +union u
> +{
> +  int v;
> +};
> +
> +int
> +f (int i, int &ir, int &&irr,
> +   int a[1], int (&ar)[1], int (&&arr)[1],
> +   struct s s, struct s &sr, struct s &&srr,
> +   union u u, union u &ur, union u &&urr)
> +{
> +  return (i + ir + irr
> +          + a[0] + ar[0] + arr[0]
> +          + s.v + sr.v + srr.v
> +          + u.v + ur.v + urr.v);
> +}
> +
> +int
> +main (void)
> +{
> +  int i = 1, j = 2;
> +  int a[1] = { 4 }, b[1] = { 5 };
> +  struct s s = { 7 }, t = { 8 };
> +  union u u = { 10 }, v = { 11 };
> +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> +}
> diff --git a/gdb/testsuite/gdb.mi/print-values.exp b/gdb/testsuite/gdb.mi/print-values.exp
> new file mode 100644
> index 00000000000..7896d773119
> --- /dev/null
> +++ b/gdb/testsuite/gdb.mi/print-values.exp
> @@ -0,0 +1,53 @@
> +# Copyright 2022 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# Test of PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
> +#
> +# Test that PRINT_SIMPLE_VALUES distinguishes scalar and non-scalar
> +# types, except for C++ reference and rvalue reference types.
> +#
> +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> +# types, including C++ reference and rvalue reference types.
> +
> +if { [skip_cplus_tests] } { continue }
> +
> +load_lib mi-support.exp
> +standard_testfile .cc
> +
> +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> +    untested "failed to compile"
> +    return -1
> +}
> +
> +mi_clean_restart $binfile
> +
> +mi_runto_main
> +
> +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> +
> +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> +
> +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> +    "run until breakpoint on f"
> +
> +mi_gdb_test "-stack-list-arguments --simple-values" \
> +    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\",value=\"@$hex: \\{5\\}\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\",value=\"@$hex: \\{6\\}\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\",value=\"@$hex: \\{v = 8\\}\"\\},\\{name=\"srr\",type=\"s &&\",value=\"@$hex: \\{v = 9\\}\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\",value=\"@$hex: \\{v = 11\\}\"\\},\\{name=\"urr\",type=\"u &&\",value=\"@$hex: \\{v = 12\\}\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
> +    "stack list arguments, simple types: names, types and values, otherwise: names and types"
> +
> +mi_gdb_test "-stack-list-arguments --scalar-values" \
> +    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\"\\},\\{name=\"srr\",type=\"s &&\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\"\\},\\{name=\"urr\",type=\"u &&\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
> +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> +
> +mi_gdb_exit
> diff --git a/gdb/testsuite/gdb.python/py-framefilter-mi.exp b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> index 344067fe4a7..fa4e559e343 100644
> --- a/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> +++ b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> @@ -120,6 +120,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2" \
>      "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
>      "stack-list-arguments --no-frame-filters 2"
>
> +mi_gdb_test "-stack-list-arguments 3" \
> +    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"\}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> +    "stack-list-arguments 3"
> +
> +mi_gdb_test "-stack-list-arguments --no-frame-filters 3" \
> +    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> +    "stack-list-arguments --no-frame-filters 3"
> +
>
>  mi_gdb_test "-stack-list-arguments 2 0 3" \
>      "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},frame={level=\"3\",args=\\\[\\\]}\\\]" \
> @@ -133,6 +141,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2 22 27" \
>      "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
>      "stack-list-arguments --no-frame-filters 2 22 27"
>
> +mi_gdb_test "-stack-list-arguments 3 22 27" \
> +    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> +    "stack-list-arguments 3 22 27"
> +
> +mi_gdb_test "-stack-list-arguments --no-frame-filters 3 22 27" \
> +    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> +    "stack-list-arguments --no-frame-filters 3 22 27"
> +
>  #stack-list-locals
>  mi_gdb_test "-stack-list-locals --no-frame-filters 0" \
>      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
> @@ -146,6 +162,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters 2" \
>      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
>      "stack-list-locals --no-frame-filters 2"
>
> +mi_gdb_test "-stack-list-locals --no-frame-filters 3" \
> +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> +    "stack-list-locals --no-frame-filters 3"
> +
>  mi_gdb_test "-stack-list-locals --no-frame-filters --no-values" \
>      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
>      "stack-list-locals --no-frame-filters --no-values"
> @@ -158,6 +178,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters --simple-values" \
>      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
>      "stack-list-locals --no-frame-filters --simple-values"
>
> +mi_gdb_test "-stack-list-locals --no-frame-filters --scalar-values" \
> +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> +    "stack-list-locals --no-frame-filters --scalar-values"
> +
>  mi_gdb_test "-stack-list-locals 0" \
>      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
>      "stack-list-locals 0"
> @@ -170,6 +194,10 @@ mi_gdb_test "-stack-list-locals 2" \
>      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
>      "stack-list-locals 2"
>
> +mi_gdb_test "-stack-list-locals 3" \
> +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> +    "stack-list-locals 3"
> +
>  # stack-list-variables
>  mi_gdb_test "-stack-list-variables --no-frame-filters 0" \
>      "\\^done,variables=\\\[{name=\"foo\",arg=\"1\"},{name=\"bar\",arg=\"1\"},{name=\"fb\",arg=\"1\"},{name=\"bf\",arg=\"1\"},{name=\"str\"},{name=\"st2\"},{name=\"b\"},{name=\"c\"}\\\]" \
> --
> 2.26.0
>

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PING] [PATCH v5] [PR mi/29554] New PRINT-VALUES option '--scalar-values'.
  2022-11-03 16:20               ` [PING] " Gareth Rees
@ 2022-11-14  9:25                 ` Gareth Rees
  0 siblings, 0 replies; 25+ messages in thread
From: Gareth Rees @ 2022-11-14  9:25 UTC (permalink / raw)
  To: gdb-patches

Ping.

On Thu, 3 Nov 2022 at 16:20, Gareth Rees <grees@undo.io> wrote:
> After four rounds of review, this must be getting close to being
> mergeable! But do let me know if there's anything else that I need to
> improve here.
>
>
> On Thu, 20 Oct 2022 at 18:47, Gareth Rees <grees@undo.io> wrote:
> >
> > SUMMARY
> >
> > The '--simple-values' argument to '-stack-list-arguments' and similar
> > GDB/MI commands does not take reference types into account, so that
> > references to arbitrarily large structures are considered "simple" and
> > printed. This means that the '--simple-values' argument cannot be used
> > by IDEs when tracing the stack due to the time taken to print large
> > structures passed by reference.
> >
> > DETAILS
> >
> > Various GDB/MI commands ('-stack-list-arguments', '-stack-list-locals',
> > '-stack-list-variables' and so on) take a PRINT-VALUES argument which
> > may be '--no-values' (0), '--all-values' (1) or '--simple-values' (2).
> > In the '--simple-values' case, the command is supposed to print the
> > name, type, and value of variables with simple types, and print only the
> > name and type of variables with compound types.
> >
> > The '--simple-values' argument ought to be suitable for IDEs that need
> > to update their user interface with the program's call stack every time
> > the program stops. However, it does not take C++ reference types into
> > account, and this makes the argument unsuitable for this purpose.
> >
> > For example, consider the following C++ program:
> >
> >     struct s {
> >         int v[10];
> >     };
> >
> >     int
> >     sum(const struct s &s)
> >     {
> >         int total = 0;
> >         for (int i = 0; i < 10; ++i) total += s.v[i];
> >         return total;
> >     }
> >
> >     int
> >     main(void)
> >     {
> >         struct s s = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
> >         return sum(s);
> >     }
> >
> > If we start GDB in MI mode and continue to 'sum', the behaviour of
> > '-stack-list-arguments' is as follows:
> >
> >     (gdb)
> >     -stack-list-arguments --simple-values
> >     ^done,stack-args=[frame={level="0",args=[{name="s",type="const s &",value="@0x7fffffffe310: {v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}"}]},frame={level="1",args=[]}]
> >
> > Note that the value of the argument 's' was printed, even though 's' is
> > a reference to a structure, which is not a simple value.
> >
> > See https://github.com/microsoft/MIEngine/pull/673 for a case where this
> > behaviour caused Microsoft to avoid the use of '--simple-values' in
> > their MIEngine debug adapter, because it caused Visual Studio Code to
> > take too long to refresh the call stack in the user interface.
> >
> > SOLUTIONS
> >
> > There are two ways we could fix this problem, depending on whether we
> > consider the current behaviour to be a bug that can be fixed.
> >
> > 1. If the current behaviour is a bug that can be fixed, then we can
> >    update the behaviour of '--simple-values' so that it takes
> >    reference types into account: that is, a value is simple if it is
> >    neither an array, struct, or union, nor a reference to an array,
> >    struct or union.
> >
> >    In this case we must add a feature to the '-list-features' command so
> >    that IDEs can detect that it is safe to use the '--simple-values'
> >    argument when refreshing the call stack.
> >
> > 2. If the current behaviour is not a bug, or cannot be changed due to
> >    backwards compatibility concerns, then we can add a new option for
> >    the PRINT-VALUES argument, for example, '--scalar-values' (3), that
> >    would be suitable for use by IDEs.
> >
> >    In this case we must add a feature to the '-list-features' command so
> >    that IDEs can detect that the '--scalar-values' argument is
> >    available for use when refreshing the call stack.
> >
> > PATCH
> >
> > This patch implements solution (2), adding a '--scalar-values' option
> > for the PRINT-VALUES argument to '-stack-list-arguments' and similar
> > commands. This option prints the value only for scalars and so matches
> > the behaviour of the 'scalars' argument to the 'set print
> > frame-arguments' command. References to structures are not scalars,
> > and so the option is suitable for use by IDEs.
> >
> > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29554
> > ---
> >  gdb/NEWS                                      |  9 +++
> >  gdb/doc/gdb.texinfo                           | 59 ++++++++++-------
> >  gdb/extension.h                               |  3 +
> >  gdb/mi/mi-cmd-stack.c                         | 16 ++---
> >  gdb/mi/mi-cmd-var.c                           | 45 ++++++++++---
> >  gdb/mi/mi-cmds.h                              | 17 ++++-
> >  gdb/mi/mi-main.c                              | 35 ++++-------
> >  gdb/mi/mi-parse.c                             |  8 ++-
> >  gdb/python/py-framefilter.c                   | 40 ++++++------
> >  gdb/testsuite/gdb.mi/mi-stack.exp             | 37 ++++++++++-
> >  gdb/testsuite/gdb.mi/print-values.cc          | 63 +++++++++++++++++++
> >  gdb/testsuite/gdb.mi/print-values.exp         | 53 ++++++++++++++++
> >  .../gdb.python/py-framefilter-mi.exp          | 28 +++++++++
> >  13 files changed, 323 insertions(+), 90 deletions(-)
> >  create mode 100644 gdb/testsuite/gdb.mi/print-values.cc
> >  create mode 100644 gdb/testsuite/gdb.mi/print-values.exp
> >
> > diff --git a/gdb/NEWS b/gdb/NEWS
> > index dee0ac2ecd8..9ad441691ea 100644
> > --- a/gdb/NEWS
> > +++ b/gdb/NEWS
> > @@ -114,6 +114,15 @@ maintenance info line-table
> >    entry corresponds to an address where a breakpoint should be placed
> >    to be at the first instruction past a function's prologue.
> >
> > +* MI changes
> > +
> > +  ** The '-stack-list-arguments', '-stack-list-locals',
> > +     '-stack-list-variables', and '-var-list-children' commands
> > +     support the '--scalar-values' option, which requests the command
> > +     to print values only for scalar types.  Support for this feature
> > +     can be verified by using the '-list-features' command, which
> > +     now includes "scalar-values".
> > +
> >  * New targets
> >
> >  GNU/Linux/LoongArch (gdbserver)        loongarch*-*-linux*
> > diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> > index 238a49b027d..b2b53de1022 100644
> > --- a/gdb/doc/gdb.texinfo
> > +++ b/gdb/doc/gdb.texinfo
> > @@ -33326,12 +33326,14 @@ larger than the actual number of frames.  On the other hand,
> >  @var{high-frame} may be larger than the actual number of frames, in
> >  which case only existing frames will be returned.
> >
> > -If @var{print-values} is 0 or @code{--no-values}, print only the names of
> > -the variables; if it is 1 or @code{--all-values}, print also their
> > -values; and if it is 2 or @code{--simple-values}, print the name,
> > -type and value for simple data types, and the name and type for arrays,
> > -structures and unions.  If the option @code{--no-frame-filters} is
> > -supplied, then Python frame filters will not be executed.
> > +If @var{print-values} is 0 or @code{--no-values}, print only the names
> > +of the variables; if it is 1 or @code{--all-values}, print also their
> > +values; if it is 2 or @code{--simple-values}, print the name, type and
> > +value for simple data types, and the name and type for arrays,
> > +structures and unions; and if it is 3 or @code{--scalar-values}, print
> > +the name, type and value for scalar data types, and the name and type
> > +otherwise.  If the option @code{--no-frame-filters} is supplied, then
> > +Python frame filters will not be executed.
> >
> >  If the @code{--skip-unavailable} option is specified, arguments that
> >  are not available are not listed.  Partially available arguments
> > @@ -33549,13 +33551,15 @@ Show a single frame:
> >  Display the local variable names for the selected frame.  If
> >  @var{print-values} is 0 or @code{--no-values}, print only the names of
> >  the variables; if it is 1 or @code{--all-values}, print also their
> > -values; and if it is 2 or @code{--simple-values}, print the name,
> > -type and value for simple data types, and the name and type for arrays,
> > -structures and unions.  In this last case, a frontend can immediately
> > -display the value of simple data types and create variable objects for
> > -other data types when the user wishes to explore their values in
> > -more detail.  If the option @code{--no-frame-filters} is supplied, then
> > -Python frame filters will not be executed.
> > +values; if it is 2 or @code{--simple-values}, print the name, type and
> > +value for simple data types, and the name and type for arrays,
> > +structures and unions; and if it is 3 or @code{--scalar-values}, print
> > +the name, type and value for scalar data types, and the name and type
> > +otherwise.  In the last two cases, a frontend can immediately display
> > +the value of simple or scalar data types and create variable objects
> > +for other data types when the user wishes to explore their values in
> > +more detail.  If the option @code{--no-frame-filters} is supplied,
> > +then Python frame filters will not be executed.
> >
> >  If the @code{--skip-unavailable} option is specified, local variables
> >  that are not available are not listed.  Partially available local
> > @@ -33594,13 +33598,16 @@ This command is deprecated in favor of the
> >   -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
> >  @end smallexample
> >
> > -Display the names of local variables and function arguments for the selected frame.  If
> > -@var{print-values} is 0 or @code{--no-values}, print only the names of
> > -the variables; if it is 1 or @code{--all-values}, print also their
> > -values; and if it is 2 or @code{--simple-values}, print the name,
> > -type and value for simple data types, and the name and type for arrays,
> > -structures and unions.  If the option @code{--no-frame-filters} is
> > -supplied, then Python frame filters will not be executed.
> > +Display the names of local variables and function arguments for the
> > +selected frame.  If @var{print-values} is 0 or @code{--no-values},
> > +print only the names of the variables; if it is 1 or
> > +@code{--all-values}, print also their values; if it is 2 or
> > +@code{--simple-values}, print the name, type and value for simple data
> > +types, and the name and type for arrays, structures and unions; and if
> > +it is 3 or @code{--scalar-values}, print the name, type and value for
> > +scalar data types, and the name and type otherwise.  If the option
> > +@code{--no-frame-filters} is supplied, then Python frame filters will
> > +not be executed.
> >
> >  If the @code{--skip-unavailable} option is specified, local variables
> >  and arguments that are not available are not listed.  Partially
> > @@ -34029,9 +34036,10 @@ create variable objects for them, if they do not already exist.  With
> >  a single argument or if @var{print-values} has a value of 0 or
> >  @code{--no-values}, print only the names of the variables; if
> >  @var{print-values} is 1 or @code{--all-values}, also print their
> > -values; and if it is 2 or @code{--simple-values} print the name and
> > -value for simple data types and just the name for arrays, structures
> > -and unions.
> > +values; if it is 2 or @code{--simple-values} print the name and value
> > +for simple data types and just the name for arrays, structures and
> > +unions; and if it is 3 or @code{--scalar-values}, print the name and
> > +value for scalar data types, and just the name otherwise.
> >
> >  @var{from} and @var{to}, if specified, indicate the range of children
> >  to report.  If @var{from} or @var{to} is less than zero, the range is
> > @@ -37295,6 +37303,11 @@ option (@pxref{GDB/MI Program Execution}).
> >  @item data-disassemble-a-option
> >  Indicates that the @code{-data-disassemble} command supports the @option{-a}
> >  option (@pxref{GDB/MI Data Manipulation}).
> > +@item scalar-values
> > +Indicates that the @code{-stack-list-arguments},
> > +@code{-stack-list-locals}, @code{-stack-list-variables}, and
> > +@code{-var-list-children} commands support the
> > +@option{--scalar-values} option (@pxref{GDB/MI Stack Manipulation}).
> >  @end ftable
> >
> >  @subheading The @code{-list-target-features} Command
> > diff --git a/gdb/extension.h b/gdb/extension.h
> > index 47839ea50be..16d12f00f41 100644
> > --- a/gdb/extension.h
> > +++ b/gdb/extension.h
> > @@ -121,6 +121,9 @@ enum ext_lang_frame_args
> >         arguments when invoked from the MI. */
> >      MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
> >
> > +    /* Print only scalar values for arguments when invoked from the MI.  */
> > +    MI_PRINT_SCALAR_VALUES = PRINT_SCALAR_VALUES,
> > +
> >      /* Print only scalar values for arguments when invoked from the CLI. */
> >      CLI_SCALAR_VALUES,
> >
> > diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
> > index 0fe204dbc66..43eea32e460 100644
> > --- a/gdb/mi/mi-cmd-stack.c
> > +++ b/gdb/mi/mi-cmd-stack.c
> > @@ -494,6 +494,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
> >    gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
> >                && arg->error == NULL)
> >               || values == PRINT_SIMPLE_VALUES
> > +             || values == PRINT_SCALAR_VALUES
> >               || (values == PRINT_ALL_VALUES
> >                   && (arg->val != NULL || arg->error != NULL)));
> >    gdb_assert (arg->entry_kind == print_entry_values_no
> > @@ -525,7 +526,8 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
> >    if (what == all && arg->sym->is_argument ())
> >      uiout->field_signed ("arg", 1);
> >
> > -  if (values == PRINT_SIMPLE_VALUES)
> > +  if (values == PRINT_SIMPLE_VALUES
> > +      || values == PRINT_SCALAR_VALUES)
> >      {
> >        check_typedef (arg->sym->type ());
> >        type_print (arg->sym->type (), "", &stb, -1);
> > @@ -571,7 +573,6 @@ list_args_or_locals (const frame_print_options &fp_opts,
> >    const struct block *block;
> >    struct symbol *sym;
> >    struct block_iterator iter;
> > -  struct type *type;
> >    const char *name_of_result;
> >    struct ui_out *uiout = current_uiout;
> >
> > @@ -647,21 +648,12 @@ list_args_or_locals (const frame_print_options &fp_opts,
> >               entryarg.sym = sym2;
> >               entryarg.entry_kind = print_entry_values_no;
> >
> > -             switch (values)
> > +             if (mi_print_type_p (sym->type (), values))
> >                 {
> > -               case PRINT_SIMPLE_VALUES:
> > -                 type = check_typedef (sym2->type ());
> > -                 if (type->code () != TYPE_CODE_ARRAY
> > -                     && type->code () != TYPE_CODE_STRUCT
> > -                     && type->code () != TYPE_CODE_UNION)
> > -                   {
> > -               case PRINT_ALL_VALUES:
> >                   if (sym->is_argument ())
> >                     read_frame_arg (fp_opts, sym2, fi, &arg, &entryarg);
> >                   else
> >                     read_frame_local (sym2, fi, &arg);
> > -                   }
> > -                 break;
> >                 }
> >
> >               if (arg.entry_kind != print_entry_values_only)
> > diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c
> > index 3db09cf7815..1d4d3ec8534 100644
> > --- a/gdb/mi/mi-cmd-var.c
> > +++ b/gdb/mi/mi-cmd-var.c
> > @@ -32,6 +32,7 @@
> >  #include "mi-parse.h"
> >  #include "gdbsupport/gdb_optional.h"
> >  #include "inferior.h"
> > +#include "valprint.h"
> >
> >  static void varobj_update_one (struct varobj *var,
> >                                enum print_values print_values,
> > @@ -314,6 +315,40 @@ mi_cmd_var_info_num_children (const char *command, char **argv, int argc)
> >    uiout->field_signed ("numchild", varobj_get_num_children (var));
> >  }
> >
> > +/* See mi-cmds.h.  */
> > +
> > +bool
> > +mi_simple_type_p (struct type *type)
> > +{
> > +  type = check_typedef (type);
> > +  switch (type->code ())
> > +    {
> > +    case TYPE_CODE_ARRAY:
> > +    case TYPE_CODE_STRUCT:
> > +    case TYPE_CODE_UNION:
> > +      return false;
> > +    default:
> > +      return true;
> > +    }
> > +}
> > +
> > +bool
> > +mi_print_type_p (struct type *type, enum print_values print_values)
> > +{
> > +  switch (print_values)
> > +    {
> > +    default:
> > +    case PRINT_NO_VALUES:
> > +      return false;
> > +    case PRINT_ALL_VALUES:
> > +      return true;
> > +    case PRINT_SIMPLE_VALUES:
> > +      return mi_simple_type_p (type);
> > +    case PRINT_SCALAR_VALUES:
> > +      return val_print_scalar_type_p (type);
> > +    }
> > +}
> > +
> >  /* Return 1 if given the argument PRINT_VALUES we should display
> >     the varobj VAR.  */
> >
> > @@ -335,15 +370,7 @@ mi_print_value_p (struct varobj *var, enum print_values print_values)
> >    if (type == NULL)
> >      return 1;
> >    else
> > -    {
> > -      type = check_typedef (type);
> > -
> > -      /* For PRINT_SIMPLE_VALUES, only print the value if it has a type
> > -        and that type is not a compound type.  */
> > -      return (type->code () != TYPE_CODE_ARRAY
> > -             && type->code () != TYPE_CODE_STRUCT
> > -             && type->code () != TYPE_CODE_UNION);
> > -    }
> > +    return mi_print_type_p (type, print_values);
> >  }
> >
> >  void
> > diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
> > index 9ffb11bf997..3a5b6b72be9 100644
> > --- a/gdb/mi/mi-cmds.h
> > +++ b/gdb/mi/mi-cmds.h
> > @@ -29,7 +29,8 @@
> >  enum print_values {
> >     PRINT_NO_VALUES,
> >     PRINT_ALL_VALUES,
> > -   PRINT_SIMPLE_VALUES
> > +   PRINT_SIMPLE_VALUES,
> > +   PRINT_SCALAR_VALUES
> >  };
> >
> >  typedef void (mi_cmd_argv_ftype) (const char *command, char **argv, int argc);
> > @@ -226,4 +227,18 @@ using remove_mi_cmd_entries_ftype
> >    = gdb::function_view<bool (mi_command *)>;
> >  extern void remove_mi_cmd_entries (remove_mi_cmd_entries_ftype callback);
> >
> > +/* Return true if TYPE is suitable for printing with PRINT_SIMPLE_VALUES: that
> > +   is, if TYPE is not an array, structure or union.
> > +
> > +   Note that reference types are always considered simple by this function, even
> > +   if the referenced type is non-scalar.  This behaviour is retained for backwards
> > +   compatibility, and PRINT_SCALAR_VALUES may be used instead to avoid printing
> > +   references to non-scalar values.  */
> > +
> > +extern bool mi_simple_type_p (struct type *type);
> > +
> > +/* Return true if TYPE is suitable for printing with PRINT_VALUES.  */
> > +
> > +extern bool mi_print_type_p (struct type *type, enum print_values values);
> > +
> >  #endif /* MI_MI_CMDS_H */
> > diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> > index b758f398e2a..9bb00390370 100644
> > --- a/gdb/mi/mi-main.c
> > +++ b/gdb/mi/mi-main.c
> > @@ -1663,6 +1663,7 @@ mi_cmd_list_features (const char *command, char **argv, int argc)
> >        uiout->field_string (NULL, "undefined-command-error-code");
> >        uiout->field_string (NULL, "exec-run-start-option");
> >        uiout->field_string (NULL, "data-disassemble-a-option");
> > +      uiout->field_string (NULL, "scalar-values");
> >
> >        if (ext_lang_initialized_p (get_ext_lang_defn (EXT_LANG_PYTHON)))
> >         uiout->field_string (NULL, "python");
> > @@ -2462,14 +2463,14 @@ static void
> >  print_variable_or_computed (const char *expression, enum print_values values)
> >  {
> >    struct value *val;
> > -  struct type *type;
> >    struct ui_out *uiout = current_uiout;
> >
> >    string_file stb;
> >
> >    expression_up expr = parse_expression (expression);
> >
> > -  if (values == PRINT_SIMPLE_VALUES)
> > +  if (values == PRINT_SIMPLE_VALUES
> > +      || values == PRINT_SCALAR_VALUES)
> >      val = evaluate_type (expr.get ());
> >    else
> >      val = evaluate_expression (expr.get ());
> > @@ -2482,31 +2483,19 @@ print_variable_or_computed (const char *expression, enum print_values values)
> >    switch (values)
> >      {
> >      case PRINT_SIMPLE_VALUES:
> > -      type = check_typedef (value_type (val));
> > +    case PRINT_SCALAR_VALUES:
> >        type_print (value_type (val), "", &stb, -1);
> >        uiout->field_stream ("type", stb);
> > -      if (type->code () != TYPE_CODE_ARRAY
> > -         && type->code () != TYPE_CODE_STRUCT
> > -         && type->code () != TYPE_CODE_UNION)
> > -       {
> > -         struct value_print_options opts;
> > -
> > -         get_no_prettyformat_print_options (&opts);
> > -         opts.deref_ref = 1;
> > -         common_val_print (val, &stb, 0, &opts, current_language);
> > -         uiout->field_stream ("value", stb);
> > -       }
> >        break;
> > -    case PRINT_ALL_VALUES:
> > -      {
> > -       struct value_print_options opts;
> > +    }
> >
> > -       get_no_prettyformat_print_options (&opts);
> > -       opts.deref_ref = 1;
> > -       common_val_print (val, &stb, 0, &opts, current_language);
> > -       uiout->field_stream ("value", stb);
> > -      }
> > -      break;
> > +  if (mi_print_type_p (value_type (val), values))
> > +    {
> > +      struct value_print_options opts;
> > +      get_no_prettyformat_print_options (&opts);
> > +      opts.deref_ref = 1;
> > +      common_val_print (val, &stb, 0, &opts, current_language);
> > +      uiout->field_stream ("value", stb);
> >      }
> >  }
> >
> > diff --git a/gdb/mi/mi-parse.c b/gdb/mi/mi-parse.c
> > index dfa7b462714..dd70e4648a1 100644
> > --- a/gdb/mi/mi-parse.c
> > +++ b/gdb/mi/mi-parse.c
> > @@ -29,6 +29,7 @@
> >  #include "language.h"
> >
> >  static const char mi_no_values[] = "--no-values";
> > +static const char mi_scalar_values[] = "--scalar-values";
> >  static const char mi_simple_values[] = "--simple-values";
> >  static const char mi_all_values[] = "--all-values";
> >
> > @@ -383,8 +384,11 @@ mi_parse_print_values (const char *name)
> >     else if (strcmp (name, "2") == 0
> >             || strcmp (name, mi_simple_values) == 0)
> >       return PRINT_SIMPLE_VALUES;
> > +   else if (strcmp (name, "3") == 0
> > +           || strcmp (name, mi_scalar_values) == 0)
> > +     return PRINT_SCALAR_VALUES;
> >     else
> >       error (_("Unknown value for PRINT_VALUES: must be: \
> > -0 or \"%s\", 1 or \"%s\", 2 or \"%s\""),
> > -           mi_no_values, mi_all_values, mi_simple_values);
> > +0 or \"%s\", 1 or \"%s\", 2 or \"%s\", 3 or \"%s\""),
> > +           mi_no_values, mi_all_values, mi_simple_values, mi_scalar_values);
> >  }
> > diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
> > index 366f3745b9d..e295036f46e 100644
> > --- a/gdb/python/py-framefilter.c
> > +++ b/gdb/python/py-framefilter.c
> > @@ -227,26 +227,27 @@ py_print_value (struct ui_out *out, struct value *val,
> >                 enum ext_lang_frame_args args_type,
> >                 const struct language_defn *language)
> >  {
> > -  int should_print = 0;
> > +  int should_print;
> >
> >    /* MI does not print certain values, differentiated by type,
> >       depending on what ARGS_TYPE indicates.  Test type against option.
> >       For CLI print all values.  */
> > -  if (args_type == MI_PRINT_SIMPLE_VALUES
> > -      || args_type == MI_PRINT_ALL_VALUES)
> > +  switch (args_type)
> >      {
> > -      struct type *type = check_typedef (value_type (val));
> > -
> > -      if (args_type == MI_PRINT_ALL_VALUES)
> > -       should_print = 1;
> > -      else if (args_type == MI_PRINT_SIMPLE_VALUES
> > -              && type->code () != TYPE_CODE_ARRAY
> > -              && type->code () != TYPE_CODE_STRUCT
> > -              && type->code () != TYPE_CODE_UNION)
> > -       should_print = 1;
> > +    case NO_VALUES:
> > +      should_print = 0;
> > +      break;
> > +    default:
> > +    case MI_PRINT_ALL_VALUES:
> > +      should_print = 1;
> > +      break;
> > +    case MI_PRINT_SIMPLE_VALUES:
> > +      should_print = mi_print_type_p (value_type (val), PRINT_SIMPLE_VALUES);
> > +      break;
> > +    case MI_PRINT_SCALAR_VALUES:
> > +      should_print = mi_print_type_p (value_type (val), PRINT_SCALAR_VALUES);
> > +      break;
> >      }
> > -  else if (args_type != NO_VALUES)
> > -    should_print = 1;
> >
> >    if (should_print)
> >      {
> > @@ -371,10 +372,12 @@ py_print_single_arg (struct ui_out *out,
> >    if (print_args_field)
> >      out->field_signed ("arg", 1);
> >
> > -  /* For MI print the type, but only for simple values.  This seems
> > -     weird, but this is how MI choose to format the various output
> > +  /* For MI print the type, but only for simple and scalar values. This
> > +     seems weird, but this is how MI chooses to format the various output
> >       types.  */
> > -  if (args_type == MI_PRINT_SIMPLE_VALUES && val != NULL)
> > +  if ((args_type == MI_PRINT_SIMPLE_VALUES
> > +       || args_type == MI_PRINT_SCALAR_VALUES)
> > +      && val != NULL)
> >      py_print_type (out, val);
> >
> >    if (val != NULL)
> > @@ -603,7 +606,8 @@ enumerate_locals (PyObject *iter,
> >        out->field_string ("name", sym_name.get ());
> >        out->text (" = ");
> >
> > -      if (args_type == MI_PRINT_SIMPLE_VALUES)
> > +      if (args_type == MI_PRINT_SIMPLE_VALUES
> > +          || args_type == MI_PRINT_SCALAR_VALUES)
> >         py_print_type (out, val);
> >
> >        /* CLI always prints values for locals.  MI uses the
> > diff --git a/gdb/testsuite/gdb.mi/mi-stack.exp b/gdb/testsuite/gdb.mi/mi-stack.exp
> > index d04c8153c65..2c74da00c18 100644
> > --- a/gdb/testsuite/gdb.mi/mi-stack.exp
> > +++ b/gdb/testsuite/gdb.mi/mi-stack.exp
> > @@ -93,6 +93,11 @@ proc test_stack_args_listing {} {
> >      # -stack-list-arguments 1 1 1
> >      # -stack-list-arguments 1 1 3
> >      # -stack-list-arguments
> > +    # -stack-list-arguments 1 1 300
> > +    # -stack-list-arguments 2 1 1
> > +    # -stack-list-arguments --simple-values 1 1
> > +    # -stack-list-arguments 3 1 1
> > +    # -stack-list-arguments --scalar-values 1 1
> >
> >      mi_gdb_test "231-stack-list-arguments 0" \
> >         "231\\^done,stack-args=\\\[frame=\{level=\"0\",args=\\\[\\\]\},frame=\{level=\"1\",args=\\\[name=\"strarg\"\\\]\},frame=\{level=\"2\",args=\\\[name=\"intarg\",name=\"strarg\"\\\]\},frame=\{level=\"3\",args=\\\[name=\"intarg\",name=\"strarg\",name=\"fltarg\"\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> > @@ -125,6 +130,22 @@ proc test_stack_args_listing {} {
> >      mi_gdb_test "235-stack-list-arguments 1 1 300" \
> >         "235\\^done,stack-args=\\\[frame=\{level=\"1\",args=\\\[\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"2\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\}\\\]\},frame=\{level=\"3\",args=\\\[\{name=\"intarg\",value=\"2\"\},\{name=\"strarg\",value=\"$hex \\\\\"A string argument.\\\\\"\"\},\{name=\"fltarg\",value=\"3.5\"\}\\\]\},frame=\{level=\"4\",args=\\\[\\\]\}\\\]" \
> >         "stack args listing 1 1 300"
> > +
> > +    mi_gdb_test "236-stack-list-arguments 2 1 1" \
> > +       "236\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> > +       "stack args listing 2 1 1"
> > +
> > +    mi_gdb_test "237-stack-list-arguments --simple-values 1 1" \
> > +       "237\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> > +       "stack args listing --simple-values 1 1"
> > +
> > +    mi_gdb_test "238-stack-list-arguments 3 1 1" \
> > +       "238\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> > +       "stack args listing 3 1 1"
> > +
> > +    mi_gdb_test "239-stack-list-arguments --scalar-values 1 1" \
> > +       "239\\^done,stack-args=\\\[frame=\\{level=\"1\",args=\\\[\\{name=\"strarg\",type=\"char \\*\",value=\"$hex \\\\\"A string argument.\\\\\"\"\\}\\\]\\}\\\]" \
> > +       "stack args listing --scalar-values 1 1"
> >  }
> >
> >  proc test_stack_info_depth {} {
> > @@ -163,7 +184,7 @@ proc test_stack_locals_listing {} {
> >      # -stack-list-locals 0 (--no-values)
> >      # -stack-list-locals 1 (--all-values)
> >      # -stack-list-locals 2 (--simple-values)
> > -    # -stack-list-arguments
> > +    # -stack-list-locals 3 (--scalar-values)
> >
> >      mi_gdb_test "232-stack-list-locals 0" \
> >         "232\\^done,locals=\\\[name=\"A\",name=\"B\",name=\"C\",name=\"D\"\\\]" \
> > @@ -179,10 +200,22 @@ proc test_stack_locals_listing {} {
> >         "232\\^done,locals=\\\[\{name=\"A\",value=\"1\"\},\{name=\"B\",value=\"2\"\},\{name=\"C\",value=\"3\"\},\{name=\"D\",value=\"\\{0, 1, 2\\}\"\}\\\]" \
> >         "stack locals listing of names and values"
> >
> > -    mi_gdb_test "232-stack-list-locals --simple-values" \
> > +    mi_gdb_test "232-stack-list-locals 2" \
> >         "232\\^done,locals=\\\[\{name=\"A\",type=\"int\",value=\"1\"\},\{name=\"B\",type=\"int\",value=\"2\"\},\{name=\"C\",type=\"int\",value=\"3\"\},\{name=\"D\",type=\"int \\\[3\\\]\"\}\\\]" \
> >         "stack locals listing, simple types: names and values, complex type: names and types"
> >
> > +    mi_gdb_test "232-stack-list-locals --simple-values" \
> > +       "232\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> > +       "stack locals listing with --simple-values"
> > +
> > +    mi_gdb_test "233-stack-list-locals 3" \
> > +       "233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> > +       "stack locals listing, scalar types: names and values, otherwise: names and types"
> > +
> > +    mi_gdb_test "233-stack-list-locals --scalar-values" \
> > +       "233\\^done,locals=\\\[\\{name=\"A\",type=\"int\",value=\"1\"\\},\\{name=\"B\",type=\"int\",value=\"2\"\\},\\{name=\"C\",type=\"int\",value=\"3\"\\},\\{name=\"D\",type=\"int \\\[3\\\]\"\\}\\\]" \
> > +       "stack locals listing with --scalar-values"
> > +
> >      mi_gdb_test "234-stack-list-locals" \
> >         "234\\^error,msg=\"-stack-list-locals: Usage.*PRINT_VALUES.*\"" \
> >         "stack locals listing wrong"
> > diff --git a/gdb/testsuite/gdb.mi/print-values.cc b/gdb/testsuite/gdb.mi/print-values.cc
> > new file mode 100644
> > index 00000000000..b52683d1537
> > --- /dev/null
> > +++ b/gdb/testsuite/gdb.mi/print-values.cc
> > @@ -0,0 +1,63 @@
> > +/* This test case is part of GDB, the GNU debugger.
> > +
> > +   Copyright 2022 Free Software Foundation, Inc.
> > +
> > +   This program is free software; you can redistribute it and/or modify
> > +   it under the terms of the GNU General Public License as published by
> > +   the Free Software Foundation; either version 3 of the License, or
> > +   (at your option) any later version.
> > +
> > +   This program is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > +   GNU General Public License for more details.
> > +
> > +   You should have received a copy of the GNU General Public License
> > +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> > +
> > +/* Test program for PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
> > +
> > +   In the function f:
> > +
> > +   * The arguments i, ir, and irr are ints or references to ints,
> > +     which must be printed by both PRINT_SIMPLE_VALUES and
> > +     PRINT_SCALAR_VALUES.
> > +
> > +   * The arguments a, s, and u are non-scalar values, which must not
> > +     be printed by either PRINT_SIMPLE_VALUES or PRINT_SCALAR_VALUES.
> > +
> > +   * The arguments ar, arr, sr, srr, ur, and urr are references to
> > +     non-scalar values, which must be printed by PRINT_SIMPLE_VALUES
> > +     but not printed by PRINT_SCALAR_VALUES.  */
> > +
> > +struct s
> > +{
> > +  int v;
> > +};
> > +
> > +union u
> > +{
> > +  int v;
> > +};
> > +
> > +int
> > +f (int i, int &ir, int &&irr,
> > +   int a[1], int (&ar)[1], int (&&arr)[1],
> > +   struct s s, struct s &sr, struct s &&srr,
> > +   union u u, union u &ur, union u &&urr)
> > +{
> > +  return (i + ir + irr
> > +          + a[0] + ar[0] + arr[0]
> > +          + s.v + sr.v + srr.v
> > +          + u.v + ur.v + urr.v);
> > +}
> > +
> > +int
> > +main (void)
> > +{
> > +  int i = 1, j = 2;
> > +  int a[1] = { 4 }, b[1] = { 5 };
> > +  struct s s = { 7 }, t = { 8 };
> > +  union u u = { 10 }, v = { 11 };
> > +  return f (i, j, 3, a, b, { 6 }, s, t, { 9 }, u, v, { 12 });
> > +}
> > diff --git a/gdb/testsuite/gdb.mi/print-values.exp b/gdb/testsuite/gdb.mi/print-values.exp
> > new file mode 100644
> > index 00000000000..7896d773119
> > --- /dev/null
> > +++ b/gdb/testsuite/gdb.mi/print-values.exp
> > @@ -0,0 +1,53 @@
> > +# Copyright 2022 Free Software Foundation, Inc.
> > +#
> > +# This program is free software; you can redistribute it and/or modify
> > +# it under the terms of the GNU General Public License as published by
> > +# the Free Software Foundation; either version 3 of the License, or
> > +# (at your option) any later version.
> > +#
> > +# This program is distributed in the hope that it will be useful,
> > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > +# GNU General Public License for more details.
> > +#
> > +# You should have received a copy of the GNU General Public License
> > +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> > +
> > +# Test of PRINT_SIMPLE_VALUES and PRINT_SCALAR_VALUES.
> > +#
> > +# Test that PRINT_SIMPLE_VALUES distinguishes scalar and non-scalar
> > +# types, except for C++ reference and rvalue reference types.
> > +#
> > +# Test that PRINT_SCALAR_VALUES distinguishes scalar and non-scalar
> > +# types, including C++ reference and rvalue reference types.
> > +
> > +if { [skip_cplus_tests] } { continue }
> > +
> > +load_lib mi-support.exp
> > +standard_testfile .cc
> > +
> > +if { [gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug c++}] != "" } {
> > +    untested "failed to compile"
> > +    return -1
> > +}
> > +
> > +mi_clean_restart $binfile
> > +
> > +mi_runto_main
> > +
> > +mi_gdb_test "-break-insert f" "\\^done.*" "set breakpoint on f"
> > +
> > +mi_send_resuming_command "exec-continue" "exec-continue to breakpoint on f"
> > +
> > +mi_expect_stop "breakpoint-hit" "f" ".*" ".*" ".*" {.* disp="keep"} \
> > +    "run until breakpoint on f"
> > +
> > +mi_gdb_test "-stack-list-arguments --simple-values" \
> > +    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\",value=\"@$hex: \\{5\\}\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\",value=\"@$hex: \\{6\\}\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\",value=\"@$hex: \\{v = 8\\}\"\\},\\{name=\"srr\",type=\"s &&\",value=\"@$hex: \\{v = 9\\}\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\",value=\"@$hex: \\{v = 11\\}\"\\},\\{name=\"urr\",type=\"u &&\",value=\"@$hex: \\{v = 12\\}\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
> > +    "stack list arguments, simple types: names, types and values, otherwise: names and types"
> > +
> > +mi_gdb_test "-stack-list-arguments --scalar-values" \
> > +    "\\^done,stack-args=\\\[frame=\\{level=\"0\",args=\\\[\\{name=\"i\",type=\"int\",value=\"1\"\\},\\{name=\"ir\",type=\"int &\",value=\"@$hex: 2\"\\},\\{name=\"irr\",type=\"int &&\",value=\"@$hex: 3\"\\},\\{name=\"a\",type=\"int \\*\",value=\"$hex\"\\},\\{name=\"ar\",type=\"int \\(&\\)\\\[1\\\]\"\\},\\{name=\"arr\",type=\"int \\(&&\\)\\\[1\\\]\"\\},\\{name=\"s\",type=\"s\"\\},\\{name=\"sr\",type=\"s &\"\\},\\{name=\"srr\",type=\"s &&\"\\},\\{name=\"u\",type=\"u\"\\},\\{name=\"ur\",type=\"u &\"\\},\\{name=\"urr\",type=\"u &&\"\\}\\\]\\},frame=\\{level=\"1\",args=\\\[\\\]\\}\\\]" \
> > +    "stack list arguments, scalar types: names, types and values, compound types: names and types"
> > +
> > +mi_gdb_exit
> > diff --git a/gdb/testsuite/gdb.python/py-framefilter-mi.exp b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> > index 344067fe4a7..fa4e559e343 100644
> > --- a/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> > +++ b/gdb/testsuite/gdb.python/py-framefilter-mi.exp
> > @@ -120,6 +120,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2" \
> >      "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> >      "stack-list-arguments --no-frame-filters 2"
> >
> > +mi_gdb_test "-stack-list-arguments 3" \
> > +    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"\}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> > +    "stack-list-arguments 3"
> > +
> > +mi_gdb_test "-stack-list-arguments --no-frame-filters 3" \
> > +    "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},.*frame={level=\"22\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> > +    "stack-list-arguments --no-frame-filters 3"
> > +
> >
> >  mi_gdb_test "-stack-list-arguments 2 0 3" \
> >      "\\^done,stack-args=\\\[frame={level=\"0\",args=\\\[{name=\"foo\",type=\"int\",value=\"21\"},{name=\"bar\",type=\"char \\\*\",value=\"$hex \\\\\"Param\\\\\"\"},{name=\"fb\",type=\"foobar \\\*\",value=\"$hex\"},{name=\"bf\",type=\"foobar\"}\\\]},frame={level=\"1\",args=\\\[\\\]},frame={level=\"2\",args=\\\[{name=\"j\",type=\"int\",value=\"10\"}\\\]},frame={level=\"3\",args=\\\[\\\]}\\\]" \
> > @@ -133,6 +141,14 @@ mi_gdb_test "-stack-list-arguments --no-frame-filters 2 22 27" \
> >      "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> >      "stack-list-arguments --no-frame-filters 2 22 27"
> >
> > +mi_gdb_test "-stack-list-arguments 3 22 27" \
> > +    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\],children=\\\[frame={level=\"23\",args=\\\[\\\]}\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> > +    "stack-list-arguments 3 22 27"
> > +
> > +mi_gdb_test "-stack-list-arguments --no-frame-filters 3 22 27" \
> > +    "\\^done,stack-args=\\\[frame={level=\"22\",args=\\\[\\\]},frame={level=\"23\",args=\\\[\\\]},.*frame={level=\"26\",args=\\\[{name=\"f\",type=\"int\",value=\"3\"},{name=\"d\",type=\"int\",value=\"5\"}\\\]},frame={level=\"27\",args=\\\[\\\]}\\\]" \
> > +    "stack-list-arguments --no-frame-filters 3 22 27"
> > +
> >  #stack-list-locals
> >  mi_gdb_test "-stack-list-locals --no-frame-filters 0" \
> >      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
> > @@ -146,6 +162,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters 2" \
> >      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> >      "stack-list-locals --no-frame-filters 2"
> >
> > +mi_gdb_test "-stack-list-locals --no-frame-filters 3" \
> > +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> > +    "stack-list-locals --no-frame-filters 3"
> > +
> >  mi_gdb_test "-stack-list-locals --no-frame-filters --no-values" \
> >      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
> >      "stack-list-locals --no-frame-filters --no-values"
> > @@ -158,6 +178,10 @@ mi_gdb_test "-stack-list-locals --no-frame-filters --simple-values" \
> >      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> >      "stack-list-locals --no-frame-filters --simple-values"
> >
> > +mi_gdb_test "-stack-list-locals --no-frame-filters --scalar-values" \
> > +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> > +    "stack-list-locals --no-frame-filters --scalar-values"
> > +
> >  mi_gdb_test "-stack-list-locals 0" \
> >      "\\^done,locals=\\\[name=\"str\",name=\"st2\",name=\"b\",name=\"c\"\\\]" \
> >      "stack-list-locals 0"
> > @@ -170,6 +194,10 @@ mi_gdb_test "-stack-list-locals 2" \
> >      "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> >      "stack-list-locals 2"
> >
> > +mi_gdb_test "-stack-list-locals 3" \
> > +    "\\^done,locals=\\\[{name=\"str\",type=\"const char \\\*\",value=\"$hex \\\\\"The End\\\\\"\"},{name=\"st2\",type=\"const char \\\*\",value=\"$hex \\\\\"Is Near\\\\\"\"},{name=\"b\",type=\"int\",value=\"12\"},{name=\"c\",type=\"short\",value=\"5\"}\\\]" \
> > +    "stack-list-locals 3"
> > +
> >  # stack-list-variables
> >  mi_gdb_test "-stack-list-variables --no-frame-filters 0" \
> >      "\\^done,variables=\\\[{name=\"foo\",arg=\"1\"},{name=\"bar\",arg=\"1\"},{name=\"fb\",arg=\"1\"},{name=\"bf\",arg=\"1\"},{name=\"str\"},{name=\"st2\"},{name=\"b\"},{name=\"c\"}\\\]" \
> > --
> > 2.26.0
> >

^ permalink raw reply	[flat|nested] 25+ messages in thread

end of thread, other threads:[~2022-11-14  9:25 UTC | newest]

Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-08  7:18 [PATCH] [gdb/mi] Don't treat references to compound values as "simple" Gareth Rees
2022-09-08 10:27 ` Andrew Burgess
2022-09-08 11:02   ` [PATCH v2] " Gareth Rees
2022-09-08 13:30     ` Eli Zaretskii
2022-09-08 13:58       ` Gareth Rees
2022-09-08 14:07         ` Eli Zaretskii
2022-09-09  8:01       ` [PATCH v3] [PR mi/29554] New PRINT-VALUES option '--scalar-values' Gareth Rees
2022-09-15  9:06         ` [PING] " Gareth Rees
2022-09-25  8:15         ` Gareth Rees
2022-09-25  8:25           ` Eli Zaretskii
2022-09-25  9:00             ` Gareth Rees
2022-09-25 10:16               ` Eli Zaretskii
2022-09-26 12:48                 ` Gareth Rees
2022-09-25 10:16           ` Eli Zaretskii
2022-09-26 12:46         ` [PATCH v4] " Gareth Rees
2022-10-04  9:08           ` [PING] " Gareth Rees
2022-10-18 11:59             ` Gareth Rees
2022-10-12 16:38           ` Andrew Burgess
2022-10-20 17:47             ` [PATCH v5] " Gareth Rees
2022-10-20 18:00               ` Eli Zaretskii
2022-11-03 16:20               ` [PING] " Gareth Rees
2022-11-14  9:25                 ` Gareth Rees
2022-10-20 17:58             ` [PATCH v4] " Gareth Rees
2022-09-09  8:04       ` [PATCH v2] [gdb/mi] Don't treat references to compound values as "simple" Gareth Rees
2022-09-08 11:09   ` [PATCH] " Gareth Rees

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