[PATCH v2 1/3] gdb: use std::string for internalvar::name

[PATCH v2 1/3] gdb: use std::string for internalvar::name

[Simon Marchi]

Change internalvar::name to std::string, automating memory management.
It becomes necessary to allocate internalvar with new instead of XNEW.

I didn't find how to trigger the code in complete_internalvar.  It is
called from condition_completer, so it should be by using the
"condition" command, but I never managed to get in the right code path.

Change-Id: I814d61361663e7becb8f3fb5f58c0180cdc414bc
---
 gdb/value.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/gdb/value.c b/gdb/value.c
index 7873aeb9558e..936949f4a1f1 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -1830,7 +1830,7 @@ union internalvar_data
 struct internalvar
 {
   struct internalvar *next;
-  char *name;
+  std::string name;
 
   /* We support various different kinds of content of an internal variable.
      enum internalvar_kind specifies the kind, and union internalvar_data
@@ -1894,7 +1894,7 @@ lookup_only_internalvar (const char *name)
   struct internalvar *var;
 
   for (var = internalvars; var; var = var->next)
-    if (strcmp (var->name, name) == 0)
+    if (var->name == name)
       return var;
 
   return NULL;
@@ -1912,8 +1912,8 @@ complete_internalvar (completion_tracker &tracker, const char *name)
   len = strlen (name);
 
   for (var = internalvars; var; var = var->next)
-    if (strncmp (var->name, name, len) == 0)
-      tracker.add_completion (make_unique_xstrdup (var->name));
+    if (var->name.compare (0, len, name) == 0)
+      tracker.add_completion (make_unique_xstrdup (var->name.c_str ()));
 }
 
 /* Create an internal variable with name NAME and with a void value.
@@ -1922,9 +1922,9 @@ complete_internalvar (completion_tracker &tracker, const char *name)
 struct internalvar *
 create_internalvar (const char *name)
 {
-  struct internalvar *var = XNEW (struct internalvar);
+  internalvar *var = new internalvar;
 
-  var->name = xstrdup (name);
+  var->name = name;
   var->kind = INTERNALVAR_VOID;
   var->next = internalvars;
   internalvars = var;
@@ -1996,7 +1996,7 @@ value_of_internalvar (struct gdbarch *gdbarch, struct internalvar *var)
 
   /* If there is a trace state variable of the same name, assume that
      is what we really want to see.  */
-  tsv = find_trace_state_variable (var->name);
+  tsv = find_trace_state_variable (var->name.c_str ());
   if (tsv)
     {
       tsv->value_known = target_get_trace_state_variable_value (tsv->number,
@@ -2149,7 +2149,7 @@ set_internalvar (struct internalvar *var, struct value *val)
   union internalvar_data new_data = { 0 };
 
   if (var->kind == INTERNALVAR_FUNCTION && var->u.fn.canonical)
-    error (_("Cannot overwrite convenience function %s"), var->name);
+    error (_("Cannot overwrite convenience function %s"), var->name.c_str ());
 
   /* Prepare new contents.  */
   switch (check_typedef (val->type ())->code ())
@@ -2261,7 +2261,7 @@ clear_internalvar (struct internalvar *var)
 const char *
 internalvar_name (const struct internalvar *var)
 {
-  return var->name;
+  return var->name.c_str ();
 }
 
 static struct internal_function *
@@ -2450,7 +2450,7 @@ show_convenience (const char *ignore, int from_tty)
 	{
 	  varseen = 1;
 	}
-      gdb_printf (("$%s = "), var->name);
+      gdb_printf (("$%s = "), var->name.c_str ());
 
       try
 	{
-- 
2.39.1

[PATCH v2 2/3] gdb: add constructor to internalvar

[Simon Marchi]

Add a constructor that takes the name as a parameter.  Initialize the

Change-Id: Ic4db0aba85f1da9f12f3eee0ac62c0e5ef0cfe88
---
 gdb/value.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/gdb/value.c b/gdb/value.c
index 936949f4a1f1..7fd11ba70db6 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -1829,14 +1829,18 @@ union internalvar_data
 
 struct internalvar
 {
-  struct internalvar *next;
+  internalvar (std::string name)
+    : name (std::move (name))
+  {}
+
+  struct internalvar *next = nullptr;
   std::string name;
 
   /* We support various different kinds of content of an internal variable.
      enum internalvar_kind specifies the kind, and union internalvar_data
      provides the data associated with this particular kind.  */
 
-  enum internalvar_kind kind;
+  enum internalvar_kind kind = INTERNALVAR_VOID;
 
   union internalvar_data u;
 };
@@ -1922,10 +1926,8 @@ complete_internalvar (completion_tracker &tracker, const char *name)
 struct internalvar *
 create_internalvar (const char *name)
 {
-  internalvar *var = new internalvar;
+  internalvar *var = new internalvar (name);
 
-  var->name = name;
-  var->kind = INTERNALVAR_VOID;
   var->next = internalvars;
   internalvars = var;
   return var;
-- 
2.39.1

Re: [PATCH v2 2/3] gdb: add constructor to internalvar

[Tom Tromey]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> Add a constructor that takes the name as a parameter.  Initialize the

This is truncated.

Tom

Re: [PATCH v2 2/3] gdb: add constructor to internalvar

[Simon Marchi]

On 2/14/23 15:42, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Simon> Add a constructor that takes the name as a parameter.  Initialize the
> 
> This is truncated.

Woops, it should have read:

    gdb: add constructor to internalvar

    Add a constructor that takes the name as a parameter.  Initialize the
    next and kind fields inline.

Simon

Re: [PATCH v2 2/3] gdb: add constructor to internalvar

[Tom Tromey]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> On 2/14/23 15:42, Tom Tromey wrote:
>>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
>> 
Simon> Add a constructor that takes the name as a parameter.  Initialize the
>> 
>> This is truncated.

Simon> Woops, it should have read:

Simon>     gdb: add constructor to internalvar

Simon>     Add a constructor that takes the name as a parameter.  Initialize the
Simon>     next and kind fields inline.

Thanks, this is fine by me.

Tom

Re: [PATCH v2 2/3] gdb: add constructor to internalvar

[Simon Marchi]

On 2/15/23 11:56, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Simon> On 2/14/23 15:42, Tom Tromey wrote:
>>>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
>>>
> Simon> Add a constructor that takes the name as a parameter.  Initialize the
>>>
>>> This is truncated.
> 
> Simon> Woops, it should have read:
> 
> Simon>     gdb: add constructor to internalvar
> 
> Simon>     Add a constructor that takes the name as a parameter.  Initialize the
> Simon>     next and kind fields inline.
> 
> Thanks, this is fine by me.
> 
> Tom

Thanks, I will push the series now.

Simon

[PATCH v2 3/3] gdb: store internalvars in an std::map

[Simon Marchi]

In a test downstream in ROCgdb, we had a test case failing when
GDB_REVERSE_INIT_FUNCTIONS was set.  The test was assuming a particular
order in the output of "show convenience".  And the order changes when
running with GDB_REVERSE_INIT_FUNCTIONS.

I think that a nice way to fix it is to make the output of "show
convenience" sorted, and therefore stable.  Ideally, I think that the
the user-visible behavior of GDB should not change when using
GDB_REVERSE_INIT_FUNCTIONS.  Plus, it makes the output of "show
convenience" look nice, not that it's really important.

Implement this by storing the internal vars in an std::map, which is a
sorted container.

Change-Id: I1fca7e7877cc984a3a3432c7639d45e68d437241
---
 gdb/value.c | 55 +++++++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/gdb/value.c b/gdb/value.c
index 7fd11ba70db6..4db6cb4ed30d 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -41,6 +41,7 @@
 #include "user-regs.h"
 #include <algorithm>
 #include <iterator>
+#include <map>
 #include <utility>
 #include <vector>
 #include "completer.h"
@@ -1833,7 +1834,6 @@ struct internalvar
     : name (std::move (name))
   {}
 
-  struct internalvar *next = nullptr;
   std::string name;
 
   /* We support various different kinds of content of an internal variable.
@@ -1845,7 +1845,10 @@ struct internalvar
   union internalvar_data u;
 };
 
-static struct internalvar *internalvars;
+/* Use std::map, a sorted container, to make the order of iteration (and
+   therefore the output of "show convenience" stable).  */
+
+static std::map<std::string, internalvar> internalvars;
 
 /* If the variable does not already exist create it and give it the
    value given.  If no value is given then the default is zero.  */
@@ -1895,13 +1898,11 @@ init_if_undefined_command (const char* args, int from_tty)
 struct internalvar *
 lookup_only_internalvar (const char *name)
 {
-  struct internalvar *var;
-
-  for (var = internalvars; var; var = var->next)
-    if (var->name == name)
-      return var;
+  auto it = internalvars.find (name);
+  if (it == internalvars.end ())
+    return nullptr;
 
-  return NULL;
+  return &it->second;
 }
 
 /* Complete NAME by comparing it to the names of internal
@@ -1910,27 +1911,29 @@ lookup_only_internalvar (const char *name)
 void
 complete_internalvar (completion_tracker &tracker, const char *name)
 {
-  struct internalvar *var;
-  int len;
+  int len = strlen (name);
 
-  len = strlen (name);
+  for (auto &pair : internalvars)
+    {
+      const internalvar &var = pair.second;
 
-  for (var = internalvars; var; var = var->next)
-    if (var->name.compare (0, len, name) == 0)
-      tracker.add_completion (make_unique_xstrdup (var->name.c_str ()));
+      if (var.name.compare (0, len, name) == 0)
+	tracker.add_completion (make_unique_xstrdup (var.name.c_str ()));
+    }
 }
 
 /* Create an internal variable with name NAME and with a void value.
-   NAME should not normally include a dollar sign.  */
+   NAME should not normally include a dollar sign.
+
+   An internal variable with that name must not exist already.  */
 
 struct internalvar *
 create_internalvar (const char *name)
 {
-  internalvar *var = new internalvar (name);
+  auto pair = internalvars.emplace (std::make_pair (name, internalvar (name)));
+  gdb_assert (pair.second);
 
-  var->next = internalvars;
-  internalvars = var;
-  return var;
+  return &pair.first->second;
 }
 
 /* Create an internal variable with name NAME and register FUN as the
@@ -2414,8 +2417,6 @@ preserve_one_varobj (struct varobj *varobj, struct objfile *objfile,
 void
 preserve_values (struct objfile *objfile)
 {
-  struct internalvar *var;
-
   /* Create the hash table.  We allocate on the objfile's obstack, since
      it is soon to be deleted.  */
   htab_up copied_types = create_copied_types_hash ();
@@ -2423,8 +2424,8 @@ preserve_values (struct objfile *objfile)
   for (const value_ref_ptr &item : value_history)
     item->preserve (objfile, copied_types.get ());
 
-  for (var = internalvars; var; var = var->next)
-    preserve_one_internalvar (var, objfile, copied_types.get ());
+  for (auto &pair : internalvars)
+    preserve_one_internalvar (&pair.second, objfile, copied_types.get ());
 
   /* For the remaining varobj, check that none has type owned by OBJFILE.  */
   all_root_varobjs ([&copied_types, objfile] (struct varobj *varobj)
@@ -2440,25 +2441,25 @@ static void
 show_convenience (const char *ignore, int from_tty)
 {
   struct gdbarch *gdbarch = get_current_arch ();
-  struct internalvar *var;
   int varseen = 0;
   struct value_print_options opts;
 
   get_user_print_options (&opts);
-  for (var = internalvars; var; var = var->next)
+  for (auto &pair : internalvars)
     {
+      internalvar &var = pair.second;
 
       if (!varseen)
 	{
 	  varseen = 1;
 	}
-      gdb_printf (("$%s = "), var->name.c_str ());
+      gdb_printf (("$%s = "), var.name.c_str ());
 
       try
 	{
 	  struct value *val;
 
-	  val = value_of_internalvar (gdbarch, var);
+	  val = value_of_internalvar (gdbarch, &var);
 	  value_print (val, gdb_stdout, &opts);
 	}
       catch (const gdb_exception_error &ex)
-- 
2.39.1

Re: [PATCH v2 3/3] gdb: store internalvars in an std::map

[Tom Tromey]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> In a test downstream in ROCgdb, we had a test case failing when
Simon> GDB_REVERSE_INIT_FUNCTIONS was set.  The test was assuming a particular
Simon> order in the output of "show convenience".  And the order changes when
Simon> running with GDB_REVERSE_INIT_FUNCTIONS.

Simon> I think that a nice way to fix it is to make the output of "show
Simon> convenience" sorted, and therefore stable.  Ideally, I think that the
Simon> the user-visible behavior of GDB should not change when using
Simon> GDB_REVERSE_INIT_FUNCTIONS.  Plus, it makes the output of "show
Simon> convenience" look nice, not that it's really important.

Simon> Implement this by storing the internal vars in an std::map, which is a
Simon> sorted container.

Makes sense to me.

Approved-By: Tom Tromey <tom@tromey.com>

Tom

Re: [PATCH v2 1/3] gdb: use std::string for internalvar::name

[Tom Tromey]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> Change internalvar::name to std::string, automating memory management.
Simon> It becomes necessary to allocate internalvar with new instead of XNEW.

Looks good.
Approved-By: Tom Tromey <tom@tromey.com>

Simon> I didn't find how to trigger the code in complete_internalvar.  It is
Simon> called from condition_completer, so it should be by using the
Simon> "condition" command, but I never managed to get in the right code path.

I am not sure either but I believe there's a bug open to the effect that
convenience variable completion does not work.

Tom