RE: [PATCH v3 1/1] gdb, infcmd: Support jump command in multi-inferior case.

["Puputti, Matti" <matti.puputti@intel.com>]

Hi Andrew,

Thank you for these comments.
I'll be addressing them as soon as I will be back in office, in few weeks

Br,
Matti Puputti

> -----Original Message-----
> From: Andrew Burgess <aburgess@redhat.com>
> Sent: Wednesday, May 24, 2023 7:33 PM
> To: Puputti, Matti <matti.puputti@intel.com>; gdb-patches@sourceware.org
> Subject: Re: [PATCH v3 1/1] gdb, infcmd: Support jump command in multi-
> inferior case.
> 
> Matti Puputti <matti.puputti@intel.com> writes:
> 
> > Fixes the issue where jump failed if multiple inferiors run the same source.
> >
> > See the below example
> >
> >     $ gdb -q ./simple
> >     Reading symbols from ./simple...
> >     (gdb) break 2
> >     Breakpoint 1 at 0x114e: file simple.c, line 2.
> >     (gdb) run
> >     Starting program: /temp/simple
> >
> >     Breakpoint 1, main () at simple.c:2
> >     2         int a = 42;
> >     (gdb) add-inferior
> >     [New inferior 2]
> >     Added inferior 2 on connection 1 (native)
> >     (gdb) inferior 2
> >     [Switching to inferior 2 [<null>] (<noexec>)]
> >     (gdb) info inferiors
> >       Num  Description       Connection           Executable
> >       1    process 6250      1 (native)           /temp/simple
> >     * 2    <null>            1 (native)
> >     (gdb) file ./simple
> >     Reading symbols from ./simple...
> >     (gdb) run
> >     Starting program: /temp/simple
> >
> >     Thread 2.1 "simple" hit Breakpoint 1, main () at simple.c:2
> >     2         int a = 42;
> >     (gdb) info inferiors
> >       Num  Description       Connection           Executable
> >       1    process 6250      1 (native)           /temp/simple
> >     * 2    process 6705      1 (native)           /temp/simple
> >     (gdb) jump 3
> >     Unreasonable jump request
> >     (gdb)
> >
> > In this example, jump fails because the debugger finds two different
> > locations, one for each inferior.
> > Solution is to limit the search to the current program space.
> > ---
> >  gdb/infcmd.c                    |   3 +-
> >  gdb/linespec.c                  |   7 +-
> >  gdb/linespec.h                  |   5 +-
> >  gdb/testsuite/gdb.base/jump.exp | 177 +++++++++++++++++--------------
> -
> >  4 files changed, 103 insertions(+), 89 deletions(-)
> >
> > diff --git a/gdb/infcmd.c b/gdb/infcmd.c
> > index 103899432f7..a79b5d3d4d6 100644
> > --- a/gdb/infcmd.c
> > +++ b/gdb/infcmd.c
> > @@ -1077,7 +1077,8 @@ jump_command (const char *arg, int from_tty)
> >      error_no_arg (_("starting address"));
> >
> >    std::vector<symtab_and_line> sals
> > -    = decode_line_with_last_displayed (arg, DECODE_LINE_FUNFIRSTLINE);
> > +    = decode_line_with_last_displayed (arg, DECODE_LINE_FUNFIRSTLINE,
> > +				       current_program_space);
> 
> I wonder if we should stop using decode_line_with_last_displayed here,
> and instead use decode_line_with_current_source?  It feels like a jump
> should always be relative to the current location, rather than what we
> happen to have listed.
> 
> >    if (sals.size () != 1)
> >      error (_("Unreasonable jump request"));
> >
> > diff --git a/gdb/linespec.c b/gdb/linespec.c
> > index 7d969f37fbf..920fd3d37b7 100644
> > --- a/gdb/linespec.c
> > +++ b/gdb/linespec.c
> > @@ -3231,7 +3231,8 @@ decode_line_with_current_source (const char
> *string, int flags)
> >  /* See linespec.h.  */
> >
> >  std::vector<symtab_and_line>
> > -decode_line_with_last_displayed (const char *string, int flags)
> > +decode_line_with_last_displayed (const char *string, int flags,
> > +				 program_space *search_pspace)
> >  {
> >    if (string == 0)
> >      error (_("Empty line specification."));
> > @@ -3240,10 +3241,10 @@ decode_line_with_last_displayed (const char
> *string, int flags)
> >  						      current_language);
> >    std::vector<symtab_and_line> sals
> >      = (last_displayed_sal_is_valid ()
> > -       ? decode_line_1 (locspec.get (), flags, NULL,
> > +       ? decode_line_1 (locspec.get (), flags, search_pspace,
> >  			get_last_displayed_symtab (),
> >  			get_last_displayed_line ())
> 
> This change is why I started looking at the details of this patch again.
> I'm not sure this change makes sense, I would have expected us to use
> get_last_displayed_pspace () here instead of search_pspace, but then it
> becomes harder to describe what search_pspace does as it would only be
> used below.
> 
> It we switch jump to use decode_line_with_current_source then I think
> this problem goes away, the changes to decode_line_with_last_displayed
> can be dropped.
> 
> At the end of this email you'll find a patch that applies on top of your
> V3, which implements the change I'm suggesting.  This passes all the
> 'jump' tests I could find in the testsuite, so I think it's fine, but
> it would be great to hear your thoughts.
> 
> Thanks,
> Andrew
> 
> > -       : decode_line_1 (locspec.get (), flags, NULL, NULL, 0));
> > +       : decode_line_1 (locspec.get (), flags, search_pspace, NULL, 0));
> >
> >    if (*string)
> >      error (_("Junk at end of line specification: %s"), string);
> > diff --git a/gdb/linespec.h b/gdb/linespec.h
> > index d5e7334fe2d..0eb9cb5d9f2 100644
> > --- a/gdb/linespec.h
> > +++ b/gdb/linespec.h
> > @@ -139,10 +139,11 @@ extern std::vector<symtab_and_line>
> decode_line_with_current_source
> >      (const char *, int);
> >
> >  /* Given a string, return the line specified by it, using the last displayed
> > -   codepoint's values as defaults, or nothing if they aren't valid.  */
> > +   codepoint's values as defaults, or nothing if they aren't valid.
> > +   Limit the search to given program space, if specified.  */
> >
> >  extern std::vector<symtab_and_line> decode_line_with_last_displayed
> > -    (const char *, int);
> > +    (const char *, int, program_space *search_pspace = nullptr);
> >
> >  /* Does P represent one of the keywords?  If so, return
> >     the keyword.  If not, return NULL.  */
> > diff --git a/gdb/testsuite/gdb.base/jump.exp
> b/gdb/testsuite/gdb.base/jump.exp
> > index 032c4a6279d..4c0d4ed2dbb 100644
> > --- a/gdb/testsuite/gdb.base/jump.exp
> > +++ b/gdb/testsuite/gdb.base/jump.exp
> > @@ -18,99 +18,110 @@ clear_xfail "*-*-*"
> >
> >  standard_testfile .c
> >
> > -# Build the test case
> > -if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable
> {debug nowarnings}] != "" } {
> > -     untested "failed to compile"
> > -     return -1
> > -    }
> > +if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
> > +    return -1
> > +}
> >
> >
> > -# Start with a fresh gdb
> > +proc do_tests {} {
> > +    global decimal srcfile
> > +
> > +    # Set a breakpoint on the statement that we're about to jump to.
> > +    # The statement doesn't contain a function call.
> > +    set non_call_line [gdb_get_line_number "bp-on-non-call"]
> > +    gdb_breakpoint "$non_call_line"
> > +    set bp_on_non_call \
> > +	[get_integer_valueof "\$bpnum" "INVALID" "bp_on_non_call"]
> > +
> > +    # Can we jump to the statement?  Do we stop there?
> > +    gdb_test "jump $non_call_line" \
> > +	"Breakpoint ${bp_on_non_call}(\.${decimal})?,
> .*${srcfile}:$non_call_line.*" \
> > +	"jump to non-call"
> > +
> > +    # Set a breakpoint on the statement that we're about to jump to.
> > +    # The statement does contain a function call.
> > +    set call_line [gdb_get_line_number "bp-on-call"]
> > +    gdb_breakpoint "$call_line"
> > +    set bp_on_call [get_integer_valueof "\$bpnum" "INVALID"
> "bp_on_call"]
> > +
> > +    # Can we jump to the statement?  Do we stop there?
> > +    gdb_test "jump $call_line" \
> > +	"Breakpoint ${bp_on_call}(\.${decimal})?, .*${srcfile}:$call_line.*" \
> > +	"jump to call"
> > +
> > +    # If we disable the breakpoint at the function call, and then
> > +    # if we jump to that statement, do we not stop there, but at
> > +    # the following breakpoint?
> > +    gdb_test_no_output "disable $bp_on_call" "disable breakpoint on call"
> > +
> > +    gdb_test "jump $call_line" \
> > +	"Breakpoint ${bp_on_non_call}(\.${decimal})?,
> .*${srcfile}:$non_call_line.*" \
> > +	"jump to call with disabled breakpoint"
> > +
> > +    # Disable the breakpoint at the non-function call, so it won't hit
> > +    # if do_test is called again.
> > +    gdb_test_no_output "disable ${bp_on_non_call}" "disable
> bp_on_non_call"
> > +
> > +    # Verify that GDB responds gracefully to the "jump" command without
> > +    # an argument.
> > +    gdb_test "jump" "Argument required .starting address.*" \
> > +	"jump without argument disallowed"
> > +
> > +    # Verify that GDB responds gracefully to the "jump" command with
> > +    # trailing junk.
> > +    gdb_test "jump $call_line 100" \
> > +	"malformed linespec error: unexpected number, \"100\"" \
> > +	"jump with trailing argument junk"
> > +
> > +    # Verify that GDB responds gracefully to a request to jump out of
> > +    # the current function.  (Note that this will very likely cause the
> > +    # inferior to die.  Be prepared to rerun the inferior, if further
> > +    # testing is desired.)
> > +    # Try it both ways: confirming and not confirming the jump.
> > +    set out_line [gdb_get_line_number "out-of-func"]
> > +    gdb_test "jump $out_line" \
> > +	"Not confirmed.*" \
> > +	"aborted jump out of current function" \
> > +	"Line $out_line is not in `main'.  Jump anyway.*y or n. $" \
> > +	"n"
> > +
> > +    gdb_test "jump $out_line" \
> > +	"Continuing at.*" \
> > +	"jump out of current function" \
> > +	"Line $out_line is not in `main'.  Jump anyway.*y or n. $" \
> > +	"y"
> > +}
> >
> > -clean_restart ${binfile}
> >
> > -if {![runto_main]} {
> > -  return -1
> > +set inferiors 1
> > +if {![use_gdb_stub]} {
> > +    set inferiors 2
> >  }
> >
> > -# Set a breakpoint on the statement that we're about to jump to.
> > -# The statement doesn't contain a function call.
> > -#
> > -set bp_on_non_call 0
> > -set non_call_line [gdb_get_line_number "bp-on-non-call"]
> > -gdb_test_multiple "break $non_call_line" "break before jump to non-call"
> {
> > -    -re "\[Bb\]reakpoint (${decimal}) at ${hex}: file .*${srcfile}, line
> $non_call_line.*$gdb_prompt $" {
> > -	set bp_on_non_call $expect_out(1,string)
> > -	pass "break before jump to non-call"
> > +# Run to main, add inferiors if needed.
> > +for {set inf 1} {$inf <= $inferiors} {incr inf} {
> > +    if {$inf != 1} {
> > +	# Start a new inferior, and run it with the same executable.
> > +	gdb_test "add-inferior -exec ${binfile}" \
> > +	    "Added inferior ${inf}.*" \
> > +	    "add inferior ${inf} with -exec "
> > +	gdb_test "inferior ${inf}" \
> > +	    "Switching to inferior ${inf} .*" \
> > +	    "switch to inferior ${inf}"
> > +    }
> > +    if {![runto_main]} {
> > +	return -1
> >      }
> >  }
> >
> > -# Can we jump to the statement?  Do we stop there?
> > -#
> > -gdb_test "jump $non_call_line" "Breakpoint ${decimal},
> .*${srcfile}:$non_call_line.*" \
> > -    "jump to non-call"
> > -
> > -# Set a breakpoint on the statement that we're about to jump to.
> > -# The statement does contain a function call.
> > -#
> > -set bp_on_call 0
> > -set call_line [gdb_get_line_number "bp-on-call"]
> > -gdb_test_multiple "break $call_line" "break before jump to call" {
> > -    -re "\[Bb\]reakpoint (${decimal}) at ${hex}: file .*${srcfile}, line
> $call_line.*$gdb_prompt $" {
> > -	set bp_on_call $expect_out(1,string)
> > -	pass "break before jump to call"
> > +# Run tests on all inferiors.
> > +for {set inf 1} {$inf <= $inferiors} {incr inf} {
> > +    with_test_prefix "inferior $inf" {
> > +	# Switch to the target inferior.
> > +	gdb_test "inferior $inf" ".*Switching to inferior $inf .*"
> > +	# Run the tests.
> > +	do_tests
> >      }
> >  }
> >
> > -# Can we jump to the statement?  Do we stop there?
> > -#
> > -gdb_test "jump $call_line" \
> > -    "Breakpoint ${decimal}, .*${srcfile}:$call_line.*" \
> > -    "jump to call"
> > -
> > -# If we disable the breakpoint at the function call, and then
> > -# if we jump to that statement, do we not stop there, but at
> > -# the following breakpoint?
> > -#
> > -gdb_test_no_output "disable $bp_on_call" "disable breakpoint on call"
> > -
> > -gdb_test "jump $call_line" "Breakpoint ${decimal},
> .*${srcfile}:$non_call_line.*" \
> > -    "jump to call with disabled breakpoint"
> > -
> > -# Verify that GDB responds gracefully to the "jump" command without
> > -# an argument.
> > -#
> > -gdb_test "jump" "Argument required .starting address.*" \
> > -    "jump without argument disallowed"
> > -
> > -
> > -# Verify that GDB responds gracefully to the "jump" command with
> > -# trailing junk.
> > -#
> > -gdb_test "jump $call_line 100" \
> > -    "malformed linespec error: unexpected number, \"100\"" \
> > -    "jump with trailing argument junk"
> > -
> > -
> > -# Verify that GDB responds gracefully to a request to jump out of
> > -# the current function.  (Note that this will very likely cause the
> > -# inferior to die.  Be prepared to rerun the inferior, if further
> > -# testing is desired.)
> > -#
> > -# Try it both ways: confirming and not confirming the jump.
> > -#
> > -
> > -set out_line [gdb_get_line_number "out-of-func"]
> > -gdb_test "jump $out_line" \
> > -    "Not confirmed.*" \
> > -    "aborted jump out of current function" \
> > -    "Line $out_line is not in `main'.  Jump anyway.*y or n. $" \
> > -    "n"
> > -
> > -gdb_test "jump $out_line" \
> > -    "Continuing at.*" \
> > -    "jump out of current function" \
> > -    "Line $out_line is not in `main'.  Jump anyway.*y or n. $" \
> > -    "y"
> > -
> >  gdb_exit
> > --
> > 2.25.1
> >
> > Intel Deutschland GmbH
> > Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
> > Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
> > Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva
> > Chairperson of the Supervisory Board: Nicole Lau
> > Registered Office: Munich
> > Commercial Register: Amtsgericht Muenchen HRB 186928
> 
> ---
> 
> diff --git a/gdb/infcmd.c b/gdb/infcmd.c
> index 1be72ed09f0..1d10e2908ca 100644
> --- a/gdb/infcmd.c
> +++ b/gdb/infcmd.c
> @@ -1068,8 +1068,7 @@ jump_command (const char *arg, int from_tty)
>      error_no_arg (_("starting address"));
> 
>    std::vector<symtab_and_line> sals
> -    = decode_line_with_last_displayed (arg, DECODE_LINE_FUNFIRSTLINE,
> -				       current_program_space);
> +    = decode_line_with_current_source (arg, DECODE_LINE_FUNFIRSTLINE);
>    if (sals.size () != 1)
>      error (_("Unreasonable jump request"));
> 
> diff --git a/gdb/linespec.c b/gdb/linespec.c
> index 920fd3d37b7..9f03a4b3604 100644
> --- a/gdb/linespec.c
> +++ b/gdb/linespec.c
> @@ -3220,7 +3220,8 @@ decode_line_with_current_source (const char
> *string, int flags)
>    location_spec_up locspec = string_to_location_spec (&string,
>  						      current_language);
>    std::vector<symtab_and_line> sals
> -    = decode_line_1 (locspec.get (), flags, NULL, cursal.symtab, cursal.line);
> +    = decode_line_1 (locspec.get (), flags, cursal.pspace, cursal.symtab,
> +		     cursal.line);
> 
>    if (*string)
>      error (_("Junk at end of line specification: %s"), string);
> @@ -3231,8 +3232,7 @@ decode_line_with_current_source (const char
> *string, int flags)
>  /* See linespec.h.  */
> 
>  std::vector<symtab_and_line>
> -decode_line_with_last_displayed (const char *string, int flags,
> -				 program_space *search_pspace)
> +decode_line_with_last_displayed (const char *string, int flags)
>  {
>    if (string == 0)
>      error (_("Empty line specification."));
> @@ -3241,10 +3241,10 @@ decode_line_with_last_displayed (const char
> *string, int flags,
>  						      current_language);
>    std::vector<symtab_and_line> sals
>      = (last_displayed_sal_is_valid ()
> -       ? decode_line_1 (locspec.get (), flags, search_pspace,
> +       ? decode_line_1 (locspec.get (), flags, NULL,
>  			get_last_displayed_symtab (),
>  			get_last_displayed_line ())
> -       : decode_line_1 (locspec.get (), flags, search_pspace, NULL, 0));
> +       : decode_line_1 (locspec.get (), flags, NULL, NULL, 0));
> 
>    if (*string)
>      error (_("Junk at end of line specification: %s"), string);
> diff --git a/gdb/linespec.h b/gdb/linespec.h
> index 0eb9cb5d9f2..c0eef7894d9 100644
> --- a/gdb/linespec.h
> +++ b/gdb/linespec.h
> @@ -143,7 +143,7 @@ extern std::vector<symtab_and_line>
> decode_line_with_current_source
>     Limit the search to given program space, if specified.  */
> 
>  extern std::vector<symtab_and_line> decode_line_with_last_displayed
> -    (const char *, int, program_space *search_pspace = nullptr);
> +    (const char *, int);
> 
>  /* Does P represent one of the keywords?  If so, return
>     the keyword.  If not, return NULL.  */

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928