RE: [PATCH v11 06/10] gdb: Skip trampoline functions for the up command.

["Ijaz, Abdul B" <abdul.b.ijaz@intel.com>]

Thanks Tom, for the feedback.

>> This change skips trampoline functions when the option 
>> 'skip-trampoline-functions' is set to 'on' for the up command.  Before 
>> this change, GDB processes trampoline functions indicated by the 
>> compiler with DIE "DW_AT_trampoline" and stops at the trampoline function for the 'up'
>> command.  For better user experience, all such frames can be skipped 
>> and hidden from the user.

Tom> Why "up" but not "down"?

Abdul> No reason and just missed, but will be added in V12. The "down" command should skip trampoline frames as well;

Currently using v11 patch,  "down" command from the frame outside a trampoline selects the trampoline, which "bt" does not show.  With ifx and gdb.fortran/func-trampoline.f90 (func_trampoline -> first_.t95p.t96p -> first -> second_.t74p.t75p -> second), stopped in "second":

  (gdb) bt
  #0  second (x=20, y=9) at func-trampoline.f90:23
  #2  0x00000000004052a3 in first (num1=16, num2=3) at func-trampoline.f90:30
  #4  0x00000000004052f4 in func_trampoline () at func-trampoline.f90:36
  (gdb) up
  #2  0x00000000004052a3 in first (num1=16, num2=3) at func-trampoline.f90:30
  (gdb) down
  #1  0x00000000004052c9 in second_.t74p.t75p () at func-trampoline.f90:31

For v12 "down" will skip trampoline frames too, stopping at the innermost frame even if that is a trampoline. 

Tom> I was thinking about this last night and wondering how this change interacts with the "frame" command as well.

The "frame" command works as expected.  Trampoline frames always exist; they are only skipped by commands like "backtrace", "finish" or "up", where they do not add useful information.  If the user wants to select a trampoline frame, "frame N" (and "frame level", "frame function", ...) still selects it, with its real level:

  (gdb) frame 1
  #1  0x00000000004052c9 in second_.t74p.t75p () at func-trampoline.f90:31
  (gdb) frame 0
  #0  second (x=20, y=9) at func-trampoline.f90:23

"frame apply all", "frame apply N" are different, though:  they walk all frames, so they also run the command in the trampoline frames that "bt" does not show.

(gdb) frame apply all -c print num1
  #0  second (x=20, y=9) at func-trampoline.f90:23
  No symbol "num1" in current context.
  #1  0x00000000004052c9 in second_.t74p.t75p () at func-trampoline.f90:31
  No symbol "num1" in current context.
  #2  0x00000000004052a3 in first (num1=16, num2=3) at func-trampoline.f90:30
  $1 = 16
  #3  0x00000000004053c9 in first_.t95p.t96p () at func-trampoline.f90:40
  No symbol "num1" in current context.
  #4  0x00000000004052f4 in func_trampoline () at func-trampoline.f90:36
  No symbol "num1" in current context.

For v12 I will make them skip trampoline frames like "bt" (or follow whatever we decide for "bt" in 04/10), and add tests accordingly.

Thanks & Best Regards,
Abdul Basit

-----Original Message-----
From: Tom Tromey <tom@tromey.com> 
Sent: Thursday, October 22, 2026 3:02 PM
To: Tom Tromey <tom@tromey.com>
Cc: Ijaz, Abdul B <abdul.b.ijaz@intel.com>; gdb-patches@sourceware.org; JiniSusan.George@amd.com; eliz@gnu.org
Subject: Re: [PATCH v11 06/10] gdb: Skip trampoline functions for the up command.

>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:

>>>>> Abdul Basit Ijaz <abdul.b.ijaz@intel.com> writes:
>> This change skips trampoline functions when the option 
>> 'skip-trampoline-functions' is set to 'on' for the up command.  
>> Before this change, GDB processes trampoline functions indicated by 
>> the compiler with DIE "DW_AT_trampoline" and stops at the trampoline function for the 'up'
>> command.  For better user experience, all such frames can be skipped 
>> and hidden from the user.

Tom> Why "up" but not "down"?

I was thinking about this last night and wondering how this change interacts with the "frame" command as well.

Tom
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