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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug gdb/29196] [gdb, gcc-12/m32/pie] FAIL: gdb.base/gdb11531.exp:
 watchpoint variable triggers at next
Date: Wed, 08 Jun 2022 09:48:45 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D29196

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
I played around a bit with the test-case and created break2.c:
...
struct some_struct
{
  int a_field;
  int b_field;
  union { int z_field; };
};

struct some_struct values[50];

void marker4 (long d)
{
  int volatile i =3D 1;
  values[0].a_field =3D d;
}
...
which I compiled with gcc-12:
...
$ gcc-12 -B ./build/gcc break2.c -c -O2 -g -m32 -pie -fPIE
...
and found:
...
00000000 <marker4>:
   0:   e8 fc ff ff ff          call   1 <marker4+0x1>
   5:   05 01 00 00 00          add    $0x1,%eax
   a:   83 ec 10                sub    $0x10,%esp
   d:   8b 54 24 14             mov    0x14(%esp),%edx
  11:   c7 44 24 0c 01 00 00    movl   $0x1,0xc(%esp)
  18:   00=20
  19:   89 90 00 00 00 00       mov    %edx,0x0(%eax)
  1f:   83 c4 10                add    $0x10,%esp
  22:   c3                      ret=20=20=20=20
...

So, in this case the get_pc_thunk call ends up _before_ the usual prologue
part, which is something the current code doesn't take into account:
...
@@ -1821,7 +1934,9 @@ i386_analyze_prologue (struct gdbarch *gdbarch,
   pc =3D i386_skip_probe (pc);
   pc =3D i386_analyze_stack_align (pc, current_pc, cache);
   pc =3D i386_analyze_frame_setup (gdbarch, pc, current_pc, cache);
-  return i386_analyze_register_saves (pc, current_pc, cache);
+  pc =3D i386_analyze_register_saves (pc, current_pc, cache);
+  pc =3D i386_skip_call_pc_thunk (gdbarch, pc, cache);
+  return pc;
 }

 /* Return PC of first real instruction.  */
...

--=20
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