https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100467
--- Comment #3 from Bernd Edlinger <edlinger at gcc dot gnu.org> ---
Okay, after some debugging I see the problem.
Usually thunks are emitted from ymtab-thunks.cc:
cfun->is_thunk = 1;
insn_locations_init ();
set_curr_insn_location (DECL_SOURCE_LOCATION (thunk_fndecl));
prologue_location = curr_insn_location ();
targetm.asm_out.output_mi_thunk (asm_out_file, thunk_fndecl,
fixed_offset, virtual_value, alias);
the only other place where prologue_location is set
is in cfgexpand.c:
if (!DECL_IS_UNDECLARED_BUILTIN (current_function_decl))
{
/* Eventually, all FEs should explicitly set function_start_locus. */
if (LOCATION_LOCUS (fun->function_start_locus) == UNKNOWN_LOCATION)
set_curr_insn_location
(DECL_SOURCE_LOCATION (current_function_decl));
else
set_curr_insn_location (fun->function_start_locus);
}
else
set_curr_insn_location (UNKNOWN_LOCATION);
prologue_location = curr_insn_location ();
BUT this special "thunk" is emitted from toplev.c:
/* This must be at the end before unwind and debug info.
Some target ports emit PIC setup thunks here. */
targetm.asm_out.code_end ();
and here the prologue_location is not initialized, also the backend
does not know about it's significance.
So the source line number for this thunk is indeed wrong.
