Re: Building scratch/igc with -fno-omit-frame-pointer

[Stefan Kangas]

Pip Cet <pipcet@protonmail.com> writes:

> Thanks!  FWIW, I think this isn't a mistake in MPS.  C libraries changed
> to "scramble" the stack pointer and base pointer in the jump buffer in
> setjmp().  They provided no good alternative way to do what MPS needs.
> Assembly register spilling isn't a good option.  Emacs uses
> __builtin_unwind_init, FWIW.
>
>> diff --git a/configure.ac b/configure.ac
>> index 885075a2f1d..1d8f69ff119 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -5622,6 +5622,7 @@ AC_DEFUN
>>  HAVE_MPS=no
>>  LIBMPS=
>>  IGCOBJ=
>> +MPS_CFLAGS=
>>  if test "${with_mps}" != "no"; then
>>    AC_CHECK_HEADER([mps.h],
>>      [AC_CHECK_LIB([mps], [mps_arena_create], [HAVE_MPS=yes], [],
>> [$LIB_PTHREAD])])
>> @@ -5635,12 +5636,16 @@ AC_DEFUN
>>      else
>>        LIBMPS="-lmps $LIB_PTHREAD"
>>      fi
>> +    # Force -fno-omit-frame-pointer to avoid MPS bug with register scanning:
>
> As explained above, I'd prefer not calling it "MPS bug".  Let's just
> call it "bug"?

Thanks, I installed the patch with that change.