Re: [r12-4457 Regression] FAIL: gfortran.dg/deferred_type_param_6.f90 -Os execution test on Linux/x86_64

[Richard Biener <richard.guenther@gmail.com>]

On Sat, Oct 16, 2021 at 8:24 PM Jan Hubicka via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi,
> >
> > FAIL: gfortran.dg/deferred_type_param_6.f90   -O1  execution test
> > FAIL: gfortran.dg/deferred_type_param_6.f90   -Os  execution test
> Sorry for the breakage.  This time it seems like bug in Fortran FE
> which was previously latent:
>
> __attribute__((fn spec (". . R ")))
> void subfunc (character(kind=1)[1:..__result] * & __result, integer(kind=8) * .__result)
> {
>   # PT = nonlocal
>   character(kind=1)[1:..__result] * & __result_3(D) = __result;
>   # PT = nonlocal null
>   integer(kind=8) * .__result_5(D) = .__result;
>   integer(kind=4) _1;
>
>   <bb 2> [local count: 1073741824]:
>   *__result_3(D) = &fifec;
>   # USE = nonlocal escaped { D.4230 } (nonlocal, escaped)
>   _1 = _gfortran_compare_string (5, &fifec, 5, &"FIVEC"[1]{lb: 1 sz: 1});
>   if (_1 != 0)
>     goto <bb 3>; [0.04%]
>   else
>     goto <bb 4>; [99.96%]
>
>   <bb 3> [local count: 429496]:
>   # USE = nonlocal escaped null
>   # CLB = nonlocal escaped null
>   _gfortran_stop_numeric (10, 0);
>
>   <bb 4> [local count: 1073312329]:
>   *.__result_5(D) = 5;
>   return;
> }
>
> The fnspec ". . R " specifies that .__result is readonly however we
> have:
>   *.__result_5(D) = 5;
>
> I am not sure I understand fortran FE well enough to figure out why
> it is set so.  The function is declared as:
>
>   function subfunc() result(res)
>     character(len=:), pointer :: res
>     res => fifec
>     if (len(res) /= 5) STOP 9
>     if (res /= "FIVEC") STOP 10
>   end function subfunc
>
> and we indeed optimize load of the result:
> -  # USE = nonlocal escaped { D.4252 D.4254 } (nonlocal, escaped)
> -  # CLB = nonlocal escaped { D.4254 } (escaped)
> +  # USE = nonlocal escaped
> +  # CLB = { D.4254 }
>    subfunc (&pstr.5, &slen.4);
> -  .s2_34 = slen.4;
> -  # PT = nonlocal escaped null { D.4254 } (escaped)
> -  s2_35 = pstr.5;
>    pstr.5 ={v} {CLOBBER};
>
> and I think tat is what breaks the testcase (I also verified that
> ignoring the fnspec 'R' fixes it).

The FE code adding the fnspec probably fails to consider the
separately passed length of the string result?

Can you open a bugreport please?

Richard.

> Honza
> >
> > with GCC configured with
> >
> > ../../gcc/configure --prefix=/local/skpandey/gccwork/toolwork/gcc-bisect-master/master/r12-4457/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap
> >
> > To reproduce:
> >
> > $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gfortran.dg/deferred_type_param_6.f90 --target_board='unix{-m32}'"
> > $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gfortran.dg/deferred_type_param_6.f90 --target_board='unix{-m32\ -march=cascadelake}'"
> > $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gfortran.dg/deferred_type_param_6.f90 --target_board='unix{-m64}'"
> > $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gfortran.dg/deferred_type_param_6.f90 --target_board='unix{-m64\ -march=cascadelake}'"
> >
> > (Please do not reply to this email, for question about this report, contact me at skpgkp2 at gmail dot com)