GMP test fails with -flto

[Richard Biener]

On Tue, Jul 2, 2019 at 12:41 PM Torbjörn Granlund <tg at gmplib.org> wrote:
>
> Richard Biener <richard.guenther at gmail.com> writes:
>
>   On Mon, Jul 1, 2019 at 11:13 PM Torbjörn Granlund <tg at gmplib.org> wrote:
>   >
>   > Vincent Lefevre <vincent at vinc17.net> writes:
>   >
>   >   Yes, with LTO, the object file does not contain the structure as is.
>   >   Thus the detection from "od -b conftest.$OBJEXT" does not work.
>   >
>   > That could be solved by generating a final executable, right?
> >
>   Yes.
>
> Does the patch below make sense?
>
> The main funcion is needed as we create an executable, its references to
> foo are needed, else LTO will remove foo altogether.

Yes, this should work.  It probably has a slightly higher chance of mismatching
the start/end patterns elsewhere in the file, but well...

Richard.

> *** /tmp/extdiff.MsIr0g/gmp-main.3300fbb5d615/acinclude.m4      Mon Jun 17 00:11:50 2019
> --- /home/tege/prec/gmp-main/acinclude.m4       Tue Jul  2 12:37:53 2019
> ***************
> *** 3307,3313 ****
>     -123456789.0,
>     { '\376', '\334', '\272', '\230', '\166', '\124', '\062', '\020' },
> ! };]
>   EOF
> ! gmp_compile="$CC $CFLAGS $CPPFLAGS -c conftest.c >&AC_FD_CC 2>&1"
>   if AC_TRY_EVAL(gmp_compile); then
>   cat >conftest.awk <<\EOF
> --- 3307,3320 ----
>     -123456789.0,
>     { '\376', '\334', '\272', '\230', '\166', '\124', '\062', '\020' },
> ! };
> ! int main(){
> !   int i;
> !   for (i = 0; i < 8; i++) {
> !     printf ("%d %d %f\n", foo.before[i] + foo.after[i], foo.x);
> !   }
> !   return 0;
> ! }]
>   EOF
> ! gmp_compile="$CC $CFLAGS $CPPFLAGS conftest.c -o conftest >&AC_FD_CC 2>&1"
>   if AC_TRY_EVAL(gmp_compile); then
>   cat >conftest.awk <<\EOF
> ***************
> *** 3462,3470 ****
>   ]
>   EOF
> !   gmp_cv_c_double_format=`od -b conftest.$OBJEXT | $AWK -f conftest.awk`
>     case $gmp_cv_c_double_format in
>     unknown*)
> !     echo "cannot match anything, conftest.$OBJEXT contains" >&AC_FD_CC
> !     od -b conftest.$OBJEXT >&AC_FD_CC
>       ;;
>     esac
> --- 3469,3477 ----
>   ]
>   EOF
> !   gmp_cv_c_double_format=`od -b conftest | $AWK -f conftest.awk`
>     case $gmp_cv_c_double_format in
>     unknown*)
> !     echo "cannot match anything, conftest contains" >&AC_FD_CC
> !     od -b conftest >&AC_FD_CC
>       ;;
>     esac
>
>
> --
> Torbjörn
> Please encrypt, key id 0xC8601622