GMP test fails with -flto

[Torbjörn Granlund]

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.

*** /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
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