glibc/sysdeps/x86_64/configure.ac
Fangrui Song 115d242456 x86_64: Remove unneeded static PIE check for undefined weak diagnostic
https://sourceware.org/bugzilla/show_bug.cgi?id=21782 dropped an ld
diagnostic for R_X86_64_PC32 referencing an undefined weak symbol in
-pie links.  Arguably keeping the diagnostic like other ports is more
correct, since statically resolving movl foo(%rip), %eax to the
link-time zero address produces a corrupted output.

It turns out that --enable-static-pie builds do not depend on the ld
behavior. GCC generates GOT indirection for weak declarations for
-fPIE/-fPIC, so what ld does with the PC-relative relocation doesn't
really matter.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2021-07-08 14:26:22 -07:00

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GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/x86_64.
dnl Check if asm supports AVX512DQ.
AC_CACHE_CHECK(for AVX512DQ support in assembler, libc_cv_asm_avx512dq, [dnl
cat > conftest.s <<\EOF
vandpd (%rax), %zmm6, %zmm1
EOF
if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
libc_cv_asm_avx512dq=yes
else
libc_cv_asm_avx512dq=no
fi
rm -f conftest*])
if test $libc_cv_asm_avx512dq = yes; then
AC_DEFINE(HAVE_AVX512DQ_ASM_SUPPORT)
fi
dnl Check if -mavx512f works.
AC_CACHE_CHECK(for AVX512 support, libc_cv_cc_avx512, [dnl
LIBC_TRY_CC_OPTION([-mavx512f], [libc_cv_cc_avx512=$libc_cv_asm_avx512dq], [libc_cv_cc_avx512=no])
])
if test $libc_cv_cc_avx512 = yes; then
AC_DEFINE(HAVE_AVX512_SUPPORT)
fi
LIBC_CONFIG_VAR([config-cflags-avx512], [$libc_cv_cc_avx512])
dnl Check if -mprefer-vector-width=128 works.
AC_CACHE_CHECK(-mprefer-vector-width=128, libc_cv_cc_mprefer_vector_width, [dnl
LIBC_TRY_CC_OPTION([-mprefer-vector-width=128],
[libc_cv_cc_mprefer_vector_width=yes],
[libc_cv_cc_mprefer_vector_width=no])
])
LIBC_CONFIG_VAR([config-cflags-mprefer-vector-width],
[$libc_cv_cc_mprefer_vector_width])
dnl Check whether asm supports Intel MPX
AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
cat > conftest.s <<\EOF
bndmov %bnd0,(%rsp)
EOF
if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
libc_cv_asm_mpx=yes
else
libc_cv_asm_mpx=no
fi
rm -f conftest*])
if test $libc_cv_asm_mpx = yes; then
AC_DEFINE(HAVE_MPX_SUPPORT)
fi
if test x"$build_mathvec" = xnotset; then
build_mathvec=yes
fi
dnl It is always possible to access static and hidden symbols in an
dnl position independent way.
AC_DEFINE(PI_STATIC_AND_HIDDEN)
dnl Static PIE is supported.
AC_DEFINE(SUPPORT_STATIC_PIE)
test -n "$critic_missing" && AC_MSG_ERROR([
*** $critic_missing])