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libgcc: aarch64: Configure check for __getauxval

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Add configure check for the __getauxval ABI symbol, which is always
available on aarch64 glibc, and may be available on other linux C
runtimes. For now only enabled on glibc, others have to override it

  target_configargs=libgcc_cv_have___getauxval=yes

This is deliberately obscure as it should be auto detected, ideally
via a feature test macro in unistd.h (link time detection is not
possible since the libc may not be installed at libgcc build time),
but currently there is no such feature test mechanism.

Without __getauxval, libgcc cannot do runtime CPU feature detection
and has to assume only the build time known features are available.

libgcc/ChangeLog:

	* config.in: Undef HAVE___GETAUXVAL.
	* configure: Regenerate.
	* configure.ac: Check for __getauxval.
This commit is contained in:
Szabolcs Nagy 2023-12-04 10:52:52 +00:00
parent 3ebb591c65
commit dbbfb52b0e
3 changed files with 48 additions and 0 deletions
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3
libgcc/config.in
View File

@ -16,6 +16,9 @@
/* Define to 1 if the assembler supports .variant_pcs. */
#undef HAVE_AS_VARIANT_PCS
/* Define to 1 if __getauxval is available. */
#undef HAVE___GETAUXVAL
/* Define to 1 if the target assembler supports thread-local storage. */
#undef HAVE_CC_TLS

26
libgcc/configure vendored
View File

@ -5658,6 +5658,32 @@ $as_echo "#define HAVE_AS_VARIANT_PCS 1" >>confdefs.h
;;
esac
# Check __getauxval ABI symbol for CPU feature detection.
case ${target} in
aarch64*-linux-*)
# No link check because the libc may not be present.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __getauxval" >&5
$as_echo_n "checking for __getauxval... " >&6; }
if ${libgcc_cv_have___getauxval+:} false; then :
$as_echo_n "(cached) " >&6
else
case ${target} in
*-linux-gnu*)
libgcc_cv_have___getauxval=yes
;;
*)
libgcc_cv_have___getauxval=no
esac
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_have___getauxval" >&5
$as_echo "$libgcc_cv_have___getauxval" >&6; }
if test x$libgcc_cv_have___getauxval = xyes; then
$as_echo "#define HAVE___GETAUXVAL 1" >>confdefs.h
fi
esac
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for init priority support" >&5
$as_echo_n "checking for init priority support... " >&6; }
if ${libgcc_cv_init_priority+:} false; then :

19
libgcc/configure.ac
View File

@ -665,6 +665,25 @@ aarch64*-*-*)
esac])
LIBGCC_CHECK_AS_VARIANT_PCS
# Check __getauxval ABI symbol for CPU feature detection.
case ${target} in
aarch64*-linux-*)
# No link check because the libc may not be present.
AC_CACHE_CHECK([for __getauxval],
[libgcc_cv_have___getauxval],
[case ${target} in
*-linux-gnu*)
libgcc_cv_have___getauxval=yes
;;
*)
libgcc_cv_have___getauxval=no
esac])
if test x$libgcc_cv_have___getauxval = xyes; then
AC_DEFINE(HAVE___GETAUXVAL, 1,
[Define to 1 if __getauxval is available.])
fi
esac
dnl Check if as supports RTM instructions.
AC_CACHE_CHECK(for init priority support, libgcc_cv_init_priority, [
AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,