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Improve our method for probing the availability of ARM CRC instructions.

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Instead of depending on glibc's getauxval() function, just try to execute
the CRC code, and trap SIGILL if that happens.

Thomas Munro

Discussion: https://postgr.es/m/HE1PR0801MB1323D171938EABC04FFE7FA9E3110@HE1PR0801MB1323.eurprd08.prod.outlook.com
This commit is contained in:
Tom Lane
2018-05-02 18:06:43 -04:00
parent 40f52b16dd
commit 1c72ec6f49
4 changed files with 29 additions and 73 deletions
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45
configure vendored
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@ -17344,46 +17344,6 @@ fi
fi
# In order to detect at runtime, if the ARM CRC Extension is available,
# we will do "getauxval(AT_HWCAP) & HWCAP_CRC32". Check if we have
# everything we need for that.
for ac_func in getauxval
do :
ac_fn_c_check_func "$LINENO" "getauxval" "ac_cv_func_getauxval"
if test "x$ac_cv_func_getauxval" = xyes; then :
cat >>confdefs.h <<_ACEOF
#define HAVE_GETAUXVAL 1
_ACEOF
fi
done
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <sys/auxv.h>
#include <asm/hwcap.h>
int
main ()
{
#ifndef AT_HWCAP
#error AT_HWCAP not defined
#endif
#ifndef HWCAP_CRC32
#error HWCAP_CRC32 not defined
#endif
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
HAVE_HWCAP_CRC32=1
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
# Select CRC-32C implementation.
#
# If we are targeting a processor that has Intel SSE 4.2 instructions, we can
@ -17414,9 +17374,8 @@ if test x"$USE_SLICING_BY_8_CRC32C" = x"" && test x"$USE_SSE42_CRC32C" = x"" &&
if test x"$pgac_armv8_crc32c_intrinsics" = x"yes" && test x"$CFLAGS_ARMV8_CRC32C" = x""; then
USE_ARMV8_CRC32C=1
else
# ARM CRC Extension, with runtime check? The getauxval() function and
# HWCAP_CRC32 are needed for the runtime check.
if test x"$pgac_armv8_crc32c_intrinsics" = x"yes" && test x"$ac_cv_func_getauxval" = x"yes" && test x"$HAVE_HWCAP_CRC32" = x"1"; then
# ARM CRC Extension, with runtime check?
if test x"$pgac_armv8_crc32c_intrinsics" = x"yes"; then
USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK=1
else
# fall back to slicing-by-8 algorithm, which doesn't require any