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Commitb4eb2d1

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Try to fix the CRC-32C autoconf magic for icc compiler.
On gcc and clang, the _mm_crc32_u8 and _mm_crc32_u64 intrinsics are notdefined at all, when not building with -msse4.2. But on icc, they are.So we cannot assume that if those intrinsics are defined, we can always usethem safely, we might still need the runtime check.To fix, check if the __SSE_4_2__ preprocessor symbol is defined. That'ssupposed to be defined only when the compiler is targeting a processor thathas SSE 4.2 support.Per buildfarm members fulmar and okapi.
1 parent0a52faf commitb4eb2d1

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2 files changed

+50
-12
lines changed

2 files changed

+50
-12
lines changed

‎configure‎

Lines changed: 32 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -14169,7 +14169,7 @@ fi
1416914169

1417014170
# Check for Intel SSE 4.2 intrinsics to do CRC calculations.
1417114171
#
14172-
# First check if the _mm_crc32_u8 and_mmcrc32_u64 intrinsics can be used
14172+
# First check if the _mm_crc32_u8 and_mm_crc32_u64 intrinsics can be used
1417314173
# with the default compiler flags. If not, check if adding the -msse4.2
1417414174
# flag helps. CFLAGS_SSE42 is set to -msse4.2 if that's required.
1417514175
{$as_echo"$as_me:${as_lineno-$LINENO}: checking for _mm_crc32_u8 and _mm_crc32_u64 with CFLAGS=">&5
@@ -14254,23 +14254,49 @@ fi
1425414254
fi
1425514255

1425614256

14257+
# Are we targeting a processor that supports SSE 4.2? gcc, clang and icc all
14258+
# define __SSE4_2__ in that case.
14259+
cat confdefs.h -<<_ACEOF >conftest.$ac_ext
14260+
/* end confdefs.h. */
14261+
14262+
int
14263+
main ()
14264+
{
14265+
14266+
#ifndef __SSE4_2__
14267+
#error __SSE4_2__ not defined
14268+
#endif
14269+
14270+
;
14271+
return 0;
14272+
}
14273+
_ACEOF
14274+
if ac_fn_c_try_compile"$LINENO";then:
14275+
SSE4_2_TARGETED=1
14276+
fi
14277+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
14278+
1425714279
# Select CRC-32C implementation.
1425814280
#
14259-
# If the SSE 4.2 intrinsics are available without extra CFLAGS, then use them
14260-
# always. If they require extra CFLAGS, compile both implementations and
14261-
# select which one to use at runtime, depending on whether SSE 4.2 is
14262-
# supported by the processor we're running on.
14281+
# If we are targeting a processor that has SSE 4.2 instructions, we can use the
14282+
# special CRC instructions for calculating CRC-32C. If we're not targeting such
14283+
# a processor, but we can nevertheless produce code that uses the SSE
14284+
# intrinsics, perhaps with some extra CFLAGS, compile both implementations and
14285+
# select which one to use at runtime, depending on whether SSE 4.2 is supported
14286+
# by the processor we're running on.
1426314287
#
1426414288
# You can override this logic by setting the appropriate USE_*_CRC32 flag to 1
1426514289
# in the template or configure command line.
1426614290
iftest x"$USE_SSE42_CRC32C" = x""&&test x"$USE_SSE42_CRC32C_WITH_RUNTIME_CHECK" = x""&&test x"$USE_SLICING_BY_8_CRC32C" = x"";then
14267-
iftest x"$pgac_sse42_crc32_intrinsics" = x"yes"&&test x"$CFLAGS_SSE42" = x"";then
14291+
iftest x"$pgac_sse42_crc32_intrinsics" = x"yes"&&test x"$SSE4_2_TARGETED" = x"1";then
1426814292
USE_SSE42_CRC32C=1
1426914293
else
1427014294
# the CPUID instruction is needed for the runtime check.
1427114295
iftest x"$pgac_sse42_crc32_intrinsics" = x"yes"&& (test x"$pgac_cv__get_cpuid" = x"yes"||test x"$pgac_cv__cpuid" = x"yes");then
1427214296
USE_SSE42_CRC32C_WITH_RUNTIME_CHECK=1
1427314297
else
14298+
# fall back to slicing-by-8 algorithm which doesn't require any special
14299+
# CPU support.
1427414300
USE_SLICING_BY_8_CRC32C=1
1427514301
fi
1427614302
fi

‎configure.in‎

Lines changed: 18 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1816,7 +1816,7 @@ fi
18161816

18171817
# Check for Intel SSE 4.2 intrinsics to do CRC calculations.
18181818
#
1819-
# First check if the _mm_crc32_u8 and_mmcrc32_u64 intrinsics can be used
1819+
# First check if the _mm_crc32_u8 and_mm_crc32_u64 intrinsics can be used
18201820
# with the default compiler flags. If not, check if adding the -msse4.2
18211821
# flag helps. CFLAGS_SSE42 is set to -msse4.2 if that's required.
18221822
PGAC_SSE42_CRC32_INTRINSICS([])
@@ -1825,23 +1825,35 @@ if test x"$pgac_sse42_crc32_intrinsics" != x"yes"; then
18251825
fi
18261826
AC_SUBST(CFLAGS_SSE42)
18271827

1828+
# Are we targeting a processor that supports SSE 4.2? gcc, clang and icc all
1829+
# define __SSE4_2__ in that case.
1830+
AC_TRY_COMPILE([], [
1831+
#ifndef __SSE4_2__
1832+
#error __SSE4_2__ not defined
1833+
#endif
1834+
], [SSE4_2_TARGETED=1])
1835+
18281836
# Select CRC-32C implementation.
18291837
#
1830-
# If the SSE 4.2 intrinsics are available without extra CFLAGS, then use them
1831-
# always. If they require extra CFLAGS, compile both implementations and
1832-
# select which one to use at runtime, depending on whether SSE 4.2 is
1833-
# supported by the processor we're running on.
1838+
# If we are targeting a processor that has SSE 4.2 instructions, we can use the
1839+
# special CRC instructions for calculating CRC-32C. If we're not targeting such
1840+
# a processor, but we can nevertheless produce code that uses the SSE
1841+
# intrinsics, perhaps with some extra CFLAGS, compile both implementations and
1842+
# select which one to use at runtime, depending on whether SSE 4.2 is supported
1843+
# by the processor we're running on.
18341844
#
18351845
# You can override this logic by setting the appropriate USE_*_CRC32 flag to 1
18361846
# in the template or configure command line.
18371847
if test x"$USE_SSE42_CRC32C" = x"" && test x"$USE_SSE42_CRC32C_WITH_RUNTIME_CHECK" = x"" && test x"$USE_SLICING_BY_8_CRC32C" = x""; then
1838-
if test x"$pgac_sse42_crc32_intrinsics" = x"yes" && test x"$CFLAGS_SSE42" = x"" ; then
1848+
if test x"$pgac_sse42_crc32_intrinsics" = x"yes" && test x"$SSE4_2_TARGETED" = x"1" ; then
18391849
USE_SSE42_CRC32C=1
18401850
else
18411851
# the CPUID instruction is needed for the runtime check.
18421852
if test x"$pgac_sse42_crc32_intrinsics" = x"yes" && (test x"$pgac_cv__get_cpuid" = x"yes" || test x"$pgac_cv__cpuid" = x"yes"); then
18431853
USE_SSE42_CRC32C_WITH_RUNTIME_CHECK=1
18441854
else
1855+
# fall back to slicing-by-8 algorithm which doesn't require any special
1856+
# CPU support.
18451857
USE_SLICING_BY_8_CRC32C=1
18461858
fi
18471859
fi

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