ceph/m4/ax_arm.m4
Yazen Ghannam 60762338a2 crc32c: add aarch64 optimized crc32c implementation
ARMv8 defines a set of optional CRC32/CRC32C instructions.
This patch defines an optimized function that uses these
instructions when available rather than table-based lookup.
Optimized function based on a Hadoop patch by Ed Nevill.

Autotools updated to check for compiler support.
Optimized function is selected at runtime based on HWCAP_CRC32.
Added crc32c "performance" unit test and arch unit test.

Tested on AMD Seattle.
Passes all crc32c unit tests.
Unit test shows ~4x performance increase versus sctp.

Signed-off-by: Yazen Ghannam <yazen.ghannam@linaro.org>
Reviewed-by: Steve Capper <steve.capper@linaro.org>
2015-03-17 13:56:52 -05:00

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AC_DEFUN([AX_ARM_FEATURES],
[
AC_REQUIRE([AC_CANONICAL_HOST])
case $target_cpu in
arm*)
AX_CHECK_COMPILE_FLAG(-mfpu=neon, ax_cv_support_neon_ext=yes, [])
if test x"$ax_cv_support_neon_ext" = x"yes"; then
ARM_NEON_FLAGS="-mfpu=neon -DARM_NEON"
AC_SUBST(ARM_NEON_FLAGS)
ARM_FLAGS="$ARM_FLAGS $ARM_NEON_FLAGS"
AC_DEFINE(HAVE_NEON,,[Support NEON instructions])
fi
;;
aarch64*)
AX_CHECK_COMPILE_FLAG(-march=armv8-a, ax_cv_support_armv8=yes, [])
if test x"$ax_cv_support_armv8" = x"yes"; then
ARM_ARCH_FLAGS="-march=armv8-a"
ARM_DEFINE_FLAGS="-DARCH_AARCH64"
fi
AX_CHECK_COMPILE_FLAG(-march=armv8-a+simd, ax_cv_support_neon_ext=yes, [])
if test x"$ax_cv_support_neon_ext" = x"yes"; then
ARM_ARCH_FLAGS="$ARM_ARCH_FLAGS+simd"
ARM_DEFINE_FLAGS="$ARM_DEFINE_FLAGS -DARM_NEON"
ARM_NEON_FLAGS="-march=armv8-a+simd -DARCH_AARCH64 -DARM_NEON"
AC_DEFINE(HAVE_NEON,,[Support NEON instructions])
AC_SUBST(ARM_NEON_FLAGS)
fi
AX_CHECK_COMPILE_FLAG(-march=armv8-a+crc, ax_cv_support_crc_ext=yes, [])
if test x"$ax_cv_support_crc_ext" = x"yes"; then
ARM_ARCH_FLAGS="$ARM_ARCH_FLAGS+crc"
ARM_CRC_FLAGS="-march=armv8-a+crc -DARCH_AARCH64"
AC_DEFINE(HAVE_ARMV8_CRC,,[Support ARMv8 CRC instructions])
AC_SUBST(ARM_CRC_FLAGS)
fi
ARM_FLAGS="$ARM_ARCH_FLAGS $ARM_DEFINE_FLAGS"
;;
esac
AC_SUBST(ARM_FLAGS)
])