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Use native CRC instructions on 64-bit LoongArch

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As with the Intel and Arm CRC instructions, compiler intrinsics for
them must be supported by the compiler. In contrast, no runtime check
is needed. Aligned memory access is faster, so use the Arm coding as
a model.

YANG Xudong

Discussion: https://postgr.es/m/b522a0c5-e3b2-99cc-6387-58134fb88cbe%40ymatrix.cn
This commit is contained in:
John Naylor
2023-08-10 11:36:15 +07:00
parent fa2e874946
commit 4d14ccd6af
8 changed files with 240 additions and 17 deletions
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33
config/c-compiler.m4
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@ -661,3 +661,36 @@ if test x"$Ac_cachevar" = x"yes"; then
fi
undefine([Ac_cachevar])dnl
])# PGAC_ARMV8_CRC32C_INTRINSICS
# PGAC_LOONGARCH_CRC32C_INTRINSICS
# ---------------------------
# Check if the compiler supports the LoongArch CRCC instructions, using
# __builtin_loongarch_crcc_w_b_w, __builtin_loongarch_crcc_w_h_w,
# __builtin_loongarch_crcc_w_w_w and __builtin_loongarch_crcc_w_d_w
# intrinsic functions.
#
# We test for the 8-byte variant since platforms capable of running
# Postgres are 64-bit only (as of PG17), and we know CRC instructions
# are available there without a runtime check.
#
# If the intrinsics are supported, sets pgac_loongarch_crc32c_intrinsics.
AC_DEFUN([PGAC_LOONGARCH_CRC32C_INTRINSICS],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_loongarch_crc32c_intrinsics])])dnl
AC_CACHE_CHECK(
[for __builtin_loongarch_crcc_w_b_w, __builtin_loongarch_crcc_w_h_w, __builtin_loongarch_crcc_w_w_w and __builtin_loongarch_crcc_w_d_w],
[Ac_cachevar],
[AC_LINK_IFELSE([AC_LANG_PROGRAM([],
[unsigned int crc = 0;
crc = __builtin_loongarch_crcc_w_b_w(0, crc);
crc = __builtin_loongarch_crcc_w_h_w(0, crc);
crc = __builtin_loongarch_crcc_w_w_w(0, crc);
crc = __builtin_loongarch_crcc_w_d_w(0, crc);
/* return computed value, to prevent the above being optimized away */
return crc == 0;])],
[Ac_cachevar=yes],
[Ac_cachevar=no])])
if test x"$Ac_cachevar" = x"yes"; then
pgac_loongarch_crc32c_intrinsics=yes
fi
undefine([Ac_cachevar])dnl
])# PGAC_LOONGARCH_CRC32C_INTRINSICS