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Fix compiler builtin usage in new pg_bitutils.c

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Split out these new functions in three parts: one in a new file that
uses the compiler builtin and gets compiled with the -mpopcnt compiler
option if it exists; another one that uses the compiler builtin but not
the compiler option; and finally the fallback with open-coded
algorithms.

Split out the configure logic: in the original commit, it was selecting
to use the -mpopcnt compiler switch together with deciding whether to
use the compiler builtin, but those two things are really separate.
Split them out.  Also, expose whether the builtin exists to
Makefile.global, so that src/port's Makefile can decide whether to
compile the hw-optimized file.

Remove CPUID test for CTZ/CLZ.  Make pg_{right,left}most_ones use either
the compiler intrinsic or open-coded algo; trying to use the
HW-optimized version is a waste of time.  Make them static inline
functions.

Discussion: https://postgr.es/m/20190213221719.GA15976@alvherre.pgsql
This commit is contained in:
Alvaro Herrera
2019-02-15 13:07:02 -03:00
parent b060e6c1f5
commit fc6c72747a
8 changed files with 327 additions and 376 deletions
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66
configure vendored
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@ -651,7 +651,7 @@ CFLAGS_ARMV8_CRC32C
CFLAGS_SSE42
have_win32_dbghelp
LIBOBJS
CFLAGS_POPCNT
have__builtin_popcount
UUID_LIBS
LDAP_LIBS_BE
LDAP_LIBS_FE
@ -733,6 +733,7 @@ CPP
BITCODE_CXXFLAGS
BITCODE_CFLAGS
CFLAGS_VECTOR
CFLAGS_POPCNT
PERMIT_DECLARATION_AFTER_STATEMENT
LLVM_BINPATH
LLVM_CXXFLAGS
@ -6581,6 +6582,48 @@ fi
fi
# Optimization flags and options for bit-twiddling
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -mpopcnt, for CFLAGS_POPCNT" >&5
$as_echo_n "checking whether ${CC} supports -mpopcnt, for CFLAGS_POPCNT... " >&6; }
if ${pgac_cv_prog_CC_cflags__mpopcnt+:} false; then :
$as_echo_n "(cached) " >&6
else
pgac_save_CFLAGS=$CFLAGS
pgac_save_CC=$CC
CC=${CC}
CFLAGS="${CFLAGS_POPCNT} -mpopcnt"
ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
pgac_cv_prog_CC_cflags__mpopcnt=yes
else
pgac_cv_prog_CC_cflags__mpopcnt=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
ac_c_werror_flag=$ac_save_c_werror_flag
CFLAGS="$pgac_save_CFLAGS"
CC="$pgac_save_CC"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CC_cflags__mpopcnt" >&5
$as_echo "$pgac_cv_prog_CC_cflags__mpopcnt" >&6; }
if test x"$pgac_cv_prog_CC_cflags__mpopcnt" = x"yes"; then
CFLAGS_POPCNT="${CFLAGS_POPCNT} -mpopcnt"
fi
CFLAGS_VECTOR=$CFLAGS_VECTOR
@ -14111,32 +14154,28 @@ $as_echo "#define HAVE__BUILTIN_CTZ 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_popcount" >&5
$as_echo_n "checking for __builtin_popcount... " >&6; }
if ${pgac_cv_popcount+:} false; then :
if ${pgac_cv__builtin_popcount+:} false; then :
$as_echo_n "(cached) " >&6
else
pgac_save_CFLAGS=$CFLAGS
CFLAGS="$pgac_save_CFLAGS -mpopcnt"
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
static int x = __builtin_popcount(255);
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
pgac_cv_popcount=yes
pgac_cv__builtin_popcount=yes
else
pgac_cv_popcount=no
pgac_cv__builtin_popcount=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
CFLAGS="$pgac_save_CFLAGS"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_popcount" >&5
$as_echo "$pgac_cv_popcount" >&6; }
if test x"$pgac_cv_popcount" = x"yes"; then
CFLAGS_POPCNT="-mpopcnt"
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_popcount" >&5
$as_echo "$pgac_cv__builtin_popcount" >&6; }
if test x"$pgac_cv__builtin_popcount" = x"yes"; then
$as_echo "#define HAVE__BUILTIN_POPCOUNT 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_unreachable" >&5
$as_echo_n "checking for __builtin_unreachable... " >&6; }
if ${pgac_cv__builtin_unreachable+:} false; then :
@ -14654,6 +14693,7 @@ $as_echo "#define LOCALE_T_IN_XLOCALE 1" >>confdefs.h
fi
have__builtin_popcount=$pgac_cv__builtin_popcount
# MSVC doesn't cope well with defining restrict to __restrict, the