From 9d25c79719859b87d2137b0cd888d1f1a7c4d3cc Mon Sep 17 00:00:00 2001 From: John Naylor Date: Wed, 11 Aug 2021 21:26:59 -0400 Subject: [PATCH v2 1/2] Use direct function calls for pg_popcount{32,64} on non-x86 platforms Previously, all pg_popcount{32,64} calls were indirected through a function pointer, even though we had no fast implementation for non-x86 platforms. Instead, use wrappers around the pg_popcount{32,64}_slow functions. --- src/include/port/pg_bitutils.h | 38 +++++++++++++++++++++- src/port/pg_bitutils.c | 58 ++++++++++++---------------------- 2 files changed, 57 insertions(+), 39 deletions(-) diff --git a/src/include/port/pg_bitutils.h b/src/include/port/pg_bitutils.h index 086bd08132..21db364984 100644 --- a/src/include/port/pg_bitutils.h +++ b/src/include/port/pg_bitutils.h @@ -253,9 +253,45 @@ pg_ceil_log2_64(uint64 num) return pg_leftmost_one_pos64(num - 1) + 1; } -/* Count the number of one-bits in a uint32 or uint64 */ +/* + * With MSVC on x86_64 builds, try using native popcnt instructions via the + * __popcnt and __popcnt64 intrinsics. These don't work the same as GCC's + * __builtin_popcount* intrinsic functions as they always emit popcnt + * instructions. + */ +#if defined(_MSC_VER) && defined(_M_AMD64) +#define HAVE_X86_64_POPCNTQ +#endif + +/* + * On x86_64, we can use the hardware popcount instruction, but only if + * we can verify that the CPU supports it via the cpuid instruction. + * + * Otherwise, we fall back to a hand-rolled implementation. + */ +#ifdef HAVE_X86_64_POPCNTQ +#if defined(HAVE__GET_CPUID) || defined(HAVE__CPUID) +#define TRY_POPCNT_FAST 1 +#endif +#endif + +#ifdef TRY_POPCNT_FAST +/* Use the POPCNT instruction, but perform a runtime check first. */ +extern int pg_popcount32_slow(uint32 word); +extern int pg_popcount64_slow(uint64 word); extern int (*pg_popcount32) (uint32 word); extern int (*pg_popcount64) (uint64 word); +extern int pg_popcount32_fast(uint32 word); +extern int pg_popcount64_fast(uint64 word); + +#else +/* Use a portable implementation. */ +extern int pg_popcount32_slow(uint32 word); +extern int pg_popcount64_slow(uint64 word); +extern int pg_popcount32(uint32 word); +extern int pg_popcount64(uint64 word); + +#endif /* TRY_POPCNT_FAST */ /* Count the number of one-bits in a byte array */ extern uint64 pg_popcount(const char *buf, int bytes); diff --git a/src/port/pg_bitutils.c b/src/port/pg_bitutils.c index 10676b285c..b5a62def6f 100644 --- a/src/port/pg_bitutils.c +++ b/src/port/pg_bitutils.c @@ -103,47 +103,13 @@ const uint8 pg_number_of_ones[256] = { 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 }; -/* - * With MSVC on x86_64 builds, try using native popcnt instructions via the - * __popcnt and __popcnt64 intrinsics. These don't work the same as GCC's - * __builtin_popcount* intrinsic functions as they always emit popcnt - * instructions. - */ -#if defined(_MSC_VER) && defined(_M_AMD64) -#define HAVE_X86_64_POPCNTQ -#endif - -/* - * On x86_64, we can use the hardware popcount instruction, but only if - * we can verify that the CPU supports it via the cpuid instruction. - * - * Otherwise, we fall back to __builtin_popcount if the compiler has that, - * or a hand-rolled implementation if not. - */ -#ifdef HAVE_X86_64_POPCNTQ -#if defined(HAVE__GET_CPUID) || defined(HAVE__CPUID) -#define TRY_POPCNT_FAST 1 -#endif -#endif - -static int pg_popcount32_slow(uint32 word); -static int pg_popcount64_slow(uint64 word); - #ifdef TRY_POPCNT_FAST static bool pg_popcount_available(void); static int pg_popcount32_choose(uint32 word); static int pg_popcount64_choose(uint64 word); -static int pg_popcount32_fast(uint32 word); -static int pg_popcount64_fast(uint64 word); int (*pg_popcount32) (uint32 word) = pg_popcount32_choose; int (*pg_popcount64) (uint64 word) = pg_popcount64_choose; -#else -int (*pg_popcount32) (uint32 word) = pg_popcount32_slow; -int (*pg_popcount64) (uint64 word) = pg_popcount64_slow; -#endif /* TRY_POPCNT_FAST */ - -#ifdef TRY_POPCNT_FAST /* * Return true if CPUID indicates that the POPCNT instruction is available. @@ -208,7 +174,7 @@ pg_popcount64_choose(uint64 word) * pg_popcount32_fast * Return the number of 1 bits set in word */ -static int +int pg_popcount32_fast(uint32 word) { #ifdef _MSC_VER @@ -225,7 +191,7 @@ __asm__ __volatile__(" popcntl %1,%0\n":"=q"(res):"rm"(word):"cc"); * pg_popcount64_fast * Return the number of 1 bits set in word */ -static int +int pg_popcount64_fast(uint64 word) { #ifdef _MSC_VER @@ -245,7 +211,7 @@ __asm__ __volatile__(" popcntq %1,%0\n":"=q"(res):"rm"(word):"cc"); * pg_popcount32_slow * Return the number of 1 bits set in word */ -static int +int pg_popcount32_slow(uint32 word) { #ifdef HAVE__BUILTIN_POPCOUNT @@ -267,7 +233,7 @@ pg_popcount32_slow(uint32 word) * pg_popcount64_slow * Return the number of 1 bits set in word */ -static int +int pg_popcount64_slow(uint64 word) { #ifdef HAVE__BUILTIN_POPCOUNT @@ -291,6 +257,22 @@ pg_popcount64_slow(uint64 word) #endif /* HAVE__BUILTIN_POPCOUNT */ } +#ifndef TRY_POPCNT_FAST + +/* call these directly rather than through a function pointer */ +int +pg_popcount32(uint32 word) +{ + return pg_popcount32_slow(word); +} + +int +pg_popcount64(uint64 word) +{ + return pg_popcount64_slow(word); +} + +#endif /* !TRY_POPCNT_FAST */ /* * pg_popcount -- 2.31.1