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Rename "fast" and "slow" popcount functions.

Browse Source 
Since we now have several implementations of the popcount
functions, let's give them more descriptive names.  This commit
replaces "slow" with "portable" and "fast" with "sse42".  While the
POPCNT instruction is technically not part of SSE4.2, this naming
scheme is close enough in practice and is arguably easier to
understand than using "popcnt" instead.

Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/aWf_InS1VrbeXAfP%40nathan
This commit is contained in:
Nathan Bossart
2026-01-21 14:21:00 -06:00
parent 79e232ca01
commit 8c6653516c
3 changed files with 53 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/include/port/pg_bitutils.h
View File

@@ -307,10 +307,10 @@ pg_ceil_log2_64(uint64 num)
#define POPCNT_AARCH64 1
#endif
extern int pg_popcount32_slow(uint32 word);
extern int pg_popcount64_slow(uint64 word);
extern uint64 pg_popcount_slow(const char *buf, int bytes);
extern uint64 pg_popcount_masked_slow(const char *buf, int bytes, bits8 mask);
extern int pg_popcount32_portable(uint32 word);
extern int pg_popcount64_portable(uint64 word);
extern uint64 pg_popcount_portable(const char *buf, int bytes);
extern uint64 pg_popcount_masked_portable(const char *buf, int bytes, bits8 mask);
#ifdef TRY_POPCNT_X86_64
/*

38
src/port/pg_bitutils.c
View File

@@ -97,11 +97,11 @@ const uint8 pg_number_of_ones[256] = {
};
/*
* pg_popcount32_slow
* pg_popcount32_portable
* Return the number of 1 bits set in word
*/
int
pg_popcount32_slow(uint32 word)
pg_popcount32_portable(uint32 word)
{
#ifdef HAVE__BUILTIN_POPCOUNT
return __builtin_popcount(word);
@@ -119,11 +119,11 @@ pg_popcount32_slow(uint32 word)
}
/*
* pg_popcount64_slow
* pg_popcount64_portable
* Return the number of 1 bits set in word
*/
int
pg_popcount64_slow(uint64 word)
pg_popcount64_portable(uint64 word)
{
#ifdef HAVE__BUILTIN_POPCOUNT
#if SIZEOF_LONG == 8
@@ -147,11 +147,11 @@ pg_popcount64_slow(uint64 word)
}
/*
* pg_popcount_slow
* pg_popcount_portable
* Returns the number of 1-bits in buf
*/
uint64
pg_popcount_slow(const char *buf, int bytes)
pg_popcount_portable(const char *buf, int bytes)
{
uint64 popcnt = 0;
@@ -163,7 +163,7 @@ pg_popcount_slow(const char *buf, int bytes)
while (bytes >= 8)
{
popcnt += pg_popcount64_slow(*words++);
popcnt += pg_popcount64_portable(*words++);
bytes -= 8;
}
@@ -177,7 +177,7 @@ pg_popcount_slow(const char *buf, int bytes)
while (bytes >= 4)
{
popcnt += pg_popcount32_slow(*words++);
popcnt += pg_popcount32_portable(*words++);
bytes -= 4;
}
@@ -193,11 +193,11 @@ pg_popcount_slow(const char *buf, int bytes)
}
/*
* pg_popcount_masked_slow
* pg_popcount_masked_portable
* Returns the number of 1-bits in buf after applying the mask to each byte
*/
uint64
pg_popcount_masked_slow(const char *buf, int bytes, bits8 mask)
pg_popcount_masked_portable(const char *buf, int bytes, bits8 mask)
{
uint64 popcnt = 0;
@@ -211,7 +211,7 @@ pg_popcount_masked_slow(const char *buf, int bytes, bits8 mask)
while (bytes >= 8)
{
popcnt += pg_popcount64_slow(*words++ & maskv);
popcnt += pg_popcount64_portable(*words++ & maskv);
bytes -= 8;
}
@@ -227,7 +227,7 @@ pg_popcount_masked_slow(const char *buf, int bytes, bits8 mask)
while (bytes >= 4)
{
popcnt += pg_popcount32_slow(*words++ & maskv);
popcnt += pg_popcount32_portable(*words++ & maskv);
bytes -= 4;
}
@@ -246,20 +246,20 @@ pg_popcount_masked_slow(const char *buf, int bytes, bits8 mask)
/*
* When special CPU instructions are not available, there's no point in using
* function pointers to vary the implementation between the fast and slow
* method. We instead just make these actual external functions. The compiler
* should be able to inline the slow versions here.
* function pointers to vary the implementation. We instead just make these
* actual external functions. The compiler should be able to inline the
* portable versions here.
*/
int
pg_popcount32(uint32 word)
{
return pg_popcount32_slow(word);
return pg_popcount32_portable(word);
}
int
pg_popcount64(uint64 word)
{
return pg_popcount64_slow(word);
return pg_popcount64_portable(word);
}
/*
@@ -269,7 +269,7 @@ pg_popcount64(uint64 word)
uint64
pg_popcount_optimized(const char *buf, int bytes)
{
return pg_popcount_slow(buf, bytes);
return pg_popcount_portable(buf, bytes);
}
/*
@@ -279,7 +279,7 @@ pg_popcount_optimized(const char *buf, int bytes)
uint64
pg_popcount_masked_optimized(const char *buf, int bytes, bits8 mask)
{
return pg_popcount_masked_slow(buf, bytes, mask);
return pg_popcount_masked_portable(buf, bytes, mask);
}
#endif /* ! TRY_POPCNT_X86_64 && ! POPCNT_AARCH64 */

56
src/port/pg_popcount_x86.c
View File

@@ -31,11 +31,15 @@
/*
* The SSE4.2 versions are built regardless of whether we are building the
* AVX-512 versions.
*
* Technically, POPCNT is not part of SSE4.2, and isn't even a vector
* operation, but in practice this is close enough, and "sse42" seems easier to
* follow than "popcnt" for these names.
*/
static inline int pg_popcount32_fast(uint32 word);
static inline int pg_popcount64_fast(uint64 word);
static uint64 pg_popcount_fast(const char *buf, int bytes);
static uint64 pg_popcount_masked_fast(const char *buf, int bytes, bits8 mask);
static inline int pg_popcount32_sse42(uint32 word);
static inline int pg_popcount64_sse42(uint64 word);
static uint64 pg_popcount_sse42(const char *buf, int bytes);
static uint64 pg_popcount_masked_sse42(const char *buf, int bytes, bits8 mask);
/*
* These are the AVX-512 implementations of the popcount functions.
@@ -64,7 +68,7 @@ uint64 (*pg_popcount_masked_optimized) (const char *buf, int bytes, bits8 mask)
* Return true if CPUID indicates that the POPCNT instruction is available.
*/
static bool
pg_popcount_available(void)
pg_popcount_sse42_available(void)
{
unsigned int exx[4] = {0, 0, 0, 0};
@@ -161,19 +165,19 @@ pg_popcount_avx512_available(void)
static inline void
choose_popcount_functions(void)
{
if (pg_popcount_available())
if (pg_popcount_sse42_available())
{
pg_popcount32 = pg_popcount32_fast;
pg_popcount64 = pg_popcount64_fast;
pg_popcount_optimized = pg_popcount_fast;
pg_popcount_masked_optimized = pg_popcount_masked_fast;
pg_popcount32 = pg_popcount32_sse42;
pg_popcount64 = pg_popcount64_sse42;
pg_popcount_optimized = pg_popcount_sse42;
pg_popcount_masked_optimized = pg_popcount_masked_sse42;
}
else
{
pg_popcount32 = pg_popcount32_slow;
pg_popcount64 = pg_popcount64_slow;
pg_popcount_optimized = pg_popcount_slow;
pg_popcount_masked_optimized = pg_popcount_masked_slow;
pg_popcount32 = pg_popcount32_portable;
pg_popcount64 = pg_popcount64_portable;
pg_popcount_optimized = pg_popcount_portable;
pg_popcount_masked_optimized = pg_popcount_masked_portable;
}
#ifdef USE_AVX512_POPCNT_WITH_RUNTIME_CHECK
@@ -335,11 +339,11 @@ pg_popcount_masked_avx512(const char *buf, int bytes, bits8 mask)
#endif /* USE_AVX512_POPCNT_WITH_RUNTIME_CHECK */
/*
* pg_popcount32_fast
* pg_popcount32_sse42
* Return the number of 1 bits set in word
*/
static inline int
pg_popcount32_fast(uint32 word)
pg_popcount32_sse42(uint32 word)
{
#ifdef _MSC_VER
return __popcnt(word);
@@ -352,11 +356,11 @@ __asm__ __volatile__(" popcntl %1,%0\n":"=q"(res):"rm"(word):"cc");
}
/*
* pg_popcount64_fast
* pg_popcount64_sse42
* Return the number of 1 bits set in word
*/
static inline int
pg_popcount64_fast(uint64 word)
pg_popcount64_sse42(uint64 word)
{
#ifdef _MSC_VER
return __popcnt64(word);
@@ -369,11 +373,11 @@ __asm__ __volatile__(" popcntq %1,%0\n":"=q"(res):"rm"(word):"cc");
}
/*
* pg_popcount_fast
* pg_popcount_sse42
* Returns the number of 1-bits in buf
*/
static uint64
pg_popcount_fast(const char *buf, int bytes)
pg_popcount_sse42(const char *buf, int bytes)
{
uint64 popcnt = 0;
@@ -385,7 +389,7 @@ pg_popcount_fast(const char *buf, int bytes)
while (bytes >= 8)
{
popcnt += pg_popcount64_fast(*words++);
popcnt += pg_popcount64_sse42(*words++);
bytes -= 8;
}
@@ -399,7 +403,7 @@ pg_popcount_fast(const char *buf, int bytes)
while (bytes >= 4)
{
popcnt += pg_popcount32_fast(*words++);
popcnt += pg_popcount32_sse42(*words++);
bytes -= 4;
}
@@ -415,11 +419,11 @@ pg_popcount_fast(const char *buf, int bytes)
}
/*
* pg_popcount_masked_fast
* pg_popcount_masked_sse42
* Returns the number of 1-bits in buf after applying the mask to each byte
*/
static uint64
pg_popcount_masked_fast(const char *buf, int bytes, bits8 mask)
pg_popcount_masked_sse42(const char *buf, int bytes, bits8 mask)
{
uint64 popcnt = 0;
@@ -433,7 +437,7 @@ pg_popcount_masked_fast(const char *buf, int bytes, bits8 mask)
while (bytes >= 8)
{
popcnt += pg_popcount64_fast(*words++ & maskv);
popcnt += pg_popcount64_sse42(*words++ & maskv);
bytes -= 8;
}
@@ -449,7 +453,7 @@ pg_popcount_masked_fast(const char *buf, int bytes, bits8 mask)
while (bytes >= 4)
{
popcnt += pg_popcount32_fast(*words++ & maskv);
popcnt += pg_popcount32_sse42(*words++ & maskv);
bytes -= 4;
}