Rename "fast" and "slow" popcount functions.

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

diff --git a/src/include/port/pg_bitutils.h b/src/include/port/pg_bitutils.h
index c9c508d4ba3e029b0113c7e00855af785fe6ae91..89b117d981796889a625cb8304842339c3df0cc5 100644 (file)
--- a/src/include/port/pg_bitutils.h
+++ b/src/include/port/pg_bitutils.h
@@ -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
 /*

diff --git a/src/port/pg_bitutils.c b/src/port/pg_bitutils.c
index 9f9f90ddd4d2237f7d5207c70dfca25505642e55..170aeef7548c0635189244efe90de02b3859caf2 100644 (file)
--- a/src/port/pg_bitutils.c
+++ b/src/port/pg_bitutils.c
@@ -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 */

diff --git a/src/port/pg_popcount_x86.c b/src/port/pg_popcount_x86.c
index a189a04a8e188a0e421ef7ffc4e7c5d6ab2dcc20..ce0ce9c8a3cf73375af3f82d35e3321c93775386 100644 (file)
--- a/src/port/pg_popcount_x86.c
+++ b/src/port/pg_popcount_x86.c
@@ -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;
        }