Revert attempts to use POPCNT etc instructions

This reverts commits fc6c72747ae6, 109de05cbb03, d0b4663c23b7 and
711bab1e4d19.

Somebody will have to try harder before submitting this patch again.
I've spent entirely too much time on it already, and the #ifdef maze yet
to be written in order for it to build at all got on my nerves.  The
amount of work needed to get a platform-specific performance improvement
that's barely above the noise level is not worth it.

1 files changed, 0 insertions, 219 deletions

diff --git a/src/port/pg_bitutils.c b/src/port/pg_bitutils.c
deleted file mode 100644
index 97bfcebe4e1..00000000000
--- a/src/port/pg_bitutils.c
+++ /dev/null
@@ -1,219 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * pg_bitutils.c
- *	  miscellaneous functions for bit-wise operations.
- *
- * Portions Copyright (c) 2019, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/port/pg_bitutils.c
- *
- *-------------------------------------------------------------------------
- */
-#include "postgres.h"
-
-#ifdef HAVE__GET_CPUID
-#include <cpuid.h>
-#endif
-
-#ifdef HAVE__CPUID
-#include <intrin.h>
-#endif
-
-#include "port/pg_bitutils.h"
-
-#ifdef HAVE__BUILTIN_POPCOUNT
-static bool pg_popcount_available(void);
-static int	pg_popcount32_choose(uint32 word);
-static int	pg_popcount32_builtin(uint32 word);
-static int	pg_popcount64_choose(uint64 word);
-static int	pg_popcount64_builtin(uint64 word);
-int			(*pg_popcount32) (uint32 word) = pg_popcount32_choose;
-int			(*pg_popcount64) (uint64 word) = pg_popcount64_choose;
-#else
-static int	pg_popcount32_slow(uint32 word);
-static int	pg_popcount64_slow(uint64 word);
-int			(*pg_popcount32) (uint32 word) = pg_popcount32_slow;
-int			(*pg_popcount64) (uint64 word) = pg_popcount64_slow;
-#endif							/* !HAVE_BUILTIN_POPCOUNT */
-
-
-/* Array marking the number of 1-bits for each value of 0-255. */
-static const uint8 number_of_ones[256] = {
-	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
-	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
-	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
-	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
-	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
-	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
-	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
-	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
-};
-
-/*
- * Return true iff we have CPUID support and it indicates that the POPCNT
- * instruction is available.
- */
-static bool
-pg_popcount_available(void)
-{
-#if defined(HAVE__GET_CPUID) || defined(HAVE__CPUID)
-	unsigned int exx[4] = {0, 0, 0, 0};
-
-#if defined(HAVE__GET_CPUID)
-	__get_cpuid(1, &exx[0], &exx[1], &exx[2], &exx[3]);
-#elif defined(HAVE__CPUID)
-	__cpuid(exx, 1);
-#endif
-
-	return (exx[2] & (1 << 23)) != 0;	/* POPCNT */
-#else							/* HAVE__GET_CPUID || HAVE__CPUID */
-
-	return false;
-#endif
-}
-
-#ifdef HAVE__BUILTIN_POPCOUNT
-/*
- * This gets called on the first call to pg_popcount32. It replaces the
- * function pointer so that subsequent calls are routed directly to the chosen
- * implementation.
- */
-static int
-pg_popcount32_choose(uint32 word)
-{
-	if (pg_popcount_available())
-		pg_popcount32 = pg_popcount32_hw;
-	else
-		pg_popcount32 = pg_popcount32_builtin;
-
-	return pg_popcount32(word);
-}
-
-static int
-pg_popcount32_builtin(uint32 word)
-{
-	return __builtin_popcount(word);
-}
-#else							/* HAVE__BUILTIN_POPCOUNT */
-/*
- * pg_popcount32_slow
- *		Return the number of 1 bits set in word
- */
-static int
-pg_popcount32_slow(uint32 word)
-{
-	int			result = 0;
-
-	while (word != 0)
-	{
-		result += number_of_ones[word & 255];
-		word >>= 8;
-	}
-
-	return result;
-}
-#endif
-
-/*
- * pg_popcount
- *		Returns the number of 1-bits in buf
- */
-uint64
-pg_popcount(const char *buf, int bytes)
-{
-	uint64		popcnt = 0;
-
-#if SIZEOF_VOID_P >= 8
-	/* Process in 64-bit chunks if the buffer is aligned. */
-	if (buf == (char *) TYPEALIGN(8, buf))
-	{
-		uint64	   *words = (uint64 *) buf;
-
-		while (bytes >= 8)
-		{
-			popcnt += pg_popcount64(*words++);
-			bytes -= 8;
-		}
-
-		buf = (char *) words;
-	}
-#else
-	/* Process in 32-bit chunks if the buffer is aligned. */
-	if (buf == (char *) TYPEALIGN(4, buf))
-	{
-		uint32	   *words = (uint32 *) buf;
-
-		while (bytes >= 4)
-		{
-			popcnt += pg_popcount32(*words++);
-			bytes -= 4;
-		}
-
-		buf = (char *) words;
-	}
-#endif
-
-	/* Process any remaining bytes */
-	while (bytes--)
-		popcnt += number_of_ones[(unsigned char) *buf++];
-
-	return popcnt;
-}
-
-#ifdef HAVE__BUILTIN_POPCOUNT
-/*
- * This gets called on the first call to pg_popcount64. It replaces the
- * function pointer so that subsequent calls are routed directly to the chosen
- * implementation.
- */
-static int
-pg_popcount64_choose(uint64 word)
-{
-	if (pg_popcount_available())
-		pg_popcount64 = pg_popcount64_hw;
-	else
-		pg_popcount64 = pg_popcount64_builtin;
-
-	return pg_popcount64(word);
-}
-
-static int
-pg_popcount64_builtin(uint64 word)
-{
-#if defined(HAVE_LONG_INT_64)
-	return __builtin_popcountl(word);
-#elif defined(HAVE_LONG_LONG_INT_64)
-	return __builtin_popcountll(word);
-#else
-#error must have a working 64-bit integer datatype
-#endif
-}
-
-#else							/* HAVE__BUILTIN_POPCOUNT */
-/*
- * pg_popcount64_slow
- *		Return the number of 1 bits set in word
- */
-static int
-pg_popcount64_slow(uint64 word)
-{
-	int			result = 0;
-
-	while (word != 0)
-	{
-		result += number_of_ones[word & 255];
-		word >>= 8;
-	}
-
-	return result;
-}
-#endif