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, 186 deletions

diff --git a/src/include/port/pg_bitutils.h b/src/include/port/pg_bitutils.h
deleted file mode 100644
index 70aae5128fa..00000000000
--- a/src/include/port/pg_bitutils.h
+++ /dev/null
@@ -1,186 +0,0 @@
-/*------------------------------------------------------------------------ -
- *
- * pg_bitutils.h
- *	  miscellaneous functions for bit-wise operations.
-  *
- *
- * Portions Copyright(c) 2019, PostgreSQL Global Development Group
- *
- * src/include/port/pg_bitutils.h
- *
- *------------------------------------------------------------------------ -
- */
-#ifndef PG_BITUTILS_H
-#define PG_BITUTILS_H
-
-extern int	(*pg_popcount32) (uint32 word);
-extern int	(*pg_popcount64) (uint64 word);
-extern uint64 pg_popcount(const char *buf, int bytes);
-
-/* in pg_bitutils_hwpopcnt.c */
-extern int	pg_popcount32_hw(uint32 word);
-extern int	pg_popcount64_hw(uint64 word);
-
-
-#ifndef HAVE__BUILTIN_CTZ
-/*
- * Array marking the position of the right-most set bit for each value of
- * 1-255.  We count the right-most position as the 0th bit, and the
- * left-most the 7th bit.  The 0th index of the array must not be used.
- */
-static const uint8 rightmost_one_pos[256] = {
-	0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
-	4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
-};
-#endif							/* !HAVE__BUILTIN_CTZ */
-
-/*
- * pg_rightmost_one32
- *		Returns the number of trailing 0-bits in word, starting at the least
- *		significant bit position. word must not be 0.
- */
-static inline int
-pg_rightmost_one32(uint32 word)
-{
-	int			result = 0;
-
-	Assert(word != 0);
-
-#ifdef HAVE__BUILTIN_CTZ
-	result = __builtin_ctz(word);
-#else
-	while ((word & 255) == 0)
-	{
-		word >>= 8;
-		result += 8;
-	}
-	result += rightmost_one_pos[word & 255];
-#endif							/* HAVE__BUILTIN_CTZ */
-
-	return result;
-}
-
-/*
- * pg_rightmost_one64
- *		Returns the number of trailing 0-bits in word, starting at the least
- *		significant bit position. word must not be 0.
- */
-static inline int
-pg_rightmost_one64(uint64 word)
-{
-	int			result = 0;
-
-	Assert(word != 0);
-#ifdef HAVE__BUILTIN_CTZ
-#if defined(HAVE_LONG_INT_64)
-	return __builtin_ctzl(word);
-#elif defined(HAVE_LONG_LONG_INT_64)
-	return __builtin_ctzll(word);
-#else
-#error must have a working 64-bit integer datatype
-#endif
-#else							/* HAVE__BUILTIN_CTZ */
-	while ((word & 255) == 0)
-	{
-		word >>= 8;
-		result += 8;
-	}
-	result += rightmost_one_pos[word & 255];
-#endif
-
-	return result;
-}
-
-#ifndef HAVE__BUILTIN_CLZ
-/*
- * Array marking the position of the left-most set bit for each value of
- * 1-255.  We count the right-most position as the 0th bit, and the
- * left-most the 7th bit.  The 0th index of the array must not be used.
- */
-static const uint8 leftmost_one_pos[256] = {
-	0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
-	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-};
-#endif							/* !HAVE_BUILTIN_CLZ */
-
-/*
- * pg_leftmost_one32
- *		Returns the 0-based position of the most significant set bit in word
- *		measured from the least significant bit.  word must not be 0.
- */
-static inline int
-pg_leftmost_one32(uint32 word)
-{
-#ifdef HAVE__BUILTIN_CLZ
-	Assert(word != 0);
-
-	return 31 - __builtin_clz(word);
-#else
-	int			shift = 32 - 8;
-
-	Assert(word != 0);
-
-	while ((word >> shift) == 0)
-		shift -= 8;
-
-	return shift + leftmost_one_pos[(word >> shift) & 255];
-#endif							/* HAVE__BUILTIN_CLZ */
-}
-
-/*
- * pg_leftmost_one64
- *		Returns the 0-based position of the most significant set bit in word
- *		measured from the least significant bit.  word must not be 0.
- */
-static inline int
-pg_leftmost_one64(uint64 word)
-{
-#ifdef HAVE__BUILTIN_CLZ
-	Assert(word != 0);
-#if defined(HAVE_LONG_INT_64)
-	return 63 - __builtin_clzl(word);
-#elif defined(HAVE_LONG_LONG_INT_64)
-	return 63 - __builtin_clzll(word);
-#else
-#error must have a working 64-bit integer datatype
-#endif
-#else							/* HAVE__BUILTIN_CLZ */
-	int			shift = 64 - 8;
-
-	Assert(word != 0);
-	while ((word >> shift) == 0)
-		shift -= 8;
-
-	return shift + leftmost_one_pos[(word >> shift) & 255];
-#endif							/* !HAVE__BUIILTIN_CLZ */
-}
-
-#endif							/* PG_BITUTILS_H */