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, 48 insertions, 25 deletions

diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c
index 9657cd0a632..931ae81fd6d 100644
--- a/src/backend/access/heap/visibilitymap.c
+++ b/src/backend/access/heap/visibilitymap.c
@@ -89,12 +89,12 @@
 #include "access/visibilitymap.h"
 #include "access/xlog.h"
 #include "miscadmin.h"
-#include "port/pg_bitutils.h"
 #include "storage/bufmgr.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/inval.h"
 
+
 /*#define TRACE_VISIBILITYMAP */
 
 /*
@@ -115,9 +115,43 @@
 #define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE)
 #define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK)
 
-/* Masks for bit counting bits in the visibility map. */
-#define VISIBLE_MASK64 0x5555555555555555 /* The lower bit of each bit pair */
-#define FROZEN_MASK64 0xaaaaaaaaaaaaaaaa /* The upper bit of each bit pair */
+/* tables for fast counting of set bits for visible and frozen */
+static const uint8 number_of_ones_for_visible[256] = {
+	0, 1, 0, 1, 1, 2, 1, 2, 0, 1, 0, 1, 1, 2, 1, 2,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	0, 1, 0, 1, 1, 2, 1, 2, 0, 1, 0, 1, 1, 2, 1, 2,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	2, 3, 2, 3, 3, 4, 3, 4, 2, 3, 2, 3, 3, 4, 3, 4,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	2, 3, 2, 3, 3, 4, 3, 4, 2, 3, 2, 3, 3, 4, 3, 4,
+	0, 1, 0, 1, 1, 2, 1, 2, 0, 1, 0, 1, 1, 2, 1, 2,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	0, 1, 0, 1, 1, 2, 1, 2, 0, 1, 0, 1, 1, 2, 1, 2,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	2, 3, 2, 3, 3, 4, 3, 4, 2, 3, 2, 3, 3, 4, 3, 4,
+	1, 2, 1, 2, 2, 3, 2, 3, 1, 2, 1, 2, 2, 3, 2, 3,
+	2, 3, 2, 3, 3, 4, 3, 4, 2, 3, 2, 3, 3, 4, 3, 4
+};
+static const uint8 number_of_ones_for_frozen[256] = {
+	0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2,
+	0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2,
+	0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	2, 2, 3, 3, 2, 2, 3, 3, 3, 3, 4, 4, 3, 3, 4, 4,
+	2, 2, 3, 3, 2, 2, 3, 3, 3, 3, 4, 4, 3, 3, 4, 4,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3,
+	2, 2, 3, 3, 2, 2, 3, 3, 3, 3, 4, 4, 3, 3, 4, 4,
+	2, 2, 3, 3, 2, 2, 3, 3, 3, 3, 4, 4, 3, 3, 4, 4
+};
 
 /* prototypes for internal routines */
 static Buffer vm_readbuf(Relation rel, BlockNumber blkno, bool extend);
@@ -374,16 +408,18 @@ void
 visibilitymap_count(Relation rel, BlockNumber *all_visible, BlockNumber *all_frozen)
 {
 	BlockNumber mapBlock;
-	BlockNumber nvisible = 0;
-	BlockNumber nfrozen = 0;
 
 	/* all_visible must be specified */
 	Assert(all_visible);
 
+	*all_visible = 0;
+	if (all_frozen)
+		*all_frozen = 0;
+
 	for (mapBlock = 0;; mapBlock++)
 	{
 		Buffer		mapBuffer;
-		uint64	   *map;
+		unsigned char *map;
 		int			i;
 
 		/*
@@ -400,30 +436,17 @@ visibilitymap_count(Relation rel, BlockNumber *all_visible, BlockNumber *all_fro
 		 * immediately stale anyway if anyone is concurrently setting or
 		 * clearing bits, and we only really need an approximate value.
 		 */
-		map = (uint64 *) PageGetContents(BufferGetPage(mapBuffer));
+		map = (unsigned char *) PageGetContents(BufferGetPage(mapBuffer));
 
-		StaticAssertStmt(MAPSIZE % sizeof(uint64) == 0,
-						 "unsupported MAPSIZE");
-		if (all_frozen == NULL)
-		{
-			for (i = 0; i < MAPSIZE / sizeof(uint64); i++)
-				nvisible += pg_popcount64(map[i] & VISIBLE_MASK64);
-		}
-		else
+		for (i = 0; i < MAPSIZE; i++)
 		{
-			for (i = 0; i < MAPSIZE / sizeof(uint64); i++)
-			{
-				nvisible += pg_popcount64(map[i] & VISIBLE_MASK64);
-				nfrozen += pg_popcount64(map[i] & FROZEN_MASK64);
-			}
+			*all_visible += number_of_ones_for_visible[map[i]];
+			if (all_frozen)
+				*all_frozen += number_of_ones_for_frozen[map[i]];
 		}
 
 		ReleaseBuffer(mapBuffer);
 	}
-
-	*all_visible = nvisible;
-	if (all_frozen)
-		*all_frozen = nfrozen;
 }
 
 /*