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Revert attempts to use POPCNT etc instructions

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This reverts commits fc6c72747a, 109de05cbb, d0b4663c23 and
711bab1e4d.

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.
This commit is contained in:
Alvaro Herrera
2019-02-15 16:32:30 -03:00
parent e89f14e2bb
commit 457aef0f1f
14 changed files with 167 additions and 707 deletions
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127
src/backend/nodes/bitmapset.c
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@ -22,7 +22,6 @@
#include "access/hash.h"
#include "nodes/pg_list.h"
#include "port/pg_bitutils.h"
#define WORDNUM(x) ((x) / BITS_PER_BITMAPWORD)
@ -52,23 +51,79 @@
#define HAS_MULTIPLE_ONES(x) ((bitmapword) RIGHTMOST_ONE(x) != (x))
/* Set the bitwise macro version we must use based on the bitmapword size */
#if BITS_PER_BITMAPWORD == 32
#define bmw_popcount(w) pg_popcount32(w)
#define bmw_rightmost_one(w) pg_rightmost_one32(w)
#define bmw_leftmost_one(w) pg_leftmost_one32(w)
/*
* Lookup tables to avoid need for bit-by-bit groveling
*
* rightmost_one_pos[x] gives the bit number (0-7) of the rightmost one bit
* in a nonzero byte value x. The entry for x=0 is never used.
*
* leftmost_one_pos[x] gives the bit number (0-7) of the leftmost one bit in a
* nonzero byte value x. The entry for x=0 is never used.
*
* number_of_ones[x] gives the number of one-bits (0-8) in a byte value x.
*
* We could make these tables larger and reduce the number of iterations
* in the functions that use them, but bytewise shifts and masks are
* especially fast on many machines, so working a byte at a time seems best.
*/
#elif BITS_PER_BITMAPWORD == 64
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
};
#define bmw_popcount(w) pg_popcount64(w)
#define bmw_rightmost_one(w) pg_rightmost_one64(w)
#define bmw_leftmost_one(w) pg_leftmost_one64(w)
#else
#error "invalid BITS_PER_BITMAPWORD"
#endif
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
};
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
};
/*
@ -552,7 +607,12 @@ bms_singleton_member(const Bitmapset *a)
if (result >= 0 || HAS_MULTIPLE_ONES(w))
elog(ERROR, "bitmapset has multiple members");
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_rightmost_one(w);
while ((w & 255) == 0)
{
w >>= 8;
result += 8;
}
result += rightmost_one_pos[w & 255];
}
}
if (result < 0)
@ -590,7 +650,12 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
if (result >= 0 || HAS_MULTIPLE_ONES(w))
return false;
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_rightmost_one(w);
while ((w & 255) == 0)
{
w >>= 8;
result += 8;
}
result += rightmost_one_pos[w & 255];
}
}
if (result < 0)
@ -616,9 +681,12 @@ bms_num_members(const Bitmapset *a)
{
bitmapword w = a->words[wordnum];
/* No need to count the bits in a zero word */
if (w != 0)
result += bmw_popcount(w);
/* we assume here that bitmapword is an unsigned type */
while (w != 0)
{
result += number_of_ones[w & 255];
w >>= 8;
}
}
return result;
}
@ -973,7 +1041,12 @@ bms_first_member(Bitmapset *a)
a->words[wordnum] &= ~w;
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_rightmost_one(w);
while ((w & 255) == 0)
{
w >>= 8;
result += 8;
}
result += rightmost_one_pos[w & 255];
return result;
}
}
@ -1023,7 +1096,12 @@ bms_next_member(const Bitmapset *a, int prevbit)
int result;
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_rightmost_one(w);
while ((w & 255) == 0)
{
w >>= 8;
result += 8;
}
result += rightmost_one_pos[w & 255];
return result;
}
@ -1090,9 +1168,14 @@ bms_prev_member(const Bitmapset *a, int prevbit)
if (w != 0)
{
int result;
int shift = BITS_PER_BITMAPWORD - 8;
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_leftmost_one(w);
while ((w >> shift) == 0)
shift -= 8;
result += shift + leftmost_one_pos[(w >> shift) & 255];
return result;
}