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Add basic support for using the POPCNT and SSE4.2s LZCNT opcodes

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These opcodes have been around in the AMD world since 2007, and 2008 in
the case of intel.  They're supported in GCC and Clang via some __builtin
macros.  The opcodes may be unavailable during runtime, in which case we
fall back on a C-based implementation of the code.  In order to get the
POPCNT instruction we must pass the -mpopcnt option to the compiler.  We
do this only for the pg_bitutils.c file.

David Rowley (with fragments taken from a patch by Thomas Munro)

Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com
This commit is contained in:
Alvaro Herrera
2019-02-13 16:10:06 -03:00
parent 754ca99314
commit 711bab1e4d
13 changed files with 912 additions and 167 deletions
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15
src/backend/lib/bloomfilter.c
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@ -37,6 +37,7 @@
#include "access/hash.h"
#include "lib/bloomfilter.h"
#include "port/pg_bitutils.h"
#define MAX_HASH_FUNCS 10
@ -187,19 +188,7 @@ double
bloom_prop_bits_set(bloom_filter *filter)
{
int bitset_bytes = filter->m / BITS_PER_BYTE;
uint64 bits_set = 0;
int i;
for (i = 0; i < bitset_bytes; i++)
{
unsigned char byte = filter->bitset[i];
while (byte)
{
bits_set++;
byte &= (byte - 1);
}
}
uint64 bits_set = pg_popcount((char *) filter->bitset, bitset_bytes);
return bits_set / (double) filter->m;
}