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Shave another 10% off GNU Make latency

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We avoid memcpy() by creating a likely branch with a constant size.
This commit is contained in:
Justine Tunney 2022-08-22 17:04:54 -07:00
parent 58d22c7c3d
commit 8722006c46
1 changed files with 8 additions and 14 deletions
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22
third_party/make/hash.c vendored
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@ -17,6 +17,8 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#include "third_party/make/makeint.inc" #include "third_party/make/makeint.inc"
/**/ /**/
#include "libc/assert.h" #include "libc/assert.h"
#include "libc/intrin/likely.h"
#include "libc/nexgen32e/bsr.h"
#include "third_party/make/hash.h" #include "third_party/make/hash.h"
/* clang-format off */ /* clang-format off */
@ -317,18 +319,8 @@ hash_dump (struct hash_table *ht, void **vector_0, qsort_cmp_t compare)
static unsigned long static unsigned long
round_up_2 (unsigned long n) round_up_2 (unsigned long n)
{ {
n |= (n >> 1); if (UNLIKELY(!n)) return 1;
n |= (n >> 2); return 2ul << bsrl(n);
n |= (n >> 4);
n |= (n >> 8);
n |= (n >> 16);
#if !defined(HAVE_LIMITS_H) || ULONG_MAX > 4294967295
/* We only need this on systems where unsigned long is >32 bits. */
n |= (n >> 32);
#endif
return n + 1;
} }
#define rol32(v, n) \ #define rol32(v, n) \
@ -421,8 +413,10 @@ jhash(unsigned const char *k, int length)
do { \ do { \
unsigned int val = 0; \ unsigned int val = 0; \
size_t pn = (plen); \ size_t pn = (plen); \
size_t n = pn < UINTSZ ? pn : UINTSZ; \ if (pn >= UINTSZ) \
memcpy (&val, (p), n); \ memcpy(&val, (p), UINTSZ); \
else \
memcpy(&val, (p), pn); \
flag = ((val - 0x01010101) & ~val) & 0x80808080; \ flag = ((val - 0x01010101) & ~val) & 0x80808080; \
if (!flag) \ if (!flag) \
r += val; \ r += val; \