diff options
| author | Justine Tunney <jtunney@gmail.com> | 2022-11-06 12:13:21 -0500 |
|---|---|---|
| committer | Paul Smith <psmith@gnu.org> | 2022-11-13 10:38:50 -0500 |
| commit | 090d99dd2da676074145f64bce940f3867c613f1 (patch) | |
| tree | a7648ffcde1900470f387ac8617250921b9d4e59 /src/hash.c | |
| parent | 6b45f89adb44527ece9d28dfb5d7365ee28d711d (diff) | |
| download | make-git-090d99dd2da676074145f64bce940f3867c613f1.tar.gz | |
* src/hash.c (jhash_string): Help the compiler optimize the hash
Invoke memcpy() with a constant length, where possible.
Copyright-paperwork-exempt: yes
Diffstat (limited to 'src/hash.c')
| -rw-r--r-- | src/hash.c | 20 |
1 files changed, 13 insertions, 7 deletions
@@ -361,7 +361,7 @@ round_up_2 (unsigned long n) #define sum_get_unaligned_32(r, p) \ do { \ unsigned int val; \ - memcpy(&val, (p), 4); \ + memcpy (&val, (p), 4); \ r += val; \ } while(0); @@ -413,13 +413,16 @@ jhash(unsigned const char *k, int length) #define UINTSZ sizeof (unsigned int) #ifdef WORDS_BIGENDIAN -/* The ifs are ordered from the first byte in memory to the last. */ +/* The ifs are ordered from the first byte in memory to the last. + Help the compiler optimize by using static memcpy length. */ #define sum_up_to_nul(r, p, plen, flag) \ do { \ unsigned int val = 0; \ size_t pn = (plen); \ - size_t n = pn < UINTSZ ? pn : UINTSZ; \ - memcpy (&val, (p), n); \ + if (pn >= UINTSZ) \ + memcpy (&val, (p), UINTSZ); \ + else \ + memcpy (&val, (p), pn); \ if ((val & 0xFF000000) == 0) \ flag = 1; \ else if ((val & 0xFF0000) == 0) \ @@ -432,13 +435,16 @@ jhash(unsigned const char *k, int length) #else /* First detect the presence of zeroes. If there is none, we can sum the 4 bytes directly. Otherwise, the ifs are ordered as in the - big endian case, from the first byte in memory to the last. */ + big endian case, from the first byte in memory to the last. + Help the compiler optimize by using static memcpy length. */ #define sum_up_to_nul(r, p, plen, flag) \ do { \ unsigned int val = 0; \ size_t pn = (plen); \ - size_t n = pn < UINTSZ ? pn : UINTSZ; \ - memcpy (&val, (p), n); \ + if (pn >= UINTSZ) \ + memcpy (&val, (p), UINTSZ); \ + else \ + memcpy (&val, (p), pn); \ flag = ((val - 0x01010101) & ~val) & 0x80808080; \ if (!flag) \ r += val; \ |