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| author | Jan Ziak <0xe2.0x9a.0x9b@gmail.com> | 2012-06-13 16:25:00 -0400 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2012-06-13 16:25:00 -0400 |
| commit | 96ab6e4a844df49738246c0758e69b72e4f71395 (patch) | |
| tree | 9a2e4634d312b28653f51de0ee6bd9a5d0332072 | |
| parent | 4a0549ffc6612f0b2490e552120ece5d24b70b09 (diff) | |
| download | go-96ab6e4a844df49738246c0758e69b72e4f71395.tar.gz go-96ab6e4a844df49738246c0758e69b72e4f71395.zip | |
[release-branch.go1] runtime: improved continuity in hash computation
««« backport c8d163b7930e
runtime: improved continuity in hash computation
Fixes #3695.
R=r, dave, rsc
CC=golang-dev
https://golang.org/cl/6304062
»»»
| -rw-r--r-- | src/pkg/runtime/alg.c | 28 |
1 files changed, 11 insertions, 17 deletions
diff --git a/src/pkg/runtime/alg.c b/src/pkg/runtime/alg.c index e3c42916e9..36973eba33 100644 --- a/src/pkg/runtime/alg.c +++ b/src/pkg/runtime/alg.c @@ -5,6 +5,9 @@ #include "runtime.h" #include "type.h" +#define M0 (sizeof(uintptr)==4 ? 2860486313UL : 33054211828000289ULL) +#define M1 (sizeof(uintptr)==4 ? 3267000013UL : 23344194077549503ULL) + /* * map and chan helpers for * dealing with unknown types @@ -16,19 +19,13 @@ runtime·memhash(uintptr *h, uintptr s, void *a) uintptr hash; b = a; - if(sizeof(hash) == 4) - hash = 2860486313U; - else - hash = 33054211828000289ULL; + hash = M0; while(s > 0) { - if(sizeof(hash) == 4) - hash = (hash ^ *b) * 3267000013UL; - else - hash = (hash ^ *b) * 23344194077549503ULL; + hash = (hash ^ *b) * M1; b++; s--; } - *h ^= hash; + *h = (*h ^ hash) * M1; } void @@ -252,7 +249,7 @@ runtime·f32hash(uintptr *h, uintptr s, void *a) hash = runtime·fastrand1(); // any kind of NaN else hash = *(uint32*)a; - *h ^= (*h ^ hash ^ 2860486313U) * 3267000013U; + *h = (*h ^ hash ^ M0) * M1; } void @@ -271,14 +268,11 @@ runtime·f64hash(uintptr *h, uintptr s, void *a) else { u = *(uint64*)a; if(sizeof(uintptr) == 4) - hash = ((uint32)(u>>32) * 3267000013UL) ^ (uint32)u; + hash = ((uint32)(u>>32) * M1) ^ (uint32)u; else hash = u; } - if(sizeof(uintptr) == 4) - *h = (*h ^ hash ^ 2860486313U) * 3267000013U; - else - *h = (*h ^ hash ^ 33054211828000289ULL) * 23344194077549503ULL; + *h = (*h ^ hash ^ M0) * M1; } void @@ -357,7 +351,7 @@ void runtime·interhash(uintptr *h, uintptr s, void *a) { USED(s); - *h ^= runtime·ifacehash(*(Iface*)a); + *h = (*h ^ runtime·ifacehash(*(Iface*)a)) * M1; } void @@ -391,7 +385,7 @@ void runtime·nilinterhash(uintptr *h, uintptr s, void *a) { USED(s); - *h ^= runtime·efacehash(*(Eface*)a); + *h = (*h ^ runtime·efacehash(*(Eface*)a)) * M1; } void |