diff options
| author | Russ Cox <rsc@golang.org> | 2012-12-22 16:42:22 -0500 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2012-12-22 16:42:22 -0500 |
| commit | ec59b840f93fff4631b60323e28a44967c704e7d (patch) | |
| tree | 50868a2cf17c483f8fa7f68d01a70e699bfcd91f /src/pkg | |
| parent | 295a4d8e6433e8a8b6df25375fb780b0f75ff4e6 (diff) | |
| download | go-ec59b840f93fff4631b60323e28a44967c704e7d.tar.xz | |
runtime: coalesce 0-size allocations
Fixes #3996.
R=ken2
CC=golang-dev
https://golang.org/cl/7001052
Diffstat (limited to 'src/pkg')
| -rw-r--r-- | src/pkg/runtime/malloc.goc | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/src/pkg/runtime/malloc.goc b/src/pkg/runtime/malloc.goc index f58045e63e..e37f8927ba 100644 --- a/src/pkg/runtime/malloc.goc +++ b/src/pkg/runtime/malloc.goc @@ -697,14 +697,22 @@ runtime·new(Type *typ, uint8 *ret) if(raceenabled) m->racepc = runtime·getcallerpc(&typ); - flag = typ->kind&KindNoPointers ? FlagNoPointers : 0; - ret = runtime·mallocgc(typ->size, flag, 1, 1); - if(UseSpanType && !flag) { - if(false) { - runtime·printf("new %S: %p\n", *typ->string, ret); + if(typ->size == 0) { + // All 0-length allocations use this pointer. + // The language does not require the allocations to + // have distinct values. + ret = (uint8*)&runtime·zerobase; + } else { + flag = typ->kind&KindNoPointers ? FlagNoPointers : 0; + ret = runtime·mallocgc(typ->size, flag, 1, 1); + + if(UseSpanType && !flag) { + if(false) { + runtime·printf("new %S: %p\n", *typ->string, ret); + } + runtime·settype(ret, (uintptr)typ | TypeInfo_SingleObject); } - runtime·settype(ret, (uintptr)typ | TypeInfo_SingleObject); } FLUSH(&ret); @@ -719,15 +727,24 @@ runtime·cnew(Type *typ) if(raceenabled) m->racepc = runtime·getcallerpc(&typ); - flag = typ->kind&KindNoPointers ? FlagNoPointers : 0; - ret = runtime·mallocgc(typ->size, flag, 1, 1); - if(UseSpanType && !flag) { - if(false) { - runtime·printf("new %S: %p\n", *typ->string, ret); + if(typ->size == 0) { + // All 0-length allocations use this pointer. + // The language does not require the allocations to + // have distinct values. + ret = (uint8*)&runtime·zerobase; + } else { + flag = typ->kind&KindNoPointers ? FlagNoPointers : 0; + ret = runtime·mallocgc(typ->size, flag, 1, 1); + + if(UseSpanType && !flag) { + if(false) { + runtime·printf("new %S: %p\n", *typ->string, ret); + } + runtime·settype(ret, (uintptr)typ | TypeInfo_SingleObject); } - runtime·settype(ret, (uintptr)typ | TypeInfo_SingleObject); } + return ret; } |