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| author | Martin Möhrmann <moehrmann@google.com> | 2018-10-22 20:47:54 +0200 |
|---|---|---|
| committer | Martin Möhrmann <martisch@uos.de> | 2018-10-23 16:48:01 +0000 |
| commit | 1e50dd02a98bce8901cf10634ee0b2c8bbe4da81 (patch) | |
| tree | b0a1ae4efcb729f5693b751fe626d60f4dae117f /src | |
| parent | 286c7ae10c71a8faeba22e29928afe7fce7e2750 (diff) | |
| download | go-1e50dd02a98bce8901cf10634ee0b2c8bbe4da81.tar.xz | |
runtime: use multiplication with overflow check for newarray
This improves performance for e.g. maps with a bucket size
(key+value*8 bytes) larger than 32 bytes and removes loading
a value from the maxElems array for smaller bucket sizes.
name old time/op new time/op delta
MakeMap/[Byte]Byte 95.5ns ± 1% 94.7ns ± 1% -0.78% (p=0.013 n=9+9)
MakeMap/[Int]Int 128ns ± 0% 121ns ± 2% -5.63% (p=0.000 n=6+10)
Updates #21588
Change-Id: I7d9eb7d49150c399c15dcab675e24bc97ff97852
Reviewed-on: https://go-review.googlesource.com/c/143997
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/malloc.go | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index dad4773cb8..12fa744052 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -106,6 +106,7 @@ package runtime import ( "runtime/internal/atomic" + "runtime/internal/math" "runtime/internal/sys" "unsafe" ) @@ -1040,10 +1041,11 @@ func newarray(typ *_type, n int) unsafe.Pointer { if n == 1 { return mallocgc(typ.size, typ, true) } - if n < 0 || uintptr(n) > maxSliceCap(typ.size) { + mem, overflow := math.MulUintptr(typ.size, uintptr(n)) + if overflow || mem > maxAlloc || n < 0 { panic(plainError("runtime: allocation size out of range")) } - return mallocgc(typ.size*uintptr(n), typ, true) + return mallocgc(mem, typ, true) } //go:linkname reflect_unsafe_NewArray reflect.unsafe_NewArray |