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hash/crc32: add noescape tags to assembly functions

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CRC-32 computation is stateless and the p slice does not get stored
anywhere. Thus, we mark the assembly functions as noescape so that
it doesn't believe that p leaks in:
	func Update(crc uint32, tab *Table, p []byte) uint32

Before:
	./crc32.go:153: leaking param: p

After:
	./crc32.go:153: Update p does not escape

Change-Id: I52ba35b6cc544fff724327140e0c27898431d1dc
Reviewed-on: https://go-review.googlesource.com/17069
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Joe Tsai 2015-11-19 17:41:57 -08:00 committed by Russ Cox
parent e5956bca41
commit 64cc5fd0b3
2 changed files with 3 additions and 0 deletions
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2
src/hash/crc32/crc32_amd64.go
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@ -15,10 +15,12 @@ func haveCLMUL() bool
// castagnoliSSE42 is defined in crc_amd64.s and uses the SSE4.2 CRC32
// instruction.
//go:noescape
func castagnoliSSE42(crc uint32, p []byte) uint32
// ieeeCLMUL is defined in crc_amd64.s and uses the PCLMULQDQ
// instruction as well as SSE 4.1.
//go:noescape
func ieeeCLMUL(crc uint32, p []byte) uint32
var sse42 = haveSSE42()

1
src/hash/crc32/crc32_amd64p32.go
View File

@ -13,6 +13,7 @@ func haveSSE42() bool
// castagnoliSSE42 is defined in crc_amd64.s and uses the SSE4.2 CRC32
// instruction.
//go:noescape
func castagnoliSSE42(crc uint32, p []byte) uint32
var sse42 = haveSSE42()