From: Joe Tsai <joetsai@digital-static.net>
Date: Fri, 20 Nov 2015 01:41:57 +0000 (-0800)
Subject: hash/crc32: add noescape tags to assembly functions
X-Git-Tag: go1.6beta1~300
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=64cc5fd0b3ad20c6e7e8b875317629df8207d9ba;p=gostls13.git

hash/crc32: add noescape tags to assembly functions

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>
---

diff --git a/src/hash/crc32/crc32_amd64.go b/src/hash/crc32/crc32_amd64.go
index 01f86840d6..ab4e2b8c8c 100644
--- a/src/hash/crc32/crc32_amd64.go
+++ b/src/hash/crc32/crc32_amd64.go
@@ -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()
diff --git a/src/hash/crc32/crc32_amd64p32.go b/src/hash/crc32/crc32_amd64p32.go
index e6c2a523df..067fbb162f 100644
--- a/src/hash/crc32/crc32_amd64p32.go
+++ b/src/hash/crc32/crc32_amd64p32.go
@@ -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()