From: Ian Lance Taylor <iant@golang.org>
Date: Wed, 8 Apr 2020 04:47:13 +0000 (-0700)
Subject: runtime: add a couple of writeBarrier.needed checks
X-Git-Tag: go1.15beta1~627
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=a59465b545cd66e0796b5c7649a87a6f1b657cb4;p=gostls13.git

runtime: add a couple of writeBarrier.needed checks

Make typedmemmove, typedmemclr, typedmemclrpartial look more like other
callers of bulkBarrierPreWrite.

Change-Id: Ic47030d88bf07d290f91198b7810ffc16d9769e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/227541
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/src/runtime/mbarrier.go b/src/runtime/mbarrier.go
index 941324782c..264376da9b 100644
--- a/src/runtime/mbarrier.go
+++ b/src/runtime/mbarrier.go
@@ -157,7 +157,7 @@ func typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 	if dst == src {
 		return
 	}
-	if typ.ptrdata != 0 {
+	if writeBarrier.needed && typ.ptrdata != 0 {
 		bulkBarrierPreWrite(uintptr(dst), uintptr(src), typ.ptrdata)
 	}
 	// There's a race here: if some other goroutine can write to
@@ -333,7 +333,7 @@ func reflect_typedslicecopy(elemType *_type, dst, src slice) int {
 //
 //go:nosplit
 func typedmemclr(typ *_type, ptr unsafe.Pointer) {
-	if typ.ptrdata != 0 {
+	if writeBarrier.needed && typ.ptrdata != 0 {
 		bulkBarrierPreWrite(uintptr(ptr), 0, typ.ptrdata)
 	}
 	memclrNoHeapPointers(ptr, typ.size)
@@ -346,7 +346,7 @@ func reflect_typedmemclr(typ *_type, ptr unsafe.Pointer) {
 
 //go:linkname reflect_typedmemclrpartial reflect.typedmemclrpartial
 func reflect_typedmemclrpartial(typ *_type, ptr unsafe.Pointer, off, size uintptr) {
-	if typ.ptrdata != 0 {
+	if writeBarrier.needed && typ.ptrdata != 0 {
 		bulkBarrierPreWrite(uintptr(ptr), 0, size)
 	}
 	memclrNoHeapPointers(ptr, size)