[dev.garbage] runtime: fix 32-bit build

TBR=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/168860046

diff --git a/src/runtime/mgc0.go b/src/runtime/mgc0.go
index 75678c52246b2cf973084b0360a8b449abc00359..22e88494a0d8bb78aa67f40d5fe88ac91dc56a2f 100644 (file)
--- a/src/runtime/mgc0.go
+++ b/src/runtime/mgc0.go
@@ -84,8 +84,8 @@ func bgsweep() {
 }
 
 const (
-       _PoisonGC    = 0xf969696969696969 & ^uintptr(0)
-       _PoisonStack = 0x6868686868686868 & ^uintptr(0)
+       _PoisonGC    = 0xf969696969696969 & (1<<(8*ptrSize) - 1)
+       _PoisonStack = 0x6868686868686868 & (1<<(8*ptrSize) - 1)
 )
 
 // NOTE: Really dst *unsafe.Pointer, src unsafe.Pointer,