diff --git a/src/cmd/compile/internal/ssa/memcombine.go b/src/cmd/compile/internal/ssa/memcombine.go
index b2c5fe3..c134643 100644
--- a/src/cmd/compile/internal/ssa/memcombine.go
+++ b/src/cmd/compile/internal/ssa/memcombine.go
@@ -41,6 +41,7 @@
 		}
 	}
 	for _, b := range f.Blocks {
+		order = order[:0]
 		for _, v := range b.Values {
 			if v.Op != OpOr16 && v.Op != OpOr32 && v.Op != OpOr64 {
 				continue