Clear next map word when folding allocations into js arrays.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 685a5e883cd4085e231cd2d2b2f99c9a8f863dde..d0d5886c8597446cdc698ccc4e970d40caa56805 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -5126,7 +5126,8 @@ class HAllocate V8_FINAL : public HTemplateInstruction<2> {
             HType type,
             PretenureFlag pretenure_flag,
             InstanceType instance_type)
-      : HTemplateInstruction<2>(type) {
+      : HTemplateInstruction<2>(type),
+        clear_next_map_word_(false) {
     SetOperandAt(0, context);
     SetOperandAt(1, size);
     set_representation(Representation::Tagged());
@@ -5145,6 +5146,7 @@ class HAllocate V8_FINAL : public HTemplateInstruction<2> {
 
   Flags flags_;
   Handle<Map> known_initial_map_;
+  bool clear_next_map_word_;

[mvstanton, 2013/08/26 10:01:27]

Actually, do you need this boolean, since you handle things directly during the
dominance walk.

[Hannes Payer (out of office), 2013/08/26 11:51:07]

Yes, otherwise would create n stores, where n is the number of folding
operations.

 };