Add flags for write barrier elimination and local allocation folding.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 889ebfd05fc6f47a4cb835269ab29ddbd686f02e..af093d9aa5488ebc541ecdc6c2ed9f14d433ed01 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3384,6 +3384,15 @@ void HAllocate::HandleSideEffectDominator(GVNFlag side_effect,
     return;
   }
 
+  // Check whether we are folding within the same block for local folding.
+  if (FLAG_use_local_allocation_folding && dominator->block() != block()) {
+    if (FLAG_trace_allocation_folding) {
+      PrintF("#%d (%s) cannot fold into #%d (%s), crosses basic blocks\n",
+          id(), Mnemonic(), dominator->id(), dominator->Mnemonic());
+    }
+    return;
+  }
+
   HAllocate* dominator_allocate = HAllocate::cast(dominator);
   HValue* dominator_size = dominator_allocate->size();
   HValue* current_size = size();