Using type feedback, eliminate store barriers for indexed stores.

runtime/vm/intermediate_language.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 2247 matching lines @@
   virtual bool CanDeoptimize() const { return false; }
   virtual intptr_t ResultCid() const { return kDynamicCid; }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LoadIndexedInstr);
 };
 
 
 class StoreIndexedInstr : public TemplateDefinition<3> {
  public:
-  StoreIndexedInstr(Value* array, Value* index, Value* value) {
+  StoreIndexedInstr(Value* array,
+                    Value* index,
+                    Value* value,
+                    bool emit_store_barrier)
+      : emit_store_barrier_(emit_store_barrier) {
     ASSERT(array != NULL);
     ASSERT(index != NULL);
     ASSERT(value != NULL);
     inputs_[0] = array;
     inputs_[1] = index;
     inputs_[2] = value;
   }
 
   DECLARE_INSTRUCTION(StoreIndexed)
   virtual RawAbstractType* CompileType() const;
 
   Value* array() const { return inputs_[0]; }
   Value* index() const { return inputs_[1]; }
   Value* value() const { return inputs_[2]; }
 
+  bool emit_store_barrier() const { return emit_store_barrier_; }
+
   virtual bool CanDeoptimize() const { return false; }
   virtual intptr_t ResultCid() const { return kDynamicCid; }
 
  private:
+  const bool emit_store_barrier_;
+
   DISALLOW_COPY_AND_ASSIGN(StoreIndexedInstr);
 };
 
 
 // Note overrideable, built-in: value? false : true.
 class BooleanNegateInstr : public TemplateDefinition<1> {
  public:
   explicit BooleanNegateInstr(Value* value) {
     ASSERT(value != NULL);
     inputs_[0] = value;
@@ skipping 1153 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_