Added non observable side effects scope and removed unnecessary calls to AddSimulate.

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 847 matching lines @@
 
   HArgumentsElements* arguments_elements_;
 
   FunctionState* outer_;
 };
 
 
 class HGraphBuilder {
  public:
   explicit HGraphBuilder(CompilationInfo* info)
-      : info_(info), graph_(NULL), current_block_(NULL) {}
+      : info_(info),
+        graph_(NULL),
+        current_block_(NULL),
+        in_no_side_effects_scope_(0) {}

[danno, 2013/04/11 12:55:51]

no_side_effects_scope_count_?

[Hannes Payer (out of office), 2013/04/11 13:00:03]

Done.

   virtual ~HGraphBuilder() {}
 
   HBasicBlock* current_block() const { return current_block_; }
   void set_current_block(HBasicBlock* block) { current_block_ = block; }
   HEnvironment* environment() const {
     return current_block()->last_environment();
   }
   Zone* zone() const { return info_->zone(); }
   HGraph* graph() const { return graph_; }
   Isolate* isolate() const { return graph_->isolate(); }
 
   HGraph* CreateGraph();
 
   // Adding instructions.
   HInstruction* AddInstruction(HInstruction* instr);
   void AddSimulate(BailoutId id,
                    RemovableSimulate removable = FIXED_SIMULATE);
   HBoundsCheck* AddBoundsCheck(
       HValue* index,
       HValue* length,
       BoundsCheckKeyMode key_mode = DONT_ALLOW_SMI_KEY,
       Representation r = Representation::None());
 
   HReturn* AddReturn(HValue* value);
 
+  void IncrementInNoSideEffectsScope() {
+    in_no_side_effects_scope_++;
+  }
+
+  void DecrementInNoSideEffectsScope() {
+    in_no_side_effects_scope_--;

[mvstanton, 2013/04/11 13:02:38]

I would add ASSERT(in_no_side_effects_scope >= 0); since this method is public
and somebody could start calling it without the nice scope class below.

+  }
+
  protected:
   virtual bool BuildGraph() = 0;
 
   HBasicBlock* CreateBasicBlock(HEnvironment* envy,
                                 BailoutId previous_ast_id);
   HBasicBlock* CreateLoopHeaderBlock(BailoutId previous_ast_id);
 
   // Building common constructs
   HInstruction* BuildExternalArrayElementAccess(
       HValue* external_elements,
@@ skipping 121 matching lines @@
     HInstruction* increment_;
     HPhi* phi_;
     HBasicBlock* header_block_;
     HBasicBlock* body_block_;
     HBasicBlock* exit_block_;
     Direction direction_;
     BailoutId id_;
     bool finished_;
   };
 
+  class NoObservableSideEffectsScope {
+   public:
+    explicit NoObservableSideEffectsScope(HGraphBuilder* builder) :
+        builder_(builder) {
+      builder_->IncrementInNoSideEffectsScope();
+    }
+    ~NoObservableSideEffectsScope() {
+      builder_->DecrementInNoSideEffectsScope();
+    }
+
+   private:
+    HGraphBuilder* builder_;
+  };
+
   HValue* BuildNewElementsCapacity(HValue* context,
                                    HValue* old_capacity);
 
   void BuildNewSpaceArrayCheck(HValue* length,
                                ElementsKind kind);
 
   HValue* BuildAllocateElements(HValue* context,
                                 ElementsKind kind,
                                 HValue* capacity);
 
@@ skipping 30 matching lines @@
                                  AllocationSiteMode mode,
                                  ElementsKind kind,
                                  BailoutId id,
                                  int length);
 
  private:
   HGraphBuilder();
   CompilationInfo* info_;
   HGraph* graph_;
   HBasicBlock* current_block_;
+  int in_no_side_effects_scope_;
 };
 
 
 class HOptimizedGraphBuilder: public HGraphBuilder, public AstVisitor {
  public:
   enum BreakType { BREAK, CONTINUE };
   enum SwitchType { UNKNOWN_SWITCH, SMI_SWITCH, STRING_SWITCH };
 
   // A class encapsulating (lazily-allocated) break and continue blocks for
   // a breakable statement.  Separated from BreakAndContinueScope so that it
@@ skipping 674 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_