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

BUG=

Review URL: https://codereview.chromium.org/14174002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14232 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/code-stubs-hydrogen.cc

@@ -147,6 +147,8 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
 
   AddSimulate(BailoutId::StubEntry());
 
+  NoObservableSideEffectsScope no_effects(this);
+
   HValue* return_value = BuildCodeStub();
 
   // We might have extra expressions to pop from the stack in addition to the
@@ -298,7 +300,6 @@ HValue* CodeStubGraphBuilder<FastCloneShallowObjectStub>::BuildCodeStub() {
                                               factory->empty_string(),
                                               value,
                                               true, i));
-    AddSimulate(BailoutId::StubEntry());
   }
 
   builder.End();
@@ -332,7 +333,6 @@ HValue* CodeStubGraphBuilder<KeyedStoreFastElementStub>::BuildCodeStub() {
       GetParameter(0), GetParameter(1), GetParameter(2), NULL,
       casted_stub()->is_js_array(), casted_stub()->elements_kind(),
       true, casted_stub()->store_mode(), Representation::Tagged());
-  AddSimulate(BailoutId::StubEntry(), REMOVABLE_SIMULATE);
 
   return GetParameter(2);
 }
@@ -388,13 +388,11 @@ HValue* CodeStubGraphBuilder<TransitionElementsKindStub>::BuildCodeStub() {
                                             factory->elements_field_string(),
                                             new_elements, true,
                                             JSArray::kElementsOffset));
-  AddSimulate(BailoutId::StubEntry());
 
   if_builder.End();
 
   AddInstruction(new(zone) HStoreNamedField(js_array, factory->length_string(),
                                             map, true, JSArray::kMapOffset));
-  AddSimulate(BailoutId::StubEntry());
   return js_array;
 }
 

src/hydrogen-instructions.cc

@@ -802,6 +802,9 @@ void HValue::ComputeInitialRange(Zone* zone) {
 
 void HInstruction::PrintTo(StringStream* stream) {
   PrintMnemonicTo(stream);
+  const char* side_effects =
+      CheckFlag(HValue::kHasNoObservableSideEffects) ? "-" : "+";
+  stream->Add("ose%s ", side_effects);
   PrintDataTo(stream);
   PrintRangeTo(stream);
   PrintChangesTo(stream);

src/hydrogen-instructions.h

@@ -828,6 +828,7 @@ class HValue: public ZoneObject {
     // This flag is set to true after the SetupInformativeDefinitions() pass
     // has processed this instruction.
     kIDefsProcessingDone,
+    kHasNoObservableSideEffects,
     kLastFlag = kIDefsProcessingDone
   };
 
@@ -1005,7 +1006,8 @@ class HValue: public ZoneObject {
     return gvn_flags_.ContainsAnyOf(AllSideEffectsFlagSet());
   }
   bool HasObservableSideEffects() const {
-    return gvn_flags_.ContainsAnyOf(AllObservableSideEffectsFlagSet());
+    return !CheckFlag(kHasNoObservableSideEffects) &&
+        gvn_flags_.ContainsAnyOf(AllObservableSideEffectsFlagSet());
   }
 
   GVNFlagSet DependsOnFlags() const {

src/hydrogen.h

@@ -865,7 +865,10 @@ class FunctionState {
 class HGraphBuilder {
  public:
   explicit HGraphBuilder(CompilationInfo* info)
-      : info_(info), graph_(NULL), current_block_(NULL) {}
+      : info_(info),
+        graph_(NULL),
+        current_block_(NULL),
+        no_side_effects_scope_count_(0) {}
   virtual ~HGraphBuilder() {}
 
   HBasicBlock* current_block() const { return current_block_; }
@@ -891,6 +894,14 @@ class HGraphBuilder {
 
   HReturn* AddReturn(HValue* value);
 
+  void IncrementInNoSideEffectsScope() {
+    no_side_effects_scope_count_++;
+  }
+
+  void DecrementInNoSideEffectsScope() {
+    no_side_effects_scope_count_--;
+  }
+
  protected:
   virtual bool BuildGraph() = 0;
 
@@ -1032,6 +1043,20 @@ class HGraphBuilder {
     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);
 
@@ -1082,6 +1107,7 @@ class HGraphBuilder {
   CompilationInfo* info_;
   HGraph* graph_;
   HBasicBlock* current_block_;
+  int no_side_effects_scope_count_;
 };