A change in the way we place TransitionElementKinds in the tree.

src/hydrogen-instructions.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 2203 matching lines @@
     return check_map;
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
   virtual void PrintDataTo(StringStream* stream);
   virtual HType CalculateInferredType();
 
   HValue* value() { return OperandAt(0); }
+  bool has_typecheck() const { return OperandAt(0) != OperandAt(1); }

[danno, 2012/11/14 15:28:18]

HasTypeCheck()

[mvstanton, 2012/11/16 15:15:06]

Done.

   SmallMapList* map_set() { return &map_set_; }
 
   DECLARE_CONCRETE_INSTRUCTION(CheckMaps)
 
  protected:
   virtual bool DataEquals(HValue* other) {
     HCheckMaps* b = HCheckMaps::cast(other);
     // Relies on the fact that map_set has been sorted before.
     if (map_set()->length() != b->map_set()->length()) return false;
     for (int i = 0; i < map_set()->length(); i++) {
@@ skipping 2021 matching lines @@
   virtual ~ArrayInstructionInterface() { };
 };
 
 
 class HLoadKeyed
     : public HTemplateInstruction<3>, public ArrayInstructionInterface {
  public:
   HLoadKeyed(HValue* obj,
              HValue* key,
              HValue* dependency,
-             ElementsKind elements_kind)
+             ElementsKind elements_kind,
+             bool defer_initialization=false)

[danno, 2012/11/14 15:28:18]

nit: separate all operators from variable names and expressions with spaces

[mvstanton, 2012/11/16 15:15:06]

Done.

       : bit_field_(0) {
     bit_field_ = ElementsKindField::encode(elements_kind);
-
+    
+#ifdef DEBUG
+    initialized_ = !defer_initialization;
+#endif
+    
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, dependency);
 
-    if (!is_external()) {
-      // I can detect the case between storing double (holey and fast) and
-      // smi/object by looking at elements_kind_.
-      ASSERT(IsFastSmiOrObjectElementsKind(elements_kind) ||
-             IsFastDoubleElementsKind(elements_kind));
+    if (!defer_initialization) {
+      InitializeFields();
+    }
+    
+    SetFlag(kUseGVN);
+  }
 
-      if (IsFastSmiOrObjectElementsKind(elements_kind)) {
-        if (IsFastSmiElementsKind(elements_kind) &&
-            IsFastPackedElementsKind(elements_kind)) {
-          set_type(HType::Smi());
-        }
-
-        set_representation(Representation::Tagged());
-        SetGVNFlag(kDependsOnArrayElements);
-      } else {
-        set_representation(Representation::Double());
-        SetGVNFlag(kDependsOnDoubleArrayElements);
-      }
-    } else {
-      if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
-          elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
-        set_representation(Representation::Double());
-      } else {
-        set_representation(Representation::Integer32());
-      }
-
-      SetGVNFlag(kDependsOnSpecializedArrayElements);
-      // Native code could change the specialized array.
-      SetGVNFlag(kDependsOnCalls);
+#ifdef DEBUG
+  bool Initialized() const { return initialized_; }
+#endif
+  
+  void PerformDeferredInitialization(ElementsKind new_elements_kind) {
+#ifdef DEBUG
+    ASSERT(!initialized_);
+    initialized_ = true;
+#endif
+    if (new_elements_kind != elements_kind()) {
+      bit_field_ = ElementsKindField::encode(new_elements_kind);
     }
-
-    SetFlag(kUseGVN);
+    
+    InitializeFields();
   }
 
   bool is_external() const {
     return IsExternalArrayElementsKind(elements_kind());
   }
   HValue* elements() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
   HValue* dependency() { return OperandAt(2); }
   uint32_t index_offset() { return IndexOffsetField::decode(bit_field_); }
   void SetIndexOffset(uint32_t index_offset) {
     bit_field_ = IndexOffsetField::update(bit_field_, index_offset);
   }
   HValue* GetKey() { return key(); }
   void SetKey(HValue* key) { SetOperandAt(1, key); }
   bool IsDehoisted() { return IsDehoistedField::decode(bit_field_); }
   void SetDehoisted(bool is_dehoisted) {
     bit_field_ = IsDehoistedField::update(bit_field_, is_dehoisted);
   }
   ElementsKind elements_kind() const {
     return ElementsKindField::decode(bit_field_);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
+#ifdef DEBUG
+    ASSERT(initialized_);
+#endif
     // kind_fast:       tagged[int32] (none)
     // kind_double:     tagged[int32] (none)
     // kind_external: external[int32] (none)
     if (index == 0) {
       return is_external() ? Representation::External()
           : Representation::Tagged();
     }
     if (index == 1) return Representation::Integer32();
     return Representation::None();
   }
@@ skipping 10 matching lines @@
   virtual bool DataEquals(HValue* other) {
     if (!other->IsLoadKeyed()) return false;
     HLoadKeyed* other_load = HLoadKeyed::cast(other);
 
     if (IsDehoisted() && index_offset() != other_load->index_offset())
       return false;
     return elements_kind() == other_load->elements_kind();
   }
 
  private:
+  void InitializeFields() {

[danno, 2012/11/14 15:28:18]

Move implementation this to the .cc file. 

And oh... Drop the "Fields." Just "Initialize." It's cleaner. ;-)

[mvstanton, 2012/11/16 15:15:06]

Done.

+    if (!is_external()) {
+      // I can detect the case between storing double (holey and fast) and
+      // smi/object by looking at elements_kind_.
+      ASSERT(IsFastSmiOrObjectElementsKind(elements_kind()) ||
+             IsFastDoubleElementsKind(elements_kind()));
+
+      if (IsFastSmiOrObjectElementsKind(elements_kind())) {
+        if (IsFastSmiElementsKind(elements_kind()) &&
+            IsFastPackedElementsKind(elements_kind())) {
+          set_type(HType::Smi());
+        }
+
+        set_representation(Representation::Tagged());
+        SetGVNFlag(kDependsOnArrayElements);
+      } else {
+        set_representation(Representation::Double());
+        SetGVNFlag(kDependsOnDoubleArrayElements);
+      }
+    } else {
+      if (elements_kind() == EXTERNAL_FLOAT_ELEMENTS ||
+          elements_kind() == EXTERNAL_DOUBLE_ELEMENTS) {
+        set_representation(Representation::Double());
+      } else {
+        set_representation(Representation::Integer32());
+      }
+
+      SetGVNFlag(kDependsOnSpecializedArrayElements);
+      // Native code could change the specialized array.
+      SetGVNFlag(kDependsOnCalls);
+    }
+  }
+  
   virtual bool IsDeletable() const {
     return !RequiresHoleCheck();
   }
 
   // Establish some checks around our packed fields
   enum LoadKeyedBits {
     kBitsForElementsKind = 5,
     kBitsForIndexOffset = 26,
     kBitsForIsDehoisted = 1,
 
     kStartElementsKind = 0,
     kStartIndexOffset = kStartElementsKind + kBitsForElementsKind,
     kStartIsDehoisted = kStartIndexOffset + kBitsForIndexOffset
   };
 
   STATIC_ASSERT((kBitsForElementsKind + kBitsForIndexOffset +
                  kBitsForIsDehoisted) <= sizeof(uint32_t)*8);
   STATIC_ASSERT(kElementsKindCount <= (1 << kBitsForElementsKind));
   class ElementsKindField:
     public BitField<ElementsKind, kStartElementsKind, kBitsForElementsKind>
     {};  // NOLINT
   class IndexOffsetField:
     public BitField<uint32_t, kStartIndexOffset, kBitsForIndexOffset>
     {};  // NOLINT
   class IsDehoistedField:
     public BitField<bool, kStartIsDehoisted, kBitsForIsDehoisted>
     {};  // NOLINT
   uint32_t bit_field_;
+#ifdef DEBUG
+  bool initialized_;
+#endif
 };
 
 
 class HLoadKeyedGeneric: public HTemplateInstruction<3> {
  public:
   HLoadKeyedGeneric(HValue* context, HValue* obj, HValue* key) {
     set_representation(Representation::Tagged());
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, context);
@@ skipping 110 matching lines @@
  private:
   Handle<String> name_;
   StrictModeFlag strict_mode_flag_;
 };
 
 
 class HStoreKeyed
     : public HTemplateInstruction<3>, public ArrayInstructionInterface {
  public:
   HStoreKeyed(HValue* obj, HValue* key, HValue* val,
-              ElementsKind elements_kind)
+              ElementsKind elements_kind,
+              bool defer_initialization=false)

[danno, 2012/11/14 15:28:18]

spaces b/a =

[mvstanton, 2012/11/16 15:15:06]

Done.

       : elements_kind_(elements_kind), index_offset_(0), is_dehoisted_(false) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
-
-    if (is_external()) {
-      SetGVNFlag(kChangesSpecializedArrayElements);
-    } else if (IsFastDoubleElementsKind(elements_kind)) {
-      SetGVNFlag(kChangesDoubleArrayElements);
-      SetFlag(kDeoptimizeOnUndefined);
-    } else {
-      SetGVNFlag(kChangesArrayElements);
-    }
+    
+#ifdef DEBUG
+    initialized_ = !defer_initialization;
+#endif
+    
+    InitializeFlags();
   }
 
+#ifdef DEBUG
+  bool Initialized() const { return initialized_; }
+#endif
+  
+  void PerformDeferredInitialization(ElementsKind new_elements_kind) {
+#ifdef DEBUG
+    ASSERT(!initialized_);
+    initialized_ = true;
+#endif
+    if (new_elements_kind != elements_kind_) {
+      elements_kind_ = new_elements_kind;
+    }
+    
+    InitializeFlags();
+  }
+  
   virtual Representation RequiredInputRepresentation(int index) {
+#ifdef DEBUG
+    ASSERT(initialized_);
+#endif
     // kind_fast:       tagged[int32] = tagged
     // kind_double:     tagged[int32] = double
     // kind_external: external[int32] = (double | int32)
     if (index == 0) {
       return is_external() ? Representation::External()
                            : Representation::Tagged();
     } else if (index == 1) {
       return Representation::Integer32();
     }
 
@@ skipping 31 matching lines @@
     }
   }
 
   bool NeedsCanonicalization();
 
   virtual void PrintDataTo(StringStream* stream);
 
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyed)
 
  private:
+  void InitializeFlags() {

[danno, 2012/11/14 15:28:18]

Again, how about just "Initialize"?

[mvstanton, 2012/11/16 15:15:06]

Done.

+    if (is_external()) {
+      SetGVNFlag(kChangesSpecializedArrayElements);
+    } else if (IsFastDoubleElementsKind(elements_kind())) {
+      SetGVNFlag(kChangesDoubleArrayElements);
+      SetFlag(kDeoptimizeOnUndefined);
+    } else {
+      SetGVNFlag(kChangesArrayElements);
+    }
+  }
   ElementsKind elements_kind_;
   uint32_t index_offset_;
   bool is_dehoisted_;
+#ifdef DEBUG
+  bool initialized_;
+#endif
 };
 
 
 class HStoreKeyedGeneric: public HTemplateInstruction<4> {
  public:
   HStoreKeyedGeneric(HValue* context,
                      HValue* object,
                      HValue* key,
                      HValue* value,
                      StrictModeFlag strict_mode_flag)
@@ skipping 685 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_