Not consider the use representation in unintiliazed ArrayLiteral which always requires SMI

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/18263002

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15450 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -5877,6 +5877,7 @@ class HStoreKeyed
       : elements_kind_(elements_kind),
       index_offset_(0),
       is_dehoisted_(false),
+      is_uninitialized_(false),
       new_space_dominator_(NULL) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
@@ -5937,6 +5938,9 @@ class HStoreKeyed
 
   virtual Representation observed_input_representation(int index) {
     if (index < 2) return RequiredInputRepresentation(index);
+    if (IsUninitialized()) {
+      return Representation::None();
+    }
     if (IsFastSmiElementsKind(elements_kind())) {
       return Representation::Smi();
     }
@@ -5963,6 +5967,10 @@ class HStoreKeyed
   void SetKey(HValue* key) { SetOperandAt(1, key); }
   bool IsDehoisted() { return is_dehoisted_; }
   void SetDehoisted(bool is_dehoisted) { is_dehoisted_ = is_dehoisted; }
+  bool IsUninitialized() { return is_uninitialized_; }
+  void SetUninitialized(bool is_uninitialized) {
+    is_uninitialized_ = is_uninitialized;
+  }
 
   bool IsConstantHoleStore() {
     return value()->IsConstant() && HConstant::cast(value())->IsTheHole();
@@ -5993,7 +6001,8 @@ class HStoreKeyed
  private:
   ElementsKind elements_kind_;
   uint32_t index_offset_;
-  bool is_dehoisted_;
+  bool is_dehoisted_ : 1;
+  bool is_uninitialized_ : 1;
   HValue* new_space_dominator_;
 };
 

src/hydrogen.cc

@@ -5544,7 +5544,9 @@ void HOptimizedGraphBuilder::VisitArrayLiteral(ArrayLiteral* expr) {
   Handle<Object> raw_boilerplate(literals->get(expr->literal_index()),
                                  isolate());
 
+  bool uninitialized = false;
   if (raw_boilerplate->IsUndefined()) {
+    uninitialized = true;
     raw_boilerplate = Runtime::CreateArrayLiteralBoilerplate(
         isolate(), literals, expr->constant_elements());
     if (raw_boilerplate.is_null()) {
@@ -5640,10 +5642,12 @@ void HOptimizedGraphBuilder::VisitArrayLiteral(ArrayLiteral* expr) {
       case FAST_ELEMENTS:
       case FAST_HOLEY_ELEMENTS:
       case FAST_DOUBLE_ELEMENTS:
-      case FAST_HOLEY_DOUBLE_ELEMENTS:
-        Add<HStoreKeyed>(elements, key, value,
-                         boilerplate_elements_kind);
+      case FAST_HOLEY_DOUBLE_ELEMENTS: {
+        HStoreKeyed* instr = Add<HStoreKeyed>(elements, key, value,
+                                              boilerplate_elements_kind);
+        instr->SetUninitialized(uninitialized);
         break;
+      }
       default:
         UNREACHABLE();
         break;