Add range information to external array loads.

Review URL: http://codereview.chromium.org/9226014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10479 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -1339,6 +1339,23 @@ Range* HShl::InferRange() {
 }
 
 
+Range* HLoadKeyedSpecializedArrayElement::InferRange() {
+  switch (elements_kind()) {
+    case EXTERNAL_PIXEL_ELEMENTS:
+      return new Range(0, 255);
+    case EXTERNAL_BYTE_ELEMENTS:
+      return new Range(-128, 127);
+    case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
+      return new Range(0, 255);
+    case EXTERNAL_SHORT_ELEMENTS:
+      return new Range(-32768, 32767);
+    case EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
+      return new Range(0, 65535);
+    default:
+      return HValue::InferRange();
+  }
+}
+
 
 void HCompareGeneric::PrintDataTo(StringStream* stream) {
   stream->Add(Token::Name(token()));

src/hydrogen-instructions.h

@@ -3844,6 +3844,8 @@ class HLoadKeyedSpecializedArrayElement: public HTemplateInstruction<2> {
   HValue* key() { return OperandAt(1); }
   ElementsKind elements_kind() const { return elements_kind_; }
 
+  virtual Range* InferRange();
+
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyedSpecializedArrayElement)
 
  protected: