Support StringCharCodeAt in hydrogen/lithium.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 5cc8432c00689865d73bc879ce0c42c09969ee0d..ad3ad9781b753b199a900fa164def4972c70826f 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -81,6 +81,7 @@ class LChunkBuilder;
 //       HStoreNamed
 //         HStoreNamedField
 //         HStoreNamedGeneric
+//       HStringChartCodeAt

[fschneider, 2011/01/14 12:06:11]

->HStringCharCodeAt

 //     HBlockEntry
 //     HCall
 //       HCallConstantFunction
@@ -136,6 +137,7 @@ class LChunkBuilder;
 //       HLoadNamedGeneric
 //       HLoadFunctionPrototype
 //       HPushArgument
+//       HStringLength
 //       HTypeof
 //       HUnaryMathOperation
 //       HUnaryPredicate
@@ -246,6 +248,8 @@ class LChunkBuilder;
   V(StoreKeyedGeneric)                         \
   V(StoreNamedField)                           \
   V(StoreNamedGeneric)                         \
+  V(StringCharCodeAt)                          \
+  V(StringLength)                              \
   V(Sub)                                       \
   V(Throw)                                     \
   V(Typeof)                                    \
@@ -2884,6 +2888,46 @@ class HStoreKeyedGeneric: public HStoreKeyed {
 };
 
 
+class HStringCharCodeAt: public HBinaryOperation {
+ public:
+  HStringCharCodeAt(HValue* string, HValue* index)
+      : HBinaryOperation(string, index){
+    set_representation(Representation::Integer32());
+    SetFlag(kUseGVN);
+  }
+
+  virtual Representation RequiredInputRepresentation(int index) const {
+    // The index is supposed to be Integer32.
+    return (index == 1) ? Representation::Integer32()
+        : Representation::Tagged();
+  }
+
+  virtual bool DataEquals(HValue* other) const { return true; }
+
+  HValue* string() const { return OperandAt(0); }
+  HValue* index() const { return OperandAt(1); }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringCharCodeAt, "string_char_code_at")
+};
+
+
+class HStringLength: public HUnaryOperation {

[fschneider, 2011/01/14 12:06:11]

Could you use HStringLength to optimize access like s.length (similar to the way
we do for ArrayLength)?

+ public:
+  explicit HStringLength(HValue* string) : HUnaryOperation(string) {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+  }
+
+  virtual Representation RequiredInputRepresentation(int index) const {
+    return Representation::Tagged();
+  }
+
+  virtual bool DataEquals(HValue* other) const { return true; }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringLength, "string_length")
+};
+
+
 class HMaterializedLiteral: public HInstruction {
  public:
   HMaterializedLiteral(int index, int depth)