[hydrogen] optimize switch with string clauses

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index fce0e30238609f38dacd3f4baa5a32076e782aa4..29744a96e62f2606712610c282b2ac29ce9a00aa 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -118,8 +118,10 @@ class LChunkBuilder;
   V(IsConstructCallAndBranch)                  \
   V(IsNilAndBranch)                            \
   V(IsObjectAndBranch)                         \
+  V(IsStringAndBranch)                         \
   V(IsSmiAndBranch)                            \
   V(IsUndetectableAndBranch)                   \
+  V(StringCompareAndBranch)                   \
   V(JSArrayLength)                             \
   V(LeaveInlined)                              \
   V(LoadContextSlot)                           \
@@ -2716,6 +2718,18 @@ class HIsObjectAndBranch: public HUnaryControlInstruction {
   DECLARE_CONCRETE_INSTRUCTION(IsObjectAndBranch)
 };
 
+class HIsStringAndBranch: public HUnaryControlInstruction {
+ public:
+  explicit HIsStringAndBranch(HValue* value)
+    : HUnaryControlInstruction(value, NULL, NULL) { }
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(IsStringAndBranch)
+};
+
 
 class HIsSmiAndBranch: public HUnaryControlInstruction {
  public:
@@ -2746,6 +2760,42 @@ class HIsUndetectableAndBranch: public HUnaryControlInstruction {
 };
 
 
+class HStringCompareAndBranch: public HTemplateControlInstruction<2, 3> {
+ public:
+  HStringCompareAndBranch(HValue* context,
+                           HValue* left,
+                           HValue* right,
+                           Token::Value token)
+      : token_(token) {
+    ASSERT(Token::IsCompareOp(token));
+    SetOperandAt(0, context);
+    SetOperandAt(1, left);
+    SetOperandAt(2, right);
+    set_representation(Representation::Tagged());
+  }
+
+  HValue* context() { return OperandAt(0); }
+  HValue* left() { return OperandAt(1); }
+  HValue* right() { return OperandAt(2); }
+  Token::Value token() const { return token_; }
+
+  virtual void PrintDataTo(StringStream* stream);
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+
+  Representation GetInputRepresentation() const {
+    return Representation::Tagged();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(StringCompareAndBranch)
+
+ private:
+  Token::Value token_;
+};
+
+
 class HIsConstructCallAndBranch: public HTemplateControlInstruction<2, 0> {
  public:
   virtual Representation RequiredInputRepresentation(int index) {