Support StringLength in hydrogen (similar to ArrayLength).

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 555ce3f13974ae7821856b5968c67ec82bab4ec7..b89e68b7163512e2156f278b1331329bc374f72f 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -822,6 +822,9 @@ MaybeObject* LoadIC::Load(State state,
   }
 
   if (FLAG_use_ic) {
+    Code* non_monomorphic_stub =
+        (state == UNINITIALIZED) ? pre_monomorphic_stub() : megamorphic_stub();
+
     // Use specialized code for getting the length of strings and
     // string wrapper objects.  The length property of string wrapper
     // objects is read-only and therefore always returns the length of
@@ -829,22 +832,27 @@ MaybeObject* LoadIC::Load(State state,
     if ((object->IsString() || object->IsStringWrapper()) &&
         name->Equals(Heap::length_symbol())) {
       HandleScope scope;
-      // Get the string if we have a string wrapper object.
-      if (object->IsJSValue()) {
-        object = Handle<Object>(Handle<JSValue>::cast(object)->value());
-      }
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#length /string]\n");
 #endif
-      Map* map = HeapObject::cast(*object)->map();
-      if (object->IsString()) {
-        const int offset = String::kLengthOffset;
-        PatchInlinedLoad(address(), map, offset);
+      if (state == PREMONOMORPHIC) {
+        if (object->IsString()) {
+          Map* map = HeapObject::cast(*object)->map();
+          const int offset = String::kLengthOffset;
+          PatchInlinedLoad(address(), map, offset);
+          set_target(Builtins::builtin(Builtins::LoadIC_StringLength));
+        } else {
+          set_target(Builtins::builtin(Builtins::LoadIC_StringWrapperLength));
+        }
+      } else if (state == MONOMORPHIC && object->IsStringWrapper()) {
+        set_target(Builtins::builtin(Builtins::LoadIC_StringWrapperLength));
+      } else {
+        set_target(non_monomorphic_stub);
+      }
+      // Get the string if we have a string wrapper object.
+      if (object->IsJSValue()) {
+        object = Handle<Object>(Handle<JSValue>::cast(object)->value());
       }
-
-      Code* target = NULL;
-      target = Builtins::builtin(Builtins::LoadIC_StringLength);
-      set_target(target);
       return Smi::FromInt(String::cast(*object)->length());
     }
 
@@ -853,12 +861,14 @@ MaybeObject* LoadIC::Load(State state,
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#length /array]\n");
 #endif
-      Map* map = HeapObject::cast(*object)->map();
-      const int offset = JSArray::kLengthOffset;
-      PatchInlinedLoad(address(), map, offset);
-
-      Code* target = Builtins::builtin(Builtins::LoadIC_ArrayLength);
-      set_target(target);
+      if (state == PREMONOMORPHIC) {
+        Map* map = HeapObject::cast(*object)->map();
+        const int offset = JSArray::kLengthOffset;
+        PatchInlinedLoad(address(), map, offset);
+        set_target(Builtins::builtin(Builtins::LoadIC_ArrayLength));
+      } else {
+        set_target(non_monomorphic_stub);
+      }
       return JSArray::cast(*object)->length();
     }
 
@@ -868,8 +878,11 @@ MaybeObject* LoadIC::Load(State state,
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#prototype /function]\n");
 #endif
-      Code* target = Builtins::builtin(Builtins::LoadIC_FunctionPrototype);
-      set_target(target);
+      if (state == PREMONOMORPHIC) {
+        set_target(Builtins::builtin(Builtins::LoadIC_FunctionPrototype));
+      } else {
+        set_target(non_monomorphic_stub);
+      }
       return Accessors::FunctionGetPrototype(*object, 0);
     }
   }