Replace ICStub for array.length with hydrogen stub

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index da2211b7b686abc9f28a586fcaba986f4b90eaec..1d3ef63656e5ec3521dba7ce4057678c79d76201 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -855,28 +855,6 @@ MaybeObject* LoadIC::Load(State state,
       return Smi::FromInt(String::cast(*string)->length());
     }
 
-    // Use specialized code for getting the length of arrays.
-    if (object->IsJSArray() &&
-        name->Equals(isolate()->heap()->length_string())) {
-      Handle<Code> stub;
-      if (state == UNINITIALIZED) {
-        stub = pre_monomorphic_stub();
-      } else if (state == PREMONOMORPHIC) {
-        ArrayLengthStub array_length_stub(kind());
-        stub = array_length_stub.GetCode(isolate());
-      } else if (state != MEGAMORPHIC) {
-        ASSERT(state != GENERIC);
-        stub = megamorphic_stub();
-      }
-      if (!stub.is_null()) {
-        set_target(*stub);
-#ifdef DEBUG
-        if (FLAG_trace_ic) PrintF("[LoadIC : +#length /array]\n");
-#endif
-      }
-      return JSArray::cast(*object)->length();
-    }
-
     // Use specialized code for getting prototype of functions.
     if (object->IsJSFunction() &&
         name->Equals(isolate()->heap()->prototype_string()) &&
@@ -941,6 +919,10 @@ MaybeObject* LoadIC::Load(State state,
     return *result;
   }
 
+  if (object->IsJSArray() &&

[danno, 2013/03/12 11:16:16]

Doesn't GetProperty already handle this (it should)?

+        name->Equals(isolate()->heap()->length_string())) {
+    return JSArray::cast(*object)->length();
+  }
   // Get the property.
   return object->GetProperty(*object, &lookup, *name, &attr);
 }
@@ -1223,6 +1205,10 @@ Handle<Code> LoadIC::ComputeLoadHandler(LookupResult* lookup,
         if (!holder->HasFastProperties()) break;
         return isolate()->stub_cache()->ComputeLoadViaGetter(
             name, receiver, holder, Handle<JSFunction>::cast(getter));
+      } else if (receiver->IsJSArray() &&
+          name->Equals(isolate()->heap()->length_string())) {
+        return isolate()->stub_cache()->ComputeLoadArrayLength(

[danno, 2013/03/12 11:16:16]

why not just:

Property index = 
  PropertyIndex::NewHeaderIndex(JSArray::kLengthOffset / kPointerSize);
return isolate()->stub_cache()->ComputeLoadField(
  name, receiver, holder, index);

That obviates the need for all the new code in stub-cache.cc

+            name, receiver, holder);
       }
       // TODO(dcarney): Handle correctly.
       if (callback->IsDeclaredAccessorInfo()) break;