Optimize typed-array length loading.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 163172d8eb4df42e68c395c528f1864fb68ca49c..782c5fac12dadb9d4faf0ff976a0bedafe59c8d8 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1371,12 +1371,18 @@ Handle<Code> LoadIC::ComputeLoadHandler(LookupResult* lookup,
         }
         return isolate()->stub_cache()->ComputeLoadViaGetter(
             name, receiver, holder, function);
-      } else if (receiver->IsJSArray() &&
-                 name->Equals(isolate()->heap()->length_string())) {
-        PropertyIndex lengthIndex = PropertyIndex::NewHeaderIndex(
-            JSArray::kLengthOffset / kPointerSize);
-        return isolate()->stub_cache()->ComputeLoadField(
-            name, receiver, holder, lengthIndex, Representation::Tagged());
+      } else if (name->Equals(isolate()->heap()->length_string())) {
+        if (receiver->IsJSArray()) {
+          PropertyIndex lengthIndex = PropertyIndex::NewHeaderIndex(
+              JSArray::kLengthOffset / kPointerSize);
+          return isolate()->stub_cache()->ComputeLoadField(
+              name, receiver, holder, lengthIndex, Representation::Tagged());
+        } else if (receiver->IsJSTypedArray()) {

[Dmitry Lomov (no reviews), 2013/09/19 17:45:46]

Are you sure you this code path is hit? For typed arrays,
callbacks->IsAccessorPair() is true, so we will not get here. Or what am I
missing?

+          PropertyIndex lengthIndex = PropertyIndex::NewHeaderIndex(
+              JSTypedArray::kLengthOffset / kPointerSize);
+          return isolate()->stub_cache()->ComputeLoadField(
+              name, receiver, holder, lengthIndex, Representation::Tagged());
+        }
       }
       // TODO(dcarney): Handle correctly.
       if (callback->IsDeclaredAccessorInfo()) break;