Optimize typed-array length loading.

src/ic.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1353 matching lines @@
         if (!holder->HasFastProperties()) break;
         Handle<JSFunction> function = Handle<JSFunction>::cast(getter);
         CallOptimization call_optimization(function);
         if (call_optimization.is_simple_api_call() &&
             call_optimization.IsCompatibleReceiver(*receiver)) {
           return isolate()->stub_cache()->ComputeLoadCallback(
               name, receiver, holder, call_optimization);
         }
         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;
       ASSERT(callback->IsForeign());
       // No IC support for old-style native accessors.
       break;
     }
     case INTERCEPTOR:
       ASSERT(HasInterceptorGetter(*holder));
       return isolate()->stub_cache()->ComputeLoadInterceptor(
@@ skipping 1766 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal