Optimize typed-array length loading.

src/hydrogen.cc

 // Copyright 2013 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 4612 matching lines @@
     for (int i = 1; i < types->length(); ++i) {
       Handle<Map> test_map = types->at(i);
       if (test_map->instance_type() != JS_ARRAY_TYPE) return false;
       if (IsFastElementsKind(test_map->elements_kind()) != is_fast) {
         return false;
       }
     }
     return true;
   }
 
+  if (IsTypedArrayLength()) {
+    for (int i = 1; i < types->length(); ++i) {
+      if (types->at(i)->instance_type() != JS_TYPED_ARRAY_TYPE) return false;
+    }
+    return true;
+  }
+
   for (int i = 1; i < types->length(); ++i) {
     PropertyAccessInfo test_info(isolate(), types->at(i), name_);
     if (!test_info.IsCompatibleForLoad(this)) return false;
   }
 
   return true;
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildLoadMonomorphic(
     PropertyAccessInfo* info,
     HValue* object,
     HInstruction* checked_object,
     BailoutId ast_id,
     BailoutId return_id,
     bool can_inline_accessor) {
   if (info->IsStringLength()) {
     return New<HLoadNamedField>(
         checked_object, HObjectAccess::ForStringLength());
   }
 
   if (info->IsArrayLength()) {
     return New<HLoadNamedField>(
         checked_object, HObjectAccess::ForArrayLength(
             info->map()->elements_kind()));
   }
 
+  if (info->IsTypedArrayLength()) {
+    return New<HLoadNamedField>(
+        checked_object, HObjectAccess::ForTypedArrayLength());
+  }
+
   HValue* checked_holder = checked_object;
   if (info->has_holder()) {
     Handle<JSObject> prototype(JSObject::cast(info->map()->prototype()));
     checked_holder = BuildCheckPrototypeMaps(prototype, info->holder());
   }
 
   if (!info->lookup()->IsFound()) return graph()->GetConstantUndefined();
 
   if (info->lookup()->IsField()) {
     return BuildLoadNamedField(checked_holder, info->access());
@@ skipping 4951 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal