Optimize typed-array length loading.

src/hydrogen-instructions.h

 // 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 5652 matching lines @@
 
   static HObjectAccess ForArrayLength(ElementsKind elements_kind) {
     return HObjectAccess(
         kArrayLengths,
         JSArray::kLengthOffset,
         IsFastElementsKind(elements_kind) &&
             FLAG_track_fields
                 ? Representation::Smi() : Representation::Tagged());
   }
 
+  static HObjectAccess ForTypedArrayLength() {
+    return HObjectAccess(
+        kInobject,
+        JSTypedArray::kLengthOffset,
+        Representation::Tagged());
+  }
+
   static HObjectAccess ForAllocationSiteTransitionInfo() {
     return HObjectAccess(kInobject, AllocationSite::kTransitionInfoOffset);
   }
 
   static HObjectAccess ForAllocationSiteDependentCode() {
     return HObjectAccess(kInobject, AllocationSite::kDependentCodeOffset);
   }
 
   static HObjectAccess ForAllocationSiteWeakNext() {
     return HObjectAccess(kInobject, AllocationSite::kWeakNextOffset);
@@ skipping 1358 matching lines @@
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_