Inlined load of string.length and array.length....

src/ic.cc

 // Copyright 2006-2009 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 578 matching lines @@
     if ((object->IsString() || object->IsStringWrapper()) &&
         name->Equals(Heap::length_symbol())) {
       HandleScope scope;
       // Get the string if we have a string wrapper object.
       if (object->IsJSValue()) {
         object = Handle<Object>(Handle<JSValue>::cast(object)->value());
       }
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#length /string]\n");
 #endif
+      Map* map = HeapObject::cast(*object)->map();
+      if (object->IsString()) {
+        const int offset = String::kLengthOffset;
+        PatchInlinedLoad(address(), map, offset);
+      }
+
       Code* target = NULL;
       target = Builtins::builtin(Builtins::LoadIC_StringLength);
       set_target(target);
-      StubCache::Set(*name, HeapObject::cast(*object)->map(), target);
+      StubCache::Set(*name, map, target);
       return Smi::FromInt(String::cast(*object)->length());
     }
 
     // Use specialized code for getting the length of arrays.
     if (object->IsJSArray() && name->Equals(Heap::length_symbol())) {
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#length /array]\n");
 #endif
+      Map* map = HeapObject::cast(*object)->map();
+      const int offset = JSArray::kLengthOffset;
+      PatchInlinedLoad(address(), map, offset);
+
       Code* target = Builtins::builtin(Builtins::LoadIC_ArrayLength);
       set_target(target);
-      StubCache::Set(*name, HeapObject::cast(*object)->map(), target);
+      StubCache::Set(*name, map, target);
       return JSArray::cast(*object)->length();
     }
 
     // Use specialized code for getting prototype of functions.
     if (object->IsJSFunction() && name->Equals(Heap::prototype_symbol()) &&
         JSFunction::cast(*object)->should_have_prototype()) {
 #ifdef DEBUG
       if (FLAG_trace_ic) PrintF("[LoadIC : +#prototype /function]\n");
 #endif
       Code* target = Builtins::builtin(Builtins::LoadIC_FunctionPrototype);
@@ skipping 876 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal