Built-in apply() performance benefits from an uninitialized IC.

src/ia32/builtins-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 1026 matching lines @@
 
 
 static void Generate_PushAppliedArguments(MacroAssembler* masm,
                                           const int argumentsOffset,
                                           const int indexOffset,
                                           const int limitOffset) {
   // Copy all arguments from the array to the stack.
   Label entry, loop;
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register key = LoadDescriptor::NameRegister();
+  Register slot = LoadDescriptor::SlotRegister();
+  Register vector = LoadWithVectorDescriptor::VectorRegister();
   __ mov(key, Operand(ebp, indexOffset));
   __ jmp(&entry);
   __ bind(&loop);
   __ mov(receiver, Operand(ebp, argumentsOffset));  // load arguments
 
   // Use inline caching to speed up access to arguments.
-  Handle<Code> ic = masm->isolate()->builtins()->KeyedLoadIC_Megamorphic();
+  FeedbackVectorSpec spec(0, Code::KEYED_LOAD_IC);
+  Handle<TypeFeedbackVector> feedback_vector =
+      masm->isolate()->factory()->NewTypeFeedbackVector(&spec);
+  int index = feedback_vector->GetIndex(FeedbackVectorICSlot(0));
+  __ mov(slot, Immediate(Smi::FromInt(index)));
+  __ mov(vector, Immediate(feedback_vector));
+  Handle<Code> ic = KeyedLoadICStub(masm->isolate()).GetCode();
   __ call(ic, RelocInfo::CODE_TARGET);
   // It is important that we do not have a test instruction after the
   // call.  A test instruction after the call is used to indicate that
   // we have generated an inline version of the keyed load.  In this
   // case, we know that we are not generating a test instruction next.
 
   // Push the nth argument.
   __ push(eax);
 
   // Update the index on the stack and in register key.
@@ skipping 636 matching lines @@
 
   __ bind(&ok);
   __ ret(0);
 }
 
 #undef __
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32