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

src/x64/builtins-x64.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_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 1087 matching lines @@
   __ InvokeCode(rdx, expected, expected, JUMP_FUNCTION, NullCallWrapper());
 }
 
 
 static void Generate_PushAppliedArguments(MacroAssembler* masm,
                                           const int argumentsOffset,
                                           const int indexOffset,
                                           const int limitOffset) {
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register key = LoadDescriptor::NameRegister();
+  Register slot = LoadDescriptor::SlotRegister();
+  Register vector = LoadWithVectorDescriptor::VectorRegister();
 
   // Copy all arguments from the array to the stack.
   Label entry, loop;
   __ movp(key, Operand(rbp, indexOffset));
   __ jmp(&entry);
   __ bind(&loop);
   __ movp(receiver, Operand(rbp, 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));
+  __ Move(slot, Smi::FromInt(index));
+  __ Move(vector, 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(rax);
 
   // Update the index on the stack and in register key.
@@ skipping 648 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64