Improve Array.shift() performance for small arrays.

src/x64/code-stubs-x64.cc

 // Copyright 2013 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 "v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "bootstrapper.h"
 #include "code-stubs.h"
@@ skipping 287 matching lines @@
 void ElementsTransitionAndStoreStub::InitializeInterfaceDescriptor(
     CodeStubInterfaceDescriptor* descriptor) {
   static Register registers[] = { rax, rbx, rcx, rdx };
   descriptor->register_param_count_ = 4;
   descriptor->register_params_ = registers;
   descriptor->deoptimization_handler_ =
       FUNCTION_ADDR(ElementsTransitionAndStoreIC_Miss);
 }
 
 
+void ArrayShiftStub::InitializeInterfaceDescriptor(
+    CodeStubInterfaceDescriptor* descriptor) {
+  static Register registers[] = { rax };
+  descriptor->register_param_count_ = 1;
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ =
+      Builtins::c_function_address(Builtins::c_ArrayShift);
+}
+
+
 void BinaryOpICStub::InitializeInterfaceDescriptor(
     CodeStubInterfaceDescriptor* descriptor) {
   static Register registers[] = { rdx, rax };
   descriptor->register_param_count_ = 2;
   descriptor->register_params_ = registers;
   descriptor->deoptimization_handler_ = FUNCTION_ADDR(BinaryOpIC_Miss);
   descriptor->SetMissHandler(
       ExternalReference(IC_Utility(IC::kBinaryOpIC_Miss), isolate()));
 }
 
@@ skipping 4699 matching lines @@
                               return_value_operand,
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64