Partial revert of rest parameter desugaring.

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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
 #include "src/ic/handler-compiler.h"
@@ skipping 823 matching lines @@
   __ bind(&runtime);
   __ PopReturnAddressTo(rax);
   __ Push(rdi);  // Push function.
   __ Push(rdx);  // Push parameters pointer.
   __ Push(rcx);  // Push parameter count.
   __ PushReturnAddressFrom(rax);
   __ TailCallRuntime(Runtime::kNewSloppyArguments, 3, 1);
 }
 
 
+void RestParamAccessStub::GenerateNew(MacroAssembler* masm) {
+  // rsp[0]  : return address
+  // rsp[8]  : language mode
+  // rsp[16] : index of rest parameter
+  // rsp[24] : number of parameters
+  // rsp[32] : receiver displacement
+
+  // Check if the calling frame is an arguments adaptor frame.
+  Label runtime;
+  __ movp(rdx, Operand(rbp, StandardFrameConstants::kCallerFPOffset));
+  __ movp(rcx, Operand(rdx, StandardFrameConstants::kContextOffset));
+  __ Cmp(rcx, Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR));
+  __ j(not_equal, &runtime);
+
+  // Patch the arguments.length and the parameters pointer.
+  StackArgumentsAccessor args(rsp, 4, ARGUMENTS_DONT_CONTAIN_RECEIVER);
+  __ movp(rcx, Operand(rdx, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ movp(args.GetArgumentOperand(1), rcx);
+  __ SmiToInteger64(rcx, rcx);
+  __ leap(rdx, Operand(rdx, rcx, times_pointer_size,
+                       StandardFrameConstants::kCallerSPOffset));
+  __ movp(args.GetArgumentOperand(0), rdx);
+
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kNewRestParam, 4, 1);
+}
+
+
 void LoadIndexedInterceptorStub::Generate(MacroAssembler* masm) {
   // Return address is on the stack.
   Label slow;
 
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register key = LoadDescriptor::NameRegister();
   Register scratch = rax;
   DCHECK(!scratch.is(receiver) && !scratch.is(key));
 
   // Check that the key is an array index, that is Uint32.
@@ skipping 4544 matching lines @@
                            kStackSpace, nullptr, return_value_operand, NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64