Introduce DropUnderReturnAddress for x64 port.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/242113005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@21082 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/builtins-x64.cc

@@ -724,7 +724,7 @@ static void Generate_NotifyStubFailureHelper(MacroAssembler* masm,
     // Tear down internal frame.
   }
 
-  __ Pop(MemOperand(rsp, 0));  // Ignore state offset
+  __ DropUnderReturnAddress(1);  // Ignore state offset
   __ ret(0);  // Return to IC Miss stub, continuation still on stack.
 }
 
@@ -901,12 +901,13 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
   __ bind(&shift_arguments);
   { Label loop;
     __ movp(rcx, rax);
+    StackArgumentsAccessor args(rsp, rcx);
     __ bind(&loop);
-    __ movp(rbx, Operand(rsp, rcx, times_pointer_size, 0));
-    __ movp(Operand(rsp, rcx, times_pointer_size, 1 * kPointerSize), rbx);
+    __ movp(rbx, args.GetArgumentOperand(1));
+    __ movp(args.GetArgumentOperand(0), rbx);
     __ decp(rcx);
-    __ j(not_sign, &loop);  // While non-negative (to copy return address).
-    __ popq(rbx);  // Discard copy of return address.
+    __ j(not_zero, &loop);  // While non-zero.
+    __ DropUnderReturnAddress(1, rbx);  // Drop one slot under return address.
     __ decp(rax);  // One fewer argument (first argument is new receiver).
   }
 

src/x64/macro-assembler-x64.cc

@@ -2685,6 +2685,20 @@ void MacroAssembler::Drop(int stack_elements) {
 }
 
 
+void MacroAssembler::DropUnderReturnAddress(int stack_elements,
+                                            Register scratch) {
+  ASSERT(stack_elements > 0);
+  if (kPointerSize == kInt64Size && stack_elements == 1) {
+    popq(MemOperand(rsp, 0));
+    return;
+  }
+
+  PopReturnAddressTo(scratch);
+  Drop(stack_elements);
+  PushReturnAddressFrom(scratch);
+}
+
+
 void MacroAssembler::Push(Register src) {
   if (kPointerSize == kInt64Size) {
     pushq(src);

src/x64/macro-assembler-x64.h

@@ -815,6 +815,11 @@ class MacroAssembler: public Assembler {
   // Emit code to discard a non-negative number of pointer-sized elements
   // from the stack, clobbering only the rsp register.
   void Drop(int stack_elements);
+  // Emit code to discard a positive number of pointer-sized elements
+  // from the stack under the return address which remains on the top,
+  // clobbering the rsp register.
+  void DropUnderReturnAddress(int stack_elements,
+                              Register scratch = kScratchRegister);
 
   void Call(Label* target) { call(target); }
   void Push(Register src);