X64/Win64: Fix bug in returning ObjectPair.

src/x64/macro-assembler-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1862 matching lines @@
     int kOffset = ExitFrameConstants::kDebugMarkOffset - kCallerSavedSize;
     lea(rbx, Operand(rbp, kOffset));
     CopyRegistersFromStackToMemory(rbx, rcx, kJSCallerSaved);
   }
 #endif
 
   // Get the return address from the stack and restore the frame pointer.
   movq(rcx, Operand(rbp, 1 * kPointerSize));
   movq(rbp, Operand(rbp, 0 * kPointerSize));
 
-#ifdef _WIN64
-  // If return value is on the stack, pop it to registers.
-  if (result_size > 1) {
-    ASSERT_EQ(2, result_size);
-    // Position above 4 argument mirrors and arguments object.
-    movq(rax, Operand(rsp, 6 * kPointerSize));
-    movq(rdx, Operand(rsp, 7 * kPointerSize));
-  }
-#endif
-
   // Pop everything up to and including the arguments and the receiver
   // from the caller stack.
   lea(rsp, Operand(r15, 1 * kPointerSize));
 
   // Restore current context from top and clear it in debug mode.
   ExternalReference context_address(Top::k_context_address);
   movq(kScratchRegister, context_address);
   movq(rsi, Operand(kScratchRegister, 0));
 #ifdef DEBUG
   movq(Operand(kScratchRegister, 0), Immediate(0));
@@ skipping 345 matching lines @@
 CodePatcher::~CodePatcher() {
   // Indicate that code has changed.
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal