Win64 - Allow returning two values from a runtime function.

src/x64/regexp-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 594 matching lines @@
   __ bind(&entry_label_);
   // Start new stack frame.
   __ push(rbp);
   __ movq(rbp, rsp);
   // Save parameters and callee-save registers. Order here should correspond
   //  to order of kBackup_ebx etc.
 #ifdef _WIN64
   // MSVC passes arguments in rcx, rdx, r8, r9, with backing stack slots.
   // Store register parameters in pre-allocated stack slots,
   __ movq(Operand(rbp, kInputString), rcx);
-  __ movzxlq(Operand(rbp, kStartIndex), rdx);  // Passed as int in eax.
+  __ movq(Operand(rbp, kStartIndex), rdx);  // Passed as int32 in edx.
   __ movq(Operand(rbp, kInputStart), r8);
   __ movq(Operand(rbp, kInputEnd), r9);
   // Callee-save on Win64.
   __ push(rsi);
   __ push(rdi);
   __ push(rbx);
 #else
   // GCC passes arguments in rdi, rsi, rdx, rcx, r8, r9 (and then on stack).
   // Push register parameters on stack for reference.
   ASSERT_EQ(kInputString, -1 * kPointerSize);
@@ skipping 664 matching lines @@
 
 void RegExpCEntryStub::Generate(MacroAssembler* masm_) {
   __ int3();  // Unused on x64.
 }
 
 #undef __
 
 #endif  // V8_NATIVE_REGEXP
 
 }}  // namespace v8::internal