Fix argument passing to generated regexp code in Win64.

src/x64/regexp-macro-assembler-x64.h

 // Copyright 2012 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 138 matching lines @@
   // stack (before the return address) to spill parameter registers. We
   // use this space to store the register passed parameters.
   static const int kInputString = kFrameAlign;
   // StartIndex is passed as 32 bit int.
   static const int kStartIndex = kInputString + kPointerSize;
   static const int kInputStart = kStartIndex + kPointerSize;
   static const int kInputEnd = kInputStart + kPointerSize;
   static const int kRegisterOutput = kInputEnd + kPointerSize;
   // For the case of global regular expression, we have room to store at least
   // one set of capture results.  For the case of non-global regexp, we ignore
-  // this value.
+  // this value. NumOutputRegisters is passed as 32-bit value.  The upper
+  // 32 bit of this 64-bit stack slot may contain garbage.
   static const int kNumOutputRegisters = kRegisterOutput + kPointerSize;
   static const int kStackHighEnd = kNumOutputRegisters + kPointerSize;
   // DirectCall is passed as 32 bit int (values 0 or 1).
   static const int kDirectCall = kStackHighEnd + kPointerSize;
   static const int kIsolate = kDirectCall + kPointerSize;
 #else
   // In AMD64 ABI Calling Convention, the first six integer parameters
   // are passed as registers, and caller must allocate space on the stack
   // if it wants them stored. We push the parameters after the frame pointer.
   static const int kInputString = kFramePointer - kPointerSize;
@@ skipping 18 matching lines @@
   static const int kBackup_rbx = kBackup_rdi - kPointerSize;
   static const int kLastCalleeSaveRegister = kBackup_rbx;
 #else
   // AMD64 Calling Convention has only one callee-save register that
   // we use. We push this after the frame pointer (and after the
   // parameters).
   static const int kBackup_rbx = kNumOutputRegisters - kPointerSize;
   static const int kLastCalleeSaveRegister = kBackup_rbx;
 #endif
 
-  static const int kSuccessfulCaptures = kBackup_rbx - kPointerSize;
+  static const int kSuccessfulCaptures = kLastCalleeSaveRegister - kPointerSize;
   // When adding local variables remember to push space for them in
   // the frame in GetCode.
   static const int kInputStartMinusOne = kSuccessfulCaptures - kPointerSize;
 
   // First register address. Following registers are below it on the stack.
   static const int kRegisterZero = kInputStartMinusOne - kPointerSize;
 
   // Initial size of code buffer.
   static const size_t kRegExpCodeSize = 1024;
 
@@ skipping 86 matching lines @@
   Label exit_label_;
   Label check_preempt_label_;
   Label stack_overflow_label_;
 };
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_X64_REGEXP_MACRO_ASSEMBLER_X64_H_