Don't pass the "at start" parameter to native RegExp...

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

 // 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 120 matching lines @@
   // Parameters (first four passed as registers, but with room on stack).
   // In Microsoft 64-bit Calling Convention, there is room on the callers
   // 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;
-  // AtStart is passed as 32 bit int (values 0 or 1).
-  static const int kAtStart = kRegisterOutput + kPointerSize;
-  static const int kStackHighEnd = kAtStart + kPointerSize;
+  static const int kStackHighEnd = kRegisterOutput + kPointerSize;
   // DirectCall is passed as 32 bit int (values 0 or 1).
   static const int kDirectCall = kStackHighEnd + 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;
   static const int kStartIndex = kInputString - kPointerSize;
   static const int kInputStart = kStartIndex - kPointerSize;
   static const int kInputEnd = kInputStart - kPointerSize;
   static const int kRegisterOutput = kInputEnd - kPointerSize;
-  static const int kAtStart = kRegisterOutput - kPointerSize;
-  static const int kStackHighEnd = kFrameAlign;
-  static const int kDirectCall = kStackHighEnd + kPointerSize;
+  static const int kStackHighEnd = kRegisterOutput - kPointerSize;
+  static const int kDirectCall = kFrameAlign;
 #endif
 
 #ifdef _WIN64
   // Microsoft calling convention has three callee-saved registers
   // (that we are using). We push these after the frame pointer.
   static const int kBackup_rsi = kFramePointer - kPointerSize;
   static const int kBackup_rdi = kBackup_rsi - kPointerSize;
   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 = kAtStart - kPointerSize;
+  static const int kBackup_rbx = kStackHighEnd - kPointerSize;
   static const int kLastCalleeSaveRegister = kBackup_rbx;
 #endif
 
   // When adding local variables remember to push space for them in
   // the frame in GetCode.
   static const int kInputStartMinusOne =
       kLastCalleeSaveRegister - kPointerSize;
+  static const int kAtStart = kInputStartMinusOne - kPointerSize;
 
   // First register address. Following registers are below it on the stack.
-  static const int kRegisterZero = kInputStartMinusOne - kPointerSize;
+  static const int kRegisterZero = kAtStart - kPointerSize;
 
   // Initial size of code buffer.
   static const size_t kRegExpCodeSize = 1024;
 
   // Load a number of characters at the given offset from the
   // current position, into the current-character register.
   void LoadCurrentCharacterUnchecked(int cp_offset, int character_count);
 
   // Check whether preemption has been requested.
   void CheckPreemption();
@@ skipping 94 matching lines @@
   Label exit_label_;
   Label check_preempt_label_;
   Label stack_overflow_label_;
 };
 
 #endif  // V8_NATIVE_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_X64_REGEXP_MACRO_ASSEMBLER_X64_H_