Simplify string copy in SubStringStub.

src/x64/code-stubs-x64.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_X64_CODE_STUBS_X64_H_
 #define V8_X64_CODE_STUBS_X64_H_
 
 #include "src/ic-inl.h"
 
 namespace v8 {
@@ skipping 22 matching lines @@
 
 class StringHelper : public AllStatic {
  public:
   // Generate code for copying characters using the rep movs instruction.
   // Copies rcx characters from rsi to rdi. Copying of overlapping regions is
   // not supported.
   static void GenerateCopyCharactersREP(MacroAssembler* masm,
                                         Register dest,     // Must be rdi.
                                         Register src,      // Must be rsi.
                                         Register count,    // Must be rcx.
-                                        bool ascii);
+                                        String::Encoding encoding);
 
 
   // Generate string hash.
   static void GenerateHashInit(MacroAssembler* masm,
                                Register hash,
                                Register character,
                                Register scratch);
   static void GenerateHashAddCharacter(MacroAssembler* masm,
                                        Register hash,
                                        Register character,
@@ skipping 359 matching lines @@
   RememberedSetAction remembered_set_action_;
   SaveFPRegsMode save_fp_regs_mode_;
   Label slow_;
   RegisterAllocation regs_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_CODE_STUBS_X64_H_