Get rid of the unused native code StringAddStub.

src/x64/code-stubs-x64.h

 // Copyright 2011 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 38 matching lines @@
  private:
   SaveFPRegsMode save_doubles_;
 
   Major MajorKey() { return StoreBufferOverflow; }
   int MinorKey() { return (save_doubles_ == kSaveFPRegs) ? 1 : 0; }
 };
 
 
 class StringHelper : public AllStatic {
  public:
-  // Generate code for copying characters using a simple loop. This should only
-  // be used in places where the number of characters is small and the
-  // additional setup and checking in GenerateCopyCharactersREP adds too much
-  // overhead. Copying of overlapping regions is not supported.
-  static void GenerateCopyCharacters(MacroAssembler* masm,
-                                     Register dest,
-                                     Register src,
-                                     Register count,
-                                     bool ascii);
-
   // 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);
 
 
-  // Probe the string table for a two character string. If the string is
-  // not found by probing a jump to the label not_found is performed. This jump
-  // does not guarantee that the string is not in the string table. If the
-  // string is found the code falls through with the string in register rax.
-  static void GenerateTwoCharacterStringTableProbe(MacroAssembler* masm,
-                                                   Register c1,
-                                                   Register c2,
-                                                   Register scratch1,
-                                                   Register scratch2,
-                                                   Register scratch3,
-                                                   Register scratch4,
-                                                   Label* not_found);
-
   // Generate string hash.
   static void GenerateHashInit(MacroAssembler* masm,
                                Register hash,
                                Register character,
                                Register scratch);
   static void GenerateHashAddCharacter(MacroAssembler* masm,
                                        Register hash,
                                        Register character,
                                        Register scratch);
   static void GenerateHashGetHash(MacroAssembler* masm,
                                   Register hash,
                                   Register scratch);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
 };
 
 
-class StringAddStub: public PlatformCodeStub {
- public:
-  explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}
-
- private:
-  Major MajorKey() { return StringAdd; }
-  int MinorKey() { return flags_; }
-
-  void Generate(MacroAssembler* masm);
-
-  void GenerateConvertArgument(MacroAssembler* masm,
-                               int stack_offset,
-                               Register arg,
-                               Register scratch1,
-                               Register scratch2,
-                               Register scratch3,
-                               Label* slow);
-
-  void GenerateRegisterArgsPush(MacroAssembler* masm);
-  void GenerateRegisterArgsPop(MacroAssembler* masm, Register temp);
-
-  const StringAddFlags flags_;
-};
-
-
 class SubStringStub: public PlatformCodeStub {
  public:
   SubStringStub() {}
 
  private:
   Major MajorKey() { return SubString; }
   int MinorKey() { return 0; }
 
   void Generate(MacroAssembler* masm);
 };
@@ skipping 332 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_