ARM: Implement native substring copying.

src/arm/codegen-arm.h

 // Copyright 2010 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 511 matching lines @@
     } else {
       PrintF("GenericBinaryOpStub (%s by %d)\n",
              Token::String(op_),
              constant_rhs_);
     }
   }
 #endif
 };
 
 
+class StringStubBase: public CodeStub {
+ 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 GenerateCopyCharactersLong adds too much
+  // overhead. Copying of overlapping regions is not supported.
+  void GenerateCopyCharacters(MacroAssembler* masm,
+                              Register dest,
+                              Register src,
+                              Register count,
+                              Register scratch,
+                              bool ascii);
+
+  // Generate code for copying a large number of characters. This function
+  // is allowed to spend extra time setting up conditions to make copying
+  // faster. Copying of overlapping regions is not supported.
+  void GenerateCopyCharactersLong(MacroAssembler* masm,
+                                  Register dest,
+                                  Register src,
+                                  Register count,
+                                  Register scratch1,
+                                  Register scratch2,
+                                  Register scratch3,
+                                  Register scratch4,
+                                  Register scratch5,
+                                  int flags);
+};
+
+
+// Flag that indicates how to generate code for the stub StringAddStub.
+enum StringAddFlags {
+  NO_STRING_ADD_FLAGS = 0,
+  NO_STRING_CHECK_IN_STUB = 1 << 0  // Omit string check in stub.
+};
+
+
+class SubStringStub: public StringStubBase {
+ public:
+  SubStringStub() {}
+
+ private:
+  Major MajorKey() { return SubString; }
+  int MinorKey() { return 0; }
+
+  void Generate(MacroAssembler* masm);
+};
+
+
+
 class StringCompareStub: public CodeStub {
  public:
   StringCompareStub() { }
 
   // Compare two flat ASCII strings and returns result in r0.
   // Does not use the stack.
   static void GenerateCompareFlatAsciiStrings(MacroAssembler* masm,
                                               Register left,
                                               Register right,
                                               Register scratch1,
                                               Register scratch2,
                                               Register scratch3,
                                               Register scratch4);
 
  private:
   Major MajorKey() { return StringCompare; }
   int MinorKey() { return 0; }
 
   void Generate(MacroAssembler* masm);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CODEGEN_ARM_H_