Simplify StringCharCodeAt in non-crankshaft codegen.

src/code-stubs.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 753 matching lines @@
 // string. Additional index constraints are specified by the
 // flags. Otherwise, bails out to the provided labels.
 //
 // Register usage: |object| may be changed to another string in a way
 // that doesn't affect charCodeAt/charAt semantics, |index| is
 // preserved, |scratch| and |result| are clobbered.
 class StringCharCodeAtGenerator {
  public:
   StringCharCodeAtGenerator(Register object,
                             Register index,
-                            Register scratch,
                             Register result,
                             Label* receiver_not_string,
                             Label* index_not_number,
                             Label* index_out_of_range,
                             StringIndexFlags index_flags)
       : object_(object),
         index_(index),
-        scratch_(scratch),
         result_(result),
         receiver_not_string_(receiver_not_string),
         index_not_number_(index_not_number),
         index_out_of_range_(index_out_of_range),
         index_flags_(index_flags) {
     ASSERT(!scratch_.is(object_));
     ASSERT(!scratch_.is(index_));
     ASSERT(!scratch_.is(result_));
     ASSERT(!result_.is(object_));
     ASSERT(!result_.is(index_));
   }
 
   // Generates the fast case code. On the fallthrough path |result|
   // register contains the result.
   void GenerateFast(MacroAssembler* masm);
 
   // Generates the slow case code. Must not be naturally
   // reachable. Expected to be put after a ret instruction (e.g., in
   // deferred code). Always jumps back to the fast case.
   void GenerateSlow(MacroAssembler* masm,
                     const RuntimeCallHelper& call_helper);
 
  private:
   Register object_;
   Register index_;
-  Register scratch_;
   Register result_;
 
   Label* receiver_not_string_;
   Label* index_not_number_;
   Label* index_out_of_range_;
 
   StringIndexFlags index_flags_;
 
   Label call_runtime_;
   Label index_not_smi_;
@@ skipping 42 matching lines @@
 // string. Additional index constraints are specified by the
 // flags. Otherwise, bails out to the provided labels.
 //
 // Register usage: |object| may be changed to another string in a way
 // that doesn't affect charCodeAt/charAt semantics, |index| is
 // preserved, |scratch1|, |scratch2|, and |result| are clobbered.
 class StringCharAtGenerator {
  public:
   StringCharAtGenerator(Register object,
                         Register index,
-                        Register scratch1,
-                        Register scratch2,
+                        Register scratch,
                         Register result,
                         Label* receiver_not_string,
                         Label* index_not_number,
                         Label* index_out_of_range,
                         StringIndexFlags index_flags)
       : char_code_at_generator_(object,
                                 index,
-                                scratch1,
-                                scratch2,
+                                scratch,
                                 receiver_not_string,
                                 index_not_number,
                                 index_out_of_range,
                                 index_flags),
-        char_from_code_generator_(scratch2, result) {}
+        char_from_code_generator_(scratch, result) {}
 
   // Generates the fast case code. On the fallthrough path |result|
   // register contains the result.
   void GenerateFast(MacroAssembler* masm);
 
   // Generates the slow case code. Must not be naturally
   // reachable. Expected to be put after a ret instruction (e.g., in
   // deferred code). Always jumps back to the fast case.
   void GenerateSlow(MacroAssembler* masm,
                     const RuntimeCallHelper& call_helper);
@@ skipping 176 matching lines @@
   int MinorKey() { return 0; }
 
   void Generate(MacroAssembler* masm);
 
   DISALLOW_COPY_AND_ASSIGN(StoreArrayLiteralElementStub);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODE_STUBS_H_