ARM: Add support for just one string argument in the string add stub...

src/arm/code-stubs-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 317 matching lines @@
     code->set_type_recording_binary_op_result_type(result_type_);
   }
 
   friend class CodeGenerator;
 };
 
 
 // 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.
+  // Omit left string check in stub (left is definitely a string).
+  NO_STRING_CHECK_LEFT_IN_STUB = 1 << 0,
+  // Omit right string check in stub (right is definitely a string).
+  NO_STRING_CHECK_RIGHT_IN_STUB = 1 << 1,
+  // Omit both string checks in stub.
+  NO_STRING_CHECK_IN_STUB =
+      NO_STRING_CHECK_LEFT_IN_STUB | NO_STRING_CHECK_RIGHT_IN_STUB
 };
 
 
 class StringAddStub: public CodeStub {
  public:
-  explicit StringAddStub(StringAddFlags flags) {
-    string_check_ = ((flags & NO_STRING_CHECK_IN_STUB) == 0);
-  }
+  explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}
 
  private:
   Major MajorKey() { return StringAdd; }
-  int MinorKey() { return string_check_ ? 0 : 1; }
+  int MinorKey() { return flags_; }
 
   void Generate(MacroAssembler* masm);
 
-  // Should the stub check whether arguments are strings?
-  bool string_check_;
+  void GenerateConvertArgument(MacroAssembler* masm,
+                               int stack_offset,
+                               Register arg,
+                               Register scratch1,
+                               Register scratch2,
+                               Register scratch3,
+                               Register scratch4,
+                               Label* slow);
+
+  const StringAddFlags flags_;
 };
 
 
 class SubStringStub: public CodeStub {
  public:
   SubStringStub() {}
 
  private:
   Major MajorKey() { return SubString; }
   int MinorKey() { return 0; }
@@ skipping 270 matching lines @@
                                  bool load_elements_from_receiver,
                                  bool load_elements_map_from_elements,
                                  Label* key_not_smi,
                                  Label* value_not_smi,
                                  Label* not_pixel_array,
                                  Label* out_of_range);
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CODE_STUBS_ARM_H_