Fix IsDeletable() for HStringAdd, HStringCharCodeAt, HStringCharFromCode.

src/hydrogen.cc

 // Copyright 2013 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 9060 matching lines @@
 
 // Fast support for Math.random().
 void HOptimizedGraphBuilder::GenerateRandomHeapNumber(CallRuntime* call) {
   HValue* context = environment()->LookupContext();
   HGlobalObject* global_object = Add<HGlobalObject>(context);
   HRandom* result = new(zone()) HRandom(global_object);
   return ast_context()->ReturnInstruction(result, call->id());
 }
 
 
-// Fast support for StringAdd.

[Michael Starzinger, 2013/07/25 14:43:18]

nit: Can we get the comment back?

[titzer, 2013/07/25 15:32:55]

Well, I wanted that one for my code offsets, but I suppose :(

('twas a vestige of trying to delete that method, actually!)

 void HOptimizedGraphBuilder::GenerateStringAdd(CallRuntime* call) {
   ASSERT_EQ(2, call->arguments()->length());
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
   CHECK_ALIVE(VisitForValue(call->arguments()->at(1)));
   HValue* right = Pop();
   HValue* left = Pop();
   HValue* context = environment()->LookupContext();
   HInstruction* result = HStringAdd::New(
       zone(), context, left, right, STRING_ADD_CHECK_BOTH);
   return ast_context()->ReturnInstruction(result, call->id());
@@ skipping 824 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal