Allow constants to be deleted by reinserting them into the graph as needed.

src/hydrogen-instructions.cc

 // Copyright 2012 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 2545 matching lines @@
   }
   set_representation(r);
   SetFlag(kUseGVN);
 }
 
 
 bool HConstant::EmitAtUses() {
   ASSERT(IsLinked());
   if (block()->graph()->has_osr() &&
       block()->graph()->IsStandardConstant(this)) {
+    // TODO(titzer): this seems like a hack that should be fixed by custom OSR.
     return true;
   }
   if (UseCount() == 0) return true;
   if (IsCell()) return false;
   if (representation().IsDouble()) return false;
   return true;
 }
 
 
 HConstant* HConstant::CopyToRepresentation(Representation r, Zone* zone) const {
@@ skipping 1701 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal