Prevent representation inference from double-visiting.

src/hydrogen-infer-representation.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 134 matching lines @@
 
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* current = it.Current();
       AddToWorklist(current);
     }
   }
 
   // Do a fixed point iteration, trying to improve representations
   while (!worklist_.is_empty()) {
     HValue* current = worklist_.RemoveLast();
+    current->InferRepresentation(this);
     in_worklist_.Remove(current->id());
-    current->InferRepresentation(this);
   }
 
   // Lastly: any instruction that we don't have representation information
   // for defaults to Tagged.
   for (int i = 0; i < graph()->blocks()->length(); ++i) {
     HBasicBlock* block = graph()->blocks()->at(i);
     const ZoneList<HPhi*>* phis = block->phis();
     for (int j = 0; j < phis->length(); ++j) {
       HPhi* phi = phis->at(j);
       if (phi->representation().IsNone()) {
         phi->ChangeRepresentation(Representation::Tagged());
       }
     }
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* current = it.Current();
       if (current->representation().IsNone() &&
           current->CheckFlag(HInstruction::kFlexibleRepresentation)) {
         if (current->CheckFlag(HInstruction::kCannotBeTagged)) {
           current->ChangeRepresentation(Representation::Double());
         } else {
           current->ChangeRepresentation(Representation::Tagged());
         }
       }
     }
   }
 }
 
 } }  // namespace v8::internal