anchor.diff:  class SsaCodeMotion extends HBaseVisitor implements OptimizationPhase {
     final String name = "SsaCodeMotion";
   
  +  bool movedCode = false;
     List<ValueSet> values;
   
     void visitGraph(HGraph graph) {
  
positive.code:         // After GVN, some instructions might need their type to be
          // updated because they now have different inputs.
          new SsaTypePropagator(compiler),
          new SsaCodeMotion(),
          new SsaLoadElimination(compiler),
          new SsaRedundantPhiEliminator(),
          new SsaDeadPhiEliminator(),
  
negative.code:             if (toRewrite != instruction) {
                successor.rewriteWithBetterUser(toRewrite, instruction);
                successor.remove(toRewrite);
                movedCode = true;
              }
            }
          }
  