if (VM.VerifyAssertions) VM.assert(s.operator != PHI);
if (VM.VerifyAssertions) VM._assert(s.operator != PHI);
  public OPT_HeapOperand[] getHeapDefs (OPT_Instruction s) {    if (VM.VerifyAssertions) VM.assert(s.operator != PHI);    return  (OPT_HeapOperand[])defs.get(s);  }