for (Enumeration e = phys.enumerateNonvolatileGPRs();
for (Enumeration e = phys.enumerateNonvolatileGPRsBackwards();
  private OPT_Register getFirstDeadGPRNotUsedIn(OPT_Register r,                                                OPT_Instruction s,                                                 ArrayList reserved) {    OPT_PhysicalRegisterSet phys = ir.regpool.getPhysicalRegisterSet();    // first try the volatiles    for (Enumeration e = phys.enumerateVolatileGPRs();         e.hasMoreElements(); ) {      OPT_Register p = (OPT_Register)e.nextElement();      if (!appearsIn(p,s) && !p.isPinned() && !reserved.contains(p)) {        if (isDeadBefore(p,s) && isLegal(r,p,s)) return p;      }    }    // next try the non-volatiles    for (Enumeration e = phys.enumerateNonvolatileGPRs();          e.hasMoreElements(); ) {      OPT_Register p = (OPT_Register)e.nextElement();      if (!appearsIn(p,s) && !p.isPinned() && !reserved.contains(p)) {        if (isDeadBefore(p,s) && isLegal(r,p,s)) return p;      }    }    return null;  }