private void verifyRegisterDefs(String where){
  DefUse.computeDU(this);
  for (Register r=regpool.getFirstSymbolicRegister(); r != null; r=r.getNext()) {
    if (r.isPhysical())     continue;
    if (r.useList != null) {
      if (r.defList == null) {
        printInstructions();
        verror(where,"verifyRegisterDefs: " + r + " has use but no defs");
      }
    }
  }
}

private void verifyRegisterDefs ( String where ) { DefUse . computeDU ( this ) ; for ( Register r = regpool . getFirstSymbolicRegister ( ) ; r != null ; r = r . getNext ( ) ) { if ( r . isPhysical ( ) ) continue ; if ( r . useList != null ) { if ( r . defList == null ) { printInstructions ( ) ; verror ( where , "verifyRegisterDefs: " + r + " has use but no defs" ) ; } } } }
verify that every non - physical , non - parameter symbolic register that has a use also has at least one def
