Re: optimization/5244: Dead code in simplify_logical()

[Kai.Tietz@onevision.de]

The following reply was made to PR optimization/5244; it has been noted by GNATS.

From: Kai.Tietz@onevision.de
To: Craig Rodrigues <rodrigc@mediaone.net>
Cc:  
Subject: Re: optimization/5244: Dead code in simplify_logical()
Date: Tue, 29 Jan 2002 11:21:39 +0100

 Hallo,
 
 the reason for this patch is the elimination of dead code., because it will
 be checked if GET_CODE(op1) is IOR or XOR and if so returned. But
 it follows code which checks also for GET_CODE(op1) is XOR, what will be
 never reached.
 
 
      if (GET_CODE (op1) == IOR || GET_CODE (op1) == XOR)
      return apply_distributive_law
        (gen_binary (GET_CODE (op1), mode,
                  gen_binary (AND, mode, XEXP (op1, 0), op0),
                  gen_binary (AND, mode, XEXP (op1, 1),
                        copy_rtx (op0))));
 
       /* Similarly, taking advantage of the fact that
       (and (not A) (xor B C)) == (xor (ior A B) (ior A C))  */
 
      if (GET_CODE (op0) == NOT && GET_CODE (op1) == XOR /* Condition is
 always false, see above */)
      return apply_distributive_law
        (gen_binary (XOR, mode,
                  gen_binary (IOR, mode, XEXP (op0, 0), XEXP (op1, 0)),
                  gen_binary (IOR, mode, copy_rtx (XEXP (op0, 0)),
                        XEXP (op1, 1))));
 
      else if (GET_CODE (op1) == NOT && GET_CODE (op0) == XOR /* Condition
 is always false, see above */)
      return apply_distributive_law
        (gen_binary (XOR, mode,
                  gen_binary (IOR, mode, XEXP (op1, 0), XEXP (op0, 0)),
                  gen_binary (IOR, mode, copy_rtx (XEXP (op1, 0)), XEXP
 (op0, 1))));
       break;
 
     case IOR:
 
 I hope this helps
 Cheers