Re: c/4214: powerpc64: wrong code from optimized mask and shift

[Alan Modra <amodra@bigpond.net.au>]

The following reply was made to PR c/4214; it has been noted by GNATS.

From: Alan Modra <amodra@bigpond.net.au>
To: Kevin Ryde <user42@zip.com.au>, mark@codesourcery.com
Cc: gcc-gnats@gcc.gnu.org, David Edelsohn <dje@watson.ibm.com>
Subject: Re: c/4214: powerpc64: wrong code from optimized mask and shift
Date: Tue, 4 Sep 2001 11:51:06 +0930

 On Tue, Sep 04, 2001 at 09:39:45AM +1000, Kevin Ryde wrote:
 > 
 > A certain mask and shift combination produces a wrong answer when
 > compiled with optimization.
 > 
 > >How-To-Repeat:
 > A program foo.c,
 > 
 >         int n = 3;
 > 
 >         int
 >         main (void)
 >         {
 >           printf ("%d\n", (n & 2) << 1);
 >           return 0;
 >         }
 
 Fixed by http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01493.html ,
 which I applied to mainline.
 
 Is the patch OK for the branch Mark?  You could argue that it contains
 optimisations (extra patterns for rldicr, no bit-shifting loops) as well
 as the bugfix for rldic, but I'm far more likely to make an error if I
 try to split the patch rather than apply the lot.  ;-)
 
 Alan