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Re: s390: Avoid CAS boolean output inefficiency
- From: Richard Henderson <rth at redhat dot com>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 07 Aug 2012 15:13:29 -0700
- Subject: Re: s390: Avoid CAS boolean output inefficiency
- References: <201208071702.q77H2DFl025511@d06av02.portsmouth.uk.ibm.com>
On 08/07/2012 10:02 AM, Ulrich Weigand wrote:
> The following patch changes the builtin expander to pass a MEM oldval
> as-is to the back-end expander, so that the back-end can move the
> store to before the CC operation. With that patch I'm also seeing
> all the IPMs disappear.
> What do you think about this solution? It has the advantage that
> we still get the same xor code if we actually do need the ipm ...
I'm ok with that patch.