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Re: s390: rearrange temp moves in s390_expand_cs_hqi
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: rth at redhat dot com (Richard Henderson)
- Cc: gcc-patches at gcc dot gnu dot org (GCC Patches)
- Date: Thu, 9 Aug 2012 00:44:49 +0200 (CEST)
- Subject: Re: s390: rearrange temp moves in s390_expand_cs_hqi
Richard Henderson wrote:
> In the same vein as your CAS boolean output patch, if we rearrange the
> copies here we can get the combined compare-and-branch insn for the z10.
> I see that the z196 prefers not to use those, but the number of insns
> in that case remains the same, merely in a different order.
Yes, on z196 the compare-and-branch insns are discouraged since they're
"cracked" (i.e. split into two micro-ops, just the same as if we'd
have two original insns, but in effect a bit worse for the pipeline).
In any case, the patch certainly makes sense.
> Can you please test with --with-arch=z10?
Tested with no regressions.
> * config/s390/s390.c (s390_expand_cs_hqi): Copy val to a temp before
> performing the compare for the restart loop.
OK.
Thanks,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com