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Re: IRA issue with shuffle copies...
- From: Peter Bergner <bergner at vnet dot ibm dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Tue, 10 Jan 2012 11:55:51 -0600
- Subject: Re: IRA issue with shuffle copies...
- References: <1325913862.17882.19.camel@otta> <4F0C735F.4060506@redhat.com>
On Tue, 2012-01-10 at 12:20 -0500, Vladimir Makarov wrote:
> > Do we really need or want to create shuffle copies for insns that do not
> > have a two operand constraint?
> Yes, I think so. As I remember I did some benchmarking and it gave some
> "order" in hard register assignments and improved code slightly (at
> least for SPEC2000) even for 3-ops insn architectures.
I'm a little skeptical about 3-op insn architectures, but will take
your word for it since you tested it. I may have someone on the team
disable completely for ppc just as a test just so we can analyze why
it helps. Sometimes just knowing why is a good thing. :)
> Your patch might work. But we need to test it for major 2-ops
> architecture x86/x86-64 and 3-ops ppc (I believe SPEC2000 would be ok
> for this).
Ok, I'll have someone on my team kick off this patch on ppc, but it would
be nice if someone else could do the runs on x86/x86_64 or other cpus that
might be affected that we don't have access to.
Peter