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Re: patch to enable LRA for ppc
- From: Vladimir Makarov <vmakarov at redhat dot com>
- To: David Edelsohn <dje dot gcc at gmail dot com>
- Cc: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>, "Bergner, Peter" <bergner at vnet dot ibm dot com>
- Date: Sun, 20 Oct 2013 22:48:08 -0400
- Subject: Re: patch to enable LRA for ppc
- Authentication-results: sourceware.org; auth=none
- References: <524DDB71 dot 6040703 at redhat dot com> <CAGWvny=AmXxjALad=L0=Lgzp+4k9-SKXsOZNAcWcumcsOiViJw at mail dot gmail dot com>
On 13-10-18 11:26 AM, David Edelsohn wrote:
On Thu, Oct 3, 2013 at 5:02 PM, Vladimir Makarov <firstname.lastname@example.org> wrote:
The following patch permits today trunk to use LRA for ppc by default.
To switch it off -mno-lra can be used.
The patch was bootstrapped on ppc64. GCC testsuite does not have
regressions too (in comparison with reload). The change in rs6000.md is
for fix LRA failure on a recently added ppc test.
I have not forgotten this patch. We are trying to figure out the right
timeframe to make this change. The patch does affect performance --
both positively and negatively; most are in the noise but not all. And
there still are some SPEC benchmarks that fail to build with the
patch, at least in Mike's tests. And Mike is implementing some patches
to utilize reload to improve use of VSX registers, which would need to
be mirrored in LRA for the equivalent functionality.
Thanks for informing me, David.
I am ready to work on any LRA ppc issues when it will be in the trunk.
It would be easier for me to work on LRA ppc if the patch is committed
to the trunk and of course LRA is used as non-default local RA.
I don't know what Mike is doing on reload to use VSX registers. I guess
it is usage of VSX regs as spilled locations for GENERAL regs instead
of memory. If it is so, it is 2 day work to add this functionality in
LRA (as it already has analogous functionality for Intel processors and
that gave a nice SPECFP2000 improvement for them) and probably more work
on resolving issues especially as I have no power8.