This is the mail archive of the
mailing list for the GCC project.
Re: RFA: enable LRA for rs6000 [patch for WRF]
- From: Michael Meissner <meissner at linux dot vnet dot ibm dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>, David Edelsohn <dje dot gcc at gmail dot com>, "Bergner, Peter" <bergner at vnet dot ibm dot com>
- Date: Wed, 17 Apr 2013 12:10:42 -0400
- Subject: Re: RFA: enable LRA for rs6000 [patch for WRF]
- References: <5166F34C dot 30901 at redhat dot com> <20130415224853 dot GA17643 at ibm-tiger dot the-meissners dot org> <20130416225639 dot GA16621 at ibm-tiger dot the-meissners dot org> <516EAE5D dot 4080601 at redhat dot com>
On Wed, Apr 17, 2013 at 10:14:53AM -0400, Vladimir Makarov wrote:
> Mike, thanks for the patch and all the SPEC2006 data (which are
> very useful as I have no access to power machine which can be used
> for benchmarking). I guess that may be some benchmark scores are
> lower because of LRA lacks some micro-optimizations which reload
> implements through many power hooks (e.g. LRA does not use push
> reload). Although sometimes it is not a bad thing (e.g. LRA does
> not use SECONDARY_MEMORY_NEEDED_RTX which permits to reuse the
> stack slots for other useful things).
SECONDARY_MEMORY_NEEDED_RTX is needed for SDmode on machines before the power7,
where we need a larger stack slot to hold spilled SDmode values (power6 did not
have the LFIWZX instruction that is needed to load SDmode values into floating
> In general I got impression that power7 is the most difficult port
> for LRA. If we manage to port it, LRA ports for other targets will
> be easier.
I dunno, has LRA been ported to the SH yet?
> I also reproduced bootstrap failure --with-cpu=power7 and I am going
> to work on this and after that on SPEC2006 you wrote about.
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460, USA
email: email@example.com, phone: +1 (978) 899-4797