This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: RFA: enable LRA for rs6000 [patch for WRF]

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
point registers).

> 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:, phone: +1 (978) 899-4797

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]