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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>, aavrunin at redhat dot com
- Date: Mon, 22 Apr 2013 15:31:49 -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> <20130417161042 dot GA22186 at ibm-tiger dot the-meissners dot org> <51705B25 dot 6020402 at redhat dot com> <5171B43B dot 5070400 at redhat dot com> <20130422043535 dot GC22536 at bubble dot grove dot modra dot org> <51758EF5 dot 8050209 at redhat dot com>
On Mon, Apr 22, 2013 at 03:26:45PM -0400, Vladimir Makarov wrote:
> On 13-04-22 12:35 AM, Alan Modra wrote:
> >On Fri, Apr 19, 2013 at 05:16:43PM -0400, Vladimir Makarov wrote:
> >> I don't understand what this check means and what comments ??? means too.
> >A lo_sum mem is only valid if you know it won't be offset (or that
> >offsetting will never cross a 64k+32k boundary). If the access is
> >smaller than a word then the load or store can be done in one insn.
> >No offset required. If the access is a DFmode *and* you are loading
> >or storing a floating point reg, then the access is also done in one
> >insn. The ??? comment is referring to the fact that you don't know
> >for sure that the DFmode is in a floating point reg. It usually is,
> >but may be in two general purpose regs. Which then need an offset to
> >load/store the second reg.
> Alan, thanks for the explanation. I'll search for another solution.
I'm suspecting secondary_reload needs more tuning for TF/TD modes.
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460, USA
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