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Re: A Question About LRA/reload
- From: lin zuojian <manjian2006 at gmail dot com>
- To: Kugan <kugan dot vivekanandarajah at linaro dot org>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 9 Dec 2014 18:14:29 +0800
- Subject: Re: A Question About LRA/reload
- Authentication-results: sourceware.org; auth=none
- References: <20141209093747 dot GA25618 at ubuntu> <5486CA2E dot 1060006 at linaro dot org>
Hi Kugan,
I have read these pdfs. My question is LRA will change the insns, so
why brother do the coloring so early. Changing the insns can
generates new pseudo registers, so they needs to re-assign. Is that
correct?
--
Thanks Kugan
On Tue, Dec 09, 2014 at 09:08:46PM +1100, Kugan wrote:
> On 09/12/14 20:37, lin zuojian wrote:
> > Hi,
> > I have read ira/lra code for a while, but still fails to understand
> > their relationship. The main question is why ira do color so early?
> > lra pass will do the assignment anyway. Sorry if I mess up coloring
> > and hard register assignment, but I think it's better to get job
> > done after lra elimiation, inheriation, ...
>
>
> IRA does the register allocation and LRA matches insn constraints.
> Therefore IRA has to do the coloring. LRA, in the process matching
> constraints may change some of these assignment. Please look at the
> following links for more info.
>
> https://ols.fedoraproject.org/GCC/Reprints-2007/makarov-reprint.pdf
> https://gcc.gnu.org/wiki/cauldron2012?action=AttachFile&do=get&target=Local_Register_Allocator_Project_Detail.pdf
>
>
> Thanks,
> Kugan
>