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Re: Finding out what backend instruction pattern matches instruction
- From: <andrewhutchinson at cox dot net>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Fri, 25 Jan 2008 8:04:44 -0500
- Subject: Re: Finding out what backend instruction pattern matches instruction
- Sensitivity: Normal
Ok, I guess I will try setting the length attribute as you describe and see if it is called at all before hard registers are allocated. Then, I can trace any usage to see if its important.
---- Ian Lance Taylor <iant@google.com> wrote:
> Andrew Hutchinson <andrewhutchinson@cox.net> writes:
>
> > I'm still trying to get my head around length attribute and when/where
> > it is used by gcc. The internal manual is vague to say the least.
> >
> > If I use the method suggested, will it only ever get evaluated after
> > reload? Or at least only with hard register assignments made?
>
> Please reply to the mailing list, not just to me. Thanks.
>
> I think the length will only ever be evaluated after reload. In any
> case, it only really matters after reload. Before reload, you can
> return pretty much anything; it won't matter.
>
> Ian