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Re: DImode speedup on i386
- To: Bernd Schmidt <crux at pool dot informatik dot rwth-aachen dot de>
- Subject: Re: DImode speedup on i386
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Sun, 22 Feb 1998 20:43:29 -0700
- cc: egcs at cygnus dot com, scox at cygnus dot com
- Reply-To: law at cygnus dot com
In message <Pine.SOL.3.90.980220113102.20928F-100000@clouseau.informatik.rwthhen.de>you write:
> > One general note -- you have to be *extremely* careful defining DImode
> > patterns on the x86 due to the bad interactions with register
> > reloading.
>
> When the patch was written, I simply used the constraints from
> the addi3/subdi3 patterns to avoid problems.
> Since it's about a year old (I've tried a couple of times to get it into
> gcc2, without success), it's quite possible that things have changed. I'll
> check that and implement Richard Henderson's suggestion, and send an updated
> patch.
OK. Yea, if you use the same constraints as the existing adddi3
and related patterns you *should* be OK.
Looking forward to the updated patch! :-)
jeff