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Re: Right way to represent flag-setting arithmetic instructions in MD files
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Fri, 10 Mar 2017 11:23 +0100
- Subject: Re: Right way to represent flag-setting arithmetic instructions in MD files
- Authentication-results: sourceware.org; auth=none
- References: <58C27B9A.firstname.lastname@example.org>
> My understanding was that the order of the two in this pattern here doesn't
> matter because there is an implicit PARALLEL around them, but I found that
> the compare-elimination pass (compare-elim.c) assumes that the COMPARE set
> must be in the second position for it to do the transformations it wants.
Why do you want to use the compare-elimination pass exactly if the flags are
exposed before reload, as is the case on Aarch64 I think? The combiner is
supposed to do the same job instead for these targets.