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Re: [PATCH, rtl-optimization]: Fix post-reload compare elimination pre-pass


On Sat, Feb 11, 2012 at 1:26 AM, Richard Henderson <rth@redhat.com> wrote:
> On 02/09/2012 03:47 PM, Uros Bizjak wrote:
>> 2012-02-10 ?Uros Bizjak ?<ubizjak@gmail.com>
>>
>> ? ? ? * compare-elim.c (find_comparisons_in_bb): Eliminate only compares
>> ? ? ? having mode compatible with the mode of previous compare. ?Substitute
>> ? ? ? compare mode of previous compare with the mode, compatible
>> ? ? ? with eliminated and previous compare.
>
> This patch is ok for 4.8.
>
> For 4.6 and 4.7 I would prefer that we simply not eliminate the compare. ?I.e.

> For 4.6 and 4.7, there are only two extant users of this pass and neither
> of them use anything besides CCmode before compare-elim.c does its own
> manipulation of the modes later.

Attached patch is what I have committed to 4.6 and 4.7.

2012-02-11  Uros Bizjak  <ubizjak@gmail.com>

	* compare-elim.c (find_comparisons_in_bb): Eliminate only compares
	having the same mode as previous compare.

Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32},
together with a target-patch that enables this functionality.

Uros.

Attachment: r.diff.txt
Description: Text document


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