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Re: [PATCH][combine][RFC] Don't transform sign and zero extends inside mults
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Uros Bizjak <ubizjak at gmail dot com>
- Cc: Kyrill Tkachov <kyrylo dot tkachov at arm dot com>, Jeff Law <law at redhat dot com>, gcc Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 13 Nov 2015 09:01:39 -0600
- Subject: Re: [PATCH][combine][RFC] Don't transform sign and zero extends inside mults
- Authentication-results: sourceware.org; auth=none
- References: <20151106005636 dot GA31412 at gate dot crashing dot org> <563CB6DE dot 7070106 at arm dot com> <563D1824 dot 8000607 at redhat dot com> <20151106220008 dot GA19110 at gate dot crashing dot org> <20151108205806 dot GA641 at gate dot crashing dot org> <CAFULd4bcHBD5fTg-hvTkoUMh8O5FWJgW1Me9vG9L3iiefaPvMQ at mail dot gmail dot com> <20151109095132 dot GA13304 at gate dot crashing dot org> <20151110195303 dot GB936 at gate dot crashing dot org> <5645B723 dot 9010109 at arm dot com> <CAFULd4b+g3nefuXMLVDrJDmQ0-NvG6w-z0tJYUFoq0G-phSa7Q at mail dot gmail dot com>
On Fri, Nov 13, 2015 at 11:17:38AM +0100, Uros Bizjak wrote:
> IMO, this is such a small code-size regression, that it should not
> block the patch submission.
In that case: Kyrill, the patch is okay for trunk. Thanks!
> It would be nice to know, what causes the
> increase (in case, this is some systematic oversight), but we can live
> with it.
After the patch it will no longer combine an imul reg,reg (+ mov) into an
imul mem,reg. _Most_ cases that end up as mem,reg are already expanded
as such, but not all. It's hard to make a smallish testcase.
Segher