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Re: [PATCH][RFA][PR tree-optimization/79095] Improve overflow test optimization and avoid invalid warnings
- From: Marc Glisse <marc dot glisse at inria dot fr>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: Jeff Law <law at redhat dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 27 Jan 2017 09:52:12 +0100 (CET)
- Subject: Re: [PATCH][RFA][PR tree-optimization/79095] Improve overflow test optimization and avoid invalid warnings
- Authentication-results: sourceware.org; auth=none
- References: <ec96ffeb-bc2e-eb61-ac46-12c94d3de155@redhat.com> <CAFiYyc2C016TFjeu+MWQ+iDnZKsP_FaOad-pcHDDc_hm7AnDQA@mail.gmail.com>
- Reply-to: gcc-patches at gcc dot gnu dot org
On Thu, 26 Jan 2017, Richard Biener wrote:
I also notice we dont' handle 1 - A CMP A anywhere.
Hmm, what are we supposed to transform that into? For ==, that would be
false (parity), but for < it is false for 0, true for 1, false for 2, then
true again after MAX/2... Nothing obvious.
--
Marc Glisse