From: Jeff Law <law@redhat.com>
To: Bernd Schmidt <bschmidt@redhat.com>,
Kyrill Tkachov <kyrylo.tkachov@foss.arm.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [PATCH][combine][RFC][2/2] PR rtl-optimization/68796: Perfer zero_extract comparison against zero rather than unsupported shorter modes
Date: Thu, 17 Dec 2015 16:52:00 -0000 [thread overview]
Message-ID: <5672E84A.7080309@redhat.com> (raw)
In-Reply-To: <5672DB97.7090800@redhat.com>
On 12/17/2015 08:58 AM, Bernd Schmidt wrote:
>
> I suspect that this is an oversight in the documentation, and if given
> two choices the simpler form is intended to be the canonical one.
The other BZ I was looking at in this space was 15596. It's PPC, but
shows a generic weakness in how we identify extractions and insertions.
Fixing it would probably help all the ports that have relatively
strong methods to set/clear a series of bits in the middle of a word.
It feels like combine has all the information necessary to improve
things, but the overall combiner flow and APIs are extremely uncooperative.
jeff
prev parent reply other threads:[~2015-12-17 16:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 15:36 Kyrill Tkachov
2015-12-17 15:58 ` Bernd Schmidt
2015-12-17 16:10 ` Kyrill Tkachov
2015-12-17 16:12 ` Bernd Schmidt
2015-12-17 16:26 ` Kyrill Tkachov
2015-12-17 16:59 ` Jeff Law
2015-12-17 17:05 ` Kyrill Tkachov
2015-12-17 17:33 ` Jeff Law
2015-12-17 17:27 ` Segher Boessenkool
2015-12-17 17:44 ` Kyrill Tkachov
2015-12-17 18:05 ` Bernd Schmidt
2015-12-17 16:46 ` Jeff Law
2015-12-17 16:52 ` Jeff Law [this message]
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