From: Richard Biener <rguenther@suse.de>
To: Marc Glisse <marc.glisse@inria.fr>
Cc: Richard Biener <richard.guenther@gmail.com>,
Marek Polacek <polacek@redhat.com>,
Jakub Jelinek <jakub@redhat.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Optimize (CST1 << A) == CST2 (PR tree-optimization/66299)
Date: Tue, 09 Jun 2015 11:49:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.11.1506091347300.30088@zhemvz.fhfr.qr> (raw)
In-Reply-To: <alpine.DEB.2.20.1506091305110.9052@stedding.saclay.inria.fr>
On Tue, 9 Jun 2015, Marc Glisse wrote:
> On Tue, 9 Jun 2015, Richard Biener wrote:
>
> > > Tweaking it so that (6<<X)==0 becomes X>=31 for TYPE_OVERFLOW_WRAPS and
> > > false for TYPE_OVERFLOW_UNDEFINED is probably more controversial.
> >
> > Hm, yes. I think signed overflow != shift amount overflow, so testing the
> > overflow macros for this isn't valid.
>
> Would it be ok to always turn it to X>=31 then? (the value 31 is conveniently
> already computed in 'cand')
I think so.
Richard.
next prev parent reply other threads:[~2015-06-09 11:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-28 12:33 Marek Polacek
2015-05-28 13:10 ` Jakub Jelinek
2015-05-28 20:33 ` Marc Glisse
2015-06-08 15:12 ` Marek Polacek
2015-06-08 17:14 ` Marc Glisse
2015-06-09 7:56 ` Richard Biener
2015-06-09 11:46 ` Marc Glisse
2015-06-09 11:49 ` Richard Biener [this message]
2015-06-09 11:57 ` Richard Biener
2015-06-09 12:13 ` Marc Glisse
2015-06-09 12:22 ` Richard Biener
2015-06-09 13:46 ` Marek Polacek
2015-06-09 14:11 ` Richard Biener
2015-05-28 13:16 ` Richard Biener
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