From: Richard Guenther <rguenther@suse.de>
To: Paolo Bonzini <bonzini@gnu.org>
Cc: Eric Botcazou <ebotcazou@adacore.com>,
gcc-patches@gcc.gnu.org, Arnaud Charlet <charlet@adacore.com>
Subject: Re: [PATCH] Keep lattice abstract in the SSA propagator, substitue lattice values at defs
Date: Sun, 08 Aug 2010 12:28:00 -0000 [thread overview]
Message-ID: <alpine.LNX.2.00.1008081410221.25856@zhemvz.fhfr.qr> (raw)
In-Reply-To: <4C5E9E67.7090004@gnu.org>
On Sun, 8 Aug 2010, Paolo Bonzini wrote:
> On 08/08/2010 04:44 AM, Richard Guenther wrote:
> > arithmetic. But - we can do so if reassociating constants only
> > as in the example above. Because if (L43b_216 - 1) - 2147483648
> > doesn't overflow then L43b_216 + 2147483647 doesn't either.
>
> Huh?
>
> a - 1 - 2147483648 is valid if a >= 1.
>
> a + 2147483647 is valid if a < 1.
Oh, indeed. Hm. I guess we have to be more careful with
constant-folding in reassoc ... (and it's one more reason for
me to pick up no-undefined-overflow again ...).
I guess as I have exposed the issue I have to look into it.
Richard.
next prev parent reply other threads:[~2010-08-08 12:12 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-04 12:22 Richard Guenther
2010-08-04 12:26 ` Arnaud Charlet
2010-08-04 12:29 ` Richard Guenther
2010-08-04 12:31 ` Arnaud Charlet
2010-08-04 12:49 ` Richard Guenther
2010-08-04 12:57 ` Eric Botcazou
2010-08-04 12:58 ` Richard Guenther
2010-08-04 13:27 ` Eric Botcazou
2010-08-08 8:01 ` Eric Botcazou
2010-08-08 8:44 ` Richard Guenther
2010-08-08 12:09 ` Paolo Bonzini
2010-08-08 12:12 ` Paolo Bonzini
2010-08-08 12:28 ` Richard Guenther [this message]
2010-08-08 12:37 ` Richard Guenther
2010-08-08 13:36 ` Richard Guenther
2010-08-08 22:46 ` Eric Botcazou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LNX.2.00.1008081410221.25856@zhemvz.fhfr.qr \
--to=rguenther@suse.de \
--cc=bonzini@gnu.org \
--cc=charlet@adacore.com \
--cc=ebotcazou@adacore.com \
--cc=gcc-patches@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).