From: Michael Matz <matz@suse.de>
To: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Cc: ebotcazou@adacore.com, gcc-patches@gcc.gnu.org, iant@google.com,
mark@codesourcery.com, richard.guenther@gmail.com
Subject: Re: [PATCH] Fix optimization regression in constant folder
Date: Thu, 11 Oct 2007 16:51:00 -0000 [thread overview]
Message-ID: <Pine.LNX.4.64.0710111840360.23011@wotan.suse.de> (raw)
In-Reply-To: <10710111621.AA25372@vlsi1.ultra.nyu.edu>
Hi,
On Thu, 11 Oct 2007, Richard Kenner wrote:
> > As shown we can't calculate with sizetypes in C anyway,
>
> We're not calculating them *in C*, but in the middle-end, as an
> *implementation* of C-language features, such as indexing.
Yes I understand that. But what we have to do in the middle-end from C++
constructs like Mark has shown has to be done in a type which does not
have the ignore_overflow "semantic" (because the justification for that
semantic, namely negative values have small magnitude simply doesn't
hold). In fact the most natural choice for a type to calculate that
expression would have been unsigned because that allows all rearrangements
of the operands. But when the natural type for doing arithmetics on such
operands is type X it simply doesn't make sense to store those operands as
having type Y, as conversions would be required all the time we actually
look at the operands.
Ciao,
Michael.
next prev parent reply other threads:[~2007-10-11 16:51 UTC|newest]
Thread overview: 140+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-17 14:35 Eric Botcazou
2007-09-17 14:45 ` Richard Guenther
2007-09-17 14:56 ` Eric Botcazou
2007-09-17 15:13 ` Richard Guenther
2007-09-18 11:12 ` Eric Botcazou
2007-09-18 11:22 ` Richard Guenther
2007-09-18 13:17 ` Richard Kenner
2007-09-19 11:33 ` Eric Botcazou
2007-09-19 14:40 ` Richard Guenther
2007-09-19 14:50 ` Richard Kenner
2007-09-19 15:50 ` Eric Botcazou
2007-09-29 10:27 ` Eric Botcazou
2007-09-29 14:59 ` Richard Guenther
2007-09-29 15:12 ` Eric Botcazou
2007-09-29 15:38 ` Richard Guenther
2007-09-29 17:46 ` Richard Guenther
2007-09-29 18:43 ` Eric Botcazou
2007-09-29 20:52 ` Richard Guenther
2007-09-30 14:38 ` Eric Botcazou
2007-09-30 16:01 ` Eric Botcazou
2007-09-30 16:03 ` Richard Guenther
2007-09-30 16:36 ` Eric Botcazou
2007-09-30 17:37 ` Richard Guenther
2007-09-30 18:53 ` Eric Botcazou
2007-09-30 17:59 ` Richard Kenner
2007-09-30 18:38 ` Richard Guenther
2007-09-30 21:16 ` Richard Kenner
2007-09-30 22:10 ` Eric Botcazou
[not found] ` <m3r6kf3gyx.fsf@localhost.localdomain>
[not found] ` <200710010127.59677.ebotcazou@adacore.com>
2007-10-01 0:10 ` Ian Lance Taylor
2007-10-01 0:51 ` Richard Kenner
2007-10-01 1:54 ` Michael Matz
2007-10-01 2:53 ` Richard Kenner
2007-10-01 3:25 ` Michael Matz
2007-10-01 3:40 ` Richard Kenner
2007-10-01 9:12 ` Richard Guenther
2007-10-01 12:29 ` Richard Kenner
2007-10-01 12:40 ` Richard Guenther
2007-10-01 13:07 ` Eric Botcazou
2007-10-01 13:15 ` Richard Kenner
2007-10-01 14:15 ` Richard Guenther
2007-10-01 14:23 ` Richard Kenner
2007-10-01 14:29 ` Richard Guenther
2007-10-01 14:35 ` Richard Kenner
2007-10-01 17:51 ` Ian Lance Taylor
2007-10-01 19:32 ` Richard Kenner
2007-10-01 19:51 ` Ian Lance Taylor
2007-10-01 20:28 ` Richard Kenner
2007-10-02 13:58 ` Michael Matz
2007-10-03 6:41 ` Eric Botcazou
2007-10-03 7:00 ` Ian Lance Taylor
2007-10-03 7:10 ` Eric Botcazou
2007-10-03 14:18 ` Ian Lance Taylor
2007-10-03 15:53 ` Eric Botcazou
2007-10-04 5:20 ` Michael Matz
2007-10-10 17:31 ` Mark Mitchell
2007-10-10 22:43 ` Richard Kenner
2007-10-11 0:40 ` Mark Mitchell
2007-10-11 1:02 ` Richard Kenner
2007-10-11 15:06 ` Michael Matz
2007-10-11 15:10 ` Richard Guenther
2007-10-11 15:55 ` Michael Matz
2007-10-11 15:57 ` Richard Guenther
2007-10-11 16:02 ` Richard Kenner
2007-10-11 15:59 ` Richard Kenner
2007-10-11 16:02 ` Richard Guenther
2007-10-11 16:08 ` Richard Kenner
2007-10-11 16:14 ` Richard Guenther
2007-10-11 16:37 ` Richard Kenner
2007-10-11 16:44 ` Richard Guenther
2007-10-11 16:50 ` Richard Kenner
2007-10-11 15:32 ` Richard Kenner
2007-10-11 16:03 ` Michael Matz
2007-10-11 16:06 ` Richard Guenther
2007-10-11 16:19 ` Richard Kenner
2007-10-11 16:25 ` Michael Matz
2007-10-11 16:12 ` Richard Kenner
2007-10-11 16:38 ` Michael Matz
2007-10-11 16:47 ` Richard Kenner
2007-10-11 17:04 ` Michael Matz
2007-10-11 17:17 ` Ian Lance Taylor
2007-10-11 18:41 ` Michael Matz
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
[not found] ` <10710111850.AA27 912@vlsi1.ultra.nyu.edu>
2007-10-11 18:45 ` Richard Kenner
2007-10-11 19:10 ` Michael Matz
2007-10-11 19:17 ` Richard Kenner
2007-10-11 19:30 ` Michael Matz
2007-10-11 20:06 ` Richard Kenner
2007-10-11 21:24 ` Ian Lance Taylor
2007-10-12 2:36 ` Richard Kenner
2007-10-12 4:40 ` Ian Lance Taylor
2007-10-12 4:56 ` Mark Mitchell
2007-10-12 12:30 ` Richard Kenner
2007-10-12 17:48 ` Mark Mitchell
2007-10-12 18:08 ` Richard Kenner
2007-10-12 18:37 ` Mark Mitchell
2007-10-12 18:51 ` Richard Kenner
2007-10-12 20:13 ` Richard Guenther
2007-10-14 11:09 ` Eric Botcazou
2007-10-12 11:42 ` Richard Kenner
2007-10-14 10:31 ` Eric Botcazou
2007-10-14 11:24 ` Richard Guenther
2007-10-14 11:58 ` Eric Botcazou
2007-10-14 12:16 ` Richard Kenner
2007-10-14 13:29 ` Richard Guenther
2007-10-15 2:12 ` Richard Kenner
2007-10-15 7:33 ` Michael Matz
2007-10-15 11:36 ` Richard Kenner
2007-10-15 13:27 ` Richard Guenther
2007-10-15 13:28 ` Richard Kenner
2007-10-14 16:07 ` Ian Lance Taylor
2007-10-14 16:27 ` Richard Guenther
2007-10-15 3:26 ` Richard Kenner
2007-10-15 9:12 ` Richard Guenther
2007-10-15 11:41 ` Richard Kenner
2007-10-15 13:15 ` Richard Guenther
2007-10-15 13:17 ` Richard Kenner
2007-10-15 3:29 ` Richard Kenner
2007-10-15 2:17 ` Richard Kenner
2007-10-15 5:21 ` Ian Lance Taylor
2007-10-15 11:01 ` Richard Kenner
2007-10-11 17:21 ` Richard Kenner
2007-10-11 16:16 ` Richard Kenner
2007-10-11 16:51 ` Michael Matz [this message]
2007-10-11 16:57 ` Richard Kenner
2007-10-11 17:06 ` Richard Guenther
2007-10-11 17:24 ` Richard Kenner
2007-10-11 17:31 ` Michael Matz
2007-10-11 17:54 ` Richard Kenner
2007-10-12 8:20 ` Richard Guenther
2007-10-12 11:47 ` Paolo Bonzini
2007-10-12 12:44 ` Richard Kenner
2007-10-12 12:49 ` Richard Guenther
2007-10-11 15:57 ` Mark Mitchell
2007-10-11 16:01 ` Richard Kenner
2007-10-11 16:03 ` Richard Guenther
2007-10-11 16:16 ` Richard Kenner
2007-10-11 16:11 ` Mark Mitchell
2007-10-11 16:29 ` Richard Kenner
2007-10-01 6:07 ` Eric Botcazou
2007-10-01 6:07 ` Eric Botcazou
2007-10-01 8:58 ` Richard Guenther
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