From: Richard Biener <rguenther@suse.de>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Eric Botcazou <botcazou@adacore.com>,
gcc-patches@gcc.gnu.org, Zhao Wei Liew <zhaoweiliew@gmail.com>
Subject: Re: [PATCH] match.pd: Fix up 1 / X for unsigned X optimization [PR104280]
Date: Thu, 3 Feb 2022 13:13:29 +0100 (CET) [thread overview]
Message-ID: <12oonr96-382n-6s3-58so-o165n768228@fhfr.qr> (raw)
In-Reply-To: <20220203111810.GL2646553@tucnak>
On Thu, 3 Feb 2022, Jakub Jelinek wrote:
> On Thu, Feb 03, 2022 at 12:03:15PM +0100, Richard Biener wrote:
> > But as said, for the libgcc2.c case I'd simply remove all of it.
>
> I can't read RMS' mind, it is indeed UB, so we can do anything, but I bet
> it was just a QoI attempt, when (most of the time) normal single-word
> or smaller division for / 0 behaves certain way (SIGFPE with FPE_INTDIV,
> or being ignored, or whatever else) that it would be nice if the multi-word
> division behaved likewise.
> On the platforms where it is SIGFPE with FPE_INTDIV, raising that would
> help people figure out what's going on.
Yes, I think the intent is clear. The question is whether we should
re-instantiate the clear intent of preserving a literal / 0 as well
(for C, without -fnon-call-exceptions).
That said, I'm fine with the asms but they are ugly ;)
Richard.
next prev parent reply other threads:[~2022-02-03 12:13 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-19 18:42 [PATCH v3] match.pd: Simplify 1 / X for integer X [PR95424] Zhao Wei Liew
2022-01-28 18:38 ` Jeff Law
2022-01-29 16:23 ` [PATCH] match.pd: Fix up 1 / X for unsigned X optimization [PR104280] Jakub Jelinek
2022-01-29 16:48 ` Jeff Law
2022-01-30 2:28 ` Zhao Wei Liew
2022-01-30 2:38 ` Andrew Pinski
2022-01-31 8:33 ` Richard Biener
2022-01-31 8:16 ` Eric Botcazou
2022-02-02 22:58 ` Andrew Pinski
2022-02-02 23:01 ` Eric Botcazou
2022-02-03 7:16 ` Richard Biener
2022-02-03 9:06 ` Eric Botcazou
2022-02-03 9:33 ` Jakub Jelinek
2022-02-03 9:40 ` Richard Biener
2022-02-03 9:55 ` Jakub Jelinek
2022-02-03 11:03 ` Richard Biener
2022-02-03 11:18 ` Jakub Jelinek
2022-02-03 12:13 ` Richard Biener [this message]
2022-02-03 12:22 ` Jakub Jelinek
2022-02-03 12:24 ` Eric Botcazou
2022-02-03 9:49 ` Eric Botcazou
2022-02-04 9:53 ` Eric Botcazou
2022-02-04 10:07 ` Jakub Jelinek
2022-02-04 10:14 ` Eric Botcazou
2022-02-04 10:26 ` Jakub Jelinek
2022-02-04 10:29 ` Jakub Jelinek
2022-01-31 8:28 ` Richard Biener
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