From: Jakub Jelinek <jakub@redhat.com>
To: Martin Uecker <muecker@gwdg.de>
Cc: Richard Biener <richard.guenther@gmail.com>,
Alexander Monakov <amonakov@ispras.ru>,
Florian Weimer <fweimer@redhat.com>,
gcc@gcc.gnu.org
Subject: Re: Concerns regarding the -ffp-contract=fast default
Date: Mon, 18 Sep 2023 13:32:35 +0200 [thread overview]
Message-ID: <ZQg1U4QDetoy56rj@tucnak> (raw)
In-Reply-To: <bb0638acaf5e472a9acbbb0973f271ea688ddeed.camel@gwdg.de>
On Mon, Sep 18, 2023 at 01:26:54PM +0200, Martin Uecker wrote:
> > I think that changing the default to =standard without -ffast-math is
> > reasonable.
> > IIRC the standard allows such default if it's indicated, so it doesn't require
> > =off anywhere.
>
> The C standard requires a pragma to turn control it on and off,
> which GCC does not support. The default is then implementation
> defined.
Perhaps we should add some initial hammer approach for the pragma, like
if you ever use the pragma to turn it somewhere off, it is turned off
globally, or ditto per function. Might be far easier than trying to
make it precise that contraction is allowed in this expression and not in
this subexpression of that etc. Of course, making it precise is the
ultimate goal.
Jakub
next prev parent reply other threads:[~2023-09-18 11:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-14 16:48 Florian Weimer
2023-09-14 17:09 ` Alexander Monakov
2023-09-18 7:50 ` Alexander Monakov
2023-09-18 8:06 ` Richard Biener
2023-09-18 10:10 ` Florian Weimer
2023-09-18 10:37 ` Richard Biener
2023-09-18 11:37 ` Florian Weimer
2023-09-18 11:12 ` Alexander Monakov
2023-09-18 11:34 ` Florian Weimer
2023-09-18 11:55 ` Alexander Monakov
2023-09-18 16:41 ` Florian Weimer
2023-09-18 17:31 ` Alexander Monakov
2023-09-18 17:39 ` Joseph Myers
2023-09-18 11:26 ` Martin Uecker
2023-09-18 11:32 ` Jakub Jelinek [this message]
2023-09-18 11:43 ` Alexander Monakov
2023-09-18 12:13 ` Martin Uecker
2023-09-18 15:38 ` Alexander Monakov
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=ZQg1U4QDetoy56rj@tucnak \
--to=jakub@redhat.com \
--cc=amonakov@ispras.ru \
--cc=fweimer@redhat.com \
--cc=gcc@gcc.gnu.org \
--cc=muecker@gwdg.de \
--cc=richard.guenther@gmail.com \
/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).