From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Cc: "Alex Rønne Petersen" <alex@alexrp.com>
Subject: Re: [musl] [PATCH] configure: prevent compilers from turning a * b + c into fma(a, b, c)
Date: Wed, 28 Aug 2024 23:32:03 +0300 (MSK) [thread overview]
Message-ID: <2f89009e-4290-90d7-d625-09dbf879340a@ispras.ru> (raw)
In-Reply-To: <20240828201514.GH10433@brightrain.aerifal.cx>
On Wed, 28 Aug 2024, Rich Felker wrote:
> With that said, I don't see how the compiler could ever generate calls
> to fma(), since we're -ffreestanding, but I think it could generate
> inline fma instructions on targets where they're available, and this
> is generally undesirable (see above). For gcc, I think -std=c99
> already has that covered, but I'm not sure what clang does.
Modern Clang implements the FP_CONTRACT pragma, with default state "on".
Of course, the -ffp-contract= command-line switch is also available.
Alexander
next prev parent reply other threads:[~2024-08-28 20:32 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-28 15:28 Alex Rønne Petersen
2024-08-28 15:53 ` Alexander Monakov
2024-08-28 16:31 ` Alex Rønne Petersen
2024-08-28 20:15 ` Rich Felker
2024-08-28 20:32 ` Alexander Monakov [this message]
2024-08-28 20:47 ` Rich Felker
2024-08-28 21:11 ` Alexander Monakov
2024-08-29 13:37 ` Alex Rønne Petersen
2024-08-28 19:56 ` Alexander Monakov
2024-08-29 13:36 ` Alex Rønne Petersen
2024-08-29 15:09 ` 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=2f89009e-4290-90d7-d625-09dbf879340a@ispras.ru \
--to=amonakov@ispras.ru \
--cc=alex@alexrp.com \
--cc=musl@lists.openwall.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.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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 NNTP newsgroup(s).