GNU bug report logs - #42147
28.0.50; pure vs side-effect-free, missing optimizations?

Previous Next

Full log

Message #104 received at 42147 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: Stefan Monnier <monnier <at> iro.umontreal.ca>,
 Andrea Corallo <andrea_corallo <at> yahoo.it>, 42147 <at> debbugs.gnu.org
Subject: Re: bug#42147: 28.0.50; pure vs side-effect-free, missing
 optimizations?
Date: Sat, 4 Jul 2020 08:57:08 -0700

[Message part 1 (text/plain, inline)]

On 7/3/20 11:47 AM, Mattias Engdegård wrote:
>> Having Emacs use --with-mfpmath=sse should improve performance a bit on x86. But
>> more important, it should make floating point more reproducible. If I get the
>> time I'll look into having 'configure' add it automatically.
> Thank you, this would be a prerequisite for further improvements.

Attached is a patch to do that. I looked at the GCC source code, and x86 is the
only platform where this sort of thing should be necessary. I'll mention this
patch on emacs-devel, to give people a heads-up before installing.

[0001-Prefer-standard-rounding-on-x86.patch (text/x-patch, attachment)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.