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

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Package: emacs;

Reported by: Andrea Corallo <andrea_corallo <at> yahoo.it>

Date: Tue, 30 Jun 2020 22:28:02 UTC

Severity: normal

Found in version 28.0.50

Done: Mattias Engdegård <mattiase <at> acm.org>

Bug is archived. No further changes may be made.

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Message #193 received at 42147-done <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattiase <at> acm.org>
To: Andrea Corallo <andrea_corallo <at> yahoo.it>
Cc: 42147-done <at> debbugs.gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>,
 Stefan Monnier <monnier <at> iro.umontreal.ca>, Andrea Corallo <akrl <at> sdf.org>
Subject: Re: bug#42147: 28.0.50; pure vs side-effect-free, missing
 optimizations?
Date: Tue, 7 Jul 2020 17:54:56 +0200

6 juli 2020 kl. 23.23 skrev Andrea Corallo <andrea_corallo <at> yahoo.it>:

> Yes I am happy :) Not sure about the floating point discussion
> originated from this but on my side this bug can be closed.

Then closed it is. I would happily write something in NEWS but -- as Eli noted -- for any noticeable change in behaviour to occur, many conditions need to be met, several of which are quite unlikely.

More improvements to the constant-folding are possible and desirable. For example, I have a patch that deals with constant expressions in let-bindings, so that

(let ((x (+ 1 2)))
  (f x))

simplifies to (f 3), with the variable x removed. This in turn generates more opportunities for further simplification and dead-code elimination. Tell me if you are interested.
This bug report was last modified 4 years and 282 days ago.

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