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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From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, Andrea Corallo <andrea_corallo <at> yahoo.it>, 42147 <at> debbugs.gnu.org
Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations?
Date: Thu, 02 Jul 2020 15:38:25 -0400

>> Better yet, there's still hope that we change things such that `eq`
>> behaves like `eql` on bignums (and maybe also on floats).
> Speaking of which, Andrea may be in a good position to provide us with
> performance data about such a change, since making 'eq' more expensive is
> likely to be more visible in native code (assuming the operation is
> open-coded) than in bytecode or interpreted lisp. On the other hand, perhaps
> his compiler thingamajig is able to eliminate some checks statically by
> type propagation?

Note that it can also be done without slowing down `eq` (by
hash-consing the bignums).


        Stefan
This bug report was last modified 4 years and 282 days ago.

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