From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Pip Cet <pipcet@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches
Date: Thu, 23 Aug 2018 11:56:18 -0400 [thread overview]
Message-ID: <jwv6001gjzu.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <CAOqdjBfrhxeH80xaR94GcrJLN5Hzw_ow3AgL1jWUwJqNbkUjWA@mail.gmail.com> (Pip Cet's message of "Thu, 23 Aug 2018 14:55:31 +0000")
> Well, it isn't `==' if we're building with
> --enable-check-lisp-object-type,
Currently, the resulting assembly code should be pretty close even in
that case, tho.
> extra condition for "overloaded" objects. Assuming some compiler
> smarts, NILP wouldn't suffer, and EQ wouldn't suffer if one side is
> known to have a normal type. I doubt the performance hit will be
> measurable; if anything, the if-fixnum-do-this-if-bignum-do-that code
> we have right now might be worse for caches than making the bignum
> code a cold function.
The whole purpose of hash-consing (for me) is to avoid turning EQ into
something like:
if (BIGNUMP (x))
return slow_eq (x, y);
else
return x == y;
What we do in slow_eq is largely irrelevant: the problem is the cost of
`if (BIGNUMP (x))`, both in terms of code size and processing time.
Stefan
next prev parent reply other threads:[~2018-08-23 15:56 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180821204437.16880.99611@vcs0.savannah.gnu.org>
[not found] ` <20180821204439.62390209A6@vcs0.savannah.gnu.org>
2018-08-22 12:36 ` [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches Pip Cet
2018-08-22 13:35 ` Ken Brown
2018-08-22 13:44 ` Paul Eggert
2018-08-22 15:50 ` Pip Cet
2018-08-22 17:27 ` Paul Eggert
2018-08-22 20:05 ` Pip Cet
2018-08-22 21:53 ` Paul Eggert
2018-08-22 20:45 ` Stefan Monnier
2018-08-23 14:55 ` Pip Cet
2018-08-23 15:56 ` Stefan Monnier [this message]
2018-08-24 18:00 ` Pip Cet
2018-08-24 20:55 ` Paul Eggert
2018-08-25 15:02 ` Pip Cet
2018-08-25 18:02 ` Stefan Monnier
2018-08-25 21:24 ` Paul Eggert
2018-08-28 14:08 ` hash-consing bignums and eq==eql Stefan Monnier
2018-08-29 13:32 ` Pip Cet
2018-08-29 19:23 ` Stefan Monnier
2018-08-29 19:31 ` Paul Eggert
2018-08-29 20:50 ` Stefan Monnier
2018-09-09 3:09 ` Stefan Monnier
2018-09-09 6:26 ` Paul Eggert
2018-08-22 13:49 ` [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches Pip Cet
2018-08-22 14:52 ` Eli Zaretskii
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