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Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches
From: |
Stefan Monnier |
Subject: |
Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches |
Date: |
Thu, 23 Aug 2018 11:56:18 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
> 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
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Pip Cet, 2018/08/22
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Ken Brown, 2018/08/22
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Stefan Monnier, 2018/08/22
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Pip Cet, 2018/08/23
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches,
Stefan Monnier <=
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Pip Cet, 2018/08/24
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Paul Eggert, 2018/08/24
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Pip Cet, 2018/08/25
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Stefan Monnier, 2018/08/25
- Re: [Emacs-diffs] master f18af6c: Audit use of lsh and fix glitches, Paul Eggert, 2018/08/25
- hash-consing bignums and eq==eql, Stefan Monnier, 2018/08/28
- Re: hash-consing bignums and eq==eql, Pip Cet, 2018/08/29
- Re: hash-consing bignums and eq==eql, Stefan Monnier, 2018/08/29
- Re: hash-consing bignums and eq==eql, Paul Eggert, 2018/08/29
- Re: hash-consing bignums and eq==eql, Stefan Monnier, 2018/08/29