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Lexical binding doesn't seem to be faster?
From: |
Hi-Angel |
Subject: |
Lexical binding doesn't seem to be faster? |
Date: |
Thu, 7 Mar 2019 02:36:39 +0300 |
I've stumbled upon a discussion about converting Emacs code to a
faster lexical-binding and that help needed. I noted that cc-mode.el
I'm regularly use doesn't have one, and figured I could help.
So I inserted to cc-mode.el in emacs-git revision I have:
;;; -*- lexical-binding: t -*-
The first bad sign happened to be sizes of cc-mode.elc:
;;; -*- lexical-binding: t -*- | 217581
;;; -*- lexical-binding: nil -*- | 212542
Lexical-binding bloats byte-code by 5KB. Odd. I tried comparing
assembly, but without experience in reading lisp assembly I haven't
come up with anything. So I thought "Okay, must be heavy inlining;
let's just compare the speed".
So, I took someone's function `with-timer` for benchmarking¹; and then
for both t and nil lexical-binding I did following steps:
1. `byte-compile` `cc-mode.el`
2. `load-file` `cc-mode.elc`
3. open a 5k lines C file²
4. Execute multiple times `(with-timer (c-font-lock-fontify-region 0
(point-max)))`
5. Kill the buffer.
These are results I got:
;;; -*- lexical-binding: t -*- | 1.174s, 1.144s, 1.177s, 1.125s, 1.177s
;;; -*- lexical-binding: nil -*- | 1.037s, 1.061s, 1.037s, 1.037s, 0.991s
1:
https://emacs.stackexchange.com/a/541/2671#how-do-i-measure-performance-of-elisp-code
2:
https://gitlab.freedesktop.org/libinput/libinput/blob/9a2d6f55b1276da11dd9b2c4c8e22a405576dfea/src/libinput.h
- Lexical binding doesn't seem to be faster?,
Hi-Angel <=
- Re: Lexical binding doesn't seem to be faster?, Stefan Monnier, 2019/03/08
- Re: Lexical binding doesn't seem to be faster?, Hi-Angel, 2019/03/08
- Re: Lexical binding doesn't seem to be faster?, Stefan Monnier, 2019/03/09
- Re: Lexical binding doesn't seem to be faster?, Hi-Angel, 2019/03/10
- Re: Lexical binding doesn't seem to be faster?, Hi-Angel, 2019/03/10
- Re: Lexical binding doesn't seem to be faster?, Stefan Monnier, 2019/03/10
- Re: Lexical binding doesn't seem to be faster?, Hi-Angel, 2019/03/10