bug#59692: 29.0.60; Reduce installation size by disabling byte-compilation for some lisp files that won't benefit

[daanturo <daanturo@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 5388 bytes --]

> measurements of code speed with and without byte-compilation

I tried to evaluate performance different:

### Load time

Helper macro:
```emacs-lisp
(defmacro my-with-deferred-gc (&rest body)
  `(dlet ((gc-cons-threshold most-positive-fixnum) (gc-cons-percentage 0.75))
     ,@body))
```

(Each of those measures was executed in a new Emacs instance, as the
second `load` is (for me) cheaper than the first `load`).

#### lisp/leim/ja-dic

(my-with-deferred-gc (benchmark-progn (load
"/usr/share/emacs/29.0.60/lisp/leim/ja-dic/ja-dic")))

> .el:
Loading /usr/share/emacs/29.0.60/lisp/leim/ja-dic/ja-dic.el (source)...done
Elapsed time: 0.707891s
> .elc:
Loading /usr/share/emacs/29.0.60/lisp/leim/ja-dic/ja-dic...done
Elapsed time: 0.104832s
> .eln:
Loading /usr/share/emacs/29.0.60/lisp/leim/ja-dic/ja-dic (native compiled elisp)...done
Elapsed time: 0.104676s


#### Other auto-generated lisp files in lisp/leim/quail, all of them are
Chinese at the moment, the largests being ZIRANMA.el, ARRAY30.el:



(my-with-deferred-gc (benchmark-progn (load
"/usr/share/emacs/29.0.60/lisp/leim/quail/ZIRANMA")))

> .el:
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ZIRANMA.el (source)...done
Elapsed time: 0.037230s
> .elc:
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ZIRANMA...done
Elapsed time: 0.058042s
> .eln:
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ZIRANMA (native compiled elisp)...
Elapsed time: 0.062904s

(my-with-deferred-gc (benchmark-progn (load
"/usr/share/emacs/29.0.60/lisp/leim/quail/ARRAY30")))

> .el
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ARRAY30.el (source)...done
Elapsed time: 0.031518s
> .elc
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ARRAY30...done
Elapsed time: 0.037412s
> .eln
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/ARRAY30 (native compiled elisp)...done
Elapsed time: 0.041110s


(my-with-deferred-gc (benchmark-progn (load
"/usr/share/emacs/29.0.60/lisp/leim/quail/QJ")))
> .el
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/QJ.el (source)...done
Elapsed time: 0.001649s
> .elc
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/QJ...done
Elapsed time: 0.004481s
> .eln
Loading /usr/share/emacs/29.0.60/lisp/leim/quail/QJ (native compiled elisp)...done
Elapsed time: 0.005001s



For "ja-dic.el", byte-compilation clearly helped speedup loading. But
native-compilation doesn't offer any more significantly. As I inspect
"ja-dic.elc", byte-compilation did by expanding macros to
`(defconst var literal-list)` forms, I think that native compilation
won't offer more about run time performance.


For auto-generated files under lisp/leim/quail (ZIRANMA, ARRAY30, QJ
tested above), sometimes compilation even slows down the loading process
compared to just interpretation.


About the run time performance, since I don't know Chinese, I will
approximately benchmark lisp/leim/quail/vnvni.el (Vietnamese) instead as
this file is quite similar to ZIRANMA.el: both has only 2 forms --
(quail-define-package ...) and (quail-define-rules ...).

ydotool is used (https://github.com/ReimuNotMoe/ydotool) to perform
auto-typing as in bench-quail.el attached. The function to be
benchmarked is #'quail-input-method.

emacs -q -l bench-quail.el --eval "(progn (my-to-new-buffer) (my-benchmark-quail nil))"
emacs -q -l bench-quail.el --eval "(progn (my-to-new-buffer) (my-benchmark-quail 'compiled))"


Benchmarking results: (note that :num means the total key pressed by ydotool).

Loading /usr/share/emacs/29.0.60/lisp/leim/quail/vnvni.el (source)...done
Elapsed time: 0.016844s (0.008795s in 1 GCs)
(:compiled nil (:num 145 :total-time 2.118776153 :average 0.014612249331034484))


Loading /usr/share/emacs/29.0.60/lisp/leim/quail/vnvni (native compiled elisp)...done
Elapsed time: 0.034253s (0.009630s in 1 GCs)
(:compiled compiled (:num 145 :total-time 2.117245182999999 :average 0.014601690917241374))



So I conclude that those quail lisp package files' compilation statuses,
whether compiled or not, doesn't affect run-time performance at all.

### lisp/international/titdic-cnv.el's pinyin-convert

It produce a single form: (defconst var literal-list) so the
corresponding produced ".elc" file is just the same with new lines
joined. Also the times taken to load lisp/language/pinyin.elc and
/lisp/language/pinyin.el aren't different anyway.

### About the patch

In the patch below, I disabled native-compile for "ja-dic" while keeping
byte-compile (by modifying `generate-lisp-file-trailer` keyword args),
and disable compilation altogether for files produced by titdic-convert,
miscdic-convert, pinyin-convert. There's no new .dir-locals files
introduced like the previous patch.

> Disk space is cheap these days.

But it's always better to be light if we don't suffer any penalties. A
little number of megabytes saved will always be appreciated by people
with metered connection and/or limited bandwidth, or people who have
multiple versions of Emacs installed. Disk space is indeed becoming
cheaper, but with varying pace among countries. I am currently using a
laptop which only has 238GiB & un-expandable, that explains my joy when
pacman shows net upgrade size being negative during system updates.

Thanks to the patch, I saved 20.20 MiB by a couple of flag flips without
making any new files. Please consider again if you think it makes more
sense than my previous justifications, thank you.

-- 
Daanturo.

[-- Attachment #2: bench-quail.el --]
[-- Type: text/x-emacs-lisp, Size: 2042 bytes --]

;; -*- lexical-binding: t; -*-

;;; Benchmark helper functions

(defvar my-benchmark-accumulate-time--num-time '(0 0))
;;;###autoload
(defun my-benchmark-accumulate-time-a (func &rest args)
  (let* ((time0 (current-time)))
    (unwind-protect
        (apply func args)
      (pcase-let* ((delta (float-time (time-since time0)))
                   (`(,num ,total-time) my-benchmark-accumulate-time--num-time))
        (setq my-benchmark-accumulate-time--num-time
              (list (+ (or num 0) 1)
                    (+ (or total-time 0) delta)))))))
(defun my-benchmark-accumulate-time-report (&optional reset)
  (prog1
      (pcase-let* ((`(,num ,total-time) my-benchmark-accumulate-time--num-time))
        (list :num num
              :total-time total-time
              :average (ignore-error arith-error (/ total-time num))))
    (when reset (setq my-benchmark-accumulate-time--num-time nil))))

(defun my-to-new-buffer ()
  (interactive)
  (switch-to-buffer
   (generate-new-buffer "new")))

;;; Perform benchmarking

(defconst my-typing
  "Emacs la2 tri2nh soa5n tha3o va8n ba3n d9a chu71c na8ng. D9a6y
la2 pha62n me62m tu75 do, cha5y d9u7o75c tre6n nhie62u he65
d9ie62u ha2nh va2 co1 the63 mo73 ro65ng d9e63 the6m va2o chu71c
na8ng mo71i."
  "https://vi.wikipedia.org/wiki/Emacs")

(defun my-benchmark-quail (&optional load-compiled-quail-package)
  (interactive "P")
  (deactivate-input-method)
  (advice-add #'quail-input-method :around #'my-benchmark-accumulate-time-a)
  (my-benchmark-accumulate-time-report 'reset)
  (benchmark-progn
    (if load-compiled-quail-package
        (load "/usr/share/emacs/29.0.60/lisp/leim/quail/vnvni")
      (load "/usr/share/emacs/29.0.60/lisp/leim/quail/vnvni.el")))
  (activate-input-method "vietnamese-vni")
  (let* ((proc (start-process "" nil "ydotool" "type" my-typing)))
    (set-process-sentinel
     proc
     (lambda (&rest _)
       (deactivate-input-method)
       (print (list :compiled load-compiled-quail-package
                    (my-benchmark-accumulate-time-report)))))))

[-- Attachment #3: 0001-Inhibit-compilation-for-some-quail-packages-generators.patch --]
[-- Type: text/x-patch, Size: 2161 bytes --]

From 1ccf494d4175f8c56ef95a0661249f42337fae77 Mon Sep 17 00:00:00 2001
From: Daanturo <daanturo@gmail.com>
Date: Wed, 30 Nov 2022 16:03:59 +0700
Subject: [PATCH] Inhibit compilation for some quail packages generators

---
 lisp/international/ja-dic-cnv.el | 3 ++-
 lisp/international/titdic-cnv.el | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/lisp/international/ja-dic-cnv.el b/lisp/international/ja-dic-cnv.el
index ec68d8c804..df70959b19 100644
--- a/lisp/international/ja-dic-cnv.el
+++ b/lisp/international/ja-dic-cnv.el
@@ -396,7 +396,8 @@ skkdic-convert
 	;; Postfix
 	(with-current-buffer buf
 	  (goto-char (point-max))
-          (generate-lisp-file-trailer ja-dic-filename :compile t)))
+          (generate-lisp-file-trailer
+           ja-dic-filename :compile t :inhibit-native-compile t)))
 
       ;; Save the working buffer.
       (set-buffer buf)
diff --git a/lisp/international/titdic-cnv.el b/lisp/international/titdic-cnv.el
index b942f5fabc..8996214dcb 100644
--- a/lisp/international/titdic-cnv.el
+++ b/lisp/international/titdic-cnv.el
@@ -527,7 +527,7 @@ titdic-convert
 	  ;; Process the body part
 	  (tit-process-body)
           (generate-lisp-file-trailer
-           filename :inhibit-provide t :compile t :coding nil))))))
+           filename :inhibit-provide t :compile nil :coding nil))))))
 
 ;;;###autoload
 (defun batch-titdic-convert (&optional force)
@@ -1161,7 +1161,7 @@ miscdic-convert
                 (with-current-buffer dstbuf
                   (funcall converter dicbuf)))))
           (generate-lisp-file-trailer
-           quailfile :inhibit-provide t :compile t :coding nil)))
+           quailfile :inhibit-provide t :compile nil :coding nil)))
       (setq tail (cdr tail)))))
 
 (defun batch-miscdic-convert ()
@@ -1218,7 +1218,7 @@ pinyin-convert
           (forward-line 1)))
       (insert ")\n\"An alist holding correspondences between pinyin syllables\
  and\nChinese characters.\")\n\n")
-      (generate-lisp-file-trailer dst-file :compile t))
+      (generate-lisp-file-trailer dst-file :compile nil))
     (kill-emacs 0)))
 
 ;;; titdic-cnv.el ends here
-- 
2.38.1