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Flatten nested concat calls

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* lisp/emacs-lisp/byte-opt.el (byte-optimize-concat):
Flatten nested forms; concat is associative.  This reduces the number
of calls and may coalesce adjacent constant strings.
This commit is contained in:
Mattias Engdegård 2023-02-08 13:45:57 +01:00
parent f3fce3a71c
commit 680bc20553
1 changed files with 22 additions and 12 deletions
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34
lisp/emacs-lisp/byte-opt.el
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@ -1132,21 +1132,31 @@ See Info node `(elisp) Integer Basics'."
form))
(defun byte-optimize-concat (form)
"Merge adjacent constant arguments to `concat'."
"Merge adjacent constant arguments to `concat' and flatten nested forms."
(let ((args (cdr form))
(newargs nil))
(while args
(let ((strings nil)
val)
(while (and args (macroexp-const-p (car args))
(progn
(setq val (byteopt--eval-const (car args)))
(and (or (stringp val)
(and (or (listp val) (vectorp val))
(not (memq nil
(mapcar #'characterp val))))))))
(push val strings)
(setq args (cdr args)))
(let ((strings nil))
(while
(and args
(let ((arg (car args)))
(pcase arg
;; Merge consecutive constant arguments.
((pred macroexp-const-p)
(let ((val (byteopt--eval-const arg)))
(and (or (stringp val)
(and (or (listp val) (vectorp val))
(not (memq nil
(mapcar #'characterp val)))))
(progn
(push val strings)
(setq args (cdr args))
t))))
;; Flatten nested `concat' form.
(`(concat . ,nested-args)
(setq args (append nested-args (cdr args)))
t)))))
(when strings
(let ((s (apply #'concat (nreverse strings))))
(when (not (zerop (length s)))