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bug#14769: 24.3.50; [PATCH] optimize `concat's literals
From: |
Lars Ingebrigtsen |
Subject: |
bug#14769: 24.3.50; [PATCH] optimize `concat's literals |
Date: |
Wed, 24 Feb 2016 15:51:00 +1100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) |
Shigeru Fukaya <shigeru.fukaya@gmail.com> writes:
> Current bytecode optimizer works only when all arguments are
> constants.
>
> With the attached small patch, adjacent successive literal arguments
> of `concat' will become optimized to a string respectively.
>
> Make successive literals of `concat' optimized to a string.
> * byte-opt.el (byte-optimize-form-code-walker): call
> byte-optimize-concat-args for `concat'.
> (byte-optimize-concat-args): New function.
I think the patch below looks sensible, but the bytecode optimiser is
not something I'm familiar with. Does this look OK to all y'all?
>
> Regards,
> Shigeru
>
> *** byte-opt.el Fri Jun 14 19:32:39 2013
> --- byte-opt.new.el Wed Jul 3 01:48:29 2013
> ***************
> *** 562,568 ****
> (if (and (get fn 'pure)
> (byte-optimize-all-constp args))
> (list 'quote (apply fn (mapcar #'eval args)))
> ! (cons fn args)))))))
>
> (defun byte-optimize-all-constp (list)
> "Non-nil if all elements of LIST satisfy `macroexp-const-p"
> --- 562,572 ----
> (if (and (get fn 'pure)
> (byte-optimize-all-constp args))
> (list 'quote (apply fn (mapcar #'eval args)))
> ! (if (eq fn 'concat)
> ! ;; Not all arguments are literals.
> ! (cons fn (byte-optimize-concat-args args))
> ! ;; Other than `concat'.
> ! (cons fn args))))))))
>
> (defun byte-optimize-all-constp (list)
> "Non-nil if all elements of LIST satisfy `macroexp-const-p"
> ***************
> *** 573,578 ****
> --- 577,605 ----
> (setq list (cdr list)))
> constant))
>
> + (defun byte-optimize-concat-args (args)
> + ;;
> + ;; Convert arguments of `concat' such that adjacent successive
> + ;; literal arguments to one string, and remove null strings.
> + ;;
> + (let (newargs)
> + (while args
> + ;; loop for literals
> + (let (l)
> + (while (and args (macroexp-const-p (car args)))
> + (push (car args) l)
> + (setq args (cdr args)))
> + (when l
> + (let ((s (apply #'concat (mapcar #'eval (nreverse l)))))
> + ;; keep non-null string
> + (unless (equal s "")
> + (push s newargs)))))
> + ;; non-literal argument
> + (when args
> + (push (car args) newargs)
> + (setq args (cdr args))))
> + (nreverse newargs)))
> +
> (defun byte-optimize-form (form &optional for-effect)
> "The source-level pass of the optimizer."
> ;;
>
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
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