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(byte-optimize-form-code-walker): Evaluate pure function calls if possible.

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(byte-optimize-all-constp): New function.
This commit is contained in:
Chong Yidong 2007-04-11 17:10:42 +00:00
parent f782c3293c
commit fb67ebdf16
1 changed files with 25 additions and 1 deletions
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26
lisp/emacs-lisp/byte-opt.el
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@ -557,8 +557,20 @@
;; Otherwise, no args can be considered to be for-effect,
;; even if the called function is for-effect, because we
;; don't know anything about that function.
(cons fn (mapcar 'byte-optimize-form (cdr form)))))))
(let ((args (mapcar #'byte-optimize-form (cdr form))))
(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 iff all elements of LIST satisfy `byte-compile-constp'."
(let ((constant t))
(while (and list constant)
(unless (byte-compile-constp (car list))
(setq constant nil))
(setq list (cdr list)))
constant))
(defun byte-optimize-form (form &optional for-effect)
"The source-level pass of the optimizer."
@ -1241,6 +1253,18 @@
(setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns)))
nil)
;; pure functions are side-effect free functions whose values depend
;; only on their arguments. For these functions, calls with constant
;; arguments can be evaluated at compile time. This may shift run time
;; errors to compile time.
(let ((pure-fns
'(concat symbol-name regexp-opt regexp-quote string-to-syntax)))
(while pure-fns
(put (car pure-fns) 'pure t)
(setq pure-fns (cdr pure-fns)))
nil)
(defun byte-compile-splice-in-already-compiled-code (form)
;; form is (byte-code "..." [...] n)