diff options
Diffstat (limited to 'lisp/emacs-lisp/byte-opt.el')
| -rw-r--r-- | lisp/emacs-lisp/byte-opt.el | 52 |
1 files changed, 32 insertions, 20 deletions
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el index bc864aab490..eb8c80af145 100644 --- a/lisp/emacs-lisp/byte-opt.el +++ b/lisp/emacs-lisp/byte-opt.el @@ -185,6 +185,7 @@ ;;; Code: (require 'bytecomp) +(eval-when-compile (require 'cl)) (defun byte-compile-log-lap-1 (format &rest args) (if (aref byte-code-vector 0) @@ -276,6 +277,8 @@ ;; Isn't it an error for `string' not to be unibyte?? --stef (if (fboundp 'string-as-unibyte) (setq string (string-as-unibyte string))) + ;; `byte-compile-splice-in-already-compiled-code' + ;; takes care of inlining the body. (cons `(lambda ,(aref fn 0) (byte-code ,string ,(aref fn 2) ,(aref fn 3))) (cdr form))) @@ -625,13 +628,24 @@ ;; ;; It is now safe to optimize code such that it introduces new bindings. -;; I'd like this to be a defsubst, but let's not be self-referential... -(defmacro byte-compile-trueconstp (form) - ;; Returns non-nil if FORM is a non-nil constant. - `(cond ((consp ,form) (eq (car ,form) 'quote)) - ((not (symbolp ,form))) - ((eq ,form t)) - ((keywordp ,form)))) +(defsubst byte-compile-trueconstp (form) + "Return non-nil if FORM always evaluates to a non-nil value." + (cond ((consp form) + (case (car form) + (quote (cadr form)) + (progn (byte-compile-trueconstp (car (last (cdr form))))))) + ((not (symbolp form))) + ((eq form t)) + ((keywordp form)))) + +(defsubst byte-compile-nilconstp (form) + "Return non-nil if FORM always evaluates to a nil value." + (cond ((consp form) + (case (car form) + (quote (null (cadr form))) + (progn (byte-compile-nilconstp (car (last (cdr form))))))) + ((not (symbolp form)) nil) + ((null form)))) ;; If the function is being called with constant numeric args, ;; evaluate as much as possible at compile-time. This optimizer @@ -990,17 +1004,17 @@ (setq rest form) (while (setq rest (cdr rest)) (cond ((byte-compile-trueconstp (car-safe (car rest))) - (cond ((eq rest (cdr form)) - (setq form - (if (cdr (car rest)) - (if (cdr (cdr (car rest))) - (cons 'progn (cdr (car rest))) - (nth 1 (car rest))) - (car (car rest))))) + ;; This branch will always be taken: kill the subsequent ones. + (cond ((eq rest (cdr form)) ;First branch of `cond'. + (setq form `(progn ,@(car rest)))) ((cdr rest) (setq form (copy-sequence form)) (setcdr (memq (car rest) form) nil))) - (setq rest nil))))) + (setq rest nil)) + ((and (consp (car rest)) + (byte-compile-nilconstp (caar rest))) + ;; This branch will never be taken: kill its body. + (setcdr (car rest) nil))))) ;; ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... )) (if (eq 'cond (car-safe form)) @@ -1031,11 +1045,9 @@ (byte-optimize-if `(if ,(car (last clause)) ,@(nthcdr 2 form))))))) ((byte-compile-trueconstp clause) - (nth 2 form)) - ((null clause) - (if (nthcdr 4 form) - (cons 'progn (nthcdr 3 form)) - (nth 3 form))) + `(progn ,clause ,(nth 2 form))) + ((byte-compile-nilconstp clause) + `(progn ,clause ,@(nthcdr 3 form))) ((nth 2 form) (if (equal '(nil) (nthcdr 3 form)) (list 'if clause (nth 2 form)) |