diff options
Diffstat (limited to 'lisp/emacs-lisp/byte-opt.el')
| -rw-r--r-- | lisp/emacs-lisp/byte-opt.el | 61 |
1 files changed, 33 insertions, 28 deletions
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el index 8ed85ff805c..62a112debca 100644 --- a/lisp/emacs-lisp/byte-opt.el +++ b/lisp/emacs-lisp/byte-opt.el @@ -1,12 +1,16 @@ -;;; The optimization passes of the emacs-lisp byte compiler. +;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler. + ;;; Copyright (c) 1991 Free Software Foundation, Inc. -;; By Jamie Zawinski <jwz@lucid.com> and Hallvard Furuseth <hbf@ulrik.uio.no>. + +;; Author: Jamie Zawinski <jwz@lucid.com> +;; Hallvard Furuseth <hbf@ulrik.uio.no> +;; Keywords: internal ;; This file is part of GNU Emacs. ;; GNU Emacs is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by -;; the Free Software Foundation; either version 1, or (at your option) +;; the Free Software Foundation; either version 2, or (at your option) ;; any later version. ;; GNU Emacs is distributed in the hope that it will be useful, @@ -18,6 +22,8 @@ ;; along with GNU Emacs; see the file COPYING. If not, write to ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. +;;; Commentary: + ;;; ======================================================================== ;;; "No matter how hard you try, you can't make a racehorse out of a pig. ;;; you can, however, make a faster pig." @@ -69,13 +75,14 @@ ;;; but beware of traps like ;;; (cons (list x y) (list x y)) ;;; -;;; Tail-recursion elimination is not really possible in elisp. Tail-recursion -;;; elimination is almost always impossible when all variables have dynamic -;;; scope, but given that the "return" byteop requires the binding stack to be -;;; empty (rather than emptying it itself), there can be no truly tail- -;;; recursive elisp functions that take any arguments or make any bindings. +;;; Tail-recursion elimination is not really possible in Emacs Lisp. +;;; Tail-recursion elimination is almost always impossible when all variables +;;; have dynamic scope, but given that the "return" byteop requires the +;;; binding stack to be empty (rather than emptying it itself), there can be +;;; no truly tail-recursive Emacs Lisp functions that take any arguments or +;;; make any bindings. ;;; -;;; Here is an example of an elisp function which could safely be +;;; Here is an example of an Emacs Lisp function which could safely be ;;; byte-compiled tail-recursively: ;;; ;;; (defun tail-map (fn list) @@ -105,7 +112,7 @@ ;;; overflow. I don't believe there is any way around this without lexical ;;; scope. ;;; -;;; Wouldn't it be nice if elisp had lexical scope. +;;; Wouldn't it be nice if Emacs Lisp had lexical scope. ;;; ;;; Idea: the form (lexical-scope) in a file means that the file may be ;;; compiled lexically. This proclamation is file-local. Then, within @@ -128,6 +135,7 @@ ;;; the board, in the interpreter and compiler, and just FIX all of ;;; the code that relies on dynamic scope of non-defvarred variables. +;;; Code: (defun byte-compile-log-lap-1 (format &rest args) (if (aref byte-code-vector 0) @@ -1029,7 +1037,7 @@ (+ (aref bytes ptr) (progn (setq ptr (1+ ptr)) (lsh (aref bytes ptr) 8)))) - ((and (>= op byte-rel-goto) + ((and (>= op byte-listN) (<= op byte-insertN)) (setq ptr (1+ ptr)) ;offset in next byte (aref bytes ptr)))) @@ -1060,13 +1068,7 @@ optr ptr offset (disassemble-offset)) ; this does dynamic-scope magic (setq op (aref byte-code-vector op)) - (cond ((or (memq op byte-goto-ops) - (cond ((memq op byte-rel-goto-ops) - (setq op (aref byte-code-vector - (- (symbol-value op) - (- byte-rel-goto byte-goto)))) - (setq offset (+ ptr (- offset 127))) - t))) + (cond ((memq op byte-goto-ops) ;; it's a pc (setq offset (cdr (or (assq offset tags) @@ -1176,16 +1178,17 @@ ;;; the BOOL variables are, and not perform this optimization on them. ;;; (defconst byte-boolean-vars - '(abbrevs-changed abbrev-all-caps inverse-video visible-bell - check-protected-fields no-redraw-on-reenter cursor-in-echo-area - noninteractive stack-trace-on-error debug-on-error debug-on-quit - debug-on-next-call insert-default-directory vms-stmlf-recfm - indent-tabs-mode meta-flag load-in-progress defining-kbd-macro - completion-auto-help completion-ignore-case enable-recursive-minibuffers - print-escape-newlines delete-exited-processes parse-sexp-ignore-comments - words-include-escapes pop-up-windows auto-new-screen - reset-terminal-on-clear truncate-partial-width-windows - mode-line-inverse-video) + '(abbrev-all-caps abbrevs-changed byte-metering-on + check-protected-fields completion-auto-help completion-ignore-case + cursor-in-echo-area debug-on-next-call debug-on-quit + defining-kbd-macro delete-exited-processes + enable-recursive-minibuffers indent-tabs-mode + insert-default-directory inverse-video load-in-progress + menu-prompting mode-line-inverse-video no-redraw-on-reenter + noninteractive parse-sexp-ignore-comments pop-up-frames + pop-up-windows print-escape-newlines print-escape-newlines + truncate-partial-width-windows visible-bell vms-stmlf-recfm + words-include-escapes x-save-under) "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t. If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer may generate incorrect code.") @@ -1721,3 +1724,5 @@ may generate incorrect code.") byte-optimize-form-code-walker byte-optimize-lapcode)))) nil) + +;;; byte-opt.el ends here |