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[Emacs-diffs] Changes to emacs/lisp/emacs-lisp/byte-opt.el [emacs-unicod
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From: |
Kenichi Handa |
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Subject: |
[Emacs-diffs] Changes to emacs/lisp/emacs-lisp/byte-opt.el [emacs-unicode-2] |
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Date: |
Mon, 08 Sep 2003 08:53:54 -0400 |
Index: emacs/lisp/emacs-lisp/byte-opt.el
diff -c /dev/null emacs/lisp/emacs-lisp/byte-opt.el:1.73.4.1
*** /dev/null Mon Sep 8 08:53:54 2003
--- emacs/lisp/emacs-lisp/byte-opt.el Mon Sep 8 08:53:39 2003
***************
*** 0 ****
--- 1,2033 ----
+ ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler
+
+ ;;; Copyright (c) 1991, 1994, 2000, 2001, 2002 Free Software Foundation, Inc.
+
+ ;; Author: Jamie Zawinski <address@hidden>
+ ;; Hallvard Furuseth <address@hidden>
+ ;; Maintainer: FSF
+ ;; 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 2, or (at your option)
+ ;; any later version.
+
+ ;; GNU Emacs is distributed in the hope that it will be useful,
+ ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+ ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ ;; GNU General Public License for more details.
+
+ ;; You should have received a copy of the GNU General Public License
+ ;; along with GNU Emacs; see the file COPYING. If not, write to the
+ ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ ;; Boston, MA 02111-1307, 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."
+ ;;
+ ;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code
+ ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
+ ;; still not going to make it go faster than 70 mph, but it might be easier
+ ;; to get it there.
+ ;;
+
+ ;; TO DO:
+ ;;
+ ;; (apply (lambda (x &rest y) ...) 1 (foo))
+ ;;
+ ;; maintain a list of functions known not to access any global variables
+ ;; (actually, give them a 'dynamically-safe property) and then
+ ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
+ ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
+ ;; by recursing on this, we might be able to eliminate the entire let.
+ ;; However certain variables should never have their bindings optimized
+ ;; away, because they affect everything.
+ ;; (put 'debug-on-error 'binding-is-magic t)
+ ;; (put 'debug-on-abort 'binding-is-magic t)
+ ;; (put 'debug-on-next-call 'binding-is-magic t)
+ ;; (put 'inhibit-quit 'binding-is-magic t)
+ ;; (put 'quit-flag 'binding-is-magic t)
+ ;; (put 't 'binding-is-magic t)
+ ;; (put 'nil 'binding-is-magic t)
+ ;; possibly also
+ ;; (put 'gc-cons-threshold 'binding-is-magic t)
+ ;; (put 'track-mouse 'binding-is-magic t)
+ ;; others?
+ ;;
+ ;; Simple defsubsts often produce forms like
+ ;; (let ((v1 (f1)) (v2 (f2)) ...)
+ ;; (FN v1 v2 ...))
+ ;; It would be nice if we could optimize this to
+ ;; (FN (f1) (f2) ...)
+ ;; but we can't unless FN is dynamically-safe (it might be dynamically
+ ;; referring to the bindings that the lambda arglist established.)
+ ;; One of the uncountable lossages introduced by dynamic scope...
+ ;;
+ ;; Maybe there should be a control-structure that says "turn on
+ ;; fast-and-loose type-assumptive optimizations here." Then when
+ ;; we see a form like (car foo) we can from then on assume that
+ ;; the variable foo is of type cons, and optimize based on that.
+ ;; But, this won't win much because of (you guessed it) dynamic
+ ;; scope. Anything down the stack could change the value.
+ ;; (Another reason it doesn't work is that it is perfectly valid
+ ;; to call car with a null argument.) A better approach might
+ ;; be to allow type-specification of the form
+ ;; (put 'foo 'arg-types '(float (list integer) dynamic))
+ ;; (put 'foo 'result-type 'bool)
+ ;; It should be possible to have these types checked to a certain
+ ;; degree.
+ ;;
+ ;; collapse common subexpressions
+ ;;
+ ;; It would be nice if redundant sequences could be factored out as well,
+ ;; when they are known to have no side-effects:
+ ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
+ ;; but beware of traps like
+ ;; (cons (list x y) (list x y))
+ ;;
+ ;; 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 Emacs Lisp function which could safely be
+ ;; byte-compiled tail-recursively:
+ ;;
+ ;; (defun tail-map (fn list)
+ ;; (cond (list
+ ;; (funcall fn (car list))
+ ;; (tail-map fn (cdr list)))))
+ ;;
+ ;; However, if there was even a single let-binding around the COND,
+ ;; it could not be byte-compiled, because there would be an "unbind"
+ ;; byte-op between the final "call" and "return." Adding a
+ ;; Bunbind_all byteop would fix this.
+ ;;
+ ;; (defun foo (x y z) ... (foo a b c))
+ ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
+ ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z)
(goto 0) END: (unbind-all) (return)
+ ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z)
(goto 0) END: (return)
+ ;;
+ ;; this also can be considered tail recursion:
+ ;;
+ ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
+ ;; could generalize this by doing the optimization
+ ;; (goto X) ... X: (return) --> (return)
+ ;;
+ ;; But this doesn't solve all of the problems: although by doing tail-
+ ;; recursion elimination in this way, the call-stack does not grow, the
+ ;; binding-stack would grow with each recursive step, and would eventually
+ ;; overflow. I don't believe there is any way around this without 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
+ ;; that file, "let" would establish lexical bindings, and "let-dynamic"
+ ;; would do things the old way. (Or we could use CL "declare" forms.)
+ ;; We'd have to notice defvars and defconsts, since those variables should
+ ;; always be dynamic, and attempting to do a lexical binding of them
+ ;; should simply do a dynamic binding instead.
+ ;; But! We need to know about variables that were not necessarily defvarred
+ ;; in the file being compiled (doing a boundp check isn't good enough.)
+ ;; Fdefvar() would have to be modified to add something to the plist.
+ ;;
+ ;; A major disadvantage of this scheme is that the interpreter and compiler
+ ;; would have different semantics for files compiled with (dynamic-scope).
+ ;; Since this would be a file-local optimization, there would be no way to
+ ;; modify the interpreter to obey this (unless the loader was hacked
+ ;; in some grody way, but that's a really bad idea.)
+
+ ;; Other things to consider:
+
+ ;;;;; Associative math should recognize subcalls to identical function:
+ ;;;(disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
+ ;;;;; This should generate the same as (1+ x) and (1- x)
+
+ ;;;(disassemble (lambda (x) (cons (+ x 1) (- x 1))))
+ ;;;;; An awful lot of functions always return a non-nil value. If they're
+ ;;;;; error free also they may act as true-constants.
+
+ ;;;(disassemble (lambda (x) (and (point) (foo))))
+ ;;;;; When
+ ;;;;; - all but one arguments to a function are constant
+ ;;;;; - the non-constant argument is an if-expression (cond-expression?)
+ ;;;;; then the outer function can be distributed. If the guarding
+ ;;;;; condition is side-effect-free [assignment-free] then the other
+ ;;;;; arguments may be any expressions. Since, however, the code size
+ ;;;;; can increase this way they should be "simple". Compare:
+
+ ;;;(disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
+ ;;;(disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
+
+ ;;;;; (car (cons A B)) -> (progn B A)
+ ;;;(disassemble (lambda (x) (car (cons (foo) 42))))
+
+ ;;;;; (cdr (cons A B)) -> (progn A B)
+ ;;;(disassemble (lambda (x) (cdr (cons 42 (foo)))))
+
+ ;;;;; (car (list A B ...)) -> (progn B ... A)
+ ;;;(disassemble (lambda (x) (car (list (foo) 42 (bar)))))
+
+ ;;;;; (cdr (list A B ...)) -> (progn A (list B ...))
+ ;;;(disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
+
+
+ ;;; Code:
+
+ (require 'bytecomp)
+
+ (defun byte-compile-log-lap-1 (format &rest args)
+ (if (aref byte-code-vector 0)
+ (error "The old version of the disassembler is loaded. Reload
new-bytecomp as well"))
+ (byte-compile-log-1
+ (apply 'format format
+ (let (c a)
+ (mapcar (lambda (arg)
+ (if (not (consp arg))
+ (if (and (symbolp arg)
+ (string-match "^byte-" (symbol-name arg)))
+ (intern (substring (symbol-name arg) 5))
+ arg)
+ (if (integerp (setq c (car arg)))
+ (error "non-symbolic byte-op %s" c))
+ (if (eq c 'TAG)
+ (setq c arg)
+ (setq a (cond ((memq c byte-goto-ops)
+ (car (cdr (cdr arg))))
+ ((memq c byte-constref-ops)
+ (car (cdr arg)))
+ (t (cdr arg))))
+ (setq c (symbol-name c))
+ (if (string-match "^byte-." c)
+ (setq c (intern (substring c 5)))))
+ (if (eq c 'constant) (setq c 'const))
+ (if (and (eq (cdr arg) 0)
+ (not (memq c '(unbind call const))))
+ c
+ (format "(%s %s)" c a))))
+ args)))))
+
+ (defmacro byte-compile-log-lap (format-string &rest args)
+ (list 'and
+ '(memq byte-optimize-log '(t byte))
+ (cons 'byte-compile-log-lap-1
+ (cons format-string args))))
+
+
+ ;;; byte-compile optimizers to support inlining
+
+ (put 'inline 'byte-optimizer 'byte-optimize-inline-handler)
+
+ (defun byte-optimize-inline-handler (form)
+ "byte-optimize-handler for the `inline' special-form."
+ (cons 'progn
+ (mapcar
+ (lambda (sexp)
+ (let ((fn (car-safe sexp)))
+ (if (and (symbolp fn)
+ (or (cdr (assq fn byte-compile-function-environment))
+ (and (fboundp fn)
+ (not (or (cdr (assq fn byte-compile-macro-environment))
+ (and (consp (setq fn (symbol-function fn)))
+ (eq (car fn) 'macro))
+ (subrp fn))))))
+ (byte-compile-inline-expand sexp)
+ sexp)))
+ (cdr form))))
+
+
+ ;; Splice the given lap code into the current instruction stream.
+ ;; If it has any labels in it, you're responsible for making sure there
+ ;; are no collisions, and that byte-compile-tag-number is reasonable
+ ;; after this is spliced in. The provided list is destroyed.
+ (defun byte-inline-lapcode (lap)
+ (setq byte-compile-output (nconc (nreverse lap) byte-compile-output)))
+
+ (defun byte-compile-inline-expand (form)
+ (let* ((name (car form))
+ (fn (or (cdr (assq name byte-compile-function-environment))
+ (and (fboundp name) (symbol-function name)))))
+ (if (null fn)
+ (progn
+ (byte-compile-warn "attempt to inline `%s' before it was defined"
+ name)
+ form)
+ ;; else
+ (when (and (consp fn) (eq (car fn) 'autoload))
+ (load (nth 1 fn))
+ (setq fn (or (and (fboundp name) (symbol-function name))
+ (cdr (assq name byte-compile-function-environment)))))
+ (if (and (consp fn) (eq (car fn) 'autoload))
+ (error "File `%s' didn't define `%s'" (nth 1 fn) name))
+ (if (symbolp fn)
+ (byte-compile-inline-expand (cons fn (cdr form)))
+ (if (byte-code-function-p fn)
+ (let (string)
+ (fetch-bytecode fn)
+ (setq string (aref fn 1))
+ (if (fboundp 'string-as-unibyte)
+ (setq string (string-as-unibyte string)))
+ (cons (list 'lambda (aref fn 0)
+ (list 'byte-code string (aref fn 2) (aref fn 3)))
+ (cdr form)))
+ (if (eq (car-safe fn) 'lambda)
+ (cons fn (cdr form))
+ ;; Give up on inlining.
+ form))))))
+
+ ;;; ((lambda ...) ...)
+ ;;;
+ (defun byte-compile-unfold-lambda (form &optional name)
+ (or name (setq name "anonymous lambda"))
+ (let ((lambda (car form))
+ (values (cdr form)))
+ (if (byte-code-function-p lambda)
+ (setq lambda (list 'lambda (aref lambda 0)
+ (list 'byte-code (aref lambda 1)
+ (aref lambda 2) (aref lambda 3)))))
+ (let ((arglist (nth 1 lambda))
+ (body (cdr (cdr lambda)))
+ optionalp restp
+ bindings)
+ (if (and (stringp (car body)) (cdr body))
+ (setq body (cdr body)))
+ (if (and (consp (car body)) (eq 'interactive (car (car body))))
+ (setq body (cdr body)))
+ (while arglist
+ (cond ((eq (car arglist) '&optional)
+ ;; ok, I'll let this slide because funcall_lambda() does...
+ ;; (if optionalp (error "multiple &optional keywords in %s"
name))
+ (if restp (error "&optional found after &rest in %s" name))
+ (if (null (cdr arglist))
+ (error "nothing after &optional in %s" name))
+ (setq optionalp t))
+ ((eq (car arglist) '&rest)
+ ;; ...but it is by no stretch of the imagination a reasonable
+ ;; thing that funcall_lambda() allows (&rest x y) and
+ ;; (&rest x &optional y) in arglists.
+ (if (null (cdr arglist))
+ (error "nothing after &rest in %s" name))
+ (if (cdr (cdr arglist))
+ (error "multiple vars after &rest in %s" name))
+ (setq restp t))
+ (restp
+ (setq bindings (cons (list (car arglist)
+ (and values (cons 'list values)))
+ bindings)
+ values nil))
+ ((and (not optionalp) (null values))
+ (byte-compile-warn "attempt to open-code `%s' with too few
arguments" name)
+ (setq arglist nil values 'too-few))
+ (t
+ (setq bindings (cons (list (car arglist) (car values))
+ bindings)
+ values (cdr values))))
+ (setq arglist (cdr arglist)))
+ (if values
+ (progn
+ (or (eq values 'too-few)
+ (byte-compile-warn
+ "attempt to open-code `%s' with too many arguments" name))
+ form)
+
+ ;; The following leads to infinite recursion when loading a
+ ;; file containing `(defsubst f () (f))', and then trying to
+ ;; byte-compile that file.
+ ;(setq body (mapcar 'byte-optimize-form body)))
+
+ (let ((newform
+ (if bindings
+ (cons 'let (cons (nreverse bindings) body))
+ (cons 'progn body))))
+ (byte-compile-log " %s\t==>\t%s" form newform)
+ newform)))))
+
+
+ ;;; implementing source-level optimizers
+
+ (defun byte-optimize-form-code-walker (form for-effect)
+ ;;
+ ;; For normal function calls, We can just mapcar the optimizer the cdr. But
+ ;; we need to have special knowledge of the syntax of the special forms
+ ;; like let and defun (that's why they're special forms :-). (Actually,
+ ;; the important aspect is that they are subrs that don't evaluate all of
+ ;; their args.)
+ ;;
+ (let ((fn (car-safe form))
+ tmp)
+ (cond ((not (consp form))
+ (if (not (and for-effect
+ (or byte-compile-delete-errors
+ (not (symbolp form))
+ (eq form t))))
+ form))
+ ((eq fn 'quote)
+ (if (cdr (cdr form))
+ (byte-compile-warn "malformed quote form: `%s'"
+ (prin1-to-string form)))
+ ;; map (quote nil) to nil to simplify optimizer logic.
+ ;; map quoted constants to nil if for-effect (just because).
+ (and (nth 1 form)
+ (not for-effect)
+ form))
+ ((or (byte-code-function-p fn)
+ (eq 'lambda (car-safe fn)))
+ (byte-compile-unfold-lambda form))
+ ((memq fn '(let let*))
+ ;; recursively enter the optimizer for the bindings and body
+ ;; of a let or let*. This for depth-firstness: forms that
+ ;; are more deeply nested are optimized first.
+ (cons fn
+ (cons
+ (mapcar (lambda (binding)
+ (if (symbolp binding)
+ binding
+ (if (cdr (cdr binding))
+ (byte-compile-warn "malformed let binding: `%s'"
+ (prin1-to-string binding)))
+ (list (car binding)
+ (byte-optimize-form (nth 1 binding) nil))))
+ (nth 1 form))
+ (byte-optimize-body (cdr (cdr form)) for-effect))))
+ ((eq fn 'cond)
+ (cons fn
+ (mapcar (lambda (clause)
+ (if (consp clause)
+ (cons
+ (byte-optimize-form (car clause) nil)
+ (byte-optimize-body (cdr clause) for-effect))
+ (byte-compile-warn "malformed cond form: `%s'"
+ (prin1-to-string clause))
+ clause))
+ (cdr form))))
+ ((eq fn 'progn)
+ ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
+ (if (cdr (cdr form))
+ (progn
+ (setq tmp (byte-optimize-body (cdr form) for-effect))
+ (if (cdr tmp) (cons 'progn tmp) (car tmp)))
+ (byte-optimize-form (nth 1 form) for-effect)))
+ ((eq fn 'prog1)
+ (if (cdr (cdr form))
+ (cons 'prog1
+ (cons (byte-optimize-form (nth 1 form) for-effect)
+ (byte-optimize-body (cdr (cdr form)) t)))
+ (byte-optimize-form (nth 1 form) for-effect)))
+ ((eq fn 'prog2)
+ (cons 'prog2
+ (cons (byte-optimize-form (nth 1 form) t)
+ (cons (byte-optimize-form (nth 2 form) for-effect)
+ (byte-optimize-body (cdr (cdr (cdr form))) t)))))
+
+ ((memq fn '(save-excursion save-restriction save-current-buffer))
+ ;; those subrs which have an implicit progn; it's not quite good
+ ;; enough to treat these like normal function calls.
+ ;; This can turn (save-excursion ...) into (save-excursion) which
+ ;; will be optimized away in the lap-optimize pass.
+ (cons fn (byte-optimize-body (cdr form) for-effect)))
+
+ ((eq fn 'with-output-to-temp-buffer)
+ ;; this is just like the above, except for the first argument.
+ (cons fn
+ (cons
+ (byte-optimize-form (nth 1 form) nil)
+ (byte-optimize-body (cdr (cdr form)) for-effect))))
+
+ ((eq fn 'if)
+ (when (< (length form) 3)
+ (byte-compile-warn "too few arguments for `if'"))
+ (cons fn
+ (cons (byte-optimize-form (nth 1 form) nil)
+ (cons
+ (byte-optimize-form (nth 2 form) for-effect)
+ (byte-optimize-body (nthcdr 3 form) for-effect)))))
+
+ ((memq fn '(and or)) ; remember, and/or are control structures.
+ ;; take forms off the back until we can't any more.
+ ;; In the future it could conceivably be a problem that the
+ ;; subexpressions of these forms are optimized in the reverse
+ ;; order, but it's ok for now.
+ (if for-effect
+ (let ((backwards (reverse (cdr form))))
+ (while (and backwards
+ (null (setcar backwards
+ (byte-optimize-form (car backwards)
+ for-effect))))
+ (setq backwards (cdr backwards)))
+ (if (and (cdr form) (null backwards))
+ (byte-compile-log
+ " all subforms of %s called for effect; deleted" form))
+ (and backwards
+ (cons fn (nreverse (mapcar 'byte-optimize-form
backwards)))))
+ (cons fn (mapcar 'byte-optimize-form (cdr form)))))
+
+ ((eq fn 'interactive)
+ (byte-compile-warn "misplaced interactive spec: `%s'"
+ (prin1-to-string form))
+ nil)
+
+ ((memq fn '(defun defmacro function
+ condition-case save-window-excursion))
+ ;; These forms are compiled as constants or by breaking out
+ ;; all the subexpressions and compiling them separately.
+ form)
+
+ ((eq fn 'unwind-protect)
+ ;; the "protected" part of an unwind-protect is compiled (and thus
+ ;; optimized) as a top-level form, so don't do it here. But the
+ ;; non-protected part has the same for-effect status as the
+ ;; unwind-protect itself. (The protected part is always for effect,
+ ;; but that isn't handled properly yet.)
+ (cons fn
+ (cons (byte-optimize-form (nth 1 form) for-effect)
+ (cdr (cdr form)))))
+
+ ((eq fn 'catch)
+ ;; the body of a catch is compiled (and thus optimized) as a
+ ;; top-level form, so don't do it here. The tag is never
+ ;; for-effect. The body should have the same for-effect status
+ ;; as the catch form itself, but that isn't handled properly yet.
+ (cons fn
+ (cons (byte-optimize-form (nth 1 form) nil)
+ (cdr (cdr form)))))
+
+ ((eq fn 'ignore)
+ ;; Don't treat the args to `ignore' as being
+ ;; computed for effect. We want to avoid the warnings
+ ;; that might occur if they were treated that way.
+ ;; However, don't actually bother calling `ignore'.
+ `(prog1 nil . ,(mapcar 'byte-optimize-form (cdr form))))
+
+ ;; If optimization is on, this is the only place that macros are
+ ;; expanded. If optimization is off, then macroexpansion happens
+ ;; in byte-compile-form. Otherwise, the macros are already expanded
+ ;; by the time that is reached.
+ ((not (eq form
+ (setq form (macroexpand form
+ byte-compile-macro-environment))))
+ (byte-optimize-form form for-effect))
+
+ ;; Support compiler macros as in cl.el.
+ ((and (fboundp 'compiler-macroexpand)
+ (symbolp (car-safe form))
+ (get (car-safe form) 'cl-compiler-macro)
+ (not (eq form
+ (setq form (compiler-macroexpand form)))))
+ (byte-optimize-form form for-effect))
+
+ ((not (symbolp fn))
+ (byte-compile-warn "`%s' is a malformed function"
+ (prin1-to-string fn))
+ form)
+
+ ((and for-effect (setq tmp (get fn 'side-effect-free))
+ (or byte-compile-delete-errors
+ (eq tmp 'error-free)
+ ;; Detect the expansion of (pop foo).
+ ;; There is no need to compile the call to `car' there.
+ (and (eq fn 'car)
+ (eq (car-safe (cadr form)) 'prog1)
+ (let ((var (cadr (cadr form)))
+ (last (nth 2 (cadr form))))
+ (and (symbolp var)
+ (null (nthcdr 3 (cadr form)))
+ (eq (car-safe last) 'setq)
+ (eq (cadr last) var)
+ (eq (car-safe (nth 2 last)) 'cdr)
+ (eq (cadr (nth 2 last)) var))))
+ (progn
+ (byte-compile-warn "`%s' called for effect"
+ (prin1-to-string (car form)))
+ nil)))
+ (byte-compile-log " %s called for effect; deleted" fn)
+ ;; appending a nil here might not be necessary, but it can't hurt.
+ (byte-optimize-form
+ (cons 'progn (append (cdr form) '(nil))) t))
+
+ (t
+ ;; 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)))))))
+
+
+ (defun byte-optimize-form (form &optional for-effect)
+ "The source-level pass of the optimizer."
+ ;;
+ ;; First, optimize all sub-forms of this one.
+ (setq form (byte-optimize-form-code-walker form for-effect))
+ ;;
+ ;; after optimizing all subforms, optimize this form until it doesn't
+ ;; optimize any further. This means that some forms will be passed through
+ ;; the optimizer many times, but that's necessary to make the for-effect
+ ;; processing do as much as possible.
+ ;;
+ (let (opt new)
+ (if (and (consp form)
+ (symbolp (car form))
+ (or (and for-effect
+ ;; we don't have any of these yet, but we might.
+ (setq opt (get (car form) 'byte-for-effect-optimizer)))
+ (setq opt (get (car form) 'byte-optimizer)))
+ (not (eq form (setq new (funcall opt form)))))
+ (progn
+ ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
+ (byte-compile-log " %s\t==>\t%s" form new)
+ (setq new (byte-optimize-form new for-effect))
+ new)
+ form)))
+
+
+ (defun byte-optimize-body (forms all-for-effect)
+ ;; optimize the cdr of a progn or implicit progn; all forms is a list of
+ ;; forms, all but the last of which are optimized with the assumption that
+ ;; they are being called for effect. the last is for-effect as well if
+ ;; all-for-effect is true. returns a new list of forms.
+ (let ((rest forms)
+ (result nil)
+ fe new)
+ (while rest
+ (setq fe (or all-for-effect (cdr rest)))
+ (setq new (and (car rest) (byte-optimize-form (car rest) fe)))
+ (if (or new (not fe))
+ (setq result (cons new result)))
+ (setq rest (cdr rest)))
+ (nreverse result)))
+
+
+ ;;; some source-level optimizers
+ ;;;
+ ;;; when writing optimizers, be VERY careful that the optimizer returns
+ ;;; something not EQ to its argument if and ONLY if it has made a change.
+ ;;; This implies that you cannot simply destructively modify the list;
+ ;;; you must return something not EQ to it if you make an optimization.
+ ;;;
+ ;;; 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))))
+
+ ;; If the function is being called with constant numeric args,
+ ;; evaluate as much as possible at compile-time. This optimizer
+ ;; assumes that the function is associative, like + or *.
+ (defun byte-optimize-associative-math (form)
+ (let ((args nil)
+ (constants nil)
+ (rest (cdr form)))
+ (while rest
+ (if (numberp (car rest))
+ (setq constants (cons (car rest) constants))
+ (setq args (cons (car rest) args)))
+ (setq rest (cdr rest)))
+ (if (cdr constants)
+ (if args
+ (list (car form)
+ (apply (car form) constants)
+ (if (cdr args)
+ (cons (car form) (nreverse args))
+ (car args)))
+ (apply (car form) constants))
+ form)))
+
+ ;; If the function is being called with constant numeric args,
+ ;; evaluate as much as possible at compile-time. This optimizer
+ ;; assumes that the function satisfies
+ ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
+ ;; like - and /.
+ (defun byte-optimize-nonassociative-math (form)
+ (if (or (not (numberp (car (cdr form))))
+ (not (numberp (car (cdr (cdr form))))))
+ form
+ (let ((constant (car (cdr form)))
+ (rest (cdr (cdr form))))
+ (while (numberp (car rest))
+ (setq constant (funcall (car form) constant (car rest))
+ rest (cdr rest)))
+ (if rest
+ (cons (car form) (cons constant rest))
+ constant))))
+
+ ;;(defun byte-optimize-associative-two-args-math (form)
+ ;; (setq form (byte-optimize-associative-math form))
+ ;; (if (consp form)
+ ;; (byte-optimize-two-args-left form)
+ ;; form))
+
+ ;;(defun byte-optimize-nonassociative-two-args-math (form)
+ ;; (setq form (byte-optimize-nonassociative-math form))
+ ;; (if (consp form)
+ ;; (byte-optimize-two-args-right form)
+ ;; form))
+
+ (defun byte-optimize-approx-equal (x y)
+ (<= (* (abs (- x y)) 100) (abs (+ x y))))
+
+ ;; Collect all the constants from FORM, after the STARTth arg,
+ ;; and apply FUN to them to make one argument at the end.
+ ;; For functions that can handle floats, that optimization
+ ;; can be incorrect because reordering can cause an overflow
+ ;; that would otherwise be avoided by encountering an arg that is a float.
+ ;; We avoid this problem by (1) not moving float constants and
+ ;; (2) not moving anything if it would cause an overflow.
+ (defun byte-optimize-delay-constants-math (form start fun)
+ ;; Merge all FORM's constants from number START, call FUN on them
+ ;; and put the result at the end.
+ (let ((rest (nthcdr (1- start) form))
+ (orig form)
+ ;; t means we must check for overflow.
+ (overflow (memq fun '(+ *))))
+ (while (cdr (setq rest (cdr rest)))
+ (if (integerp (car rest))
+ (let (constants)
+ (setq form (copy-sequence form)
+ rest (nthcdr (1- start) form))
+ (while (setq rest (cdr rest))
+ (cond ((integerp (car rest))
+ (setq constants (cons (car rest) constants))
+ (setcar rest nil))))
+ ;; If necessary, check now for overflow
+ ;; that might be caused by reordering.
+ (if (and overflow
+ ;; We have overflow if the result of doing the arithmetic
+ ;; on floats is not even close to the result
+ ;; of doing it on integers.
+ (not (byte-optimize-approx-equal
+ (apply fun (mapcar 'float constants))
+ (float (apply fun constants)))))
+ (setq form orig)
+ (setq form (nconc (delq nil form)
+ (list (apply fun (nreverse constants)))))))))
+ form))
+
+ (defun byte-optimize-plus (form)
+ (setq form (byte-optimize-delay-constants-math form 1 '+))
+ (if (memq 0 form) (setq form (delq 0 (copy-sequence form))))
+ ;;(setq form (byte-optimize-associative-two-args-math form))
+ (cond ((null (cdr form))
+ (condition-case ()
+ (eval form)
+ (error form)))
+ ;;; It is not safe to delete the function entirely
+ ;;; (actually, it would be safe if we know the sole arg
+ ;;; is not a marker).
+ ;; ((null (cdr (cdr form))) (nth 1 form))
+ ((null (cddr form))
+ (if (numberp (nth 1 form))
+ (nth 1 form)
+ form))
+ ((and (null (nthcdr 3 form))
+ (or (memq (nth 1 form) '(1 -1))
+ (memq (nth 2 form) '(1 -1))))
+ ;; Optimize (+ x 1) into (1+ x) and (+ x -1) into (1- x).
+ (let ((integer
+ (if (memq (nth 1 form) '(1 -1))
+ (nth 1 form)
+ (nth 2 form)))
+ (other
+ (if (memq (nth 1 form) '(1 -1))
+ (nth 2 form)
+ (nth 1 form))))
+ (list (if (eq integer 1) '1+ '1-)
+ other)))
+ (t form)))
+
+ (defun byte-optimize-minus (form)
+ ;; Put constants at the end, except the last constant.
+ (setq form (byte-optimize-delay-constants-math form 2 '+))
+ ;; Now only first and last element can be a number.
+ (let ((last (car (reverse (nthcdr 3 form)))))
+ (cond ((eq 0 last)
+ ;; (- x y ... 0) --> (- x y ...)
+ (setq form (copy-sequence form))
+ (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form))))
+ ((equal (nthcdr 2 form) '(1))
+ (setq form (list '1- (nth 1 form))))
+ ((equal (nthcdr 2 form) '(-1))
+ (setq form (list '1+ (nth 1 form))))
+ ;; If form is (- CONST foo... CONST), merge first and last.
+ ((and (numberp (nth 1 form))
+ (numberp last))
+ (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
+ (delq last (copy-sequence (nthcdr 3 form))))))))
+ ;;; It is not safe to delete the function entirely
+ ;;; (actually, it would be safe if we know the sole arg
+ ;;; is not a marker).
+ ;;; (if (eq (nth 2 form) 0)
+ ;;; (nth 1 form) ; (- x 0) --> x
+ (byte-optimize-predicate
+ (if (and (null (cdr (cdr (cdr form))))
+ (eq (nth 1 form) 0)) ; (- 0 x) --> (- x)
+ (cons (car form) (cdr (cdr form)))
+ form))
+ ;;; )
+ )
+
+ (defun byte-optimize-multiply (form)
+ (setq form (byte-optimize-delay-constants-math form 1 '*))
+ ;; If there is a constant in FORM, it is now the last element.
+ (cond ((null (cdr form)) 1)
+ ;;; It is not safe to delete the function entirely
+ ;;; (actually, it would be safe if we know the sole arg
+ ;;; is not a marker or if it appears in other arithmetic).
+ ;;; ((null (cdr (cdr form))) (nth 1 form))
+ ((let ((last (car (reverse form))))
+ (cond ((eq 0 last) (cons 'progn (cdr form)))
+ ((eq 1 last) (delq 1 (copy-sequence form)))
+ ((eq -1 last) (list '- (delq -1 (copy-sequence form))))
+ ((and (eq 2 last)
+ (memq t (mapcar 'symbolp (cdr form))))
+ (prog1 (setq form (delq 2 (copy-sequence form)))
+ (while (not (symbolp (car (setq form (cdr form))))))
+ (setcar form (list '+ (car form) (car form)))))
+ (form))))))
+
+ (defsubst byte-compile-butlast (form)
+ (nreverse (cdr (reverse form))))
+
+ (defun byte-optimize-divide (form)
+ (setq form (byte-optimize-delay-constants-math form 2 '*))
+ (let ((last (car (reverse (cdr (cdr form))))))
+ (if (numberp last)
+ (cond ((= (length form) 3)
+ (if (and (numberp (nth 1 form))
+ (not (zerop last))
+ (condition-case nil
+ (/ (nth 1 form) last)
+ (error nil)))
+ (setq form (list 'progn (/ (nth 1 form) last)))))
+ ((= last 1)
+ (setq form (byte-compile-butlast form)))
+ ((numberp (nth 1 form))
+ (setq form (cons (car form)
+ (cons (/ (nth 1 form) last)
+ (byte-compile-butlast (cdr (cdr form)))))
+ last nil))))
+ (cond
+ ;;; ((null (cdr (cdr form)))
+ ;;; (nth 1 form))
+ ((eq (nth 1 form) 0)
+ (append '(progn) (cdr (cdr form)) '(0)))
+ ((eq last -1)
+ (list '- (if (nthcdr 3 form)
+ (byte-compile-butlast form)
+ (nth 1 form))))
+ (form))))
+
+ (defun byte-optimize-logmumble (form)
+ (setq form (byte-optimize-delay-constants-math form 1 (car form)))
+ (byte-optimize-predicate
+ (cond ((memq 0 form)
+ (setq form (if (eq (car form) 'logand)
+ (cons 'progn (cdr form))
+ (delq 0 (copy-sequence form)))))
+ ((and (eq (car-safe form) 'logior)
+ (memq -1 form))
+ (cons 'progn (cdr form)))
+ (form))))
+
+
+ (defun byte-optimize-binary-predicate (form)
+ (if (byte-compile-constp (nth 1 form))
+ (if (byte-compile-constp (nth 2 form))
+ (condition-case ()
+ (list 'quote (eval form))
+ (error form))
+ ;; This can enable some lapcode optimizations.
+ (list (car form) (nth 2 form) (nth 1 form)))
+ form))
+
+ (defun byte-optimize-predicate (form)
+ (let ((ok t)
+ (rest (cdr form)))
+ (while (and rest ok)
+ (setq ok (byte-compile-constp (car rest))
+ rest (cdr rest)))
+ (if ok
+ (condition-case ()
+ (list 'quote (eval form))
+ (error form))
+ form)))
+
+ (defun byte-optimize-identity (form)
+ (if (and (cdr form) (null (cdr (cdr form))))
+ (nth 1 form)
+ (byte-compile-warn "identity called with %d arg%s, but requires 1"
+ (length (cdr form))
+ (if (= 1 (length (cdr form))) "" "s"))
+ form))
+
+ (put 'identity 'byte-optimizer 'byte-optimize-identity)
+
+ (put '+ 'byte-optimizer 'byte-optimize-plus)
+ (put '* 'byte-optimizer 'byte-optimize-multiply)
+ (put '- 'byte-optimizer 'byte-optimize-minus)
+ (put '/ 'byte-optimizer 'byte-optimize-divide)
+ (put 'max 'byte-optimizer 'byte-optimize-associative-math)
+ (put 'min 'byte-optimizer 'byte-optimize-associative-math)
+
+ (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
+ (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
+ (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
+ (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
+ (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
+
+ (put '< 'byte-optimizer 'byte-optimize-predicate)
+ (put '> 'byte-optimizer 'byte-optimize-predicate)
+ (put '<= 'byte-optimizer 'byte-optimize-predicate)
+ (put '>= 'byte-optimizer 'byte-optimize-predicate)
+ (put '1+ 'byte-optimizer 'byte-optimize-predicate)
+ (put '1- 'byte-optimizer 'byte-optimize-predicate)
+ (put 'not 'byte-optimizer 'byte-optimize-predicate)
+ (put 'null 'byte-optimizer 'byte-optimize-predicate)
+ (put 'memq 'byte-optimizer 'byte-optimize-predicate)
+ (put 'consp 'byte-optimizer 'byte-optimize-predicate)
+ (put 'listp 'byte-optimizer 'byte-optimize-predicate)
+ (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
+ (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
+ (put 'string< 'byte-optimizer 'byte-optimize-predicate)
+ (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
+
+ (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
+ (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
+ (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
+ (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
+
+ (put 'car 'byte-optimizer 'byte-optimize-predicate)
+ (put 'cdr 'byte-optimizer 'byte-optimize-predicate)
+ (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
+ (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
+
+
+ ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
+ ;; take care of this? - Jamie
+ ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
+ ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
+ (put 'quote 'byte-optimizer 'byte-optimize-quote)
+ (defun byte-optimize-quote (form)
+ (if (or (consp (nth 1 form))
+ (and (symbolp (nth 1 form))
+ (not (byte-compile-const-symbol-p form))))
+ form
+ (nth 1 form)))
+
+ (defun byte-optimize-zerop (form)
+ (cond ((numberp (nth 1 form))
+ (eval form))
+ (byte-compile-delete-errors
+ (list '= (nth 1 form) 0))
+ (form)))
+
+ (put 'zerop 'byte-optimizer 'byte-optimize-zerop)
+
+ (defun byte-optimize-and (form)
+ ;; Simplify if less than 2 args.
+ ;; if there is a literal nil in the args to `and', throw it and following
+ ;; forms away, and surround the `and' with (progn ... nil).
+ (cond ((null (cdr form)))
+ ((memq nil form)
+ (list 'progn
+ (byte-optimize-and
+ (prog1 (setq form (copy-sequence form))
+ (while (nth 1 form)
+ (setq form (cdr form)))
+ (setcdr form nil)))
+ nil))
+ ((null (cdr (cdr form)))
+ (nth 1 form))
+ ((byte-optimize-predicate form))))
+
+ (defun byte-optimize-or (form)
+ ;; Throw away nil's, and simplify if less than 2 args.
+ ;; If there is a literal non-nil constant in the args to `or', throw away
all
+ ;; following forms.
+ (if (memq nil form)
+ (setq form (delq nil (copy-sequence form))))
+ (let ((rest form))
+ (while (cdr (setq rest (cdr rest)))
+ (if (byte-compile-trueconstp (car rest))
+ (setq form (copy-sequence form)
+ rest (setcdr (memq (car rest) form) nil))))
+ (if (cdr (cdr form))
+ (byte-optimize-predicate form)
+ (nth 1 form))))
+
+ (defun byte-optimize-cond (form)
+ ;; if any clauses have a literal nil as their test, throw them away.
+ ;; if any clause has a literal non-nil constant as its test, throw
+ ;; away all following clauses.
+ (let (rest)
+ ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
+ (while (setq rest (assq nil (cdr form)))
+ (setq form (delq rest (copy-sequence form))))
+ (if (memq nil (cdr form))
+ (setq form (delq nil (copy-sequence form))))
+ (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)))))
+ ((cdr rest)
+ (setq form (copy-sequence form))
+ (setcdr (memq (car rest) form) nil)))
+ (setq rest nil)))))
+ ;;
+ ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
+ (if (eq 'cond (car-safe form))
+ (let ((clauses (cdr form)))
+ (if (and (consp (car clauses))
+ (null (cdr (car clauses))))
+ (list 'or (car (car clauses))
+ (byte-optimize-cond
+ (cons (car form) (cdr (cdr form)))))
+ form))
+ form))
+
+ (defun byte-optimize-if (form)
+ ;; (if <true-constant> <then> <else...>) ==> <then>
+ ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
+ ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
+ ;; (if <test> <then> nil) ==> (if <test> <then>)
+ (let ((clause (nth 1 form)))
+ (cond ((byte-compile-trueconstp clause)
+ (nth 2 form))
+ ((null clause)
+ (if (nthcdr 4 form)
+ (cons 'progn (nthcdr 3 form))
+ (nth 3 form)))
+ ((nth 2 form)
+ (if (equal '(nil) (nthcdr 3 form))
+ (list 'if clause (nth 2 form))
+ form))
+ ((or (nth 3 form) (nthcdr 4 form))
+ (list 'if
+ ;; Don't make a double negative;
+ ;; instead, take away the one that is there.
+ (if (and (consp clause) (memq (car clause) '(not null))
+ (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
+ (nth 1 clause)
+ (list 'not clause))
+ (if (nthcdr 4 form)
+ (cons 'progn (nthcdr 3 form))
+ (nth 3 form))))
+ (t
+ (list 'progn clause nil)))))
+
+ (defun byte-optimize-while (form)
+ (when (< (length form) 2)
+ (byte-compile-warn "too few arguments for `while'"))
+ (if (nth 1 form)
+ form))
+
+ (put 'and 'byte-optimizer 'byte-optimize-and)
+ (put 'or 'byte-optimizer 'byte-optimize-or)
+ (put 'cond 'byte-optimizer 'byte-optimize-cond)
+ (put 'if 'byte-optimizer 'byte-optimize-if)
+ (put 'while 'byte-optimizer 'byte-optimize-while)
+
+ ;; byte-compile-negation-optimizer lives in bytecomp.el
+ (put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
+ (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
+ (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
+
+
+ (defun byte-optimize-funcall (form)
+ ;; (funcall (lambda ...) ...) ==> ((lambda ...) ...)
+ ;; (funcall foo ...) ==> (foo ...)
+ (let ((fn (nth 1 form)))
+ (if (memq (car-safe fn) '(quote function))
+ (cons (nth 1 fn) (cdr (cdr form)))
+ form)))
+
+ (defun byte-optimize-apply (form)
+ ;; If the last arg is a literal constant, turn this into a funcall.
+ ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
+ (let ((fn (nth 1 form))
+ (last (nth (1- (length form)) form))) ; I think this really is fastest
+ (or (if (or (null last)
+ (eq (car-safe last) 'quote))
+ (if (listp (nth 1 last))
+ (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
+ (nconc (list 'funcall fn) butlast
+ (mapcar (lambda (x) (list 'quote x)) (nth 1 last))))
+ (byte-compile-warn
+ "last arg to apply can't be a literal atom: `%s'"
+ (prin1-to-string last))
+ nil))
+ form)))
+
+ (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
+ (put 'apply 'byte-optimizer 'byte-optimize-apply)
+
+
+ (put 'let 'byte-optimizer 'byte-optimize-letX)
+ (put 'let* 'byte-optimizer 'byte-optimize-letX)
+ (defun byte-optimize-letX (form)
+ (cond ((null (nth 1 form))
+ ;; No bindings
+ (cons 'progn (cdr (cdr form))))
+ ((or (nth 2 form) (nthcdr 3 form))
+ form)
+ ;; The body is nil
+ ((eq (car form) 'let)
+ (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
+ '(nil)))
+ (t
+ (let ((binds (reverse (nth 1 form))))
+ (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
+
+
+ (put 'nth 'byte-optimizer 'byte-optimize-nth)
+ (defun byte-optimize-nth (form)
+ (if (= (safe-length form) 3)
+ (if (memq (nth 1 form) '(0 1))
+ (list 'car (if (zerop (nth 1 form))
+ (nth 2 form)
+ (list 'cdr (nth 2 form))))
+ (byte-optimize-predicate form))
+ form))
+
+ (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
+ (defun byte-optimize-nthcdr (form)
+ (if (= (safe-length form) 3)
+ (if (memq (nth 1 form) '(0 1 2))
+ (let ((count (nth 1 form)))
+ (setq form (nth 2 form))
+ (while (>= (setq count (1- count)) 0)
+ (setq form (list 'cdr form)))
+ form)
+ (byte-optimize-predicate form))
+ form))
+
+ (put 'concat 'byte-optimizer 'byte-optimize-concat)
+ (defun byte-optimize-concat (form)
+ (let ((args (cdr form))
+ (constant t))
+ (while (and args constant)
+ (or (byte-compile-constp (car args))
+ (setq constant nil))
+ (setq args (cdr args)))
+ (if constant
+ (eval form)
+ form)))
+
+ ;; Avoid having to write forward-... with a negative arg for speed.
+ ;; Fixme: don't be limited to constant args.
+ (put 'backward-char 'byte-optimizer 'byte-optimize-backward-char)
+ (defun byte-optimize-backward-char (form)
+ (cond ((and (= 2 (safe-length form))
+ (numberp (nth 1 form)))
+ (list 'forward-char (eval (- (nth 1 form)))))
+ ((= 1 (safe-length form))
+ '(forward-char -1))
+ (t form)))
+
+ (put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
+ (defun byte-optimize-backward-word (form)
+ (cond ((and (= 2 (safe-length form))
+ (numberp (nth 1 form)))
+ (list 'forward-word (eval (- (nth 1 form)))))
+ ((= 1 (safe-length form))
+ '(forward-char -1))
+ (t form)))
+
+ (put 'char-before 'byte-optimizer 'byte-optimize-char-before)
+ (defun byte-optimize-char-before (form)
+ (cond ((= 2 (safe-length form))
+ `(char-after (1- ,(nth 1 form))))
+ ((= 1 (safe-length form))
+ '(char-after (1- (point))))
+ (t form)))
+
+ ;; Fixme: delete-char -> delete-region (byte-coded)
+ ;; optimize string-as-unibyte, string-as-multibyte, string-make-unibyte,
+ ;; string-make-multibyte for constant args.
+
+ (put 'featurep 'byte-optimizer 'byte-optimize-featurep)
+ (defun byte-optimize-featurep (form)
+ ;; Emacs-21's byte-code doesn't run under XEmacs anyway, so we can
+ ;; safely optimize away this test.
+ (if (equal '((quote xemacs)) (cdr-safe form))
+ nil
+ form))
+
+ (put 'set 'byte-optimizer 'byte-optimize-set)
+ (defun byte-optimize-set (form)
+ (let ((var (car-safe (cdr-safe form))))
+ (cond
+ ((and (eq (car-safe var) 'quote) (consp (cdr var)))
+ `(setq ,(cadr var) ,@(cddr form)))
+ ((and (eq (car-safe var) 'make-local-variable)
+ (eq (car-safe (setq var (car-safe (cdr var)))) 'quote)
+ (consp (cdr var)))
+ `(progn ,(cadr form) (setq ,(cadr var) ,@(cddr form))))
+ (t form))))
+
+ ;;; enumerating those functions which need not be called if the returned
+ ;;; value is not used. That is, something like
+ ;;; (progn (list (something-with-side-effects) (yow))
+ ;;; (foo))
+ ;;; may safely be turned into
+ ;;; (progn (progn (something-with-side-effects) (yow))
+ ;;; (foo))
+ ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
+
+ ;;; Some of these functions have the side effect of allocating memory
+ ;;; and it would be incorrect to replace two calls with one.
+ ;;; But we don't try to do those kinds of optimizations,
+ ;;; so it is safe to list such functions here.
+ ;;; Some of these functions return values that depend on environment
+ ;;; state, so that constant folding them would be wrong,
+ ;;; but we don't do constant folding based on this list.
+
+ ;;; However, at present the only optimization we normally do
+ ;;; is delete calls that need not occur, and we only do that
+ ;;; with the error-free functions.
+
+ ;;; I wonder if I missed any :-\)
+ (let ((side-effect-free-fns
+ '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
+ assoc assq
+ boundp buffer-file-name buffer-local-variables buffer-modified-p
+ buffer-substring byte-code-function-p
+ capitalize car-less-than-car car cdr ceiling char-after char-before
+ char-equal char-to-string char-width
+ compare-strings concat coordinates-in-window-p
+ copy-alist copy-sequence copy-marker cos count-lines
+ decdoe-char
+ decode-time default-boundp default-value documentation downcase
+ elt encode-char exp expt encode-time error-message-string
+ fboundp fceiling featurep ffloor
+ file-directory-p file-exists-p file-locked-p file-name-absolute-p
+ file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
+ float float-time floor format format-time-string frame-visible-p
+ fround ftruncate
+ get gethash get-buffer get-buffer-window getenv get-file-buffer
+ hash-table-count
+ int-to-string intern-soft
+ keymap-parent
+ length local-variable-if-set-p local-variable-p log log10 logand
+ logb logior lognot logxor lsh langinfo
+ make-list make-string make-symbol
+ marker-buffer max member memq min mod multibyte-char-to-unibyte
+ next-window nth nthcdr number-to-string
+ parse-colon-path plist-get plist-member
+ prefix-numeric-value previous-window prin1-to-string propertize
+ radians-to-degrees rassq rassoc read-from-string regexp-quote
+ region-beginning region-end reverse round
+ sin sqrt string string< string= string-equal string-lessp
string-to-char
+ string-to-int string-to-number substring sxhash symbol-function
+ symbol-name symbol-plist symbol-value string-make-unibyte
+ string-make-multibyte string-as-multibyte string-as-unibyte
+ string-to-multibyte
+ tan truncate
+ unibyte-char-to-multibyte upcase user-full-name
+ user-login-name user-original-login-name user-variable-p
+ vconcat
+ window-buffer window-dedicated-p window-edges window-height
+ window-hscroll window-minibuffer-p window-width
+ zerop))
+ (side-effect-and-error-free-fns
+ '(arrayp atom
+ bobp bolp bool-vector-p
+ buffer-end buffer-list buffer-size buffer-string bufferp
+ car-safe case-table-p cdr-safe char-or-string-p characterp
+ charsetp commandp cons consp
+ current-buffer current-global-map current-indentation
+ current-local-map current-minor-mode-maps current-time
+ current-time-string current-time-zone
+ eobp eolp eq equal eventp
+ floatp following-char framep
+ get-largest-window get-lru-window
+ hash-table-p
+ identity ignore integerp integer-or-marker-p interactive-p
+ invocation-directory invocation-name
+ keymapp
+ line-beginning-position line-end-position list listp
+ make-marker mark mark-marker markerp max-char
+ memory-limit minibuffer-window
+ mouse-movement-p
+ natnump nlistp not null number-or-marker-p numberp
+ one-window-p overlayp
+ point point-marker point-min point-max preceding-char primary-charset
+ processp
+ recent-keys recursion-depth
+ safe-length selected-frame selected-window sequencep
+ standard-case-table standard-syntax-table stringp subrp symbolp
+ syntax-table syntax-table-p
+ this-command-keys this-command-keys-vector this-single-command-keys
+ this-single-command-raw-keys
+ user-real-login-name user-real-uid user-uid
+ vector vectorp visible-frame-list
+ wholenump window-configuration-p window-live-p windowp)))
+ (while side-effect-free-fns
+ (put (car side-effect-free-fns) 'side-effect-free t)
+ (setq side-effect-free-fns (cdr side-effect-free-fns)))
+ (while side-effect-and-error-free-fns
+ (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free)
+ (setq side-effect-and-error-free-fns (cdr
side-effect-and-error-free-fns)))
+ nil)
+
+
+ (defun byte-compile-splice-in-already-compiled-code (form)
+ ;; form is (byte-code "..." [...] n)
+ (if (not (memq byte-optimize '(t lap)))
+ (byte-compile-normal-call form)
+ (byte-inline-lapcode
+ (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t))
+ (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form))
+ byte-compile-maxdepth))
+ (setq byte-compile-depth (1+ byte-compile-depth))))
+
+ (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code)
+
+
+ (defconst byte-constref-ops
+ '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
+
+ ;;; This function extracts the bitfields from variable-length opcodes.
+ ;;; Originally defined in disass.el (which no longer uses it.)
+
+ (defun disassemble-offset ()
+ "Don't call this!"
+ ;; fetch and return the offset for the current opcode.
+ ;; return nil if this opcode has no offset
+ ;; OP, PTR and BYTES are used and set dynamically
+ (defvar op)
+ (defvar ptr)
+ (defvar bytes)
+ (cond ((< op byte-nth)
+ (let ((tem (logand op 7)))
+ (setq op (logand op 248))
+ (cond ((eq tem 6)
+ (setq ptr (1+ ptr)) ;offset in next byte
+ (aref bytes ptr))
+ ((eq tem 7)
+ (setq ptr (1+ ptr)) ;offset in next 2 bytes
+ (+ (aref bytes ptr)
+ (progn (setq ptr (1+ ptr))
+ (lsh (aref bytes ptr) 8))))
+ (t tem)))) ;offset was in opcode
+ ((>= op byte-constant)
+ (prog1 (- op byte-constant) ;offset in opcode
+ (setq op byte-constant)))
+ ((and (>= op byte-constant2)
+ (<= op byte-goto-if-not-nil-else-pop))
+ (setq ptr (1+ ptr)) ;offset in next 2 bytes
+ (+ (aref bytes ptr)
+ (progn (setq ptr (1+ ptr))
+ (lsh (aref bytes ptr) 8))))
+ ((and (>= op byte-listN)
+ (<= op byte-insertN))
+ (setq ptr (1+ ptr)) ;offset in next byte
+ (aref bytes ptr))))
+
+
+ ;;; This de-compiler is used for inline expansion of compiled functions,
+ ;;; and by the disassembler.
+ ;;;
+ ;;; This list contains numbers, which are pc values,
+ ;;; before each instruction.
+ (defun byte-decompile-bytecode (bytes constvec)
+ "Turns BYTECODE into lapcode, referring to CONSTVEC."
+ (let ((byte-compile-constants nil)
+ (byte-compile-variables nil)
+ (byte-compile-tag-number 0))
+ (byte-decompile-bytecode-1 bytes constvec)))
+
+ ;; As byte-decompile-bytecode, but updates
+ ;; byte-compile-{constants, variables, tag-number}.
+ ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
+ ;; with `goto's destined for the end of the code.
+ ;; That is for use by the compiler.
+ ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
+ ;; In that case, we put a pc value into the list
+ ;; before each insn (or its label).
+ (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
+ (let ((length (length bytes))
+ (ptr 0) optr tag tags op offset
+ lap tmp
+ endtag
+ (retcount 0))
+ (while (not (= ptr length))
+ (or make-spliceable
+ (setq lap (cons ptr lap)))
+ (setq op (aref bytes ptr)
+ optr ptr
+ offset (disassemble-offset)) ; this does dynamic-scope magic
+ (setq op (aref byte-code-vector op))
+ (cond ((memq op byte-goto-ops)
+ ;; it's a pc
+ (setq offset
+ (cdr (or (assq offset tags)
+ (car (setq tags
+ (cons (cons offset
+ (byte-compile-make-tag))
+ tags)))))))
+ ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t)
+ ((memq op byte-constref-ops)))
+ (setq tmp (if (>= offset (length constvec))
+ (list 'out-of-range offset)
+ (aref constvec offset))
+ offset (if (eq op 'byte-constant)
+ (byte-compile-get-constant tmp)
+ (or (assq tmp byte-compile-variables)
+ (car (setq byte-compile-variables
+ (cons (list tmp)
+ byte-compile-variables)))))))
+ ((and make-spliceable
+ (eq op 'byte-return))
+ (if (= ptr (1- length))
+ (setq op nil)
+ (setq offset (or endtag (setq endtag (byte-compile-make-tag)))
+ op 'byte-goto))))
+ ;; lap = ( [ (pc . (op . arg)) ]* )
+ (setq lap (cons (cons optr (cons op (or offset 0)))
+ lap))
+ (setq ptr (1+ ptr)))
+ ;; take off the dummy nil op that we replaced a trailing "return" with.
+ (let ((rest lap))
+ (while rest
+ (cond ((numberp (car rest)))
+ ((setq tmp (assq (car (car rest)) tags))
+ ;; this addr is jumped to
+ (setcdr rest (cons (cons nil (cdr tmp))
+ (cdr rest)))
+ (setq tags (delq tmp tags))
+ (setq rest (cdr rest))))
+ (setq rest (cdr rest))))
+ (if tags (error "optimizer error: missed tags %s" tags))
+ (if (null (car (cdr (car lap))))
+ (setq lap (cdr lap)))
+ (if endtag
+ (setq lap (cons (cons nil endtag) lap)))
+ ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
+ (mapcar (function (lambda (elt)
+ (if (numberp elt)
+ elt
+ (cdr elt))))
+ (nreverse lap))))
+
+
+ ;;; peephole optimizer
+
+ (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
+
+ (defconst byte-conditional-ops
+ '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
+ byte-goto-if-not-nil-else-pop))
+
+ (defconst byte-after-unbind-ops
+ '(byte-constant byte-dup
+ byte-symbolp byte-consp byte-stringp byte-listp byte-numberp
byte-integerp
+ byte-eq byte-not
+ byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
+ byte-interactive-p)
+ ;; How about other side-effect-free-ops? Is it safe to move an
+ ;; error invocation (such as from nth) out of an unwind-protect?
+ ;; No, it is not, because the unwind-protect forms can alter
+ ;; the inside of the object to which nth would apply.
+ ;; For the same reason, byte-equal was deleted from this list.
+ "Byte-codes that can be moved past an unbind.")
+
+ (defconst byte-compile-side-effect-and-error-free-ops
+ '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
+ byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
+ byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
+ byte-point-min byte-following-char byte-preceding-char
+ byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
+ byte-current-buffer byte-interactive-p))
+
+ (defconst byte-compile-side-effect-free-ops
+ (nconc
+ '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
+ byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
+ byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
+ byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
+ byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
+ byte-member byte-assq byte-quo byte-rem)
+ byte-compile-side-effect-and-error-free-ops))
+
+ ;;; This crock is because of the way DEFVAR_BOOL variables work.
+ ;;; Consider the code
+ ;;;
+ ;;; (defun foo (flag)
+ ;;; (let ((old-pop-ups pop-up-windows)
+ ;;; (pop-up-windows flag))
+ ;;; (cond ((not (eq pop-up-windows old-pop-ups))
+ ;;; (setq old-pop-ups pop-up-windows)
+ ;;; ...))))
+ ;;;
+ ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
+ ;;; something else. But if we optimize
+ ;;;
+ ;;; varref flag
+ ;;; varbind pop-up-windows
+ ;;; varref pop-up-windows
+ ;;; not
+ ;;; to
+ ;;; varref flag
+ ;;; dup
+ ;;; varbind pop-up-windows
+ ;;; not
+ ;;;
+ ;;; we break the program, because it will appear that pop-up-windows and
+ ;;; old-pop-ups are not EQ when really they are. So we have to know what
+ ;;; the BOOL variables are, and not perform this optimization on them.
+
+ ;;; The variable `byte-boolean-vars' is now primitive and updated
+ ;;; automatically by DEFVAR_BOOL.
+
+ (defun byte-optimize-lapcode (lap &optional for-effect)
+ "Simple peephole optimizer. LAP is both modified and returned."
+ (let (lap0
+ lap1
+ lap2
+ (keep-going 'first-time)
+ (add-depth 0)
+ rest tmp tmp2 tmp3
+ (side-effect-free (if byte-compile-delete-errors
+ byte-compile-side-effect-free-ops
+ byte-compile-side-effect-and-error-free-ops)))
+ (while keep-going
+ (or (eq keep-going 'first-time)
+ (byte-compile-log-lap " ---- next pass"))
+ (setq rest lap
+ keep-going nil)
+ (while rest
+ (setq lap0 (car rest)
+ lap1 (nth 1 rest)
+ lap2 (nth 2 rest))
+
+ ;; You may notice that sequences like "dup varset discard" are
+ ;; optimized but sequences like "dup varset TAG1: discard" are not.
+ ;; You may be tempted to change this; resist that temptation.
+ (cond ;;
+ ;; <side-effect-free> pop --> <deleted>
+ ;; ...including:
+ ;; const-X pop --> <deleted>
+ ;; varref-X pop --> <deleted>
+ ;; dup pop --> <deleted>
+ ;;
+ ((and (eq 'byte-discard (car lap1))
+ (memq (car lap0) side-effect-free))
+ (setq keep-going t)
+ (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
+ (setq rest (cdr rest))
+ (cond ((= tmp 1)
+ (byte-compile-log-lap
+ " %s discard\t-->\t<deleted>" lap0)
+ (setq lap (delq lap0 (delq lap1 lap))))
+ ((= tmp 0)
+ (byte-compile-log-lap
+ " %s discard\t-->\t<deleted> discard" lap0)
+ (setq lap (delq lap0 lap)))
+ ((= tmp -1)
+ (byte-compile-log-lap
+ " %s discard\t-->\tdiscard discard" lap0)
+ (setcar lap0 'byte-discard)
+ (setcdr lap0 0))
+ ((error "Optimizer error: too much on the stack"))))
+ ;;
+ ;; goto*-X X: --> X:
+ ;;
+ ((and (memq (car lap0) byte-goto-ops)
+ (eq (cdr lap0) lap1))
+ (cond ((eq (car lap0) 'byte-goto)
+ (setq lap (delq lap0 lap))
+ (setq tmp "<deleted>"))
+ ((memq (car lap0) byte-goto-always-pop-ops)
+ (setcar lap0 (setq tmp 'byte-discard))
+ (setcdr lap0 0))
+ ((error "Depth conflict at tag %d" (nth 2 lap0))))
+ (and (memq byte-optimize-log '(t byte))
+ (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
+ (nth 1 lap1) (nth 1 lap1)
+ tmp (nth 1 lap1)))
+ (setq keep-going t))
+ ;;
+ ;; varset-X varref-X --> dup varset-X
+ ;; varbind-X varref-X --> dup varbind-X
+ ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
+ ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
+ ;; The latter two can enable other optimizations.
+ ;;
+ ((and (eq 'byte-varref (car lap2))
+ (eq (cdr lap1) (cdr lap2))
+ (memq (car lap1) '(byte-varset byte-varbind)))
+ (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars))
+ (not (eq (car lap0) 'byte-constant)))
+ nil
+ (setq keep-going t)
+ (if (memq (car lap0) '(byte-constant byte-dup))
+ (progn
+ (setq tmp (if (or (not tmp)
+ (byte-compile-const-symbol-p
+ (car (cdr lap0))))
+ (cdr lap0)
+ (byte-compile-get-constant t)))
+ (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
+ lap0 lap1 lap2 lap0 lap1
+ (cons (car lap0) tmp))
+ (setcar lap2 (car lap0))
+ (setcdr lap2 tmp))
+ (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
+ (setcar lap2 (car lap1))
+ (setcar lap1 'byte-dup)
+ (setcdr lap1 0)
+ ;; The stack depth gets locally increased, so we will
+ ;; increase maxdepth in case depth = maxdepth here.
+ ;; This can cause the third argument to byte-code to
+ ;; be larger than necessary.
+ (setq add-depth 1))))
+ ;;
+ ;; dup varset-X discard --> varset-X
+ ;; dup varbind-X discard --> varbind-X
+ ;; (the varbind variant can emerge from other optimizations)
+ ;;
+ ((and (eq 'byte-dup (car lap0))
+ (eq 'byte-discard (car lap2))
+ (memq (car lap1) '(byte-varset byte-varbind)))
+ (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
+ (setq keep-going t
+ rest (cdr rest))
+ (setq lap (delq lap0 (delq lap2 lap))))
+ ;;
+ ;; not goto-X-if-nil --> goto-X-if-non-nil
+ ;; not goto-X-if-non-nil --> goto-X-if-nil
+ ;;
+ ;; it is wrong to do the same thing for the -else-pop variants.
+ ;;
+ ((and (eq 'byte-not (car lap0))
+ (or (eq 'byte-goto-if-nil (car lap1))
+ (eq 'byte-goto-if-not-nil (car lap1))))
+ (byte-compile-log-lap " not %s\t-->\t%s"
+ lap1
+ (cons
+ (if (eq (car lap1) 'byte-goto-if-nil)
+ 'byte-goto-if-not-nil
+ 'byte-goto-if-nil)
+ (cdr lap1)))
+ (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
+ 'byte-goto-if-not-nil
+ 'byte-goto-if-nil))
+ (setq lap (delq lap0 lap))
+ (setq keep-going t))
+ ;;
+ ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
+ ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
+ ;;
+ ;; it is wrong to do the same thing for the -else-pop variants.
+ ;;
+ ((and (or (eq 'byte-goto-if-nil (car lap0))
+ (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX
+ (eq 'byte-goto (car lap1)) ; gotoY
+ (eq (cdr lap0) lap2)) ; TAG X
+ (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
+ 'byte-goto-if-not-nil 'byte-goto-if-nil)))
+ (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
+ lap0 lap1 lap2
+ (cons inverse (cdr lap1)) lap2)
+ (setq lap (delq lap0 lap))
+ (setcar lap1 inverse)
+ (setq keep-going t)))
+ ;;
+ ;; const goto-if-* --> whatever
+ ;;
+ ((and (eq 'byte-constant (car lap0))
+ (memq (car lap1) byte-conditional-ops))
+ (cond ((if (or (eq (car lap1) 'byte-goto-if-nil)
+ (eq (car lap1) 'byte-goto-if-nil-else-pop))
+ (car (cdr lap0))
+ (not (car (cdr lap0))))
+ (byte-compile-log-lap " %s %s\t-->\t<deleted>"
+ lap0 lap1)
+ (setq rest (cdr rest)
+ lap (delq lap0 (delq lap1 lap))))
+ (t
+ (if (memq (car lap1) byte-goto-always-pop-ops)
+ (progn
+ (byte-compile-log-lap " %s %s\t-->\t%s"
+ lap0 lap1 (cons 'byte-goto (cdr lap1)))
+ (setq lap (delq lap0 lap)))
+ (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
+ (cons 'byte-goto (cdr lap1))))
+ (setcar lap1 'byte-goto)))
+ (setq keep-going t))
+ ;;
+ ;; varref-X varref-X --> varref-X dup
+ ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
+ ;; We don't optimize the const-X variations on this here,
+ ;; because that would inhibit some goto optimizations; we
+ ;; optimize the const-X case after all other optimizations.
+ ;;
+ ((and (eq 'byte-varref (car lap0))
+ (progn
+ (setq tmp (cdr rest))
+ (while (eq (car (car tmp)) 'byte-dup)
+ (setq tmp (cdr tmp)))
+ t)
+ (eq (cdr lap0) (cdr (car tmp)))
+ (eq 'byte-varref (car (car tmp))))
+ (if (memq byte-optimize-log '(t byte))
+ (let ((str ""))
+ (setq tmp2 (cdr rest))
+ (while (not (eq tmp tmp2))
+ (setq tmp2 (cdr tmp2)
+ str (concat str " dup")))
+ (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
+ lap0 str lap0 lap0 str)))
+ (setq keep-going t)
+ (setcar (car tmp) 'byte-dup)
+ (setcdr (car tmp) 0)
+ (setq rest tmp))
+ ;;
+ ;; TAG1: TAG2: --> TAG1: <deleted>
+ ;; (and other references to TAG2 are replaced with TAG1)
+ ;;
+ ((and (eq (car lap0) 'TAG)
+ (eq (car lap1) 'TAG))
+ (and (memq byte-optimize-log '(t byte))
+ (byte-compile-log " adjacent tags %d and %d merged"
+ (nth 1 lap1) (nth 1 lap0)))
+ (setq tmp3 lap)
+ (while (setq tmp2 (rassq lap0 tmp3))
+ (setcdr tmp2 lap1)
+ (setq tmp3 (cdr (memq tmp2 tmp3))))
+ (setq lap (delq lap0 lap)
+ keep-going t))
+ ;;
+ ;; unused-TAG: --> <deleted>
+ ;;
+ ((and (eq 'TAG (car lap0))
+ (not (rassq lap0 lap)))
+ (and (memq byte-optimize-log '(t byte))
+ (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
+ (setq lap (delq lap0 lap)
+ keep-going t))
+ ;;
+ ;; goto ... --> goto <delete until TAG or end>
+ ;; return ... --> return <delete until TAG or end>
+ ;;
+ ((and (memq (car lap0) '(byte-goto byte-return))
+ (not (memq (car lap1) '(TAG nil))))
+ (setq tmp rest)
+ (let ((i 0)
+ (opt-p (memq byte-optimize-log '(t lap)))
+ str deleted)
+ (while (and (setq tmp (cdr tmp))
+ (not (eq 'TAG (car (car tmp)))))
+ (if opt-p (setq deleted (cons (car tmp) deleted)
+ str (concat str " %s")
+ i (1+ i))))
+ (if opt-p
+ (let ((tagstr
+ (if (eq 'TAG (car (car tmp)))
+ (format "%d:" (car (cdr (car tmp))))
+ (or (car tmp) ""))))
+ (if (< i 6)
+ (apply 'byte-compile-log-lap-1
+ (concat " %s" str
+ " %s\t-->\t%s <deleted> %s")
+ lap0
+ (nconc (nreverse deleted)
+ (list tagstr lap0 tagstr)))
+ (byte-compile-log-lap
+ " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
+ lap0 i (if (= i 1) "" "s")
+ tagstr lap0 tagstr))))
+ (rplacd rest tmp))
+ (setq keep-going t))
+ ;;
+ ;; <safe-op> unbind --> unbind <safe-op>
+ ;; (this may enable other optimizations.)
+ ;;
+ ((and (eq 'byte-unbind (car lap1))
+ (memq (car lap0) byte-after-unbind-ops))
+ (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
+ (setcar rest lap1)
+ (setcar (cdr rest) lap0)
+ (setq keep-going t))
+ ;;
+ ;; varbind-X unbind-N --> discard unbind-(N-1)
+ ;; save-excursion unbind-N --> unbind-(N-1)
+ ;; save-restriction unbind-N --> unbind-(N-1)
+ ;;
+ ((and (eq 'byte-unbind (car lap1))
+ (memq (car lap0) '(byte-varbind byte-save-excursion
+ byte-save-restriction))
+ (< 0 (cdr lap1)))
+ (if (zerop (setcdr lap1 (1- (cdr lap1))))
+ (delq lap1 rest))
+ (if (eq (car lap0) 'byte-varbind)
+ (setcar rest (cons 'byte-discard 0))
+ (setq lap (delq lap0 lap)))
+ (byte-compile-log-lap " %s %s\t-->\t%s %s"
+ lap0 (cons (car lap1) (1+ (cdr lap1)))
+ (if (eq (car lap0) 'byte-varbind)
+ (car rest)
+ (car (cdr rest)))
+ (if (and (/= 0 (cdr lap1))
+ (eq (car lap0) 'byte-varbind))
+ (car (cdr rest))
+ ""))
+ (setq keep-going t))
+ ;;
+ ;; goto*-X ... X: goto-Y --> goto*-Y
+ ;; goto-X ... X: return --> return
+ ;;
+ ((and (memq (car lap0) byte-goto-ops)
+ (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
+ '(byte-goto byte-return)))
+ (cond ((and (not (eq tmp lap0))
+ (or (eq (car lap0) 'byte-goto)
+ (eq (car tmp) 'byte-goto)))
+ (byte-compile-log-lap " %s [%s]\t-->\t%s"
+ (car lap0) tmp tmp)
+ (if (eq (car tmp) 'byte-return)
+ (setcar lap0 'byte-return))
+ (setcdr lap0 (cdr tmp))
+ (setq keep-going t))))
+ ;;
+ ;; goto-*-else-pop X ... X: goto-if-* --> whatever
+ ;; goto-*-else-pop X ... X: discard --> whatever
+ ;;
+ ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
+ byte-goto-if-not-nil-else-pop))
+ (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
+ (eval-when-compile
+ (cons 'byte-discard byte-conditional-ops)))
+ (not (eq lap0 (car tmp))))
+ (setq tmp2 (car tmp))
+ (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
+ byte-goto-if-nil)
+ (byte-goto-if-not-nil-else-pop
+ byte-goto-if-not-nil))))
+ (if (memq (car tmp2) tmp3)
+ (progn (setcar lap0 (car tmp2))
+ (setcdr lap0 (cdr tmp2))
+ (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
+ (car lap0) tmp2 lap0))
+ ;; Get rid of the -else-pop's and jump one step further.
+ (or (eq 'TAG (car (nth 1 tmp)))
+ (setcdr tmp (cons (byte-compile-make-tag)
+ (cdr tmp))))
+ (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
+ (car lap0) tmp2 (nth 1 tmp3))
+ (setcar lap0 (nth 1 tmp3))
+ (setcdr lap0 (nth 1 tmp)))
+ (setq keep-going t))
+ ;;
+ ;; const goto-X ... X: goto-if-* --> whatever
+ ;; const goto-X ... X: discard --> whatever
+ ;;
+ ((and (eq (car lap0) 'byte-constant)
+ (eq (car lap1) 'byte-goto)
+ (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
+ (eval-when-compile
+ (cons 'byte-discard byte-conditional-ops)))
+ (not (eq lap1 (car tmp))))
+ (setq tmp2 (car tmp))
+ (cond ((memq (car tmp2)
+ (if (null (car (cdr lap0)))
+ '(byte-goto-if-nil byte-goto-if-nil-else-pop)
+ '(byte-goto-if-not-nil
+ byte-goto-if-not-nil-else-pop)))
+ (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
+ lap0 tmp2 lap0 tmp2)
+ (setcar lap1 (car tmp2))
+ (setcdr lap1 (cdr tmp2))
+ ;; Let next step fix the (const,goto-if*) sequence.
+ (setq rest (cons nil rest)))
+ (t
+ ;; Jump one step further
+ (byte-compile-log-lap
+ " %s goto [%s]\t-->\t<deleted> goto <skip>"
+ lap0 tmp2)
+ (or (eq 'TAG (car (nth 1 tmp)))
+ (setcdr tmp (cons (byte-compile-make-tag)
+ (cdr tmp))))
+ (setcdr lap1 (car (cdr tmp)))
+ (setq lap (delq lap0 lap))))
+ (setq keep-going t))
+ ;;
+ ;; X: varref-Y ... varset-Y goto-X -->
+ ;; X: varref-Y Z: ... dup varset-Y goto-Z
+ ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
+ ;; (This is so usual for while loops that it is worth handling).
+ ;;
+ ((and (eq (car lap1) 'byte-varset)
+ (eq (car lap2) 'byte-goto)
+ (not (memq (cdr lap2) rest)) ;Backwards jump
+ (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
+ 'byte-varref)
+ (eq (cdr (car tmp)) (cdr lap1))
+ (not (memq (car (cdr lap1)) byte-boolean-vars)))
+ ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
+ (let ((newtag (byte-compile-make-tag)))
+ (byte-compile-log-lap
+ " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
+ (nth 1 (cdr lap2)) (car tmp)
+ lap1 lap2
+ (nth 1 (cdr lap2)) (car tmp)
+ (nth 1 newtag) 'byte-dup lap1
+ (cons 'byte-goto newtag)
+ )
+ (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
+ (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
+ (setq add-depth 1)
+ (setq keep-going t))
+ ;;
+ ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
+ ;; (This can pull the loop test to the end of the loop)
+ ;;
+ ((and (eq (car lap0) 'byte-goto)
+ (eq (car lap1) 'TAG)
+ (eq lap1
+ (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
+ (memq (car (car tmp))
+ '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
+ byte-goto-if-nil-else-pop)))
+ ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
+ ;; lap0 lap1 (cdr lap0) (car tmp))
+ (let ((newtag (byte-compile-make-tag)))
+ (byte-compile-log-lap
+ "%s %s: ... %s: %s\t-->\t%s ... %s:"
+ lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
+ (cons (cdr (assq (car (car tmp))
+ '((byte-goto-if-nil . byte-goto-if-not-nil)
+ (byte-goto-if-not-nil . byte-goto-if-nil)
+ (byte-goto-if-nil-else-pop .
+ byte-goto-if-not-nil-else-pop)
+ (byte-goto-if-not-nil-else-pop .
+ byte-goto-if-nil-else-pop))))
+ newtag)
+
+ (nth 1 newtag)
+ )
+ (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
+ (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
+ ;; We can handle this case but not the -if-not-nil case,
+ ;; because we won't know which non-nil constant to push.
+ (setcdr rest (cons (cons 'byte-constant
+ (byte-compile-get-constant nil))
+ (cdr rest))))
+ (setcar lap0 (nth 1 (memq (car (car tmp))
+ '(byte-goto-if-nil-else-pop
+ byte-goto-if-not-nil
+ byte-goto-if-nil
+ byte-goto-if-not-nil
+ byte-goto byte-goto))))
+ )
+ (setq keep-going t))
+ )
+ (setq rest (cdr rest)))
+ )
+ ;; Cleanup stage:
+ ;; Rebuild byte-compile-constants / byte-compile-variables.
+ ;; Simple optimizations that would inhibit other optimizations if they
+ ;; were done in the optimizing loop, and optimizations which there is no
+ ;; need to do more than once.
+ (setq byte-compile-constants nil
+ byte-compile-variables nil)
+ (setq rest lap)
+ (while rest
+ (setq lap0 (car rest)
+ lap1 (nth 1 rest))
+ (if (memq (car lap0) byte-constref-ops)
+ (if (or (eq (car lap0) 'byte-constant)
+ (eq (car lap0) 'byte-constant2))
+ (unless (memq (cdr lap0) byte-compile-constants)
+ (setq byte-compile-constants (cons (cdr lap0)
+ byte-compile-constants)))
+ (unless (memq (cdr lap0) byte-compile-variables)
+ (setq byte-compile-variables (cons (cdr lap0)
+ byte-compile-variables)))))
+ (cond (;;
+ ;; const-C varset-X const-C --> const-C dup varset-X
+ ;; const-C varbind-X const-C --> const-C dup varbind-X
+ ;;
+ (and (eq (car lap0) 'byte-constant)
+ (eq (car (nth 2 rest)) 'byte-constant)
+ (eq (cdr lap0) (cdr (nth 2 rest)))
+ (memq (car lap1) '(byte-varbind byte-varset)))
+ (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
+ lap0 lap1 lap0 lap0 lap1)
+ (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
+ (setcar (cdr rest) (cons 'byte-dup 0))
+ (setq add-depth 1))
+ ;;
+ ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
+ ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
+ ;;
+ ((memq (car lap0) '(byte-constant byte-varref))
+ (setq tmp rest
+ tmp2 nil)
+ (while (progn
+ (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
+ (and (eq (cdr lap0) (cdr (car tmp)))
+ (eq (car lap0) (car (car tmp)))))
+ (setcar tmp (cons 'byte-dup 0))
+ (setq tmp2 t))
+ (if tmp2
+ (byte-compile-log-lap
+ " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
+ ;;
+ ;; unbind-N unbind-M --> unbind-(N+M)
+ ;;
+ ((and (eq 'byte-unbind (car lap0))
+ (eq 'byte-unbind (car lap1)))
+ (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
+ (cons 'byte-unbind
+ (+ (cdr lap0) (cdr lap1))))
+ (setq keep-going t)
+ (setq lap (delq lap0 lap))
+ (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
+ )
+ (setq rest (cdr rest)))
+ (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
+ lap)
+
+ (provide 'byte-opt)
+
+
+ ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
+ ;; itself, compile some of its most used recursive functions (at load time).
+ ;;
+ (eval-when-compile
+ (or (byte-code-function-p (symbol-function 'byte-optimize-form))
+ (assq 'byte-code (symbol-function 'byte-optimize-form))
+ (let ((byte-optimize nil)
+ (byte-compile-warnings nil))
+ (mapcar (lambda (x)
+ (or noninteractive (message "compiling %s..." x))
+ (byte-compile x)
+ (or noninteractive (message "compiling %s...done" x)))
+ '(byte-optimize-form
+ byte-optimize-body
+ byte-optimize-predicate
+ byte-optimize-binary-predicate
+ ;; Inserted some more than necessary, to speed it up.
+ byte-optimize-form-code-walker
+ byte-optimize-lapcode))))
+ nil)
+
+ ;;; byte-opt.el ends here
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- [Emacs-diffs] Changes to emacs/lisp/emacs-lisp/byte-opt.el [emacs-unicode-2],
Kenichi Handa <=