1 ;;; byte-optimize.el --- the optimization passes of the emacs-lisp byte compiler.
3 ;;; Copyright (c) 1991, 1994 Free Software Foundation, Inc.
5 ;; Authors: Jamie Zawinski <jwz@jwz.org>
6 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
7 ;; Martin Buchholz <martin@xemacs.org>
10 ;; This file is part of XEmacs.
12 ;; XEmacs is free software; you can redistribute it and/or modify it
13 ;; under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation; either version 2, or (at your option)
17 ;; XEmacs is distributed in the hope that it will be useful, but
18 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 ;; General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with XEmacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
25 ;; Boston, MA 02111-1307, USA.
27 ;;; Synched up with: FSF 20.7.
31 ;; ========================================================================
32 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
33 ;; You can, however, make a faster pig."
35 ;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code
36 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
37 ;; still not going to make it go faster than 70 mph, but it might be easier
43 ;; (apply #'(lambda (x &rest y) ...) 1 (foo))
45 ;; maintain a list of functions known not to access any global variables
46 ;; (actually, give them a 'dynamically-safe property) and then
47 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
48 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
49 ;; by recursing on this, we might be able to eliminate the entire let.
50 ;; However certain variables should never have their bindings optimized
51 ;; away, because they affect everything.
52 ;; (put 'debug-on-error 'binding-is-magic t)
53 ;; (put 'debug-on-abort 'binding-is-magic t)
54 ;; (put 'debug-on-next-call 'binding-is-magic t)
55 ;; (put 'mocklisp-arguments 'binding-is-magic t)
56 ;; (put 'inhibit-quit 'binding-is-magic t)
57 ;; (put 'quit-flag 'binding-is-magic t)
58 ;; (put 't 'binding-is-magic t)
59 ;; (put 'nil 'binding-is-magic t)
61 ;; (put 'gc-cons-threshold 'binding-is-magic t)
62 ;; (put 'track-mouse 'binding-is-magic t)
65 ;; Simple defsubsts often produce forms like
66 ;; (let ((v1 (f1)) (v2 (f2)) ...)
68 ;; It would be nice if we could optimize this to
70 ;; but we can't unless FN is dynamically-safe (it might be dynamically
71 ;; referring to the bindings that the lambda arglist established.)
72 ;; One of the uncountable lossages introduced by dynamic scope...
74 ;; Maybe there should be a control-structure that says "turn on
75 ;; fast-and-loose type-assumptive optimizations here." Then when
76 ;; we see a form like (car foo) we can from then on assume that
77 ;; the variable foo is of type cons, and optimize based on that.
78 ;; But, this won't win much because of (you guessed it) dynamic
79 ;; scope. Anything down the stack could change the value.
80 ;; (Another reason it doesn't work is that it is perfectly valid
81 ;; to call car with a null argument.) A better approach might
82 ;; be to allow type-specification of the form
83 ;; (put 'foo 'arg-types '(float (list integer) dynamic))
84 ;; (put 'foo 'result-type 'bool)
85 ;; It should be possible to have these types checked to a certain
88 ;; collapse common subexpressions
90 ;; It would be nice if redundant sequences could be factored out as well,
91 ;; when they are known to have no side-effects:
92 ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
93 ;; but beware of traps like
94 ;; (cons (list x y) (list x y))
96 ;; Tail-recursion elimination is not really possible in Emacs Lisp.
97 ;; Tail-recursion elimination is almost always impossible when all variables
98 ;; have dynamic scope, but given that the "return" byteop requires the
99 ;; binding stack to be empty (rather than emptying it itself), there can be
100 ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
101 ;; make any bindings.
103 ;; Here is an example of an Emacs Lisp function which could safely be
104 ;; byte-compiled tail-recursively:
106 ;; (defun tail-map (fn list)
108 ;; (funcall fn (car list))
109 ;; (tail-map fn (cdr list)))))
111 ;; However, if there was even a single let-binding around the COND,
112 ;; it could not be byte-compiled, because there would be an "unbind"
113 ;; byte-op between the final "call" and "return." Adding a
114 ;; Bunbind_all byteop would fix this.
116 ;; (defun foo (x y z) ... (foo a b c))
117 ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
118 ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
119 ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
121 ;; this also can be considered tail recursion:
123 ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
124 ;; could generalize this by doing the optimization
125 ;; (goto X) ... X: (return) --> (return)
127 ;; But this doesn't solve all of the problems: although by doing tail-
128 ;; recursion elimination in this way, the call-stack does not grow, the
129 ;; binding-stack would grow with each recursive step, and would eventually
130 ;; overflow. I don't believe there is any way around this without lexical
133 ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
135 ;; Idea: the form (lexical-scope) in a file means that the file may be
136 ;; compiled lexically. This proclamation is file-local. Then, within
137 ;; that file, "let" would establish lexical bindings, and "let-dynamic"
138 ;; would do things the old way. (Or we could use CL "declare" forms.)
139 ;; We'd have to notice defvars and defconsts, since those variables should
140 ;; always be dynamic, and attempting to do a lexical binding of them
141 ;; should simply do a dynamic binding instead.
142 ;; But! We need to know about variables that were not necessarily defvarred
143 ;; in the file being compiled (doing a boundp check isn't good enough.)
144 ;; Fdefvar() would have to be modified to add something to the plist.
146 ;; A major disadvantage of this scheme is that the interpreter and compiler
147 ;; would have different semantics for files compiled with (dynamic-scope).
148 ;; Since this would be a file-local optimization, there would be no way to
149 ;; modify the interpreter to obey this (unless the loader was hacked
150 ;; in some grody way, but that's a really bad idea.)
152 ;; HA! RMS removed the following paragraph from his version of
155 ;; Really the Right Thing is to make lexical scope the default across
156 ;; the board, in the interpreter and compiler, and just FIX all of
157 ;; the code that relies on dynamic scope of non-defvarred variables.
159 ;; Other things to consider:
161 ;; Associative math should recognize subcalls to identical function:
162 ;;(disassemble #'(lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
163 ;; This should generate the same as (1+ x) and (1- x)
165 ;;(disassemble #'(lambda (x) (cons (+ x 1) (- x 1))))
166 ;; An awful lot of functions always return a non-nil value. If they're
167 ;; error free also they may act as true-constants.
169 ;;(disassemble #'(lambda (x) (and (point) (foo))))
171 ;; - all but one arguments to a function are constant
172 ;; - the non-constant argument is an if-expression (cond-expression?)
173 ;; then the outer function can be distributed. If the guarding
174 ;; condition is side-effect-free [assignment-free] then the other
175 ;; arguments may be any expressions. Since, however, the code size
176 ;; can increase this way they should be "simple". Compare:
178 ;;(disassemble #'(lambda (x) (eq (if (point) 'a 'b) 'c)))
179 ;;(disassemble #'(lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
181 ;; (car (cons A B)) -> (prog1 A B)
182 ;;(disassemble #'(lambda (x) (car (cons (foo) 42))))
184 ;; (cdr (cons A B)) -> (progn A B)
185 ;;(disassemble #'(lambda (x) (cdr (cons 42 (foo)))))
187 ;; (car (list A B ...)) -> (prog1 A ... B)
188 ;;(disassemble #'(lambda (x) (car (list (foo) 42 (bar)))))
190 ;; (cdr (list A B ...)) -> (progn A (list B ...))
191 ;;(disassemble #'(lambda (x) (cdr (list 42 (foo) (bar)))))
196 (require 'byte-compile "bytecomp")
198 (defun byte-compile-log-lap-1 (format &rest args)
199 (if (aref byte-code-vector 0)
200 (error "The old version of the disassembler is loaded. Reload new-bytecomp as well."))
202 (apply 'format format
206 (if (not (consp arg))
207 (if (and (symbolp arg)
208 (string-match "^byte-" (symbol-name arg)))
209 (intern (substring (symbol-name arg) 5))
211 (if (integerp (setq c (car arg)))
212 (error "non-symbolic byte-op %s" c))
215 (setq a (cond ((memq c byte-goto-ops)
216 (car (cdr (cdr arg))))
217 ((memq c byte-constref-ops)
220 (setq c (symbol-name c))
221 (if (string-match "^byte-." c)
222 (setq c (intern (substring c 5)))))
223 (if (eq c 'constant) (setq c 'const))
224 (if (and (eq (cdr arg) 0)
225 (not (memq c '(unbind call const))))
227 (format "(%s %s)" c a))))
230 (defmacro byte-compile-log-lap (format-string &rest args)
232 '(memq byte-optimize-log '(t byte))
233 (cons 'byte-compile-log-lap-1
234 (cons format-string args))))
237 ;;; byte-compile optimizers to support inlining
239 (put 'inline 'byte-optimizer 'byte-optimize-inline-handler)
241 (defun byte-optimize-inline-handler (form)
242 "byte-optimize-handler for the `inline' special-form."
247 (let ((fn (car-safe sexp)))
248 (if (and (symbolp fn)
249 (or (cdr (assq fn byte-compile-function-environment))
251 (not (or (cdr (assq fn byte-compile-macro-environment))
252 (and (consp (setq fn (symbol-function fn)))
253 (eq (car fn) 'macro))
255 (byte-compile-inline-expand sexp)
260 ;; Splice the given lap code into the current instruction stream.
261 ;; If it has any labels in it, you're responsible for making sure there
262 ;; are no collisions, and that byte-compile-tag-number is reasonable
263 ;; after this is spliced in. The provided list is destroyed.
264 (defun byte-inline-lapcode (lap)
265 (setq byte-compile-output (nconc (nreverse lap) byte-compile-output)))
268 (defun byte-compile-inline-expand (form)
269 (let* ((name (car form))
270 (fn (or (cdr (assq name byte-compile-function-environment))
271 (and (fboundp name) (symbol-function name)))))
274 (byte-compile-warn "attempt to inline %s before it was defined" name)
277 (if (and (consp fn) (eq (car fn) 'autoload))
280 (setq fn (or (cdr (assq name byte-compile-function-environment))
281 (and (fboundp name) (symbol-function name))))))
282 (if (and (consp fn) (eq (car fn) 'autoload))
283 (error "file \"%s\" didn't define \"%s\"" (nth 1 fn) name))
285 (byte-compile-inline-expand (cons fn (cdr form)))
286 (if (compiled-function-p fn)
289 (cons (list 'lambda (compiled-function-arglist fn)
291 (compiled-function-instructions fn)
292 (compiled-function-constants fn)
293 (compiled-function-stack-depth fn)))
295 (if (not (eq (car fn) 'lambda)) (error "%s is not a lambda" name))
296 (cons fn (cdr form)))))))
298 ;;; ((lambda ...) ...)
300 (defun byte-compile-unfold-lambda (form &optional name)
301 (or name (setq name "anonymous lambda"))
302 (let ((lambda (car form))
304 (if (compiled-function-p lambda)
305 (setq lambda (list 'lambda (compiled-function-arglist lambda)
307 (compiled-function-instructions lambda)
308 (compiled-function-constants lambda)
309 (compiled-function-stack-depth lambda)))))
310 (let ((arglist (nth 1 lambda))
311 (body (cdr (cdr lambda)))
314 (if (and (stringp (car body)) (cdr body))
315 (setq body (cdr body)))
316 (if (and (consp (car body)) (eq 'interactive (car (car body))))
317 (setq body (cdr body)))
319 (cond ((eq (car arglist) '&optional)
320 ;; ok, I'll let this slide because funcall_lambda() does...
321 ;; (if optionalp (error "multiple &optional keywords in %s" name))
322 (if restp (error "&optional found after &rest in %s" name))
323 (if (null (cdr arglist))
324 (error "nothing after &optional in %s" name))
326 ((eq (car arglist) '&rest)
327 ;; ...but it is by no stretch of the imagination a reasonable
328 ;; thing that funcall_lambda() allows (&rest x y) and
329 ;; (&rest x &optional y) in arglists.
330 (if (null (cdr arglist))
331 (error "nothing after &rest in %s" name))
332 (if (cdr (cdr arglist))
333 (error "multiple vars after &rest in %s" name))
336 (setq bindings (cons (list (car arglist)
337 (and values (cons 'list values)))
340 ((and (not optionalp) (null values))
341 (byte-compile-warn "attempt to open-code %s with too few arguments" name)
342 (setq arglist nil values 'too-few))
344 (setq bindings (cons (list (car arglist) (car values))
346 values (cdr values))))
347 (setq arglist (cdr arglist)))
350 (or (eq values 'too-few)
352 "attempt to open-code %s with too many arguments" name))
356 (cons 'let (cons (nreverse bindings) body))
357 (cons 'progn body))))
358 (byte-compile-log " %s\t==>\t%s" form newform)
362 ;;; implementing source-level optimizers
364 (defun byte-optimize-form-code-walker (form for-effect)
366 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
367 ;; we need to have special knowledge of the syntax of the special forms
368 ;; like let and defun (that's why they're special forms :-). (Actually,
369 ;; the important aspect is that they are subrs that don't evaluate all of
372 (let ((fn (car-safe form))
374 (cond ((not (consp form))
375 (if (not (and for-effect
376 (or byte-compile-delete-errors
382 (byte-compile-warn "malformed quote form: %s"
383 (prin1-to-string form)))
384 ;; map (quote nil) to nil to simplify optimizer logic.
385 ;; map quoted constants to nil if for-effect (just because).
389 ((or (compiled-function-p fn)
390 (eq 'lambda (car-safe fn)))
391 (byte-compile-unfold-lambda form))
392 ((memq fn '(let let*))
393 ;; recursively enter the optimizer for the bindings and body
394 ;; of a let or let*. This for depth-firstness: forms that
395 ;; are more deeply nested are optimized first.
400 (if (symbolp binding)
402 (if (cdr (cdr binding))
403 (byte-compile-warn "malformed let binding: %s"
404 (prin1-to-string binding)))
406 (byte-optimize-form (nth 1 binding) nil))))
408 (byte-optimize-body (cdr (cdr form)) for-effect))))
415 (byte-optimize-form (car clause) nil)
416 (byte-optimize-body (cdr clause) for-effect))
417 (byte-compile-warn "malformed cond form: %s"
418 (prin1-to-string clause))
422 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
425 (setq tmp (byte-optimize-body (cdr form) for-effect))
426 (if (cdr tmp) (cons 'progn tmp) (car tmp)))
427 (byte-optimize-form (nth 1 form) for-effect)))
431 (cons (byte-optimize-form (nth 1 form) for-effect)
432 (byte-optimize-body (cdr (cdr form)) t)))
433 (byte-optimize-form (nth 1 form) for-effect)))
436 (cons (byte-optimize-form (nth 1 form) t)
437 (cons (byte-optimize-form (nth 2 form) for-effect)
438 (byte-optimize-body (cdr (cdr (cdr form))) t)))))
440 ((memq fn '(save-excursion save-restriction save-current-buffer))
441 ;; those subrs which have an implicit progn; it's not quite good
442 ;; enough to treat these like normal function calls.
443 ;; This can turn (save-excursion ...) into (save-excursion) which
444 ;; will be optimized away in the lap-optimize pass.
445 (cons fn (byte-optimize-body (cdr form) for-effect)))
447 ((eq fn 'with-output-to-temp-buffer)
448 ;; this is just like the above, except for the first argument.
451 (byte-optimize-form (nth 1 form) nil)
452 (byte-optimize-body (cdr (cdr form)) for-effect))))
456 (cons (byte-optimize-form (nth 1 form) nil)
458 (byte-optimize-form (nth 2 form) for-effect)
459 (byte-optimize-body (nthcdr 3 form) for-effect)))))
461 ((memq fn '(and or)) ; remember, and/or are control structures.
462 ;; take forms off the back until we can't any more.
463 ;; In the future it could conceivably be a problem that the
464 ;; subexpressions of these forms are optimized in the reverse
465 ;; order, but it's ok for now.
467 (let ((backwards (reverse (cdr form))))
468 (while (and backwards
469 (null (setcar backwards
470 (byte-optimize-form (car backwards)
472 (setq backwards (cdr backwards)))
473 (if (and (cdr form) (null backwards))
475 " all subforms of %s called for effect; deleted" form))
477 ;; Now optimize the rest of the forms. We need the return
478 ;; values. We already did the car.
480 (mapcar 'byte-optimize-form (cdr backwards)))
481 (cons fn (nreverse backwards))))
482 (cons fn (mapcar 'byte-optimize-form (cdr form)))))
484 ((eq fn 'interactive)
485 (byte-compile-warn "misplaced interactive spec: %s"
486 (prin1-to-string form))
489 ((memq fn '(defun defmacro function
490 condition-case save-window-excursion))
491 ;; These forms are compiled as constants or by breaking out
492 ;; all the subexpressions and compiling them separately.
495 ((eq fn 'unwind-protect)
496 ;; the "protected" part of an unwind-protect is compiled (and thus
497 ;; optimized) as a top-level form, so don't do it here. But the
498 ;; non-protected part has the same for-effect status as the
499 ;; unwind-protect itself. (The protected part is always for effect,
500 ;; but that isn't handled properly yet.)
502 (cons (byte-optimize-form (nth 1 form) for-effect)
506 ;; the body of a catch is compiled (and thus optimized) as a
507 ;; top-level form, so don't do it here. The tag is never
508 ;; for-effect. The body should have the same for-effect status
509 ;; as the catch form itself, but that isn't handled properly yet.
511 (cons (byte-optimize-form (nth 1 form) nil)
514 ;; If optimization is on, this is the only place that macros are
515 ;; expanded. If optimization is off, then macroexpansion happens
516 ;; in byte-compile-form. Otherwise, the macros are already expanded
517 ;; by the time that is reached.
519 (setq form (macroexpand form
520 byte-compile-macro-environment))))
521 (byte-optimize-form form for-effect))
524 (or (eq 'mocklisp (car-safe fn)) ; ha!
525 (byte-compile-warn "%s is a malformed function"
526 (prin1-to-string fn)))
529 ((and for-effect (setq tmp (get fn 'side-effect-free))
530 (or byte-compile-delete-errors
533 (byte-compile-warn "%s called for effect"
534 (prin1-to-string form))
536 (byte-compile-log " %s called for effect; deleted" fn)
537 ;; appending a nil here might not be necessary, but it can't hurt.
539 (cons 'progn (append (cdr form) '(nil))) t))
542 ;; Otherwise, no args can be considered to be for-effect,
543 ;; even if the called function is for-effect, because we
544 ;; don't know anything about that function.
545 (cons fn (mapcar 'byte-optimize-form (cdr form)))))))
548 (defun byte-optimize-form (form &optional for-effect)
549 "The source-level pass of the optimizer."
551 ;; First, optimize all sub-forms of this one.
552 (setq form (byte-optimize-form-code-walker form for-effect))
554 ;; After optimizing all subforms, optimize this form until it doesn't
555 ;; optimize any further. This means that some forms will be passed through
556 ;; the optimizer many times, but that's necessary to make the for-effect
557 ;; processing do as much as possible.
560 (if (and (consp form)
563 ;; we don't have any of these yet, but we might.
564 (setq opt (get (car form) 'byte-for-effect-optimizer)))
565 (setq opt (get (car form) 'byte-optimizer)))
566 (not (eq form (setq new (funcall opt form)))))
568 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
569 (byte-compile-log " %s\t==>\t%s" form new)
570 (byte-optimize-form new for-effect))
574 (defun byte-optimize-body (forms all-for-effect)
575 ;; Optimize the cdr of a progn or implicit progn; `forms' is a list of
576 ;; forms, all but the last of which are optimized with the assumption that
577 ;; they are being called for effect. The last is for-effect as well if
578 ;; all-for-effect is true. Returns a new list of forms.
583 (setq fe (or all-for-effect (cdr rest)))
584 (setq new (and (car rest) (byte-optimize-form (car rest) fe)))
585 (if (or new (not fe))
586 (setq result (cons new result)))
587 (setq rest (cdr rest)))
591 ;;; some source-level optimizers
593 ;;; when writing optimizers, be VERY careful that the optimizer returns
594 ;;; something not EQ to its argument if and ONLY if it has made a change.
595 ;;; This implies that you cannot simply destructively modify the list;
596 ;;; you must return something not EQ to it if you make an optimization.
598 ;;; It is now safe to optimize code such that it introduces new bindings.
600 ;; I'd like this to be a defsubst, but let's not be self-referential...
601 (defmacro byte-compile-trueconstp (form)
602 ;; Returns non-nil if FORM is a non-nil constant.
603 `(cond ((consp ,form) (eq (car ,form) 'quote))
604 ((not (symbolp ,form)))
608 ;; If the function is being called with constant numeric args,
609 ;; evaluate as much as possible at compile-time. This optimizer
610 ;; assumes that the function is associative, like + or *.
611 (defun byte-optimize-associative-math (form)
616 (if (numberp (car rest))
617 (setq constants (cons (car rest) constants))
618 (setq args (cons (car rest) args)))
619 (setq rest (cdr rest)))
623 (apply (car form) constants)
625 (cons (car form) (nreverse args))
627 (apply (car form) constants))
630 ;; If the function is being called with constant numeric args,
631 ;; evaluate as much as possible at compile-time. This optimizer
632 ;; assumes that the function satisfies
633 ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
635 (defun byte-optimize-nonassociative-math (form)
636 (if (or (not (numberp (car (cdr form))))
637 (not (numberp (car (cdr (cdr form))))))
639 (let ((constant (car (cdr form)))
640 (rest (cdr (cdr form))))
641 (while (numberp (car rest))
642 (setq constant (funcall (car form) constant (car rest))
645 (cons (car form) (cons constant rest))
648 ;;(defun byte-optimize-associative-two-args-math (form)
649 ;; (setq form (byte-optimize-associative-math form))
651 ;; (byte-optimize-two-args-left form)
654 ;;(defun byte-optimize-nonassociative-two-args-math (form)
655 ;; (setq form (byte-optimize-nonassociative-math form))
657 ;; (byte-optimize-two-args-right form)
660 ;; jwz: (byte-optimize-approx-equal 0.0 0.0) was returning nil
661 ;; in xemacs 19.15 because it used < instead of <=.
662 (defun byte-optimize-approx-equal (x y)
663 (<= (* (abs (- x y)) 100) (abs (+ x y))))
665 ;; Collect all the constants from FORM, after the STARTth arg,
666 ;; and apply FUN to them to make one argument at the end.
667 ;; For functions that can handle floats, that optimization
668 ;; can be incorrect because reordering can cause an overflow
669 ;; that would otherwise be avoided by encountering an arg that is a float.
670 ;; We avoid this problem by (1) not moving float constants and
671 ;; (2) not moving anything if it would cause an overflow.
672 (defun byte-optimize-delay-constants-math (form start fun)
673 ;; Merge all FORM's constants from number START, call FUN on them
674 ;; and put the result at the end.
675 (let ((rest (nthcdr (1- start) form))
677 ;; t means we must check for overflow.
678 (overflow (memq fun '(+ *))))
679 (while (cdr (setq rest (cdr rest)))
680 (if (integerp (car rest))
682 (setq form (copy-sequence form)
683 rest (nthcdr (1- start) form))
684 (while (setq rest (cdr rest))
685 (cond ((integerp (car rest))
686 (setq constants (cons (car rest) constants))
688 ;; If necessary, check now for overflow
689 ;; that might be caused by reordering.
691 ;; We have overflow if the result of doing the arithmetic
692 ;; on floats is not even close to the result
693 ;; of doing it on integers.
694 (not (byte-optimize-approx-equal
695 (apply fun (mapcar 'float constants))
696 (float (apply fun constants)))))
698 (setq form (nconc (delq nil form)
699 (list (apply fun (nreverse constants)))))))))
702 ;;; It is not safe to optimize calls to arithmetic ops with one arg
703 ;;; away entirely (actually, it would be safe if we know the sole arg
704 ;;; is not a marker or if it appears in other arithmetic).
706 ;;; But this degree of paranoia is normally unjustified, so optimize unless
707 ;;; the user has done (declaim (safety 3)). Implemented in bytecomp.el.
709 (defun byte-optimize-plus (form)
710 (byte-optimize-predicate (byte-optimize-delay-constants-math form 1 '+)))
712 (defun byte-optimize-multiply (form)
713 (setq form (byte-optimize-delay-constants-math form 1 '*))
714 ;; If there is a constant integer in FORM, it is now the last element.
716 (case (car (last form))
717 ;; (* x y 0) --> (progn x y 0)
718 (0 (cons 'progn (cdr form)))
719 (t (byte-optimize-predicate form))))
721 (defun byte-optimize-minus (form)
722 ;; Put constants at the end, except the first arg.
723 (setq form (byte-optimize-delay-constants-math form 2 '+))
724 ;; Now only the first and last args can be integers.
725 (let ((last (car (last (nthcdr 3 form)))))
727 ;; If form is (- CONST foo... CONST), merge first and last.
728 ((and (numberp (nth 1 form)) (numberp last))
729 (decf (nth 1 form) last)
732 ;; (- 0 x ...) --> (- (- x) ...)
733 ((and (eq 0 (nth 1 form)) (>= (length form) 3))
734 `(- (- ,(nth 2 form)) ,@(nthcdr 3 form)))
736 (t (byte-optimize-predicate form)))))
738 (defun byte-optimize-divide (form)
739 ;; Put constants at the end, except the first arg.
740 (setq form (byte-optimize-delay-constants-math form 2 '*))
741 ;; Now only the first and last args can be integers.
742 (let ((last (car (last (nthcdr 3 form)))))
744 ;; If form is (/ CONST foo... CONST), merge first and last.
745 ((and (numberp (nth 1 form)) (numberp last))
748 (cons (/ (nth 1 form) last)
749 (butlast (cdr (cdr form)))))
752 ;; (/ 0 x y) --> (progn x y 0)
754 (append '(progn) (cdr (cdr form)) '(0)))
756 ;; We don't have to check for divide-by-zero because `/' does.
757 (t (byte-optimize-predicate form)))))
759 (defun byte-optimize-logmumble (form)
760 (setq form (byte-optimize-delay-constants-math form 1 (car form)))
761 (byte-optimize-predicate
763 (setq form (if (eq (car form) 'logand)
764 (cons 'progn (cdr form))
765 (delq 0 (copy-sequence form)))))
766 ((and (eq (car-safe form) 'logior)
768 (cons 'progn (cdr form)))
772 (defun byte-optimize-binary-predicate (form)
773 (if (byte-compile-constp (nth 1 form))
774 (if (byte-compile-constp (nth 2 form))
776 (list 'quote (eval form))
778 ;; This can enable some lapcode optimizations.
779 (list (car form) (nth 2 form) (nth 1 form)))
782 (defun byte-optimize-predicate (form)
786 (setq ok (byte-compile-constp (car rest))
790 (list 'quote (eval form))
792 (byte-compile-warn "evaluating %s: %s" form err)
796 (defun byte-optimize-identity (form)
797 (if (and (cdr form) (null (cdr (cdr form))))
799 (byte-compile-warn "identity called with %d arg%s, but requires 1"
801 (if (= 1 (length (cdr form))) "" "s"))
804 (defun byte-optimize-car (form)
805 (let ((arg (cadr form)))
807 ((and (byte-compile-trueconstp arg)
808 (not (and (consp arg)
809 (eq (car arg) 'quote)
810 (listp (cadr arg)))))
812 "taking car of a constant: %s" arg)
814 ((and (eq (car-safe arg) 'cons)
816 `(prog1 ,(nth 1 arg) ,(nth 2 arg)))
817 ((eq (car-safe arg) 'list)
818 `(prog1 ,@(cdr arg)))
820 (byte-optimize-predicate form)))))
822 (defun byte-optimize-cdr (form)
823 (let ((arg (cadr form)))
825 ((and (byte-compile-trueconstp arg)
826 (not (and (consp arg)
827 (eq (car arg) 'quote)
828 (listp (cadr arg)))))
830 "taking cdr of a constant: %s" arg)
832 ((and (eq (car-safe arg) 'cons)
834 `(progn ,(nth 1 arg) ,(nth 2 arg)))
835 ((eq (car-safe arg) 'list)
836 (if (> (length arg) 2)
837 `(progn ,(cadr arg) (list ,@(cddr arg)))
840 (byte-optimize-predicate form)))))
842 (put 'identity 'byte-optimizer 'byte-optimize-identity)
844 (put '+ 'byte-optimizer 'byte-optimize-plus)
845 (put '* 'byte-optimizer 'byte-optimize-multiply)
846 (put '- 'byte-optimizer 'byte-optimize-minus)
847 (put '/ 'byte-optimizer 'byte-optimize-divide)
848 (put '% 'byte-optimizer 'byte-optimize-predicate)
849 (put 'max 'byte-optimizer 'byte-optimize-associative-math)
850 (put 'min 'byte-optimizer 'byte-optimize-associative-math)
852 (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
853 (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
854 (put 'eql 'byte-optimizer 'byte-optimize-binary-predicate)
855 (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
856 (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
857 (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
859 (put '< 'byte-optimizer 'byte-optimize-predicate)
860 (put '> 'byte-optimizer 'byte-optimize-predicate)
861 (put '<= 'byte-optimizer 'byte-optimize-predicate)
862 (put '>= 'byte-optimizer 'byte-optimize-predicate)
863 (put '1+ 'byte-optimizer 'byte-optimize-predicate)
864 (put '1- 'byte-optimizer 'byte-optimize-predicate)
865 (put 'not 'byte-optimizer 'byte-optimize-predicate)
866 (put 'null 'byte-optimizer 'byte-optimize-predicate)
867 (put 'memq 'byte-optimizer 'byte-optimize-predicate)
868 (put 'consp 'byte-optimizer 'byte-optimize-predicate)
869 (put 'listp 'byte-optimizer 'byte-optimize-predicate)
870 (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
871 (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
872 (put 'string< 'byte-optimizer 'byte-optimize-predicate)
873 (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
874 (put 'length 'byte-optimizer 'byte-optimize-predicate)
876 (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
877 (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
878 (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
879 (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
881 (put 'car 'byte-optimizer 'byte-optimize-car)
882 (put 'cdr 'byte-optimizer 'byte-optimize-cdr)
883 (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
884 (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
887 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
888 ;; take care of this? - Jamie
889 ;; I think this may some times be necessary to reduce eg. (quote 5) to 5,
890 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
891 (put 'quote 'byte-optimizer 'byte-optimize-quote)
892 (defun byte-optimize-quote (form)
893 (if (or (consp (nth 1 form))
894 (and (symbolp (nth 1 form))
896 (not (keywordp (nth 1 form)))
897 (not (memq (nth 1 form) '(nil t)))))
901 (defun byte-optimize-zerop (form)
902 (cond ((numberp (nth 1 form))
904 (byte-compile-delete-errors
905 (list '= (nth 1 form) 0))
908 (put 'zerop 'byte-optimizer 'byte-optimize-zerop)
910 (defun byte-optimize-and (form)
911 ;; Simplify if less than 2 args.
912 ;; if there is a literal nil in the args to `and', throw it and following
913 ;; forms away, and surround the `and' with (progn ... nil).
914 (cond ((null (cdr form)))
918 (prog1 (setq form (copy-sequence form))
920 (setq form (cdr form)))
923 ((null (cdr (cdr form)))
925 ((byte-optimize-predicate form))))
927 (defun byte-optimize-or (form)
928 ;; Throw away nil's, and simplify if less than 2 args.
929 ;; If there is a literal non-nil constant in the args to `or', throw away all
932 (setq form (delq nil (copy-sequence form))))
934 (while (cdr (setq rest (cdr rest)))
935 (if (byte-compile-trueconstp (car rest))
936 (setq form (copy-sequence form)
937 rest (setcdr (memq (car rest) form) nil))))
939 (byte-optimize-predicate form)
942 (defun byte-optimize-cond (form)
943 ;; if any clauses have a literal nil as their test, throw them away.
944 ;; if any clause has a literal non-nil constant as its test, throw
945 ;; away all following clauses.
947 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
948 (while (setq rest (assq nil (cdr form)))
949 (setq form (delq rest (copy-sequence form))))
950 (if (memq nil (cdr form))
951 (setq form (delq nil (copy-sequence form))))
953 (while (setq rest (cdr rest))
954 (cond ((byte-compile-trueconstp (car-safe (car rest)))
955 (cond ((eq rest (cdr form))
958 (if (cdr (cdr (car rest)))
959 (cons 'progn (cdr (car rest)))
963 (setq form (copy-sequence form))
964 (setcdr (memq (car rest) form) nil)))
967 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
968 (if (eq 'cond (car-safe form))
969 (let ((clauses (cdr form)))
970 (if (and (consp (car clauses))
971 (null (cdr (car clauses))))
972 (list 'or (car (car clauses))
974 (cons (car form) (cdr (cdr form)))))
978 (defun byte-optimize-if (form)
979 ;; (if <true-constant> <then> <else...>) ==> <then>
980 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
981 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
982 ;; (if <test> <then> nil) ==> (if <test> <then>)
983 (let ((clause (nth 1 form)))
984 (cond ((byte-compile-trueconstp clause)
988 (cons 'progn (nthcdr 3 form))
991 (if (equal '(nil) (nthcdr 3 form))
992 (list 'if clause (nth 2 form))
994 ((or (nth 3 form) (nthcdr 4 form))
996 ;; Don't make a double negative;
997 ;; instead, take away the one that is there.
998 (if (and (consp clause) (memq (car clause) '(not null))
999 (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
1003 (cons 'progn (nthcdr 3 form))
1006 (list 'progn clause nil)))))
1008 (defun byte-optimize-while (form)
1012 (put 'and 'byte-optimizer 'byte-optimize-and)
1013 (put 'or 'byte-optimizer 'byte-optimize-or)
1014 (put 'cond 'byte-optimizer 'byte-optimize-cond)
1015 (put 'if 'byte-optimizer 'byte-optimize-if)
1016 (put 'while 'byte-optimizer 'byte-optimize-while)
1018 ;; The supply of bytecodes is small and constrained by backward compatibility.
1019 ;; Several functions have byte-coded versions and hence are very efficient.
1020 ;; Related functions which can be expressed in terms of the byte-coded
1021 ;; ones should be transformed into bytecoded calls for efficiency.
1022 ;; This is especially the case for functions with a backward- and
1023 ;; forward- version, but with a bytecode only for the forward one.
1025 ;; Some programmers have hand-optimized calls like (backward-char)
1026 ;; into the call (forward-char -1).
1027 ;; But it's so much nicer for the byte-compiler to do this automatically!
1029 ;; (char-before) ==> (char-after (1- (point)))
1030 (put 'char-before 'byte-optimizer 'byte-optimize-char-before)
1031 (defun byte-optimize-char-before (form)
1034 ((null (nth 1 form))
1036 ((equal '(point) (nth 1 form))
1038 (t `(1- (or ,(nth 1 form) (point)))))
1039 ,@(cdr (cdr form))))
1041 ;; (backward-char n) ==> (forward-char (- n))
1042 (put 'backward-char 'byte-optimizer 'byte-optimize-backward-char)
1043 (defun byte-optimize-backward-char (form)
1045 ,(typecase (nth 1 form)
1047 (integer (- (nth 1 form)))
1048 (t `(- (or ,(nth 1 form) 1))))
1049 ,@(cdr (cdr form))))
1051 ;; (backward-word n) ==> (forward-word (- n))
1052 (put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
1053 (defun byte-optimize-backward-word (form)
1055 ,(typecase (nth 1 form)
1057 (integer (- (nth 1 form)))
1058 (t `(- (or ,(nth 1 form) 1))))
1059 ,@(cdr (cdr form))))
1061 ;; The following would be a valid optimization of the above kind, but
1062 ;; the gain in performance is very small, since the saved funcall is
1063 ;; counterbalanced by the necessity of adding a bytecode for (point).
1065 ;; Also, users are more likely to have modified the behavior of
1066 ;; delete-char via advice or some similar mechanism. This is much
1067 ;; less of a problem for the previous functions because it wouldn't
1068 ;; make sense to modify the behaviour of `backward-char' without also
1069 ;; modifying `forward-char', for example.
1071 ;; (delete-char n) ==> (delete-region (point) (+ (point) n))
1072 ;; (put 'delete-char 'byte-optimizer 'byte-optimize-delete-char)
1073 ;; (defun byte-optimize-delete-char (form)
1074 ;; (case (length (cdr form))
1075 ;; (0 `(delete-region (point) (1+ (point))))
1076 ;; (1 `(delete-region (point) (+ (point) ,(nth 1 form))))
1079 ;; byte-compile-negation-optimizer lives in bytecomp.el
1080 ;(put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
1081 (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
1082 (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
1084 (defun byte-optimize-funcall (form)
1085 ;; (funcall '(lambda ...) ...) ==> ((lambda ...) ...)
1086 ;; (funcall 'foo ...) ==> (foo ...)
1087 (let ((fn (nth 1 form)))
1088 (if (memq (car-safe fn) '(quote function))
1089 (cons (nth 1 fn) (cdr (cdr form)))
1092 (defun byte-optimize-apply (form)
1093 ;; If the last arg is a literal constant, turn this into a funcall.
1094 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1095 (let ((fn (nth 1 form))
1096 (last (nth (1- (length form)) form))) ; I think this really is fastest
1097 (or (if (or (null last)
1098 (eq (car-safe last) 'quote))
1099 (if (listp (nth 1 last))
1100 (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
1101 (nconc (list 'funcall fn) butlast
1102 (mapcar #'(lambda (x) (list 'quote x)) (nth 1 last))))
1104 "last arg to apply can't be a literal atom: %s"
1105 (prin1-to-string last))
1109 (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
1110 (put 'apply 'byte-optimizer 'byte-optimize-apply)
1113 (put 'let 'byte-optimizer 'byte-optimize-letX)
1114 (put 'let* 'byte-optimizer 'byte-optimize-letX)
1115 (defun byte-optimize-letX (form)
1116 (cond ((null (nth 1 form))
1118 (cons 'progn (cdr (cdr form))))
1119 ((or (nth 2 form) (nthcdr 3 form))
1122 ((eq (car form) 'let)
1123 (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
1126 (let ((binds (reverse (nth 1 form))))
1127 (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
1130 (put 'nth 'byte-optimizer 'byte-optimize-nth)
1131 (defun byte-optimize-nth (form)
1132 (if (and (= (safe-length form) 3) (memq (nth 1 form) '(0 1)))
1133 (list 'car (if (zerop (nth 1 form))
1135 (list 'cdr (nth 2 form))))
1136 (byte-optimize-predicate form)))
1138 (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
1139 (defun byte-optimize-nthcdr (form)
1140 (if (and (= (safe-length form) 3) (not (memq (nth 1 form) '(0 1 2))))
1141 (byte-optimize-predicate form)
1142 (let ((count (nth 1 form)))
1143 (setq form (nth 2 form))
1144 (while (>= (setq count (1- count)) 0)
1145 (setq form (list 'cdr form)))
1148 (put 'concat 'byte-optimizer 'byte-optimize-concat)
1149 (defun byte-optimize-concat (form)
1150 (let ((args (cdr form))
1152 (while (and args constant)
1153 (or (byte-compile-constp (car args))
1154 (setq constant nil))
1155 (setq args (cdr args)))
1160 ;;; enumerating those functions which need not be called if the returned
1161 ;;; value is not used. That is, something like
1162 ;;; (progn (list (something-with-side-effects) (yow))
1164 ;;; may safely be turned into
1165 ;;; (progn (progn (something-with-side-effects) (yow))
1167 ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1169 ;;; I wonder if I missed any :-\)
1170 (let ((side-effect-free-fns
1171 '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
1173 boundp buffer-file-name buffer-local-variables buffer-modified-p
1175 capitalize car-less-than-car car cdr ceiling concat
1176 ;; coordinates-in-window-p not in XEmacs
1177 copy-marker cos count-lines
1178 default-boundp default-value documentation downcase
1179 elt exp expt fboundp featurep
1180 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1181 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1183 get get-buffer get-buffer-window getenv get-file-buffer
1184 ;; hash-table functions
1185 make-hash-table copy-hash-table
1188 hash-table-rehash-size
1189 hash-table-rehash-threshold
1195 length log log10 logand logb logior lognot logxor lsh
1196 marker-buffer max member memq min mod
1197 next-window nth nthcdr number-to-string
1198 parse-colon-path plist-get previous-window
1199 radians-to-degrees rassq regexp-quote reverse round
1200 sin sqrt string< string= string-equal string-lessp string-to-char
1201 string-to-int string-to-number substring symbol-plist
1202 tan upcase user-variable-p vconcat
1203 ;; XEmacs change: window-edges -> window-pixel-edges
1204 window-buffer window-dedicated-p window-pixel-edges window-height
1205 window-hscroll window-minibuffer-p window-width
1207 ;; functions defined by cl
1208 oddp evenp plusp minusp
1209 abs expt signum last butlast ldiff
1211 isqrt floor* ceiling* truncate* round* mod* rem* subseq
1214 (side-effect-and-error-free-fns
1216 bobp bolp buffer-end buffer-list buffer-size buffer-string bufferp
1217 car-safe case-table-p cdr-safe char-or-string-p char-table-p
1218 characterp commandp cons
1219 consolep console-live-p consp
1221 ;; XEmacs: extent functions, frame-live-p, various other stuff
1222 devicep device-live-p
1223 dot dot-marker eobp eolp eq eql equal eventp extentp
1224 extent-live-p floatp framep frame-live-p
1225 get-largest-window get-lru-window
1227 identity ignore integerp integer-or-marker-p interactive-p
1228 invocation-directory invocation-name
1230 make-marker mark mark-marker markerp memory-limit minibuffer-window
1231 ;; mouse-movement-p not in XEmacs
1232 natnump nlistp not null number-or-marker-p numberp
1233 one-window-p ;; overlayp not in XEmacs
1234 point point-marker point-min point-max processp
1236 selected-window sequencep stringp subrp symbolp syntax-table-p
1237 user-full-name user-login-name user-original-login-name
1238 user-real-login-name user-real-uid user-uid
1240 window-configuration-p window-live-p windowp
1241 ;; Functions defined by cl
1242 eql floatp-safe list* subst acons equalp random-state-p
1245 (dolist (fn side-effect-free-fns)
1246 (put fn 'side-effect-free t))
1247 (dolist (fn side-effect-and-error-free-fns)
1248 (put fn 'side-effect-free 'error-free)))
1251 (defun byte-compile-splice-in-already-compiled-code (form)
1252 ;; form is (byte-code "..." [...] n)
1253 (if (not (memq byte-optimize '(t byte)))
1254 (byte-compile-normal-call form)
1255 (byte-inline-lapcode
1256 (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t))
1257 (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form))
1258 byte-compile-maxdepth))
1259 (setq byte-compile-depth (1+ byte-compile-depth))))
1261 (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code)
1264 (defconst byte-constref-ops
1265 '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
1267 ;;; This function extracts the bitfields from variable-length opcodes.
1268 ;;; Originally defined in disass.el (which no longer uses it.)
1270 (defun disassemble-offset ()
1272 ;; fetch and return the offset for the current opcode.
1273 ;; return NIL if this opcode has no offset
1274 ;; OP, PTR and BYTES are used and set dynamically
1275 (declare (special op ptr bytes))
1276 (cond ((< op byte-nth)
1277 (let ((tem (logand op 7)))
1278 (setq op (logand op 248))
1280 (setq ptr (1+ ptr)) ;offset in next byte
1281 ;; char-to-int to avoid downstream problems
1282 ;; caused by chars appearing where ints are
1283 ;; expected. In bytecode the bytes in the
1284 ;; opcode string are always interpreted as ints.
1285 (char-to-int (aref bytes ptr)))
1287 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1289 (progn (setq ptr (1+ ptr))
1290 (lsh (aref bytes ptr) 8))))
1291 (t tem)))) ;offset was in opcode
1292 ((>= op byte-constant)
1293 (prog1 (- op byte-constant) ;offset in opcode
1294 (setq op byte-constant)))
1295 ((and (>= op byte-constant2)
1296 (<= op byte-goto-if-not-nil-else-pop))
1297 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1299 (progn (setq ptr (1+ ptr))
1300 (lsh (aref bytes ptr) 8))))
1301 ;; XEmacs: this code was here before. FSF's first comparison
1302 ;; is (>= op byte-listN). It appears that the rel-goto stuff
1303 ;; does not exist in FSF 19.30. It doesn't exist in 19.28
1304 ;; either, so I'm going to assume that this is an improvement
1305 ;; on our part and leave it in. --ben
1306 ((and (>= op byte-rel-goto)
1307 (<= op byte-insertN))
1308 (setq ptr (1+ ptr)) ;offset in next byte
1309 ;; Use char-to-int to avoid downstream problems caused by
1310 ;; chars appearing where ints are expected. In bytecode
1311 ;; the bytes in the opcode string are always interpreted as
1313 (char-to-int (aref bytes ptr)))))
1316 ;;; This de-compiler is used for inline expansion of compiled functions,
1317 ;;; and by the disassembler.
1319 ;;; This list contains numbers, which are pc values,
1320 ;;; before each instruction.
1321 (defun byte-decompile-bytecode (bytes constvec)
1322 "Turns BYTECODE into lapcode, referring to CONSTVEC."
1323 (let ((byte-compile-constants nil)
1324 (byte-compile-variables nil)
1325 (byte-compile-tag-number 0))
1326 (byte-decompile-bytecode-1 bytes constvec)))
1328 ;; As byte-decompile-bytecode, but updates
1329 ;; byte-compile-{constants, variables, tag-number}.
1330 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1331 ;; with `goto's destined for the end of the code.
1332 ;; That is for use by the compiler.
1333 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1334 ;; In that case, we put a pc value into the list
1335 ;; before each insn (or its label).
1336 (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
1337 (let ((length (length bytes))
1338 (ptr 0) optr tags op offset
1342 ;; (retcount 0) unused
1344 (while (not (= ptr length))
1346 (setq lap (cons ptr lap)))
1347 (setq op (aref bytes ptr)
1349 offset (disassemble-offset)) ; this does dynamic-scope magic
1350 (setq op (aref byte-code-vector op))
1351 ;; XEmacs: the next line in FSF 19.30 reads
1352 ;; (cond ((memq op byte-goto-ops)
1353 ;; see the comment above about byte-rel-goto in XEmacs.
1354 (cond ((or (memq op byte-goto-ops)
1355 (cond ((memq op byte-rel-goto-ops)
1356 (setq op (aref byte-code-vector
1357 (- (symbol-value op)
1358 (- byte-rel-goto byte-goto))))
1359 (setq offset (+ ptr (- offset 127)))
1363 (cdr (or (assq offset tags)
1366 (byte-compile-make-tag))
1368 ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t)
1369 ((memq op byte-constref-ops)))
1370 (setq tmp (aref constvec offset)
1371 offset (if (eq op 'byte-constant)
1372 (byte-compile-get-constant tmp)
1373 (or (assq tmp byte-compile-variables)
1374 (car (setq byte-compile-variables
1376 byte-compile-variables)))))))
1377 ((and make-spliceable
1378 (eq op 'byte-return))
1379 (if (= ptr (1- length))
1381 (setq offset (or endtag (setq endtag (byte-compile-make-tag)))
1383 ;; lap = ( [ (pc . (op . arg)) ]* )
1384 (setq lap (cons (cons optr (cons op (or offset 0)))
1386 (setq ptr (1+ ptr)))
1387 ;; take off the dummy nil op that we replaced a trailing "return" with.
1390 (cond ((numberp (car rest)))
1391 ((setq tmp (assq (car (car rest)) tags))
1392 ;; this addr is jumped to
1393 (setcdr rest (cons (cons nil (cdr tmp))
1395 (setq tags (delq tmp tags))
1396 (setq rest (cdr rest))))
1397 (setq rest (cdr rest))))
1398 (if tags (error "optimizer error: missed tags %s" tags))
1399 (if (null (car (cdr (car lap))))
1400 (setq lap (cdr lap)))
1402 (setq lap (cons (cons nil endtag) lap)))
1403 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1404 (mapcar #'(lambda (elt) (if (numberp elt) elt (cdr elt)))
1408 ;;; peephole optimizer
1410 (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
1412 (defconst byte-conditional-ops
1413 '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
1414 byte-goto-if-not-nil-else-pop))
1416 (defconst byte-after-unbind-ops
1417 '(byte-constant byte-dup
1418 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1420 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1422 ;; How about other side-effect-free-ops? Is it safe to move an
1423 ;; error invocation (such as from nth) out of an unwind-protect?
1424 ;; No, it is not, because the unwind-protect forms can alter
1425 ;; the inside of the object to which nth would apply.
1426 ;; For the same reason, byte-equal was deleted from this list.
1427 "Byte-codes that can be moved past an unbind.")
1429 (defconst byte-compile-side-effect-and-error-free-ops
1430 '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
1431 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1432 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1433 byte-point-min byte-following-char byte-preceding-char
1434 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1435 byte-current-buffer byte-interactive-p))
1437 (defconst byte-compile-side-effect-free-ops
1439 '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
1440 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1441 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1442 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1443 byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
1444 byte-member byte-assq byte-quo byte-rem)
1445 byte-compile-side-effect-and-error-free-ops))
1447 ;;; This piece of shit is because of the way DEFVAR_BOOL() variables work.
1448 ;;; Consider the code
1450 ;;; (defun foo (flag)
1451 ;;; (let ((old-pop-ups pop-up-windows)
1452 ;;; (pop-up-windows flag))
1453 ;;; (cond ((not (eq pop-up-windows old-pop-ups))
1454 ;;; (setq old-pop-ups pop-up-windows)
1457 ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1458 ;;; something else. But if we optimize
1461 ;;; varbind pop-up-windows
1462 ;;; varref pop-up-windows
1467 ;;; varbind pop-up-windows
1470 ;;; we break the program, because it will appear that pop-up-windows and
1471 ;;; old-pop-ups are not EQ when really they are. So we have to know what
1472 ;;; the BOOL variables are, and not perform this optimization on them.
1475 ;;; This used to hold a large list of boolean variables, which had to
1476 ;;; be updated every time a new DEFVAR_BOOL is added, making it very
1477 ;;; hard to maintain. Such a list is not necessary under XEmacs,
1478 ;;; where we can use `built-in-variable-type' to query for boolean
1481 ;(defconst byte-boolean-vars
1482 ; '(abbrev-all-caps purify-flag find-file-compare-truenames
1483 ; find-file-use-truenames delete-auto-save-files byte-metering-on
1484 ; x-seppuku-on-epipe zmacs-regions zmacs-region-active-p
1485 ; zmacs-region-stays atomic-extent-goto-char-p
1486 ; suppress-early-error-handler-backtrace noninteractive
1487 ; inhibit-early-packages inhibit-autoloads debug-paths
1488 ; inhibit-site-lisp debug-on-quit debug-on-next-call
1489 ; modifier-keys-are-sticky x-allow-sendevents
1490 ; mswindows-dynamic-frame-resize focus-follows-mouse
1491 ; inhibit-input-event-recording enable-multibyte-characters
1492 ; disable-auto-save-when-buffer-shrinks
1493 ; allow-deletion-of-last-visible-frame indent-tabs-mode
1494 ; load-in-progress load-warn-when-source-newer
1495 ; load-warn-when-source-only load-ignore-elc-files
1496 ; load-force-doc-strings fail-on-bucky-bit-character-escapes
1497 ; popup-menu-titles menubar-show-keybindings completion-ignore-case
1498 ; canna-empty-info canna-through-info canna-underline
1499 ; canna-inhibit-hankakukana enable-multibyte-characters
1500 ; re-short-flag x-handle-non-fully-specified-fonts
1501 ; print-escape-newlines print-readably delete-exited-processes
1502 ; windowed-process-io visible-bell no-redraw-on-reenter
1503 ; cursor-in-echo-area inhibit-warning-display
1504 ; column-number-start-at-one parse-sexp-ignore-comments
1505 ; words-include-escapes scroll-on-clipped-lines)
1506 ; "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t.
1507 ;If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer
1508 ;may generate incorrect code.")
1510 (defun byte-optimize-lapcode (lap &optional for-effect)
1511 "Simple peephole optimizer. LAP is both modified and returned."
1516 (keep-going 'first-time)
1519 (side-effect-free (if byte-compile-delete-errors
1520 byte-compile-side-effect-free-ops
1521 byte-compile-side-effect-and-error-free-ops)))
1523 (or (eq keep-going 'first-time)
1524 (byte-compile-log-lap " ---- next pass"))
1528 (setq lap0 (car rest)
1532 ;; You may notice that sequences like "dup varset discard" are
1533 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1534 ;; You may be tempted to change this; resist that temptation.
1536 ;; <side-effect-free> pop --> <deleted>
1538 ;; const-X pop --> <deleted>
1539 ;; varref-X pop --> <deleted>
1540 ;; dup pop --> <deleted>
1542 ((and (eq 'byte-discard (car lap1))
1543 (memq (car lap0) side-effect-free))
1545 (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
1546 (setq rest (cdr rest))
1548 (byte-compile-log-lap
1549 " %s discard\t-->\t<deleted>" lap0)
1550 (setq lap (delq lap0 (delq lap1 lap))))
1552 (byte-compile-log-lap
1553 " %s discard\t-->\t<deleted> discard" lap0)
1554 (setq lap (delq lap0 lap)))
1556 (byte-compile-log-lap
1557 " %s discard\t-->\tdiscard discard" lap0)
1558 (setcar lap0 'byte-discard)
1560 ((error "Optimizer error: too much on the stack"))))
1562 ;; goto*-X X: --> X:
1564 ((and (memq (car lap0) byte-goto-ops)
1565 (eq (cdr lap0) lap1))
1566 (cond ((eq (car lap0) 'byte-goto)
1567 (setq lap (delq lap0 lap))
1568 (setq tmp "<deleted>"))
1569 ((memq (car lap0) byte-goto-always-pop-ops)
1570 (setcar lap0 (setq tmp 'byte-discard))
1572 ((error "Depth conflict at tag %d" (nth 2 lap0))))
1573 (and (memq byte-optimize-log '(t byte))
1574 (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
1575 (nth 1 lap1) (nth 1 lap1)
1577 (setq keep-going t))
1579 ;; varset-X varref-X --> dup varset-X
1580 ;; varbind-X varref-X --> dup varbind-X
1581 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1582 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1583 ;; The latter two can enable other optimizations.
1585 ((and (eq 'byte-varref (car lap2))
1586 (eq (cdr lap1) (cdr lap2))
1587 (memq (car lap1) '(byte-varset byte-varbind)))
1588 (if (and (setq tmp (eq (built-in-variable-type (car (cdr lap2)))
1590 (not (eq (car lap0) 'byte-constant)))
1593 (if (memq (car lap0) '(byte-constant byte-dup))
1595 (setq tmp (if (or (not tmp)
1596 (memq (car (cdr lap0)) '(nil t)))
1598 (byte-compile-get-constant t)))
1599 (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
1600 lap0 lap1 lap2 lap0 lap1
1601 (cons (car lap0) tmp))
1602 (setcar lap2 (car lap0))
1604 (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
1605 (setcar lap2 (car lap1))
1606 (setcar lap1 'byte-dup)
1608 ;; The stack depth gets locally increased, so we will
1609 ;; increase maxdepth in case depth = maxdepth here.
1610 ;; This can cause the third argument to byte-code to
1611 ;; be larger than necessary.
1612 (setq add-depth 1))))
1614 ;; dup varset-X discard --> varset-X
1615 ;; dup varbind-X discard --> varbind-X
1616 ;; (the varbind variant can emerge from other optimizations)
1618 ((and (eq 'byte-dup (car lap0))
1619 (eq 'byte-discard (car lap2))
1620 (memq (car lap1) '(byte-varset byte-varbind)))
1621 (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
1624 (setq lap (delq lap0 (delq lap2 lap))))
1626 ;; not goto-X-if-nil --> goto-X-if-non-nil
1627 ;; not goto-X-if-non-nil --> goto-X-if-nil
1629 ;; it is wrong to do the same thing for the -else-pop variants.
1631 ((and (eq 'byte-not (car lap0))
1632 (or (eq 'byte-goto-if-nil (car lap1))
1633 (eq 'byte-goto-if-not-nil (car lap1))))
1634 (byte-compile-log-lap " not %s\t-->\t%s"
1637 (if (eq (car lap1) 'byte-goto-if-nil)
1638 'byte-goto-if-not-nil
1641 (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
1642 'byte-goto-if-not-nil
1644 (setq lap (delq lap0 lap))
1645 (setq keep-going t))
1647 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1648 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1650 ;; it is wrong to do the same thing for the -else-pop variants.
1652 ((and (or (eq 'byte-goto-if-nil (car lap0))
1653 (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX
1654 (eq 'byte-goto (car lap1)) ; gotoY
1655 (eq (cdr lap0) lap2)) ; TAG X
1656 (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
1657 'byte-goto-if-not-nil 'byte-goto-if-nil)))
1658 (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
1660 (cons inverse (cdr lap1)) lap2)
1661 (setq lap (delq lap0 lap))
1662 (setcar lap1 inverse)
1663 (setq keep-going t)))
1665 ;; const goto-if-* --> whatever
1667 ((and (eq 'byte-constant (car lap0))
1668 (memq (car lap1) byte-conditional-ops))
1669 (cond ((if (or (eq (car lap1) 'byte-goto-if-nil)
1670 (eq (car lap1) 'byte-goto-if-nil-else-pop))
1672 (not (car (cdr lap0))))
1673 (byte-compile-log-lap " %s %s\t-->\t<deleted>"
1675 (setq rest (cdr rest)
1676 lap (delq lap0 (delq lap1 lap))))
1678 (if (memq (car lap1) byte-goto-always-pop-ops)
1680 (byte-compile-log-lap " %s %s\t-->\t%s"
1681 lap0 lap1 (cons 'byte-goto (cdr lap1)))
1682 (setq lap (delq lap0 lap)))
1683 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1684 (cons 'byte-goto (cdr lap1))))
1685 (setcar lap1 'byte-goto)))
1686 (setq keep-going t))
1688 ;; varref-X varref-X --> varref-X dup
1689 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1690 ;; We don't optimize the const-X variations on this here,
1691 ;; because that would inhibit some goto optimizations; we
1692 ;; optimize the const-X case after all other optimizations.
1694 ((and (eq 'byte-varref (car lap0))
1696 (setq tmp (cdr rest))
1697 (while (eq (car (car tmp)) 'byte-dup)
1698 (setq tmp (cdr tmp)))
1700 (eq (cdr lap0) (cdr (car tmp)))
1701 (eq 'byte-varref (car (car tmp))))
1702 (if (memq byte-optimize-log '(t byte))
1704 (setq tmp2 (cdr rest))
1705 (while (not (eq tmp tmp2))
1706 (setq tmp2 (cdr tmp2)
1707 str (concat str " dup")))
1708 (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
1709 lap0 str lap0 lap0 str)))
1711 (setcar (car tmp) 'byte-dup)
1712 (setcdr (car tmp) 0)
1715 ;; TAG1: TAG2: --> TAG1: <deleted>
1716 ;; (and other references to TAG2 are replaced with TAG1)
1718 ((and (eq (car lap0) 'TAG)
1719 (eq (car lap1) 'TAG))
1720 (and (memq byte-optimize-log '(t byte))
1721 (byte-compile-log " adjacent tags %d and %d merged"
1722 (nth 1 lap1) (nth 1 lap0)))
1724 (while (setq tmp2 (rassq lap0 tmp3))
1726 (setq tmp3 (cdr (memq tmp2 tmp3))))
1727 (setq lap (delq lap0 lap)
1730 ;; unused-TAG: --> <deleted>
1732 ((and (eq 'TAG (car lap0))
1733 (not (rassq lap0 lap)))
1734 (and (memq byte-optimize-log '(t byte))
1735 (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
1736 (setq lap (delq lap0 lap)
1739 ;; goto ... --> goto <delete until TAG or end>
1740 ;; return ... --> return <delete until TAG or end>
1742 ((and (memq (car lap0) '(byte-goto byte-return))
1743 (not (memq (car lap1) '(TAG nil))))
1746 (opt-p (memq byte-optimize-log '(t lap)))
1748 (while (and (setq tmp (cdr tmp))
1749 (not (eq 'TAG (car (car tmp)))))
1750 (if opt-p (setq deleted (cons (car tmp) deleted)
1751 str (concat str " %s")
1755 (if (eq 'TAG (car (car tmp)))
1756 (format "%d:" (car (cdr (car tmp))))
1757 (or (car tmp) ""))))
1759 (apply 'byte-compile-log-lap-1
1761 " %s\t-->\t%s <deleted> %s")
1763 (nconc (nreverse deleted)
1764 (list tagstr lap0 tagstr)))
1765 (byte-compile-log-lap
1766 " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
1767 lap0 i (if (= i 1) "" "s")
1768 tagstr lap0 tagstr))))
1770 (setq keep-going t))
1772 ;; <safe-op> unbind --> unbind <safe-op>
1773 ;; (this may enable other optimizations.)
1775 ((and (eq 'byte-unbind (car lap1))
1776 (memq (car lap0) byte-after-unbind-ops))
1777 (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
1779 (setcar (cdr rest) lap0)
1780 (setq keep-going t))
1782 ;; varbind-X unbind-N --> discard unbind-(N-1)
1783 ;; save-excursion unbind-N --> unbind-(N-1)
1784 ;; save-restriction unbind-N --> unbind-(N-1)
1786 ((and (eq 'byte-unbind (car lap1))
1787 (memq (car lap0) '(byte-varbind byte-save-excursion
1788 byte-save-restriction))
1790 (if (zerop (setcdr lap1 (1- (cdr lap1))))
1792 (if (eq (car lap0) 'byte-varbind)
1793 (setcar rest (cons 'byte-discard 0))
1794 (setq lap (delq lap0 lap)))
1795 (byte-compile-log-lap " %s %s\t-->\t%s %s"
1796 lap0 (cons (car lap1) (1+ (cdr lap1)))
1797 (if (eq (car lap0) 'byte-varbind)
1800 (if (and (/= 0 (cdr lap1))
1801 (eq (car lap0) 'byte-varbind))
1804 (setq keep-going t))
1806 ;; goto*-X ... X: goto-Y --> goto*-Y
1807 ;; goto-X ... X: return --> return
1809 ((and (memq (car lap0) byte-goto-ops)
1810 (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
1811 '(byte-goto byte-return)))
1812 (cond ((and (not (eq tmp lap0))
1813 (or (eq (car lap0) 'byte-goto)
1814 (eq (car tmp) 'byte-goto)))
1815 (byte-compile-log-lap " %s [%s]\t-->\t%s"
1817 (if (eq (car tmp) 'byte-return)
1818 (setcar lap0 'byte-return))
1819 (setcdr lap0 (cdr tmp))
1820 (setq keep-going t))))
1822 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1823 ;; goto-*-else-pop X ... X: discard --> whatever
1825 ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
1826 byte-goto-if-not-nil-else-pop))
1827 (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
1829 (cons 'byte-discard byte-conditional-ops)))
1830 (not (eq lap0 (car tmp))))
1831 (setq tmp2 (car tmp))
1832 (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
1834 (byte-goto-if-not-nil-else-pop
1835 byte-goto-if-not-nil))))
1836 (if (memq (car tmp2) tmp3)
1837 (progn (setcar lap0 (car tmp2))
1838 (setcdr lap0 (cdr tmp2))
1839 (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
1840 (car lap0) tmp2 lap0))
1841 ;; Get rid of the -else-pop's and jump one step further.
1842 (or (eq 'TAG (car (nth 1 tmp)))
1843 (setcdr tmp (cons (byte-compile-make-tag)
1845 (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
1846 (car lap0) tmp2 (nth 1 tmp3))
1847 (setcar lap0 (nth 1 tmp3))
1848 (setcdr lap0 (nth 1 tmp)))
1849 (setq keep-going t))
1851 ;; const goto-X ... X: goto-if-* --> whatever
1852 ;; const goto-X ... X: discard --> whatever
1854 ((and (eq (car lap0) 'byte-constant)
1855 (eq (car lap1) 'byte-goto)
1856 (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
1858 (cons 'byte-discard byte-conditional-ops)))
1859 (not (eq lap1 (car tmp))))
1860 (setq tmp2 (car tmp))
1861 (cond ((memq (car tmp2)
1862 (if (null (car (cdr lap0)))
1863 '(byte-goto-if-nil byte-goto-if-nil-else-pop)
1864 '(byte-goto-if-not-nil
1865 byte-goto-if-not-nil-else-pop)))
1866 (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
1867 lap0 tmp2 lap0 tmp2)
1868 (setcar lap1 (car tmp2))
1869 (setcdr lap1 (cdr tmp2))
1870 ;; Let next step fix the (const,goto-if*) sequence.
1871 (setq rest (cons nil rest)))
1873 ;; Jump one step further
1874 (byte-compile-log-lap
1875 " %s goto [%s]\t-->\t<deleted> goto <skip>"
1877 (or (eq 'TAG (car (nth 1 tmp)))
1878 (setcdr tmp (cons (byte-compile-make-tag)
1880 (setcdr lap1 (car (cdr tmp)))
1881 (setq lap (delq lap0 lap))))
1882 (setq keep-going t))
1884 ;; X: varref-Y ... varset-Y goto-X -->
1885 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1886 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1887 ;; (This is so usual for while loops that it is worth handling).
1889 ((and (eq (car lap1) 'byte-varset)
1890 (eq (car lap2) 'byte-goto)
1891 (not (memq (cdr lap2) rest)) ;Backwards jump
1892 (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
1894 (eq (cdr (car tmp)) (cdr lap1))
1895 (not (eq (built-in-variable-type (car (cdr lap1)))
1897 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1898 (let ((newtag (byte-compile-make-tag)))
1899 (byte-compile-log-lap
1900 " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
1901 (nth 1 (cdr lap2)) (car tmp)
1903 (nth 1 (cdr lap2)) (car tmp)
1904 (nth 1 newtag) 'byte-dup lap1
1905 (cons 'byte-goto newtag)
1907 (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
1908 (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
1910 (setq keep-going t))
1912 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1913 ;; (This can pull the loop test to the end of the loop)
1915 ((and (eq (car lap0) 'byte-goto)
1916 (eq (car lap1) 'TAG)
1918 (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
1919 (memq (car (car tmp))
1920 '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
1921 byte-goto-if-nil-else-pop)))
1922 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1923 ;; lap0 lap1 (cdr lap0) (car tmp))
1924 (let ((newtag (byte-compile-make-tag)))
1925 (byte-compile-log-lap
1926 "%s %s: ... %s: %s\t-->\t%s ... %s:"
1927 lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
1928 (cons (cdr (assq (car (car tmp))
1929 '((byte-goto-if-nil . byte-goto-if-not-nil)
1930 (byte-goto-if-not-nil . byte-goto-if-nil)
1931 (byte-goto-if-nil-else-pop .
1932 byte-goto-if-not-nil-else-pop)
1933 (byte-goto-if-not-nil-else-pop .
1934 byte-goto-if-nil-else-pop))))
1939 (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
1940 (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
1941 ;; We can handle this case but not the -if-not-nil case,
1942 ;; because we won't know which non-nil constant to push.
1943 (setcdr rest (cons (cons 'byte-constant
1944 (byte-compile-get-constant nil))
1946 (setcar lap0 (nth 1 (memq (car (car tmp))
1947 '(byte-goto-if-nil-else-pop
1948 byte-goto-if-not-nil
1950 byte-goto-if-not-nil
1951 byte-goto byte-goto))))
1953 (setq keep-going t))
1955 (setq rest (cdr rest)))
1958 ;; Rebuild byte-compile-constants / byte-compile-variables.
1959 ;; Simple optimizations that would inhibit other optimizations if they
1960 ;; were done in the optimizing loop, and optimizations which there is no
1961 ;; need to do more than once.
1962 (setq byte-compile-constants nil
1963 byte-compile-variables nil
1964 variable-frequency (make-hash-table :test 'eq))
1967 (setq lap0 (car rest)
1970 ((byte-varref byte-varset byte-varbind)
1971 (incf (gethash (cdr lap0) variable-frequency 0))
1972 (unless (memq (cdr lap0) byte-compile-variables)
1973 (push (cdr lap0) byte-compile-variables)))
1975 (unless (memq (cdr lap0) byte-compile-constants)
1976 (push (cdr lap0) byte-compile-constants))))
1978 ;; const-C varset-X const-C --> const-C dup varset-X
1979 ;; const-C varbind-X const-C --> const-C dup varbind-X
1981 (and (eq (car lap0) 'byte-constant)
1982 (eq (car (nth 2 rest)) 'byte-constant)
1983 (eq (cdr lap0) (cdr (nth 2 rest)))
1984 (memq (car lap1) '(byte-varbind byte-varset)))
1985 (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
1986 lap0 lap1 lap0 lap0 lap1)
1987 (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
1988 (setcar (cdr rest) (cons 'byte-dup 0))
1991 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1992 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1994 ((memq (car lap0) '(byte-constant byte-varref))
1998 (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
1999 (and (eq (cdr lap0) (cdr (car tmp)))
2000 (eq (car lap0) (car (car tmp)))))
2001 (setcar tmp (cons 'byte-dup 0))
2004 (byte-compile-log-lap
2005 " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
2007 ;; unbind-N unbind-M --> unbind-(N+M)
2009 ((and (eq 'byte-unbind (car lap0))
2010 (eq 'byte-unbind (car lap1)))
2011 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
2013 (+ (cdr lap0) (cdr lap1))))
2015 (setq lap (delq lap0 lap))
2016 (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
2018 (setq rest (cdr rest)))
2019 ;; Since the first 6 entries of the compiled-function constants
2020 ;; vector are most efficient for varref/set/bind ops, we sort by
2021 ;; reference count. This generates maximally space efficient and
2022 ;; pretty time-efficient byte-code. See `byte-compile-constants-vector'.
2023 (setq byte-compile-variables
2024 (sort byte-compile-variables
2026 (< (gethash v1 variable-frequency)
2027 (gethash v2 variable-frequency)))))
2028 ;; Another hack - put the most used variable in position 6, for
2029 ;; better locality of reference with adjoining constants.
2030 (let ((tail (last byte-compile-variables 6)))
2031 (setq byte-compile-variables
2032 (append (nbutlast byte-compile-variables 6)
2034 (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
2037 (provide 'byte-optimize)
2040 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
2041 ;; itself, compile some of its most used recursive functions (at load time).
2044 (or (compiled-function-p (symbol-function 'byte-optimize-form))
2045 (assq 'byte-code (symbol-function 'byte-optimize-form))
2046 (let ((byte-optimize nil)
2047 (byte-compile-warnings nil))
2050 (or noninteractive (message "compiling %s..." x))
2052 (or noninteractive (message "compiling %s...done" x)))
2053 '(byte-optimize-form
2055 byte-optimize-predicate
2056 byte-optimize-binary-predicate
2057 ;; Inserted some more than necessary, to speed it up.
2058 byte-optimize-form-code-walker
2059 byte-optimize-lapcode))))
2062 ;;; byte-optimize.el ends here