1 ;;; byte-optimize.el --- the optimization passes of the emacs-lisp byte compiler.
3 ;;; Copyright (c) 1991, 1994 Free Software Foundation, Inc.
5 ;; Author: Jamie Zawinski <jwz@jwz.org>
6 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
9 ;; This file is part of XEmacs.
11 ;; XEmacs is free software; you can redistribute it and/or modify it
12 ;; under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; XEmacs is distributed in the hope that it will be useful, but
17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 ;; General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with XEmacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
26 ;;; Synched up with: FSF 19.30.
30 ;; ========================================================================
31 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
32 ;; You can, however, make a faster pig."
34 ;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code
35 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
36 ;; still not going to make it go faster than 70 mph, but it might be easier
42 ;; (apply #'(lambda (x &rest y) ...) 1 (foo))
44 ;; maintain a list of functions known not to access any global variables
45 ;; (actually, give them a 'dynamically-safe property) and then
46 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
47 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
48 ;; by recursing on this, we might be able to eliminate the entire let.
49 ;; However certain variables should never have their bindings optimized
50 ;; away, because they affect everything.
51 ;; (put 'debug-on-error 'binding-is-magic t)
52 ;; (put 'debug-on-abort 'binding-is-magic t)
53 ;; (put 'debug-on-next-call 'binding-is-magic t)
54 ;; (put 'mocklisp-arguments 'binding-is-magic t)
55 ;; (put 'inhibit-quit 'binding-is-magic t)
56 ;; (put 'quit-flag 'binding-is-magic t)
57 ;; (put 't 'binding-is-magic t)
58 ;; (put 'nil 'binding-is-magic t)
60 ;; (put 'gc-cons-threshold 'binding-is-magic t)
61 ;; (put 'track-mouse 'binding-is-magic t)
64 ;; Simple defsubsts often produce forms like
65 ;; (let ((v1 (f1)) (v2 (f2)) ...)
67 ;; It would be nice if we could optimize this to
69 ;; but we can't unless FN is dynamically-safe (it might be dynamically
70 ;; referring to the bindings that the lambda arglist established.)
71 ;; One of the uncountable lossages introduced by dynamic scope...
73 ;; Maybe there should be a control-structure that says "turn on
74 ;; fast-and-loose type-assumptive optimizations here." Then when
75 ;; we see a form like (car foo) we can from then on assume that
76 ;; the variable foo is of type cons, and optimize based on that.
77 ;; But, this won't win much because of (you guessed it) dynamic
78 ;; scope. Anything down the stack could change the value.
79 ;; (Another reason it doesn't work is that it is perfectly valid
80 ;; to call car with a null argument.) A better approach might
81 ;; be to allow type-specification of the form
82 ;; (put 'foo 'arg-types '(float (list integer) dynamic))
83 ;; (put 'foo 'result-type 'bool)
84 ;; It should be possible to have these types checked to a certain
87 ;; collapse common subexpressions
89 ;; It would be nice if redundant sequences could be factored out as well,
90 ;; when they are known to have no side-effects:
91 ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
92 ;; but beware of traps like
93 ;; (cons (list x y) (list x y))
95 ;; Tail-recursion elimination is not really possible in Emacs Lisp.
96 ;; Tail-recursion elimination is almost always impossible when all variables
97 ;; have dynamic scope, but given that the "return" byteop requires the
98 ;; binding stack to be empty (rather than emptying it itself), there can be
99 ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
100 ;; make any bindings.
102 ;; Here is an example of an Emacs Lisp function which could safely be
103 ;; byte-compiled tail-recursively:
105 ;; (defun tail-map (fn list)
107 ;; (funcall fn (car list))
108 ;; (tail-map fn (cdr list)))))
110 ;; However, if there was even a single let-binding around the COND,
111 ;; it could not be byte-compiled, because there would be an "unbind"
112 ;; byte-op between the final "call" and "return." Adding a
113 ;; Bunbind_all byteop would fix this.
115 ;; (defun foo (x y z) ... (foo a b c))
116 ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
117 ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
118 ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
120 ;; this also can be considered tail recursion:
122 ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
123 ;; could generalize this by doing the optimization
124 ;; (goto X) ... X: (return) --> (return)
126 ;; But this doesn't solve all of the problems: although by doing tail-
127 ;; recursion elimination in this way, the call-stack does not grow, the
128 ;; binding-stack would grow with each recursive step, and would eventually
129 ;; overflow. I don't believe there is any way around this without lexical
132 ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
134 ;; Idea: the form (lexical-scope) in a file means that the file may be
135 ;; compiled lexically. This proclamation is file-local. Then, within
136 ;; that file, "let" would establish lexical bindings, and "let-dynamic"
137 ;; would do things the old way. (Or we could use CL "declare" forms.)
138 ;; We'd have to notice defvars and defconsts, since those variables should
139 ;; always be dynamic, and attempting to do a lexical binding of them
140 ;; should simply do a dynamic binding instead.
141 ;; But! We need to know about variables that were not necessarily defvarred
142 ;; in the file being compiled (doing a boundp check isn't good enough.)
143 ;; Fdefvar() would have to be modified to add something to the plist.
145 ;; A major disadvantage of this scheme is that the interpreter and compiler
146 ;; would have different semantics for files compiled with (dynamic-scope).
147 ;; Since this would be a file-local optimization, there would be no way to
148 ;; modify the interpreter to obey this (unless the loader was hacked
149 ;; in some grody way, but that's a really bad idea.)
151 ;; HA! RMS removed the following paragraph from his version of
154 ;; Really the Right Thing is to make lexical scope the default across
155 ;; the board, in the interpreter and compiler, and just FIX all of
156 ;; the code that relies on dynamic scope of non-defvarred variables.
158 ;; Other things to consider:
160 ;; Associative math should recognize subcalls to identical function:
161 ;;(disassemble #'(lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
162 ;; This should generate the same as (1+ x) and (1- x)
164 ;;(disassemble #'(lambda (x) (cons (+ x 1) (- x 1))))
165 ;; An awful lot of functions always return a non-nil value. If they're
166 ;; error free also they may act as true-constants.
168 ;;(disassemble #'(lambda (x) (and (point) (foo))))
170 ;; - all but one arguments to a function are constant
171 ;; - the non-constant argument is an if-expression (cond-expression?)
172 ;; then the outer function can be distributed. If the guarding
173 ;; condition is side-effect-free [assignment-free] then the other
174 ;; arguments may be any expressions. Since, however, the code size
175 ;; can increase this way they should be "simple". Compare:
177 ;;(disassemble #'(lambda (x) (eq (if (point) 'a 'b) 'c)))
178 ;;(disassemble #'(lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
180 ;; (car (cons A B)) -> (progn B A)
181 ;;(disassemble #'(lambda (x) (car (cons (foo) 42))))
183 ;; (cdr (cons A B)) -> (progn A B)
184 ;;(disassemble #'(lambda (x) (cdr (cons 42 (foo)))))
186 ;; (car (list A B ...)) -> (progn B ... A)
187 ;;(disassemble #'(lambda (x) (car (list (foo) 42 (bar)))))
189 ;; (cdr (list A B ...)) -> (progn A (list B ...))
190 ;;(disassemble #'(lambda (x) (cdr (list 42 (foo) (bar)))))
195 (require 'byte-compile "bytecomp")
197 (defun byte-compile-log-lap-1 (format &rest args)
198 (if (aref byte-code-vector 0)
199 (error "The old version of the disassembler is loaded. Reload new-bytecomp as well."))
201 (apply 'format format
205 (if (not (consp arg))
206 (if (and (symbolp arg)
207 (string-match "^byte-" (symbol-name arg)))
208 (intern (substring (symbol-name arg) 5))
210 (if (integerp (setq c (car arg)))
211 (error "non-symbolic byte-op %s" c))
214 (setq a (cond ((memq c byte-goto-ops)
215 (car (cdr (cdr arg))))
216 ((memq c byte-constref-ops)
219 (setq c (symbol-name c))
220 (if (string-match "^byte-." c)
221 (setq c (intern (substring c 5)))))
222 (if (eq c 'constant) (setq c 'const))
223 (if (and (eq (cdr arg) 0)
224 (not (memq c '(unbind call const))))
226 (format "(%s %s)" c a))))
229 (defmacro byte-compile-log-lap (format-string &rest args)
231 '(memq byte-optimize-log '(t byte))
232 (cons 'byte-compile-log-lap-1
233 (cons format-string args))))
236 ;;; byte-compile optimizers to support inlining
238 (put 'inline 'byte-optimizer 'byte-optimize-inline-handler)
240 (defun byte-optimize-inline-handler (form)
241 "byte-optimize-handler for the `inline' special-form."
246 (let ((fn (car-safe sexp)))
247 (if (and (symbolp fn)
248 (or (cdr (assq fn byte-compile-function-environment))
250 (not (or (cdr (assq fn byte-compile-macro-environment))
251 (and (consp (setq fn (symbol-function fn)))
252 (eq (car fn) 'macro))
254 (byte-compile-inline-expand sexp)
259 ;; Splice the given lap code into the current instruction stream.
260 ;; If it has any labels in it, you're responsible for making sure there
261 ;; are no collisions, and that byte-compile-tag-number is reasonable
262 ;; after this is spliced in. The provided list is destroyed.
263 (defun byte-inline-lapcode (lap)
264 (setq byte-compile-output (nconc (nreverse lap) byte-compile-output)))
267 (defun byte-compile-inline-expand (form)
268 (let* ((name (car form))
269 (fn (or (cdr (assq name byte-compile-function-environment))
270 (and (fboundp name) (symbol-function name)))))
273 (byte-compile-warn "attempt to inline %s before it was defined" name)
276 (if (and (consp fn) (eq (car fn) 'autoload))
279 (setq fn (or (cdr (assq name byte-compile-function-environment))
280 (and (fboundp name) (symbol-function name))))))
281 (if (and (consp fn) (eq (car fn) 'autoload))
282 (error "file \"%s\" didn't define \"%s\"" (nth 1 fn) name))
284 (byte-compile-inline-expand (cons fn (cdr form)))
285 (if (compiled-function-p fn)
288 (cons (list 'lambda (compiled-function-arglist fn)
290 (compiled-function-instructions fn)
291 (compiled-function-constants fn)
292 (compiled-function-stack-depth fn)))
294 (if (not (eq (car fn) 'lambda)) (error "%s is not a lambda" name))
295 (cons fn (cdr form)))))))
297 ;;; ((lambda ...) ...)
299 (defun byte-compile-unfold-lambda (form &optional name)
300 (or name (setq name "anonymous lambda"))
301 (let ((lambda (car form))
303 (if (compiled-function-p lambda)
304 (setq lambda (list 'lambda (compiled-function-arglist lambda)
306 (compiled-function-instructions lambda)
307 (compiled-function-constants lambda)
308 (compiled-function-stack-depth lambda)))))
309 (let ((arglist (nth 1 lambda))
310 (body (cdr (cdr lambda)))
313 (if (and (stringp (car body)) (cdr body))
314 (setq body (cdr body)))
315 (if (and (consp (car body)) (eq 'interactive (car (car body))))
316 (setq body (cdr body)))
318 (cond ((eq (car arglist) '&optional)
319 ;; ok, I'll let this slide because funcall_lambda() does...
320 ;; (if optionalp (error "multiple &optional keywords in %s" name))
321 (if restp (error "&optional found after &rest in %s" name))
322 (if (null (cdr arglist))
323 (error "nothing after &optional in %s" name))
325 ((eq (car arglist) '&rest)
326 ;; ...but it is by no stretch of the imagination a reasonable
327 ;; thing that funcall_lambda() allows (&rest x y) and
328 ;; (&rest x &optional y) in arglists.
329 (if (null (cdr arglist))
330 (error "nothing after &rest in %s" name))
331 (if (cdr (cdr arglist))
332 (error "multiple vars after &rest in %s" name))
335 (setq bindings (cons (list (car arglist)
336 (and values (cons 'list values)))
339 ((and (not optionalp) (null values))
340 (byte-compile-warn "attempt to open-code %s with too few arguments" name)
341 (setq arglist nil values 'too-few))
343 (setq bindings (cons (list (car arglist) (car values))
345 values (cdr values))))
346 (setq arglist (cdr arglist)))
349 (or (eq values 'too-few)
351 "attempt to open-code %s with too many arguments" name))
355 (cons 'let (cons (nreverse bindings) body))
356 (cons 'progn body))))
357 (byte-compile-log " %s\t==>\t%s" form newform)
361 ;;; implementing source-level optimizers
363 (defun byte-optimize-form-code-walker (form for-effect)
365 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
366 ;; we need to have special knowledge of the syntax of the special forms
367 ;; like let and defun (that's why they're special forms :-). (Actually,
368 ;; the important aspect is that they are subrs that don't evaluate all of
371 (let ((fn (car-safe form))
373 (cond ((not (consp form))
374 (if (not (and for-effect
375 (or byte-compile-delete-errors
381 (byte-compile-warn "malformed quote form: %s"
382 (prin1-to-string form)))
383 ;; map (quote nil) to nil to simplify optimizer logic.
384 ;; map quoted constants to nil if for-effect (just because).
388 ((or (compiled-function-p fn)
389 (eq 'lambda (car-safe fn)))
390 (byte-compile-unfold-lambda form))
391 ((memq fn '(let let*))
392 ;; recursively enter the optimizer for the bindings and body
393 ;; of a let or let*. This for depth-firstness: forms that
394 ;; are more deeply nested are optimized first.
399 (if (symbolp binding)
401 (if (cdr (cdr binding))
402 (byte-compile-warn "malformed let binding: %s"
403 (prin1-to-string binding)))
405 (byte-optimize-form (nth 1 binding) nil))))
407 (byte-optimize-body (cdr (cdr form)) for-effect))))
414 (byte-optimize-form (car clause) nil)
415 (byte-optimize-body (cdr clause) for-effect))
416 (byte-compile-warn "malformed cond form: %s"
417 (prin1-to-string clause))
421 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
424 (setq tmp (byte-optimize-body (cdr form) for-effect))
425 (if (cdr tmp) (cons 'progn tmp) (car tmp)))
426 (byte-optimize-form (nth 1 form) for-effect)))
430 (cons (byte-optimize-form (nth 1 form) for-effect)
431 (byte-optimize-body (cdr (cdr form)) t)))
432 (byte-optimize-form (nth 1 form) for-effect)))
435 (cons (byte-optimize-form (nth 1 form) t)
436 (cons (byte-optimize-form (nth 2 form) for-effect)
437 (byte-optimize-body (cdr (cdr (cdr form))) t)))))
439 ((memq fn '(save-excursion save-restriction save-current-buffer))
440 ;; those subrs which have an implicit progn; it's not quite good
441 ;; enough to treat these like normal function calls.
442 ;; This can turn (save-excursion ...) into (save-excursion) which
443 ;; will be optimized away in the lap-optimize pass.
444 (cons fn (byte-optimize-body (cdr form) for-effect)))
446 ((eq fn 'with-output-to-temp-buffer)
447 ;; this is just like the above, except for the first argument.
450 (byte-optimize-form (nth 1 form) nil)
451 (byte-optimize-body (cdr (cdr form)) for-effect))))
455 (cons (byte-optimize-form (nth 1 form) nil)
457 (byte-optimize-form (nth 2 form) for-effect)
458 (byte-optimize-body (nthcdr 3 form) for-effect)))))
460 ((memq fn '(and or)) ; remember, and/or are control structures.
461 ;; take forms off the back until we can't any more.
462 ;; In the future it could conceivably be a problem that the
463 ;; subexpressions of these forms are optimized in the reverse
464 ;; order, but it's ok for now.
466 (let ((backwards (reverse (cdr form))))
467 (while (and backwards
468 (null (setcar backwards
469 (byte-optimize-form (car backwards)
471 (setq backwards (cdr backwards)))
472 (if (and (cdr form) (null backwards))
474 " all subforms of %s called for effect; deleted" form))
476 ;; Now optimize the rest of the forms. We need the return
477 ;; values. We already did the car.
479 (mapcar 'byte-optimize-form (cdr backwards)))
480 (cons fn (nreverse backwards))))
481 (cons fn (mapcar 'byte-optimize-form (cdr form)))))
483 ((eq fn 'interactive)
484 (byte-compile-warn "misplaced interactive spec: %s"
485 (prin1-to-string form))
488 ((memq fn '(defun defmacro function
489 condition-case save-window-excursion))
490 ;; These forms are compiled as constants or by breaking out
491 ;; all the subexpressions and compiling them separately.
494 ((eq fn 'unwind-protect)
495 ;; the "protected" part of an unwind-protect is compiled (and thus
496 ;; optimized) as a top-level form, so don't do it here. But the
497 ;; non-protected part has the same for-effect status as the
498 ;; unwind-protect itself. (The protected part is always for effect,
499 ;; but that isn't handled properly yet.)
501 (cons (byte-optimize-form (nth 1 form) for-effect)
505 ;; the body of a catch is compiled (and thus optimized) as a
506 ;; top-level form, so don't do it here. The tag is never
507 ;; for-effect. The body should have the same for-effect status
508 ;; as the catch form itself, but that isn't handled properly yet.
510 (cons (byte-optimize-form (nth 1 form) nil)
513 ;; If optimization is on, this is the only place that macros are
514 ;; expanded. If optimization is off, then macroexpansion happens
515 ;; in byte-compile-form. Otherwise, the macros are already expanded
516 ;; by the time that is reached.
518 (setq form (macroexpand form
519 byte-compile-macro-environment))))
520 (byte-optimize-form form for-effect))
523 (or (eq 'mocklisp (car-safe fn)) ; ha!
524 (byte-compile-warn "%s is a malformed function"
525 (prin1-to-string fn)))
528 ((and for-effect (setq tmp (get fn 'side-effect-free))
529 (or byte-compile-delete-errors
532 (byte-compile-warn "%s called for effect"
533 (prin1-to-string form))
535 (byte-compile-log " %s called for effect; deleted" fn)
536 ;; appending a nil here might not be necessary, but it can't hurt.
538 (cons 'progn (append (cdr form) '(nil))) t))
541 ;; Otherwise, no args can be considered to be for-effect,
542 ;; even if the called function is for-effect, because we
543 ;; don't know anything about that function.
544 (cons fn (mapcar 'byte-optimize-form (cdr form)))))))
547 (defun byte-optimize-form (form &optional for-effect)
548 "The source-level pass of the optimizer."
550 ;; First, optimize all sub-forms of this one.
551 (setq form (byte-optimize-form-code-walker form for-effect))
553 ;; After optimizing all subforms, optimize this form until it doesn't
554 ;; optimize any further. This means that some forms will be passed through
555 ;; the optimizer many times, but that's necessary to make the for-effect
556 ;; processing do as much as possible.
559 (if (and (consp form)
562 ;; we don't have any of these yet, but we might.
563 (setq opt (get (car form) 'byte-for-effect-optimizer)))
564 (setq opt (get (car form) 'byte-optimizer)))
565 (not (eq form (setq new (funcall opt form)))))
567 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
568 (byte-compile-log " %s\t==>\t%s" form new)
569 (setq new (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 (defun byte-optimize-plus (form)
703 (setq form (byte-optimize-delay-constants-math form 1 '+))
704 (if (memq 0 form) (setq form (delq 0 (copy-sequence form))))
705 ;;(setq form (byte-optimize-associative-two-args-math form))
707 (case (length (cdr form))
713 ;; It is not safe to delete the function entirely
714 ;; (actually, it would be safe if we knew the sole arg
720 (byte-optimize-predicate
722 ;; `add1' and `sub1' are a marginally fewer instructions
723 ;; than `plus' and `minus', so use them when possible.
724 ((eq (nth 1 form) 1) `(1+ ,(nth 2 form))) ; (+ 1 x) --> (1+ x)
725 ((eq (nth 2 form) 1) `(1+ ,(nth 1 form))) ; (+ x 1) --> (1+ x)
726 ((eq (nth 1 form) -1) `(1- ,(nth 2 form))) ; (+ -1 x) --> (1- x)
727 ((eq (nth 2 form) -1) `(1- ,(nth 1 form))) ; (+ x -1) --> (1- x)
730 (t (byte-optimize-predicate form))))
732 (defun byte-optimize-minus (form)
733 ;; Put constants at the end, except the last constant.
734 (setq form (byte-optimize-delay-constants-math form 2 '+))
735 ;; Now only first and last element can be an integer.
736 (let ((last (last (nthcdr 3 form))))
738 ;; (- x y ... 0) --> (- x y ...)
739 (setq form (copy-sequence form))
740 (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form))))
741 ;; If form is (- CONST foo... CONST), merge first and last.
742 ((and (numberp (nth 1 form))
744 (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
745 (delq last (copy-sequence (nthcdr 3 form))))))))
747 (case (length (cdr form))
753 ;; It is not safe to delete the function entirely
754 ;; (actually, it would be safe if we knew the sole arg
760 (byte-optimize-predicate
762 ;; `add1' and `sub1' are a marginally fewer instructions than `plus'
763 ;; and `minus', so use them when possible.
764 ((eq (nth 2 form) 1) `(1- ,(nth 1 form))) ; (- x 1) --> (1- x)
765 ((eq (nth 2 form) -1) `(1+ ,(nth 1 form))) ; (- x -1) --> (1+ x)
766 ((eq (nth 1 form) 0) `(- ,(nth 2 form))) ; (- 0 x) --> (- x)
769 (t (byte-optimize-predicate form))))
771 (defun byte-optimize-multiply (form)
772 (setq form (byte-optimize-delay-constants-math form 1 '*))
773 ;; If there is a constant integer in FORM, it is now the last element.
774 (cond ((null (cdr form)) 1)
775 ;;; It is not safe to delete the function entirely
776 ;;; (actually, it would be safe if we know the sole arg
777 ;;; is not a marker or if it appears in other arithmetic).
778 ;;; ((null (cdr (cdr form))) (nth 1 form))
779 ((let ((last (last form)))
780 (byte-optimize-predicate
781 (cond ((eq 0 last) (cons 'progn (cdr form)))
782 ((eq 1 last) (delq 1 (copy-sequence form)))
783 ((eq -1 last) (list '- (delq -1 (copy-sequence form))))
785 (memq t (mapcar 'symbolp (cdr form))))
786 (prog1 (setq form (delq 2 (copy-sequence form)))
787 (while (not (symbolp (car (setq form (cdr form))))))
788 (setcar form (list '+ (car form) (car form)))))
791 (defun byte-optimize-divide (form)
792 (setq form (byte-optimize-delay-constants-math form 2 '*))
793 ;; If there is a constant integer in FORM, it is now the last element.
794 (let ((last (last (cdr (cdr form)))))
796 (cond ((= (length form) 3)
797 (if (and (numberp (nth 1 form))
800 (/ (nth 1 form) last)
802 (setq form (list 'progn (/ (nth 1 form) last)))))
804 (setq form (butlast form)))
805 ((numberp (nth 1 form))
806 (setq form (cons (car form)
807 (cons (/ (nth 1 form) last)
808 (butlast (cdr (cdr form)))))
811 ;;; ((null (cdr (cdr form)))
814 (append '(progn) (cdr (cdr form)) '(0)))
816 (list '- (if (nthcdr 3 form)
821 (defun byte-optimize-logmumble (form)
822 (setq form (byte-optimize-delay-constants-math form 1 (car form)))
823 (byte-optimize-predicate
825 (setq form (if (eq (car form) 'logand)
826 (cons 'progn (cdr form))
827 (delq 0 (copy-sequence form)))))
828 ((and (eq (car-safe form) 'logior)
830 (cons 'progn (cdr form)))
834 (defun byte-optimize-binary-predicate (form)
835 (if (byte-compile-constp (nth 1 form))
836 (if (byte-compile-constp (nth 2 form))
838 (list 'quote (eval form))
840 ;; This can enable some lapcode optimizations.
841 (list (car form) (nth 2 form) (nth 1 form)))
844 (defun byte-optimize-predicate (form)
848 (setq ok (byte-compile-constp (car rest))
852 (list 'quote (eval form))
856 (defun byte-optimize-identity (form)
857 (if (and (cdr form) (null (cdr (cdr form))))
859 (byte-compile-warn "identity called with %d arg%s, but requires 1"
861 (if (= 1 (length (cdr form))) "" "s"))
864 (put 'identity 'byte-optimizer 'byte-optimize-identity)
866 (put '+ 'byte-optimizer 'byte-optimize-plus)
867 (put '* 'byte-optimizer 'byte-optimize-multiply)
868 (put '- 'byte-optimizer 'byte-optimize-minus)
869 (put '/ 'byte-optimizer 'byte-optimize-divide)
870 (put 'max 'byte-optimizer 'byte-optimize-associative-math)
871 (put 'min 'byte-optimizer 'byte-optimize-associative-math)
873 (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
874 (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
875 (put 'eql 'byte-optimizer 'byte-optimize-binary-predicate)
876 (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
877 (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
878 (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
880 (put '< 'byte-optimizer 'byte-optimize-predicate)
881 (put '> 'byte-optimizer 'byte-optimize-predicate)
882 (put '<= 'byte-optimizer 'byte-optimize-predicate)
883 (put '>= 'byte-optimizer 'byte-optimize-predicate)
884 (put '1+ 'byte-optimizer 'byte-optimize-predicate)
885 (put '1- 'byte-optimizer 'byte-optimize-predicate)
886 (put 'not 'byte-optimizer 'byte-optimize-predicate)
887 (put 'null 'byte-optimizer 'byte-optimize-predicate)
888 (put 'memq 'byte-optimizer 'byte-optimize-predicate)
889 (put 'consp 'byte-optimizer 'byte-optimize-predicate)
890 (put 'listp 'byte-optimizer 'byte-optimize-predicate)
891 (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
892 (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
893 (put 'string< 'byte-optimizer 'byte-optimize-predicate)
894 (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
895 (put 'length 'byte-optimizer 'byte-optimize-predicate)
897 (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
898 (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
899 (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
900 (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
902 (put 'car 'byte-optimizer 'byte-optimize-predicate)
903 (put 'cdr 'byte-optimizer 'byte-optimize-predicate)
904 (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
905 (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
908 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
909 ;; take care of this? - Jamie
910 ;; I think this may some times be necessary to reduce eg. (quote 5) to 5,
911 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
912 (put 'quote 'byte-optimizer 'byte-optimize-quote)
913 (defun byte-optimize-quote (form)
914 (if (or (consp (nth 1 form))
915 (and (symbolp (nth 1 form))
917 (not (keywordp (nth 1 form)))
918 (not (memq (nth 1 form) '(nil t)))))
922 (defun byte-optimize-zerop (form)
923 (cond ((numberp (nth 1 form))
925 (byte-compile-delete-errors
926 (list '= (nth 1 form) 0))
929 (put 'zerop 'byte-optimizer 'byte-optimize-zerop)
931 (defun byte-optimize-and (form)
932 ;; Simplify if less than 2 args.
933 ;; if there is a literal nil in the args to `and', throw it and following
934 ;; forms away, and surround the `and' with (progn ... nil).
935 (cond ((null (cdr form)))
939 (prog1 (setq form (copy-sequence form))
941 (setq form (cdr form)))
944 ((null (cdr (cdr form)))
946 ((byte-optimize-predicate form))))
948 (defun byte-optimize-or (form)
949 ;; Throw away nil's, and simplify if less than 2 args.
950 ;; If there is a literal non-nil constant in the args to `or', throw away all
953 (setq form (delq nil (copy-sequence form))))
955 (while (cdr (setq rest (cdr rest)))
956 (if (byte-compile-trueconstp (car rest))
957 (setq form (copy-sequence form)
958 rest (setcdr (memq (car rest) form) nil))))
960 (byte-optimize-predicate form)
963 (defun byte-optimize-cond (form)
964 ;; if any clauses have a literal nil as their test, throw them away.
965 ;; if any clause has a literal non-nil constant as its test, throw
966 ;; away all following clauses.
968 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
969 (while (setq rest (assq nil (cdr form)))
970 (setq form (delq rest (copy-sequence form))))
971 (if (memq nil (cdr form))
972 (setq form (delq nil (copy-sequence form))))
974 (while (setq rest (cdr rest))
975 (cond ((byte-compile-trueconstp (car-safe (car rest)))
976 (cond ((eq rest (cdr form))
979 (if (cdr (cdr (car rest)))
980 (cons 'progn (cdr (car rest)))
984 (setq form (copy-sequence form))
985 (setcdr (memq (car rest) form) nil)))
988 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
989 (if (eq 'cond (car-safe form))
990 (let ((clauses (cdr form)))
991 (if (and (consp (car clauses))
992 (null (cdr (car clauses))))
993 (list 'or (car (car clauses))
995 (cons (car form) (cdr (cdr form)))))
999 (defun byte-optimize-if (form)
1000 ;; (if <true-constant> <then> <else...>) ==> <then>
1001 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
1002 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
1003 ;; (if <test> <then> nil) ==> (if <test> <then>)
1004 (let ((clause (nth 1 form)))
1005 (cond ((byte-compile-trueconstp clause)
1009 (cons 'progn (nthcdr 3 form))
1012 (if (equal '(nil) (nthcdr 3 form))
1013 (list 'if clause (nth 2 form))
1015 ((or (nth 3 form) (nthcdr 4 form))
1017 ;; Don't make a double negative;
1018 ;; instead, take away the one that is there.
1019 (if (and (consp clause) (memq (car clause) '(not null))
1020 (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
1024 (cons 'progn (nthcdr 3 form))
1027 (list 'progn clause nil)))))
1029 (defun byte-optimize-while (form)
1033 (put 'and 'byte-optimizer 'byte-optimize-and)
1034 (put 'or 'byte-optimizer 'byte-optimize-or)
1035 (put 'cond 'byte-optimizer 'byte-optimize-cond)
1036 (put 'if 'byte-optimizer 'byte-optimize-if)
1037 (put 'while 'byte-optimizer 'byte-optimize-while)
1039 ;; Remove any reason for avoiding `char-before'.
1040 (defun byte-optimize-char-before (form)
1041 `(char-after (1- ,(or (nth 1 form) '(point))) ,@(cdr (cdr form))))
1043 (put 'char-before 'byte-optimizer 'byte-optimize-char-before)
1045 ;; byte-compile-negation-optimizer lives in bytecomp.el
1046 ;(put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
1047 (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
1048 (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
1051 (defun byte-optimize-funcall (form)
1052 ;; (funcall '(lambda ...) ...) ==> ((lambda ...) ...)
1053 ;; (funcall 'foo ...) ==> (foo ...)
1054 (let ((fn (nth 1 form)))
1055 (if (memq (car-safe fn) '(quote function))
1056 (cons (nth 1 fn) (cdr (cdr form)))
1059 (defun byte-optimize-apply (form)
1060 ;; If the last arg is a literal constant, turn this into a funcall.
1061 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1062 (let ((fn (nth 1 form))
1063 (last (nth (1- (length form)) form))) ; I think this really is fastest
1064 (or (if (or (null last)
1065 (eq (car-safe last) 'quote))
1066 (if (listp (nth 1 last))
1067 (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
1068 (nconc (list 'funcall fn) butlast
1069 (mapcar #'(lambda (x) (list 'quote x)) (nth 1 last))))
1071 "last arg to apply can't be a literal atom: %s"
1072 (prin1-to-string last))
1076 (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
1077 (put 'apply 'byte-optimizer 'byte-optimize-apply)
1080 (put 'let 'byte-optimizer 'byte-optimize-letX)
1081 (put 'let* 'byte-optimizer 'byte-optimize-letX)
1082 (defun byte-optimize-letX (form)
1083 (cond ((null (nth 1 form))
1085 (cons 'progn (cdr (cdr form))))
1086 ((or (nth 2 form) (nthcdr 3 form))
1089 ((eq (car form) 'let)
1090 (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
1093 (let ((binds (reverse (nth 1 form))))
1094 (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
1097 (put 'nth 'byte-optimizer 'byte-optimize-nth)
1098 (defun byte-optimize-nth (form)
1099 (if (and (= (safe-length form) 3) (memq (nth 1 form) '(0 1)))
1100 (list 'car (if (zerop (nth 1 form))
1102 (list 'cdr (nth 2 form))))
1103 (byte-optimize-predicate form)))
1105 (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
1106 (defun byte-optimize-nthcdr (form)
1107 (if (and (= (safe-length form) 3) (not (memq (nth 1 form) '(0 1 2))))
1108 (byte-optimize-predicate form)
1109 (let ((count (nth 1 form)))
1110 (setq form (nth 2 form))
1111 (while (>= (setq count (1- count)) 0)
1112 (setq form (list 'cdr form)))
1115 ;;; enumerating those functions which need not be called if the returned
1116 ;;; value is not used. That is, something like
1117 ;;; (progn (list (something-with-side-effects) (yow))
1119 ;;; may safely be turned into
1120 ;;; (progn (progn (something-with-side-effects) (yow))
1122 ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1124 ;;; I wonder if I missed any :-\)
1125 (let ((side-effect-free-fns
1126 '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
1128 boundp buffer-file-name buffer-local-variables buffer-modified-p
1130 capitalize car-less-than-car car cdr ceiling concat
1131 ;; coordinates-in-window-p not in XEmacs
1132 copy-marker cos count-lines
1133 default-boundp default-value documentation downcase
1134 elt exp expt fboundp featurep
1135 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1136 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1138 get get-buffer get-buffer-window getenv get-file-buffer
1139 ;; hash-table functions
1140 make-hash-table copy-hash-table
1143 hash-table-rehash-size
1144 hash-table-rehash-threshold
1150 length log log10 logand logb logior lognot logxor lsh
1151 marker-buffer max member memq min mod
1152 next-window nth nthcdr number-to-string
1153 parse-colon-path plist-get previous-window
1154 radians-to-degrees rassq regexp-quote reverse round
1155 sin sqrt string< string= string-equal string-lessp string-to-char
1156 string-to-int string-to-number substring symbol-plist
1157 tan upcase user-variable-p vconcat
1158 ;; XEmacs change: window-edges -> window-pixel-edges
1159 window-buffer window-dedicated-p window-pixel-edges window-height
1160 window-hscroll window-minibuffer-p window-width
1162 ;; functions defined by cl
1163 oddp evenp plusp minusp
1164 abs expt signum last butlast ldiff
1166 isqrt floor* ceiling* truncate* round* mod* rem* subseq
1169 (side-effect-and-error-free-fns
1171 bobp bolp buffer-end buffer-list buffer-size buffer-string bufferp
1172 car-safe case-table-p cdr-safe char-or-string-p char-table-p
1173 characterp commandp cons
1174 consolep console-live-p consp
1176 ;; XEmacs: extent functions, frame-live-p, various other stuff
1177 devicep device-live-p
1178 dot dot-marker eobp eolp eq eql equal eventp extentp
1179 extent-live-p floatp framep frame-live-p
1180 get-largest-window get-lru-window
1182 identity ignore integerp integer-or-marker-p interactive-p
1183 invocation-directory invocation-name
1184 ;; keymapp may autoload in XEmacs, so not on this list!
1186 make-marker mark mark-marker markerp memory-limit minibuffer-window
1187 ;; mouse-movement-p not in XEmacs
1188 natnump nlistp not null number-or-marker-p numberp
1189 one-window-p ;; overlayp not in XEmacs
1190 point point-marker point-min point-max processp
1192 selected-window sequencep stringp subrp symbolp syntax-table-p
1193 user-full-name user-login-name user-original-login-name
1194 user-real-login-name user-real-uid user-uid
1196 window-configuration-p window-live-p windowp
1197 ;; Functions defined by cl
1198 eql floatp-safe list* subst acons equalp random-state-p
1201 (dolist (fn side-effect-free-fns)
1202 (put fn 'side-effect-free t))
1203 (dolist (fn side-effect-and-error-free-fns)
1204 (put fn 'side-effect-free 'error-free)))
1207 (defun byte-compile-splice-in-already-compiled-code (form)
1208 ;; form is (byte-code "..." [...] n)
1209 (if (not (memq byte-optimize '(t lap)))
1210 (byte-compile-normal-call form)
1211 (byte-inline-lapcode
1212 (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t))
1213 (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form))
1214 byte-compile-maxdepth))
1215 (setq byte-compile-depth (1+ byte-compile-depth))))
1217 (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code)
1220 (defconst byte-constref-ops
1221 '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
1223 ;;; This function extracts the bitfields from variable-length opcodes.
1224 ;;; Originally defined in disass.el (which no longer uses it.)
1226 (defun disassemble-offset ()
1228 ;; fetch and return the offset for the current opcode.
1229 ;; return NIL if this opcode has no offset
1230 ;; OP, PTR and BYTES are used and set dynamically
1234 (cond ((< op byte-nth)
1235 (let ((tem (logand op 7)))
1236 (setq op (logand op 248))
1238 (setq ptr (1+ ptr)) ;offset in next byte
1239 ;; char-to-int to avoid downstream problems
1240 ;; caused by chars appearing where ints are
1241 ;; expected. In bytecode the bytes in the
1242 ;; opcode string are always interpreted as ints.
1243 (char-to-int (aref bytes ptr)))
1245 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1247 (progn (setq ptr (1+ ptr))
1248 (lsh (aref bytes ptr) 8))))
1249 (t tem)))) ;offset was in opcode
1250 ((>= op byte-constant)
1251 (prog1 (- op byte-constant) ;offset in opcode
1252 (setq op byte-constant)))
1253 ((and (>= op byte-constant2)
1254 (<= op byte-goto-if-not-nil-else-pop))
1255 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1257 (progn (setq ptr (1+ ptr))
1258 (lsh (aref bytes ptr) 8))))
1259 ;; XEmacs: this code was here before. FSF's first comparison
1260 ;; is (>= op byte-listN). It appears that the rel-goto stuff
1261 ;; does not exist in FSF 19.30. It doesn't exist in 19.28
1262 ;; either, so I'm going to assume that this is an improvement
1263 ;; on our part and leave it in. --ben
1264 ((and (>= op byte-rel-goto)
1265 (<= op byte-insertN))
1266 (setq ptr (1+ ptr)) ;offset in next byte
1267 ;; Use char-to-int to avoid downstream problems caused by
1268 ;; chars appearing where ints are expected. In bytecode
1269 ;; the bytes in the opcode string are always interpreted as
1271 (char-to-int (aref bytes ptr)))))
1274 ;;; This de-compiler is used for inline expansion of compiled functions,
1275 ;;; and by the disassembler.
1277 ;;; This list contains numbers, which are pc values,
1278 ;;; before each instruction.
1279 (defun byte-decompile-bytecode (bytes constvec)
1280 "Turns BYTECODE into lapcode, referring to CONSTVEC."
1281 (let ((byte-compile-constants nil)
1282 (byte-compile-variables nil)
1283 (byte-compile-tag-number 0))
1284 (byte-decompile-bytecode-1 bytes constvec)))
1286 ;; As byte-decompile-bytecode, but updates
1287 ;; byte-compile-{constants, variables, tag-number}.
1288 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1289 ;; with `goto's destined for the end of the code.
1290 ;; That is for use by the compiler.
1291 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1292 ;; In that case, we put a pc value into the list
1293 ;; before each insn (or its label).
1294 (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
1295 (let ((length (length bytes))
1296 (ptr 0) optr tags op offset
1300 ;; (retcount 0) unused
1302 (while (not (= ptr length))
1304 (setq lap (cons ptr lap)))
1305 (setq op (aref bytes ptr)
1307 offset (disassemble-offset)) ; this does dynamic-scope magic
1308 (setq op (aref byte-code-vector op))
1309 ;; XEmacs: the next line in FSF 19.30 reads
1310 ;; (cond ((memq op byte-goto-ops)
1311 ;; see the comment above about byte-rel-goto in XEmacs.
1312 (cond ((or (memq op byte-goto-ops)
1313 (cond ((memq op byte-rel-goto-ops)
1314 (setq op (aref byte-code-vector
1315 (- (symbol-value op)
1316 (- byte-rel-goto byte-goto))))
1317 (setq offset (+ ptr (- offset 127)))
1321 (cdr (or (assq offset tags)
1324 (byte-compile-make-tag))
1326 ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t)
1327 ((memq op byte-constref-ops)))
1328 (setq tmp (aref constvec offset)
1329 offset (if (eq op 'byte-constant)
1330 (byte-compile-get-constant tmp)
1331 (or (assq tmp byte-compile-variables)
1332 (car (setq byte-compile-variables
1334 byte-compile-variables)))))))
1335 ((and make-spliceable
1336 (eq op 'byte-return))
1337 (if (= ptr (1- length))
1339 (setq offset (or endtag (setq endtag (byte-compile-make-tag)))
1341 ;; lap = ( [ (pc . (op . arg)) ]* )
1342 (setq lap (cons (cons optr (cons op (or offset 0)))
1344 (setq ptr (1+ ptr)))
1345 ;; take off the dummy nil op that we replaced a trailing "return" with.
1348 (cond ((numberp (car rest)))
1349 ((setq tmp (assq (car (car rest)) tags))
1350 ;; this addr is jumped to
1351 (setcdr rest (cons (cons nil (cdr tmp))
1353 (setq tags (delq tmp tags))
1354 (setq rest (cdr rest))))
1355 (setq rest (cdr rest))))
1356 (if tags (error "optimizer error: missed tags %s" tags))
1357 (if (null (car (cdr (car lap))))
1358 (setq lap (cdr lap)))
1360 (setq lap (cons (cons nil endtag) lap)))
1361 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1362 (mapcar #'(lambda (elt) (if (numberp elt) elt (cdr elt)))
1366 ;;; peephole optimizer
1368 (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
1370 (defconst byte-conditional-ops
1371 '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
1372 byte-goto-if-not-nil-else-pop))
1374 (defconst byte-after-unbind-ops
1375 '(byte-constant byte-dup
1376 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1377 byte-eq byte-equal byte-not
1378 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1380 ;; How about other side-effect-free-ops? Is it safe to move an
1381 ;; error invocation (such as from nth) out of an unwind-protect?
1382 "Byte-codes that can be moved past an unbind.")
1384 (defconst byte-compile-side-effect-and-error-free-ops
1385 '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
1386 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1387 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1388 byte-point-min byte-following-char byte-preceding-char
1389 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1390 byte-current-buffer byte-interactive-p))
1392 (defconst byte-compile-side-effect-free-ops
1394 '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
1395 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1396 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1397 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1398 byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
1399 byte-member byte-assq byte-quo byte-rem)
1400 byte-compile-side-effect-and-error-free-ops))
1402 ;;; This piece of shit is because of the way DEFVAR_BOOL() variables work.
1403 ;;; Consider the code
1405 ;;; (defun foo (flag)
1406 ;;; (let ((old-pop-ups pop-up-windows)
1407 ;;; (pop-up-windows flag))
1408 ;;; (cond ((not (eq pop-up-windows old-pop-ups))
1409 ;;; (setq old-pop-ups pop-up-windows)
1412 ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1413 ;;; something else. But if we optimize
1416 ;;; varbind pop-up-windows
1417 ;;; varref pop-up-windows
1422 ;;; varbind pop-up-windows
1425 ;;; we break the program, because it will appear that pop-up-windows and
1426 ;;; old-pop-ups are not EQ when really they are. So we have to know what
1427 ;;; the BOOL variables are, and not perform this optimization on them.
1430 ;;; This used to hold a large list of boolean variables, which had to
1431 ;;; be updated every time a new DEFVAR_BOOL is added, making it very
1432 ;;; hard to maintain. Such a list is not necessary under XEmacs,
1433 ;;; where we can use `built-in-variable-type' to query for boolean
1436 ;(defconst byte-boolean-vars
1437 ; '(abbrev-all-caps purify-flag find-file-compare-truenames
1438 ; find-file-use-truenames delete-auto-save-files byte-metering-on
1439 ; x-seppuku-on-epipe zmacs-regions zmacs-region-active-p
1440 ; zmacs-region-stays atomic-extent-goto-char-p
1441 ; suppress-early-error-handler-backtrace noninteractive
1442 ; inhibit-early-packages inhibit-autoloads debug-paths
1443 ; inhibit-site-lisp debug-on-quit debug-on-next-call
1444 ; modifier-keys-are-sticky x-allow-sendevents
1445 ; mswindows-dynamic-frame-resize focus-follows-mouse
1446 ; inhibit-input-event-recording enable-multibyte-characters
1447 ; disable-auto-save-when-buffer-shrinks
1448 ; allow-deletion-of-last-visible-frame indent-tabs-mode
1449 ; load-in-progress load-warn-when-source-newer
1450 ; load-warn-when-source-only load-ignore-elc-files
1451 ; load-force-doc-strings fail-on-bucky-bit-character-escapes
1452 ; popup-menu-titles menubar-show-keybindings completion-ignore-case
1453 ; canna-empty-info canna-through-info canna-underline
1454 ; canna-inhibit-hankakukana enable-multibyte-characters
1455 ; re-short-flag x-handle-non-fully-specified-fonts
1456 ; print-escape-newlines print-readably delete-exited-processes
1457 ; windowed-process-io visible-bell no-redraw-on-reenter
1458 ; cursor-in-echo-area inhibit-warning-display
1459 ; column-number-start-at-one parse-sexp-ignore-comments
1460 ; words-include-escapes scroll-on-clipped-lines)
1461 ; "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t.
1462 ;If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer
1463 ;may generate incorrect code.")
1465 (defun byte-optimize-lapcode (lap &optional for-effect)
1466 "Simple peephole optimizer. LAP is both modified and returned."
1467 (let (lap0 ;; off0 unused
1470 (keep-going 'first-time)
1473 (side-effect-free (if byte-compile-delete-errors
1474 byte-compile-side-effect-free-ops
1475 byte-compile-side-effect-and-error-free-ops)))
1477 (or (eq keep-going 'first-time)
1478 (byte-compile-log-lap " ---- next pass"))
1482 (setq lap0 (car rest)
1486 ;; You may notice that sequences like "dup varset discard" are
1487 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1488 ;; You may be tempted to change this; resist that temptation.
1490 ;; <side-effect-free> pop --> <deleted>
1492 ;; const-X pop --> <deleted>
1493 ;; varref-X pop --> <deleted>
1494 ;; dup pop --> <deleted>
1496 ((and (eq 'byte-discard (car lap1))
1497 (memq (car lap0) side-effect-free))
1499 (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
1500 (setq rest (cdr rest))
1502 (byte-compile-log-lap
1503 " %s discard\t-->\t<deleted>" lap0)
1504 (setq lap (delq lap0 (delq lap1 lap))))
1506 (byte-compile-log-lap
1507 " %s discard\t-->\t<deleted> discard" lap0)
1508 (setq lap (delq lap0 lap)))
1510 (byte-compile-log-lap
1511 " %s discard\t-->\tdiscard discard" lap0)
1512 (setcar lap0 'byte-discard)
1514 ((error "Optimizer error: too much on the stack"))))
1516 ;; goto*-X X: --> X:
1518 ((and (memq (car lap0) byte-goto-ops)
1519 (eq (cdr lap0) lap1))
1520 (cond ((eq (car lap0) 'byte-goto)
1521 (setq lap (delq lap0 lap))
1522 (setq tmp "<deleted>"))
1523 ((memq (car lap0) byte-goto-always-pop-ops)
1524 (setcar lap0 (setq tmp 'byte-discard))
1526 ((error "Depth conflict at tag %d" (nth 2 lap0))))
1527 (and (memq byte-optimize-log '(t byte))
1528 (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
1529 (nth 1 lap1) (nth 1 lap1)
1531 (setq keep-going t))
1533 ;; varset-X varref-X --> dup varset-X
1534 ;; varbind-X varref-X --> dup varbind-X
1535 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1536 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1537 ;; The latter two can enable other optimizations.
1539 ((and (eq 'byte-varref (car lap2))
1540 (eq (cdr lap1) (cdr lap2))
1541 (memq (car lap1) '(byte-varset byte-varbind)))
1542 (if (and (setq tmp (eq (built-in-variable-type (car (cdr lap2)))
1544 (not (eq (car lap0) 'byte-constant)))
1547 (if (memq (car lap0) '(byte-constant byte-dup))
1549 (setq tmp (if (or (not tmp)
1550 (memq (car (cdr lap0)) '(nil t)))
1552 (byte-compile-get-constant t)))
1553 (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
1554 lap0 lap1 lap2 lap0 lap1
1555 (cons (car lap0) tmp))
1556 (setcar lap2 (car lap0))
1558 (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
1559 (setcar lap2 (car lap1))
1560 (setcar lap1 'byte-dup)
1562 ;; The stack depth gets locally increased, so we will
1563 ;; increase maxdepth in case depth = maxdepth here.
1564 ;; This can cause the third argument to byte-code to
1565 ;; be larger than necessary.
1566 (setq add-depth 1))))
1568 ;; dup varset-X discard --> varset-X
1569 ;; dup varbind-X discard --> varbind-X
1570 ;; (the varbind variant can emerge from other optimizations)
1572 ((and (eq 'byte-dup (car lap0))
1573 (eq 'byte-discard (car lap2))
1574 (memq (car lap1) '(byte-varset byte-varbind)))
1575 (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
1578 (setq lap (delq lap0 (delq lap2 lap))))
1580 ;; not goto-X-if-nil --> goto-X-if-non-nil
1581 ;; not goto-X-if-non-nil --> goto-X-if-nil
1583 ;; it is wrong to do the same thing for the -else-pop variants.
1585 ((and (eq 'byte-not (car lap0))
1586 (or (eq 'byte-goto-if-nil (car lap1))
1587 (eq 'byte-goto-if-not-nil (car lap1))))
1588 (byte-compile-log-lap " not %s\t-->\t%s"
1591 (if (eq (car lap1) 'byte-goto-if-nil)
1592 'byte-goto-if-not-nil
1595 (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
1596 'byte-goto-if-not-nil
1598 (setq lap (delq lap0 lap))
1599 (setq keep-going t))
1601 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1602 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1604 ;; it is wrong to do the same thing for the -else-pop variants.
1606 ((and (or (eq 'byte-goto-if-nil (car lap0))
1607 (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX
1608 (eq 'byte-goto (car lap1)) ; gotoY
1609 (eq (cdr lap0) lap2)) ; TAG X
1610 (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
1611 'byte-goto-if-not-nil 'byte-goto-if-nil)))
1612 (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
1614 (cons inverse (cdr lap1)) lap2)
1615 (setq lap (delq lap0 lap))
1616 (setcar lap1 inverse)
1617 (setq keep-going t)))
1619 ;; const goto-if-* --> whatever
1621 ((and (eq 'byte-constant (car lap0))
1622 (memq (car lap1) byte-conditional-ops))
1623 (cond ((if (or (eq (car lap1) 'byte-goto-if-nil)
1624 (eq (car lap1) 'byte-goto-if-nil-else-pop))
1626 (not (car (cdr lap0))))
1627 (byte-compile-log-lap " %s %s\t-->\t<deleted>"
1629 (setq rest (cdr rest)
1630 lap (delq lap0 (delq lap1 lap))))
1632 (if (memq (car lap1) byte-goto-always-pop-ops)
1634 (byte-compile-log-lap " %s %s\t-->\t%s"
1635 lap0 lap1 (cons 'byte-goto (cdr lap1)))
1636 (setq lap (delq lap0 lap)))
1637 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1638 (cons 'byte-goto (cdr lap1))))
1639 (setcar lap1 'byte-goto)))
1640 (setq keep-going t))
1642 ;; varref-X varref-X --> varref-X dup
1643 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1644 ;; We don't optimize the const-X variations on this here,
1645 ;; because that would inhibit some goto optimizations; we
1646 ;; optimize the const-X case after all other optimizations.
1648 ((and (eq 'byte-varref (car lap0))
1650 (setq tmp (cdr rest))
1651 (while (eq (car (car tmp)) 'byte-dup)
1652 (setq tmp (cdr tmp)))
1654 (eq (cdr lap0) (cdr (car tmp)))
1655 (eq 'byte-varref (car (car tmp))))
1656 (if (memq byte-optimize-log '(t byte))
1658 (setq tmp2 (cdr rest))
1659 (while (not (eq tmp tmp2))
1660 (setq tmp2 (cdr tmp2)
1661 str (concat str " dup")))
1662 (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
1663 lap0 str lap0 lap0 str)))
1665 (setcar (car tmp) 'byte-dup)
1666 (setcdr (car tmp) 0)
1669 ;; TAG1: TAG2: --> TAG1: <deleted>
1670 ;; (and other references to TAG2 are replaced with TAG1)
1672 ((and (eq (car lap0) 'TAG)
1673 (eq (car lap1) 'TAG))
1674 (and (memq byte-optimize-log '(t byte))
1675 (byte-compile-log " adjacent tags %d and %d merged"
1676 (nth 1 lap1) (nth 1 lap0)))
1678 (while (setq tmp2 (rassq lap0 tmp3))
1680 (setq tmp3 (cdr (memq tmp2 tmp3))))
1681 (setq lap (delq lap0 lap)
1684 ;; unused-TAG: --> <deleted>
1686 ((and (eq 'TAG (car lap0))
1687 (not (rassq lap0 lap)))
1688 (and (memq byte-optimize-log '(t byte))
1689 (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
1690 (setq lap (delq lap0 lap)
1693 ;; goto ... --> goto <delete until TAG or end>
1694 ;; return ... --> return <delete until TAG or end>
1696 ((and (memq (car lap0) '(byte-goto byte-return))
1697 (not (memq (car lap1) '(TAG nil))))
1700 (opt-p (memq byte-optimize-log '(t lap)))
1702 (while (and (setq tmp (cdr tmp))
1703 (not (eq 'TAG (car (car tmp)))))
1704 (if opt-p (setq deleted (cons (car tmp) deleted)
1705 str (concat str " %s")
1709 (if (eq 'TAG (car (car tmp)))
1710 (format "%d:" (car (cdr (car tmp))))
1711 (or (car tmp) ""))))
1713 (apply 'byte-compile-log-lap-1
1715 " %s\t-->\t%s <deleted> %s")
1717 (nconc (nreverse deleted)
1718 (list tagstr lap0 tagstr)))
1719 (byte-compile-log-lap
1720 " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
1721 lap0 i (if (= i 1) "" "s")
1722 tagstr lap0 tagstr))))
1724 (setq keep-going t))
1726 ;; <safe-op> unbind --> unbind <safe-op>
1727 ;; (this may enable other optimizations.)
1729 ((and (eq 'byte-unbind (car lap1))
1730 (memq (car lap0) byte-after-unbind-ops))
1731 (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
1733 (setcar (cdr rest) lap0)
1734 (setq keep-going t))
1736 ;; varbind-X unbind-N --> discard unbind-(N-1)
1737 ;; save-excursion unbind-N --> unbind-(N-1)
1738 ;; save-restriction unbind-N --> unbind-(N-1)
1740 ((and (eq 'byte-unbind (car lap1))
1741 (memq (car lap0) '(byte-varbind byte-save-excursion
1742 byte-save-restriction))
1744 (if (zerop (setcdr lap1 (1- (cdr lap1))))
1746 (if (eq (car lap0) 'byte-varbind)
1747 (setcar rest (cons 'byte-discard 0))
1748 (setq lap (delq lap0 lap)))
1749 (byte-compile-log-lap " %s %s\t-->\t%s %s"
1750 lap0 (cons (car lap1) (1+ (cdr lap1)))
1751 (if (eq (car lap0) 'byte-varbind)
1754 (if (and (/= 0 (cdr lap1))
1755 (eq (car lap0) 'byte-varbind))
1758 (setq keep-going t))
1760 ;; goto*-X ... X: goto-Y --> goto*-Y
1761 ;; goto-X ... X: return --> return
1763 ((and (memq (car lap0) byte-goto-ops)
1764 (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
1765 '(byte-goto byte-return)))
1766 (cond ((and (not (eq tmp lap0))
1767 (or (eq (car lap0) 'byte-goto)
1768 (eq (car tmp) 'byte-goto)))
1769 (byte-compile-log-lap " %s [%s]\t-->\t%s"
1771 (if (eq (car tmp) 'byte-return)
1772 (setcar lap0 'byte-return))
1773 (setcdr lap0 (cdr tmp))
1774 (setq keep-going t))))
1776 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1777 ;; goto-*-else-pop X ... X: discard --> whatever
1779 ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
1780 byte-goto-if-not-nil-else-pop))
1781 (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
1783 (cons 'byte-discard byte-conditional-ops)))
1784 (not (eq lap0 (car tmp))))
1785 (setq tmp2 (car tmp))
1786 (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
1788 (byte-goto-if-not-nil-else-pop
1789 byte-goto-if-not-nil))))
1790 (if (memq (car tmp2) tmp3)
1791 (progn (setcar lap0 (car tmp2))
1792 (setcdr lap0 (cdr tmp2))
1793 (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
1794 (car lap0) tmp2 lap0))
1795 ;; Get rid of the -else-pop's and jump one step further.
1796 (or (eq 'TAG (car (nth 1 tmp)))
1797 (setcdr tmp (cons (byte-compile-make-tag)
1799 (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
1800 (car lap0) tmp2 (nth 1 tmp3))
1801 (setcar lap0 (nth 1 tmp3))
1802 (setcdr lap0 (nth 1 tmp)))
1803 (setq keep-going t))
1805 ;; const goto-X ... X: goto-if-* --> whatever
1806 ;; const goto-X ... X: discard --> whatever
1808 ((and (eq (car lap0) 'byte-constant)
1809 (eq (car lap1) 'byte-goto)
1810 (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
1812 (cons 'byte-discard byte-conditional-ops)))
1813 (not (eq lap1 (car tmp))))
1814 (setq tmp2 (car tmp))
1815 (cond ((memq (car tmp2)
1816 (if (null (car (cdr lap0)))
1817 '(byte-goto-if-nil byte-goto-if-nil-else-pop)
1818 '(byte-goto-if-not-nil
1819 byte-goto-if-not-nil-else-pop)))
1820 (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
1821 lap0 tmp2 lap0 tmp2)
1822 (setcar lap1 (car tmp2))
1823 (setcdr lap1 (cdr tmp2))
1824 ;; Let next step fix the (const,goto-if*) sequence.
1825 (setq rest (cons nil rest)))
1827 ;; Jump one step further
1828 (byte-compile-log-lap
1829 " %s goto [%s]\t-->\t<deleted> goto <skip>"
1831 (or (eq 'TAG (car (nth 1 tmp)))
1832 (setcdr tmp (cons (byte-compile-make-tag)
1834 (setcdr lap1 (car (cdr tmp)))
1835 (setq lap (delq lap0 lap))))
1836 (setq keep-going t))
1838 ;; X: varref-Y ... varset-Y goto-X -->
1839 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1840 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1841 ;; (This is so usual for while loops that it is worth handling).
1843 ((and (eq (car lap1) 'byte-varset)
1844 (eq (car lap2) 'byte-goto)
1845 (not (memq (cdr lap2) rest)) ;Backwards jump
1846 (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
1848 (eq (cdr (car tmp)) (cdr lap1))
1849 (not (eq (built-in-variable-type (car (cdr lap1)))
1851 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1852 (let ((newtag (byte-compile-make-tag)))
1853 (byte-compile-log-lap
1854 " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
1855 (nth 1 (cdr lap2)) (car tmp)
1857 (nth 1 (cdr lap2)) (car tmp)
1858 (nth 1 newtag) 'byte-dup lap1
1859 (cons 'byte-goto newtag)
1861 (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
1862 (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
1864 (setq keep-going t))
1866 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1867 ;; (This can pull the loop test to the end of the loop)
1869 ((and (eq (car lap0) 'byte-goto)
1870 (eq (car lap1) 'TAG)
1872 (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
1873 (memq (car (car tmp))
1874 '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
1875 byte-goto-if-nil-else-pop)))
1876 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1877 ;; lap0 lap1 (cdr lap0) (car tmp))
1878 (let ((newtag (byte-compile-make-tag)))
1879 (byte-compile-log-lap
1880 "%s %s: ... %s: %s\t-->\t%s ... %s:"
1881 lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
1882 (cons (cdr (assq (car (car tmp))
1883 '((byte-goto-if-nil . byte-goto-if-not-nil)
1884 (byte-goto-if-not-nil . byte-goto-if-nil)
1885 (byte-goto-if-nil-else-pop .
1886 byte-goto-if-not-nil-else-pop)
1887 (byte-goto-if-not-nil-else-pop .
1888 byte-goto-if-nil-else-pop))))
1893 (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
1894 (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
1895 ;; We can handle this case but not the -if-not-nil case,
1896 ;; because we won't know which non-nil constant to push.
1897 (setcdr rest (cons (cons 'byte-constant
1898 (byte-compile-get-constant nil))
1900 (setcar lap0 (nth 1 (memq (car (car tmp))
1901 '(byte-goto-if-nil-else-pop
1902 byte-goto-if-not-nil
1904 byte-goto-if-not-nil
1905 byte-goto byte-goto))))
1907 (setq keep-going t))
1909 (setq rest (cdr rest)))
1912 ;; Rebuild byte-compile-constants / byte-compile-variables.
1913 ;; Simple optimizations that would inhibit other optimizations if they
1914 ;; were done in the optimizing loop, and optimizations which there is no
1915 ;; need to do more than once.
1916 (setq byte-compile-constants nil
1917 byte-compile-variables nil)
1920 (setq lap0 (car rest)
1922 (if (memq (car lap0) byte-constref-ops)
1923 (if (eq (cdr lap0) 'byte-constant)
1924 (or (memq (cdr lap0) byte-compile-variables)
1925 (setq byte-compile-variables (cons (cdr lap0)
1926 byte-compile-variables)))
1927 (or (memq (cdr lap0) byte-compile-constants)
1928 (setq byte-compile-constants (cons (cdr lap0)
1929 byte-compile-constants)))))
1931 ;; const-C varset-X const-C --> const-C dup varset-X
1932 ;; const-C varbind-X const-C --> const-C dup varbind-X
1934 (and (eq (car lap0) 'byte-constant)
1935 (eq (car (nth 2 rest)) 'byte-constant)
1936 (eq (cdr lap0) (car (nth 2 rest)))
1937 (memq (car lap1) '(byte-varbind byte-varset)))
1938 (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
1939 lap0 lap1 lap0 lap0 lap1)
1940 (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
1941 (setcar (cdr rest) (cons 'byte-dup 0))
1944 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1945 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1947 ((memq (car lap0) '(byte-constant byte-varref))
1951 (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
1952 (and (eq (cdr lap0) (cdr (car tmp)))
1953 (eq (car lap0) (car (car tmp)))))
1954 (setcar tmp (cons 'byte-dup 0))
1957 (byte-compile-log-lap
1958 " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
1960 ;; unbind-N unbind-M --> unbind-(N+M)
1962 ((and (eq 'byte-unbind (car lap0))
1963 (eq 'byte-unbind (car lap1)))
1964 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1966 (+ (cdr lap0) (cdr lap1))))
1968 (setq lap (delq lap0 lap))
1969 (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
1971 (setq rest (cdr rest)))
1972 (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
1975 (provide 'byte-optimize)
1978 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
1979 ;; itself, compile some of its most used recursive functions (at load time).
1982 (or (compiled-function-p (symbol-function 'byte-optimize-form))
1983 (assq 'byte-code (symbol-function 'byte-optimize-form))
1984 (let ((byte-optimize nil)
1985 (byte-compile-warnings nil))
1988 (or noninteractive (message "compiling %s..." x))
1990 (or noninteractive (message "compiling %s...done" x)))
1991 '(byte-optimize-form
1993 byte-optimize-predicate
1994 byte-optimize-binary-predicate
1995 ;; Inserted some more than necessary, to speed it up.
1996 byte-optimize-form-code-walker
1997 byte-optimize-lapcode))))
2000 ;;; byte-optimize.el ends here