1 ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler.
3 ;;; Copyright (c) 1991, 1994 Free Software Foundation, Inc.
5 ;; Author: Jamie Zawinski <jwz@lucid.com>
6 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it 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 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; 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.
28 ;; ========================================================================
29 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
30 ;; You can, however, make a faster pig."
32 ;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code
33 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
34 ;; still not going to make it go faster than 70 mph, but it might be easier
40 ;; (apply '(lambda (x &rest y) ...) 1 (foo))
42 ;; maintain a list of functions known not to access any global variables
43 ;; (actually, give them a 'dynamically-safe property) and then
44 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
45 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
46 ;; by recursing on this, we might be able to eliminate the entire let.
47 ;; However certain variables should never have their bindings optimized
48 ;; away, because they affect everything.
49 ;; (put 'debug-on-error 'binding-is-magic t)
50 ;; (put 'debug-on-abort 'binding-is-magic t)
51 ;; (put 'debug-on-next-call 'binding-is-magic t)
52 ;; (put 'mocklisp-arguments 'binding-is-magic t)
53 ;; (put 'inhibit-quit 'binding-is-magic t)
54 ;; (put 'quit-flag 'binding-is-magic t)
55 ;; (put 't 'binding-is-magic t)
56 ;; (put 'nil 'binding-is-magic t)
58 ;; (put 'gc-cons-threshold 'binding-is-magic t)
59 ;; (put 'track-mouse 'binding-is-magic t)
62 ;; Simple defsubsts often produce forms like
63 ;; (let ((v1 (f1)) (v2 (f2)) ...)
65 ;; It would be nice if we could optimize this to
67 ;; but we can't unless FN is dynamically-safe (it might be dynamically
68 ;; referring to the bindings that the lambda arglist established.)
69 ;; One of the uncountable lossages introduced by dynamic scope...
71 ;; Maybe there should be a control-structure that says "turn on
72 ;; fast-and-loose type-assumptive optimizations here." Then when
73 ;; we see a form like (car foo) we can from then on assume that
74 ;; the variable foo is of type cons, and optimize based on that.
75 ;; But, this won't win much because of (you guessed it) dynamic
76 ;; scope. Anything down the stack could change the value.
77 ;; (Another reason it doesn't work is that it is perfectly valid
78 ;; to call car with a null argument.) A better approach might
79 ;; be to allow type-specification of the form
80 ;; (put 'foo 'arg-types '(float (list integer) dynamic))
81 ;; (put 'foo 'result-type 'bool)
82 ;; It should be possible to have these types checked to a certain
85 ;; collapse common subexpressions
87 ;; It would be nice if redundant sequences could be factored out as well,
88 ;; when they are known to have no side-effects:
89 ;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2
90 ;; but beware of traps like
91 ;; (cons (list x y) (list x y))
93 ;; Tail-recursion elimination is not really possible in Emacs Lisp.
94 ;; Tail-recursion elimination is almost always impossible when all variables
95 ;; have dynamic scope, but given that the "return" byteop requires the
96 ;; binding stack to be empty (rather than emptying it itself), there can be
97 ;; no truly tail-recursive Emacs Lisp functions that take any arguments or
100 ;; Here is an example of an Emacs Lisp function which could safely be
101 ;; byte-compiled tail-recursively:
103 ;; (defun tail-map (fn list)
105 ;; (funcall fn (car list))
106 ;; (tail-map fn (cdr list)))))
108 ;; However, if there was even a single let-binding around the COND,
109 ;; it could not be byte-compiled, because there would be an "unbind"
110 ;; byte-op between the final "call" and "return." Adding a
111 ;; Bunbind_all byteop would fix this.
113 ;; (defun foo (x y z) ... (foo a b c))
114 ;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return)
115 ;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return)
116 ;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return)
118 ;; this also can be considered tail recursion:
120 ;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return)
121 ;; could generalize this by doing the optimization
122 ;; (goto X) ... X: (return) --> (return)
124 ;; But this doesn't solve all of the problems: although by doing tail-
125 ;; recursion elimination in this way, the call-stack does not grow, the
126 ;; binding-stack would grow with each recursive step, and would eventually
127 ;; overflow. I don't believe there is any way around this without lexical
130 ;; Wouldn't it be nice if Emacs Lisp had lexical scope.
132 ;; Idea: the form (lexical-scope) in a file means that the file may be
133 ;; compiled lexically. This proclamation is file-local. Then, within
134 ;; that file, "let" would establish lexical bindings, and "let-dynamic"
135 ;; would do things the old way. (Or we could use CL "declare" forms.)
136 ;; We'd have to notice defvars and defconsts, since those variables should
137 ;; always be dynamic, and attempting to do a lexical binding of them
138 ;; should simply do a dynamic binding instead.
139 ;; But! We need to know about variables that were not necessarily defvarred
140 ;; in the file being compiled (doing a boundp check isn't good enough.)
141 ;; Fdefvar() would have to be modified to add something to the plist.
143 ;; A major disadvantage of this scheme is that the interpreter and compiler
144 ;; would have different semantics for files compiled with (dynamic-scope).
145 ;; Since this would be a file-local optimization, there would be no way to
146 ;; modify the interpreter to obey this (unless the loader was hacked
147 ;; in some grody way, but that's a really bad idea.)
149 ;; Other things to consider:
151 ;;;;; Associative math should recognize subcalls to identical function:
152 ;;;(disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
153 ;;;;; This should generate the same as (1+ x) and (1- x)
155 ;;;(disassemble (lambda (x) (cons (+ x 1) (- x 1))))
156 ;;;;; An awful lot of functions always return a non-nil value. If they're
157 ;;;;; error free also they may act as true-constants.
159 ;;;(disassemble (lambda (x) (and (point) (foo))))
161 ;;;;; - all but one arguments to a function are constant
162 ;;;;; - the non-constant argument is an if-expression (cond-expression?)
163 ;;;;; then the outer function can be distributed. If the guarding
164 ;;;;; condition is side-effect-free [assignment-free] then the other
165 ;;;;; arguments may be any expressions. Since, however, the code size
166 ;;;;; can increase this way they should be "simple". Compare:
168 ;;;(disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
169 ;;;(disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
171 ;;;;; (car (cons A B)) -> (progn B A)
172 ;;;(disassemble (lambda (x) (car (cons (foo) 42))))
174 ;;;;; (cdr (cons A B)) -> (progn A B)
175 ;;;(disassemble (lambda (x) (cdr (cons 42 (foo)))))
177 ;;;;; (car (list A B ...)) -> (progn B ... A)
178 ;;;(disassemble (lambda (x) (car (list (foo) 42 (bar)))))
180 ;;;;; (cdr (list A B ...)) -> (progn A (list B ...))
181 ;;;(disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
188 (defun byte-compile-log-lap-1 (format &rest args)
189 (if (aref byte-code-vector 0)
190 (error "The old version of the disassembler is loaded. Reload new-bytecomp as well."))
192 (apply 'format format
194 (mapcar '(lambda (arg)
195 (if (not (consp arg))
196 (if (and (symbolp arg)
197 (string-match "^byte-" (symbol-name arg)))
198 (intern (substring (symbol-name arg) 5))
200 (if (integerp (setq c (car arg)))
201 (error "non-symbolic byte-op %s" c))
204 (setq a (cond ((memq c byte-goto-ops)
205 (car (cdr (cdr arg))))
206 ((memq c byte-constref-ops)
209 (setq c (symbol-name c))
210 (if (string-match "^byte-." c)
211 (setq c (intern (substring c 5)))))
212 (if (eq c 'constant) (setq c 'const))
213 (if (and (eq (cdr arg) 0)
214 (not (memq c '(unbind call const))))
216 (format "(%s %s)" c a))))
219 (defmacro byte-compile-log-lap (format-string &rest args)
221 '(memq byte-optimize-log '(t byte))
222 (cons 'byte-compile-log-lap-1
223 (cons format-string args))))
226 ;;; byte-compile optimizers to support inlining
228 (put 'inline 'byte-optimizer 'byte-optimize-inline-handler)
230 (defun byte-optimize-inline-handler (form)
231 "byte-optimize-handler for the `inline' special-form."
235 (let ((fn (car-safe sexp)))
236 (if (and (symbolp fn)
237 (or (cdr (assq fn byte-compile-function-environment))
239 (not (or (cdr (assq fn byte-compile-macro-environment))
240 (and (consp (setq fn (symbol-function fn)))
241 (eq (car fn) 'macro))
243 (byte-compile-inline-expand sexp)
248 ;; Splice the given lap code into the current instruction stream.
249 ;; If it has any labels in it, you're responsible for making sure there
250 ;; are no collisions, and that byte-compile-tag-number is reasonable
251 ;; after this is spliced in. The provided list is destroyed.
252 (defun byte-inline-lapcode (lap)
253 (setq byte-compile-output (nconc (nreverse lap) byte-compile-output)))
256 (defun byte-compile-inline-expand (form)
257 (let* ((name (car form))
258 (fn (or (cdr (assq name byte-compile-function-environment))
259 (and (fboundp name) (symbol-function name)))))
262 (byte-compile-warn "attempt to inline %s before it was defined" name)
265 (if (and (consp fn) (eq (car fn) 'autoload))
268 (setq fn (or (cdr (assq name byte-compile-function-environment))
269 (and (fboundp name) (symbol-function name))))))
270 (if (and (consp fn) (eq (car fn) 'autoload))
271 (error "file \"%s\" didn't define \"%s\"" (nth 1 fn) name))
273 (byte-compile-inline-expand (cons fn (cdr form)))
274 (if (byte-code-function-p fn)
277 (setq string (aref fn 1))
278 (if (fboundp 'string-as-unibyte)
279 (setq string (string-as-unibyte string)))
280 (cons (list 'lambda (aref fn 0)
281 (list 'byte-code string (aref fn 2) (aref fn 3)))
283 (if (eq (car-safe fn) 'lambda)
285 ;; Give up on inlining.
288 ;;; ((lambda ...) ...)
290 (defun byte-compile-unfold-lambda (form &optional name)
291 (or name (setq name "anonymous lambda"))
292 (let ((lambda (car form))
294 (if (byte-code-function-p lambda)
295 (setq lambda (list 'lambda (aref lambda 0)
296 (list 'byte-code (aref lambda 1)
297 (aref lambda 2) (aref lambda 3)))))
298 (let ((arglist (nth 1 lambda))
299 (body (cdr (cdr lambda)))
302 (if (and (stringp (car body)) (cdr body))
303 (setq body (cdr body)))
304 (if (and (consp (car body)) (eq 'interactive (car (car body))))
305 (setq body (cdr body)))
307 (cond ((eq (car arglist) '&optional)
308 ;; ok, I'll let this slide because funcall_lambda() does...
309 ;; (if optionalp (error "multiple &optional keywords in %s" name))
310 (if restp (error "&optional found after &rest in %s" name))
311 (if (null (cdr arglist))
312 (error "nothing after &optional in %s" name))
314 ((eq (car arglist) '&rest)
315 ;; ...but it is by no stretch of the imagination a reasonable
316 ;; thing that funcall_lambda() allows (&rest x y) and
317 ;; (&rest x &optional y) in arglists.
318 (if (null (cdr arglist))
319 (error "nothing after &rest in %s" name))
320 (if (cdr (cdr arglist))
321 (error "multiple vars after &rest in %s" name))
324 (setq bindings (cons (list (car arglist)
325 (and values (cons 'list values)))
328 ((and (not optionalp) (null values))
329 (byte-compile-warn "attempt to open-code %s with too few arguments" name)
330 (setq arglist nil values 'too-few))
332 (setq bindings (cons (list (car arglist) (car values))
334 values (cdr values))))
335 (setq arglist (cdr arglist)))
338 (or (eq values 'too-few)
340 "attempt to open-code %s with too many arguments" name))
342 (setq body (mapcar 'byte-optimize-form body))
345 (cons 'let (cons (nreverse bindings) body))
346 (cons 'progn body))))
347 (byte-compile-log " %s\t==>\t%s" form newform)
351 ;;; implementing source-level optimizers
353 (defun byte-optimize-form-code-walker (form for-effect)
355 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
356 ;; we need to have special knowledge of the syntax of the special forms
357 ;; like let and defun (that's why they're special forms :-). (Actually,
358 ;; the important aspect is that they are subrs that don't evaluate all of
361 (let ((fn (car-safe form))
363 (cond ((not (consp form))
364 (if (not (and for-effect
365 (or byte-compile-delete-errors
371 (byte-compile-warn "malformed quote form: %s"
372 (prin1-to-string form)))
373 ;; map (quote nil) to nil to simplify optimizer logic.
374 ;; map quoted constants to nil if for-effect (just because).
378 ((or (byte-code-function-p fn)
379 (eq 'lambda (car-safe fn)))
380 (byte-compile-unfold-lambda form))
381 ((memq fn '(let let*))
382 ;; recursively enter the optimizer for the bindings and body
383 ;; of a let or let*. This for depth-firstness: forms that
384 ;; are more deeply nested are optimized first.
387 (mapcar '(lambda (binding)
388 (if (symbolp binding)
390 (if (cdr (cdr binding))
391 (byte-compile-warn "malformed let binding: %s"
392 (prin1-to-string binding)))
394 (byte-optimize-form (nth 1 binding) nil))))
396 (byte-optimize-body (cdr (cdr form)) for-effect))))
399 (mapcar '(lambda (clause)
402 (byte-optimize-form (car clause) nil)
403 (byte-optimize-body (cdr clause) for-effect))
404 (byte-compile-warn "malformed cond form: %s"
405 (prin1-to-string clause))
409 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
412 (setq tmp (byte-optimize-body (cdr form) for-effect))
413 (if (cdr tmp) (cons 'progn tmp) (car tmp)))
414 (byte-optimize-form (nth 1 form) for-effect)))
418 (cons (byte-optimize-form (nth 1 form) for-effect)
419 (byte-optimize-body (cdr (cdr form)) t)))
420 (byte-optimize-form (nth 1 form) for-effect)))
423 (cons (byte-optimize-form (nth 1 form) t)
424 (cons (byte-optimize-form (nth 2 form) for-effect)
425 (byte-optimize-body (cdr (cdr (cdr form))) t)))))
427 ((memq fn '(save-excursion save-restriction save-current-buffer))
428 ;; those subrs which have an implicit progn; it's not quite good
429 ;; enough to treat these like normal function calls.
430 ;; This can turn (save-excursion ...) into (save-excursion) which
431 ;; will be optimized away in the lap-optimize pass.
432 (cons fn (byte-optimize-body (cdr form) for-effect)))
434 ((eq fn 'with-output-to-temp-buffer)
435 ;; this is just like the above, except for the first argument.
438 (byte-optimize-form (nth 1 form) nil)
439 (byte-optimize-body (cdr (cdr form)) for-effect))))
443 (cons (byte-optimize-form (nth 1 form) nil)
445 (byte-optimize-form (nth 2 form) for-effect)
446 (byte-optimize-body (nthcdr 3 form) for-effect)))))
448 ((memq fn '(and or)) ; remember, and/or are control structures.
449 ;; take forms off the back until we can't any more.
450 ;; In the future it could conceivably be a problem that the
451 ;; subexpressions of these forms are optimized in the reverse
452 ;; order, but it's ok for now.
454 (let ((backwards (reverse (cdr form))))
455 (while (and backwards
456 (null (setcar backwards
457 (byte-optimize-form (car backwards)
459 (setq backwards (cdr backwards)))
460 (if (and (cdr form) (null backwards))
462 " all subforms of %s called for effect; deleted" form))
464 (cons fn (nreverse backwards))))
465 (cons fn (mapcar 'byte-optimize-form (cdr form)))))
467 ((eq fn 'interactive)
468 (byte-compile-warn "misplaced interactive spec: %s"
469 (prin1-to-string form))
472 ((memq fn '(defun defmacro function
473 condition-case save-window-excursion))
474 ;; These forms are compiled as constants or by breaking out
475 ;; all the subexpressions and compiling them separately.
478 ((eq fn 'unwind-protect)
479 ;; the "protected" part of an unwind-protect is compiled (and thus
480 ;; optimized) as a top-level form, so don't do it here. But the
481 ;; non-protected part has the same for-effect status as the
482 ;; unwind-protect itself. (The protected part is always for effect,
483 ;; but that isn't handled properly yet.)
485 (cons (byte-optimize-form (nth 1 form) for-effect)
489 ;; the body of a catch is compiled (and thus optimized) as a
490 ;; top-level form, so don't do it here. The tag is never
491 ;; for-effect. The body should have the same for-effect status
492 ;; as the catch form itself, but that isn't handled properly yet.
494 (cons (byte-optimize-form (nth 1 form) nil)
497 ;; If optimization is on, this is the only place that macros are
498 ;; expanded. If optimization is off, then macroexpansion happens
499 ;; in byte-compile-form. Otherwise, the macros are already expanded
500 ;; by the time that is reached.
502 (setq form (macroexpand form
503 byte-compile-macro-environment))))
504 (byte-optimize-form form for-effect))
506 ;; Support compiler macros as in cl.el.
507 ((and (fboundp 'compiler-macroexpand)
508 (symbolp (car-safe form))
509 (get (car-safe form) 'cl-compiler-macro)
511 (setq form (compiler-macroexpand form)))))
512 (byte-optimize-form form for-effect))
515 (or (eq 'mocklisp (car-safe fn)) ; ha!
516 (byte-compile-warn "%s is a malformed function"
517 (prin1-to-string fn)))
520 ((and for-effect (setq tmp (get fn 'side-effect-free))
521 (or byte-compile-delete-errors
524 (byte-compile-warn "%s called for effect"
525 (prin1-to-string form))
527 (byte-compile-log " %s called for effect; deleted" fn)
528 ;; appending a nil here might not be necessary, but it can't hurt.
530 (cons 'progn (append (cdr form) '(nil))) t))
533 ;; Otherwise, no args can be considered to be for-effect,
534 ;; even if the called function is for-effect, because we
535 ;; don't know anything about that function.
536 (cons fn (mapcar 'byte-optimize-form (cdr form)))))))
539 (defun byte-optimize-form (form &optional for-effect)
540 "The source-level pass of the optimizer."
542 ;; First, optimize all sub-forms of this one.
543 (setq form (byte-optimize-form-code-walker form for-effect))
545 ;; after optimizing all subforms, optimize this form until it doesn't
546 ;; optimize any further. This means that some forms will be passed through
547 ;; the optimizer many times, but that's necessary to make the for-effect
548 ;; processing do as much as possible.
551 (if (and (consp form)
554 ;; we don't have any of these yet, but we might.
555 (setq opt (get (car form) 'byte-for-effect-optimizer)))
556 (setq opt (get (car form) 'byte-optimizer)))
557 (not (eq form (setq new (funcall opt form)))))
559 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
560 (byte-compile-log " %s\t==>\t%s" form new)
561 (setq new (byte-optimize-form new for-effect))
566 (defun byte-optimize-body (forms all-for-effect)
567 ;; optimize the cdr of a progn or implicit progn; all forms is a list of
568 ;; forms, all but the last of which are optimized with the assumption that
569 ;; they are being called for effect. the last is for-effect as well if
570 ;; all-for-effect is true. returns a new list of forms.
575 (setq fe (or all-for-effect (cdr rest)))
576 (setq new (and (car rest) (byte-optimize-form (car rest) fe)))
577 (if (or new (not fe))
578 (setq result (cons new result)))
579 (setq rest (cdr rest)))
583 ;;; some source-level optimizers
585 ;;; when writing optimizers, be VERY careful that the optimizer returns
586 ;;; something not EQ to its argument if and ONLY if it has made a change.
587 ;;; This implies that you cannot simply destructively modify the list;
588 ;;; you must return something not EQ to it if you make an optimization.
590 ;;; It is now safe to optimize code such that it introduces new bindings.
592 ;; I'd like this to be a defsubst, but let's not be self-referential...
593 (defmacro byte-compile-trueconstp (form)
594 ;; Returns non-nil if FORM is a non-nil constant.
595 (` (cond ((consp (, form)) (eq (car (, form)) 'quote))
596 ((not (symbolp (, form))))
599 ;; If the function is being called with constant numeric args,
600 ;; evaluate as much as possible at compile-time. This optimizer
601 ;; assumes that the function is associative, like + or *.
602 (defun byte-optimize-associative-math (form)
607 (if (numberp (car rest))
608 (setq constants (cons (car rest) constants))
609 (setq args (cons (car rest) args)))
610 (setq rest (cdr rest)))
614 (apply (car form) constants)
616 (cons (car form) (nreverse args))
618 (apply (car form) constants))
621 ;; If the function is being called with constant numeric args,
622 ;; evaluate as much as possible at compile-time. This optimizer
623 ;; assumes that the function satisfies
624 ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
626 (defun byte-optimize-nonassociative-math (form)
627 (if (or (not (numberp (car (cdr form))))
628 (not (numberp (car (cdr (cdr form))))))
630 (let ((constant (car (cdr form)))
631 (rest (cdr (cdr form))))
632 (while (numberp (car rest))
633 (setq constant (funcall (car form) constant (car rest))
636 (cons (car form) (cons constant rest))
639 ;;(defun byte-optimize-associative-two-args-math (form)
640 ;; (setq form (byte-optimize-associative-math form))
642 ;; (byte-optimize-two-args-left form)
645 ;;(defun byte-optimize-nonassociative-two-args-math (form)
646 ;; (setq form (byte-optimize-nonassociative-math form))
648 ;; (byte-optimize-two-args-right form)
651 (defun byte-optimize-approx-equal (x y)
652 (<= (* (abs (- x y)) 100) (abs (+ x y))))
654 ;; Collect all the constants from FORM, after the STARTth arg,
655 ;; and apply FUN to them to make one argument at the end.
656 ;; For functions that can handle floats, that optimization
657 ;; can be incorrect because reordering can cause an overflow
658 ;; that would otherwise be avoided by encountering an arg that is a float.
659 ;; We avoid this problem by (1) not moving float constants and
660 ;; (2) not moving anything if it would cause an overflow.
661 (defun byte-optimize-delay-constants-math (form start fun)
662 ;; Merge all FORM's constants from number START, call FUN on them
663 ;; and put the result at the end.
664 (let ((rest (nthcdr (1- start) form))
666 ;; t means we must check for overflow.
667 (overflow (memq fun '(+ *))))
668 (while (cdr (setq rest (cdr rest)))
669 (if (integerp (car rest))
671 (setq form (copy-sequence form)
672 rest (nthcdr (1- start) form))
673 (while (setq rest (cdr rest))
674 (cond ((integerp (car rest))
675 (setq constants (cons (car rest) constants))
677 ;; If necessary, check now for overflow
678 ;; that might be caused by reordering.
680 ;; We have overflow if the result of doing the arithmetic
681 ;; on floats is not even close to the result
682 ;; of doing it on integers.
683 (not (byte-optimize-approx-equal
684 (apply fun (mapcar 'float constants))
685 (float (apply fun constants)))))
687 (setq form (nconc (delq nil form)
688 (list (apply fun (nreverse constants)))))))))
691 (defun byte-optimize-plus (form)
692 (setq form (byte-optimize-delay-constants-math form 1 '+))
693 (if (memq 0 form) (setq form (delq 0 (copy-sequence form))))
694 ;;(setq form (byte-optimize-associative-two-args-math form))
695 (cond ((null (cdr form))
699 ;;; It is not safe to delete the function entirely
700 ;;; (actually, it would be safe if we know the sole arg
701 ;;; is not a marker).
702 ;; ((null (cdr (cdr form))) (nth 1 form))
704 (if (numberp (nth 1 form))
707 ((and (null (nthcdr 3 form))
708 (or (memq (nth 1 form) '(1 -1))
709 (memq (nth 2 form) '(1 -1))))
710 ;; Optimize (+ x 1) into (1+ x) and (+ x -1) into (1- x).
712 (if (memq (nth 1 form) '(1 -1))
716 (if (memq (nth 1 form) '(1 -1))
719 (list (if (eq integer 1) '1+ '1-)
723 (defun byte-optimize-minus (form)
724 ;; Put constants at the end, except the last constant.
725 (setq form (byte-optimize-delay-constants-math form 2 '+))
726 ;; Now only first and last element can be a number.
727 (let ((last (car (reverse (nthcdr 3 form)))))
729 ;; (- x y ... 0) --> (- x y ...)
730 (setq form (copy-sequence form))
731 (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form))))
732 ((equal (nthcdr 2 form) '(1))
733 (setq form (list '1- (nth 1 form))))
734 ((equal (nthcdr 2 form) '(-1))
735 (setq form (list '1+ (nth 1 form))))
736 ;; If form is (- CONST foo... CONST), merge first and last.
737 ((and (numberp (nth 1 form))
739 (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
740 (delq last (copy-sequence (nthcdr 3 form))))))))
741 ;;; It is not safe to delete the function entirely
742 ;;; (actually, it would be safe if we know the sole arg
743 ;;; is not a marker).
744 ;;; (if (eq (nth 2 form) 0)
745 ;;; (nth 1 form) ; (- x 0) --> x
746 (byte-optimize-predicate
747 (if (and (null (cdr (cdr (cdr form))))
748 (eq (nth 1 form) 0)) ; (- 0 x) --> (- x)
749 (cons (car form) (cdr (cdr form)))
754 (defun byte-optimize-multiply (form)
755 (setq form (byte-optimize-delay-constants-math form 1 '*))
756 ;; If there is a constant in FORM, it is now the last element.
757 (cond ((null (cdr form)) 1)
758 ;;; It is not safe to delete the function entirely
759 ;;; (actually, it would be safe if we know the sole arg
760 ;;; is not a marker or if it appears in other arithmetic).
761 ;;; ((null (cdr (cdr form))) (nth 1 form))
762 ((let ((last (car (reverse form))))
763 (cond ((eq 0 last) (cons 'progn (cdr form)))
764 ((eq 1 last) (delq 1 (copy-sequence form)))
765 ((eq -1 last) (list '- (delq -1 (copy-sequence form))))
767 (memq t (mapcar 'symbolp (cdr form))))
768 (prog1 (setq form (delq 2 (copy-sequence form)))
769 (while (not (symbolp (car (setq form (cdr form))))))
770 (setcar form (list '+ (car form) (car form)))))
773 (defsubst byte-compile-butlast (form)
774 (nreverse (cdr (reverse form))))
776 (defun byte-optimize-divide (form)
777 (setq form (byte-optimize-delay-constants-math form 2 '*))
778 (let ((last (car (reverse (cdr (cdr form))))))
780 (cond ((= (length form) 3)
781 (if (and (numberp (nth 1 form))
784 (/ (nth 1 form) last)
786 (setq form (list 'progn (/ (nth 1 form) last)))))
788 (setq form (byte-compile-butlast form)))
789 ((numberp (nth 1 form))
790 (setq form (cons (car form)
791 (cons (/ (nth 1 form) last)
792 (byte-compile-butlast (cdr (cdr form)))))
795 ;;; ((null (cdr (cdr form)))
798 (append '(progn) (cdr (cdr form)) '(0)))
800 (list '- (if (nthcdr 3 form)
801 (byte-compile-butlast form)
805 (defun byte-optimize-logmumble (form)
806 (setq form (byte-optimize-delay-constants-math form 1 (car form)))
807 (byte-optimize-predicate
809 (setq form (if (eq (car form) 'logand)
810 (cons 'progn (cdr form))
811 (delq 0 (copy-sequence form)))))
812 ((and (eq (car-safe form) 'logior)
814 (cons 'progn (cdr form)))
818 (defun byte-optimize-binary-predicate (form)
819 (if (byte-compile-constp (nth 1 form))
820 (if (byte-compile-constp (nth 2 form))
822 (list 'quote (eval form))
824 ;; This can enable some lapcode optimizations.
825 (list (car form) (nth 2 form) (nth 1 form)))
828 (defun byte-optimize-predicate (form)
832 (setq ok (byte-compile-constp (car rest))
836 (list 'quote (eval form))
840 (defun byte-optimize-identity (form)
841 (if (and (cdr form) (null (cdr (cdr form))))
843 (byte-compile-warn "identity called with %d arg%s, but requires 1"
845 (if (= 1 (length (cdr form))) "" "s"))
848 (put 'identity 'byte-optimizer 'byte-optimize-identity)
850 (put '+ 'byte-optimizer 'byte-optimize-plus)
851 (put '* 'byte-optimizer 'byte-optimize-multiply)
852 (put '- 'byte-optimizer 'byte-optimize-minus)
853 (put '/ 'byte-optimizer 'byte-optimize-divide)
854 (put 'max 'byte-optimizer 'byte-optimize-associative-math)
855 (put 'min 'byte-optimizer 'byte-optimize-associative-math)
857 (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
858 (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
859 (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
860 (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
861 (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
863 (put '< 'byte-optimizer 'byte-optimize-predicate)
864 (put '> 'byte-optimizer 'byte-optimize-predicate)
865 (put '<= 'byte-optimizer 'byte-optimize-predicate)
866 (put '>= 'byte-optimizer 'byte-optimize-predicate)
867 (put '1+ 'byte-optimizer 'byte-optimize-predicate)
868 (put '1- 'byte-optimizer 'byte-optimize-predicate)
869 (put 'not 'byte-optimizer 'byte-optimize-predicate)
870 (put 'null 'byte-optimizer 'byte-optimize-predicate)
871 (put 'memq 'byte-optimizer 'byte-optimize-predicate)
872 (put 'consp 'byte-optimizer 'byte-optimize-predicate)
873 (put 'listp 'byte-optimizer 'byte-optimize-predicate)
874 (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
875 (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
876 (put 'string< 'byte-optimizer 'byte-optimize-predicate)
877 (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
879 (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
880 (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
881 (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
882 (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
884 (put 'car 'byte-optimizer 'byte-optimize-predicate)
885 (put 'cdr 'byte-optimizer 'byte-optimize-predicate)
886 (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
887 (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
890 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
891 ;; take care of this? - Jamie
892 ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
893 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
894 (put 'quote 'byte-optimizer 'byte-optimize-quote)
895 (defun byte-optimize-quote (form)
896 (if (or (consp (nth 1 form))
897 (and (symbolp (nth 1 form))
898 (not (memq (nth 1 form) '(nil t)))))
902 (defun byte-optimize-zerop (form)
903 (cond ((numberp (nth 1 form))
905 (byte-compile-delete-errors
906 (list '= (nth 1 form) 0))
909 (put 'zerop 'byte-optimizer 'byte-optimize-zerop)
911 (defun byte-optimize-and (form)
912 ;; Simplify if less than 2 args.
913 ;; if there is a literal nil in the args to `and', throw it and following
914 ;; forms away, and surround the `and' with (progn ... nil).
915 (cond ((null (cdr form)))
919 (prog1 (setq form (copy-sequence form))
921 (setq form (cdr form)))
924 ((null (cdr (cdr form)))
926 ((byte-optimize-predicate form))))
928 (defun byte-optimize-or (form)
929 ;; Throw away nil's, and simplify if less than 2 args.
930 ;; If there is a literal non-nil constant in the args to `or', throw away all
933 (setq form (delq nil (copy-sequence form))))
935 (while (cdr (setq rest (cdr rest)))
936 (if (byte-compile-trueconstp (car rest))
937 (setq form (copy-sequence form)
938 rest (setcdr (memq (car rest) form) nil))))
940 (byte-optimize-predicate form)
943 (defun byte-optimize-cond (form)
944 ;; if any clauses have a literal nil as their test, throw them away.
945 ;; if any clause has a literal non-nil constant as its test, throw
946 ;; away all following clauses.
948 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
949 (while (setq rest (assq nil (cdr form)))
950 (setq form (delq rest (copy-sequence form))))
951 (if (memq nil (cdr form))
952 (setq form (delq nil (copy-sequence form))))
954 (while (setq rest (cdr rest))
955 (cond ((byte-compile-trueconstp (car-safe (car rest)))
956 (cond ((eq rest (cdr form))
959 (if (cdr (cdr (car rest)))
960 (cons 'progn (cdr (car rest)))
964 (setq form (copy-sequence form))
965 (setcdr (memq (car rest) form) nil)))
968 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
969 (if (eq 'cond (car-safe form))
970 (let ((clauses (cdr form)))
971 (if (and (consp (car clauses))
972 (null (cdr (car clauses))))
973 (list 'or (car (car clauses))
975 (cons (car form) (cdr (cdr form)))))
979 (defun byte-optimize-if (form)
980 ;; (if <true-constant> <then> <else...>) ==> <then>
981 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
982 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
983 ;; (if <test> <then> nil) ==> (if <test> <then>)
984 (let ((clause (nth 1 form)))
985 (cond ((byte-compile-trueconstp clause)
989 (cons 'progn (nthcdr 3 form))
992 (if (equal '(nil) (nthcdr 3 form))
993 (list 'if clause (nth 2 form))
995 ((or (nth 3 form) (nthcdr 4 form))
997 ;; Don't make a double negative;
998 ;; instead, take away the one that is there.
999 (if (and (consp clause) (memq (car clause) '(not null))
1000 (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
1004 (cons 'progn (nthcdr 3 form))
1007 (list 'progn clause nil)))))
1009 (defun byte-optimize-while (form)
1013 (put 'and 'byte-optimizer 'byte-optimize-and)
1014 (put 'or 'byte-optimizer 'byte-optimize-or)
1015 (put 'cond 'byte-optimizer 'byte-optimize-cond)
1016 (put 'if 'byte-optimizer 'byte-optimize-if)
1017 (put 'while 'byte-optimizer 'byte-optimize-while)
1019 ;; byte-compile-negation-optimizer lives in bytecomp.el
1020 (put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
1021 (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
1022 (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
1025 (defun byte-optimize-funcall (form)
1026 ;; (funcall '(lambda ...) ...) ==> ((lambda ...) ...)
1027 ;; (funcall 'foo ...) ==> (foo ...)
1028 (let ((fn (nth 1 form)))
1029 (if (memq (car-safe fn) '(quote function))
1030 (cons (nth 1 fn) (cdr (cdr form)))
1033 (defun byte-optimize-apply (form)
1034 ;; If the last arg is a literal constant, turn this into a funcall.
1035 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1036 (let ((fn (nth 1 form))
1037 (last (nth (1- (length form)) form))) ; I think this really is fastest
1038 (or (if (or (null last)
1039 (eq (car-safe last) 'quote))
1040 (if (listp (nth 1 last))
1041 (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
1042 (nconc (list 'funcall fn) butlast
1043 (mapcar '(lambda (x) (list 'quote x)) (nth 1 last))))
1045 "last arg to apply can't be a literal atom: %s"
1046 (prin1-to-string last))
1050 (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
1051 (put 'apply 'byte-optimizer 'byte-optimize-apply)
1054 (put 'let 'byte-optimizer 'byte-optimize-letX)
1055 (put 'let* 'byte-optimizer 'byte-optimize-letX)
1056 (defun byte-optimize-letX (form)
1057 (cond ((null (nth 1 form))
1059 (cons 'progn (cdr (cdr form))))
1060 ((or (nth 2 form) (nthcdr 3 form))
1063 ((eq (car form) 'let)
1064 (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
1067 (let ((binds (reverse (nth 1 form))))
1068 (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
1071 (put 'nth 'byte-optimizer 'byte-optimize-nth)
1072 (defun byte-optimize-nth (form)
1073 (if (and (= (safe-length form) 3) (memq (nth 1 form) '(0 1)))
1074 (list 'car (if (zerop (nth 1 form))
1076 (list 'cdr (nth 2 form))))
1077 (byte-optimize-predicate form)))
1079 (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
1080 (defun byte-optimize-nthcdr (form)
1081 (if (and (= (safe-length form) 3) (not (memq (nth 1 form) '(0 1 2))))
1082 (byte-optimize-predicate form)
1083 (let ((count (nth 1 form)))
1084 (setq form (nth 2 form))
1085 (while (>= (setq count (1- count)) 0)
1086 (setq form (list 'cdr form)))
1089 (put 'concat 'byte-optimizer 'byte-optimize-concat)
1090 (defun byte-optimize-concat (form)
1091 (let ((args (cdr form))
1093 (while (and args constant)
1094 (or (byte-compile-constp (car args))
1095 (setq constant nil))
1096 (setq args (cdr args)))
1101 ;; Avoid having to write forward-... with a negative arg for speed.
1102 (put 'backward-char 'byte-optimizer 'byte-optimize-backward-char)
1103 (defun byte-optimize-backward-char (form)
1104 (cond ((and (= 2 (safe-length form))
1105 (numberp (nth 1 form)))
1106 (list 'forward-char (eval (- (nth 1 form)))))
1107 ((= 1 (safe-length form))
1111 (put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
1112 (defun byte-optimize-backward-word (form)
1113 (cond ((and (= 2 (safe-length form))
1114 (numberp (nth 1 form)))
1115 (list 'forward-word (eval (- (nth 1 form)))))
1116 ((= 1 (safe-length form))
1120 ;;; enumerating those functions which need not be called if the returned
1121 ;;; value is not used. That is, something like
1122 ;;; (progn (list (something-with-side-effects) (yow))
1124 ;;; may safely be turned into
1125 ;;; (progn (progn (something-with-side-effects) (yow))
1127 ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1129 ;;; I wonder if I missed any :-\)
1130 (let ((side-effect-free-fns
1131 '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
1133 boundp buffer-file-name buffer-local-variables buffer-modified-p
1135 capitalize car-less-than-car car cdr ceiling concat coordinates-in-window-p
1136 char-width copy-marker cos count-lines
1137 default-boundp default-value documentation downcase
1138 elt exp expt fboundp featurep
1139 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1140 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1141 float floor format frame-visible-p
1142 get gethash get-buffer get-buffer-window getenv get-file-buffer
1146 length local-variable-if-set-p local-variable-p log log10 logand logb logior lognot logxor lsh
1147 marker-buffer max member memq min mod
1148 next-window nth nthcdr number-to-string
1149 parse-colon-path prefix-numeric-value previous-window
1150 radians-to-degrees rassq regexp-quote reverse round
1151 sin sqrt string< string= string-equal string-lessp string-to-char
1152 string-to-int string-to-number substring symbol-function symbol-plist
1154 tan unibyte-char-to-multibyte upcase user-variable-p vconcat
1155 window-buffer window-dedicated-p window-edges window-height
1156 window-hscroll window-minibuffer-p window-width
1158 (side-effect-and-error-free-fns
1160 bobp bolp buffer-end buffer-list buffer-size buffer-string bufferp
1161 car-safe case-table-p cdr-safe char-or-string-p commandp cons consp
1162 current-buffer current-global-map current-indentation
1163 current-local-map current-minor-mode-maps
1164 dot dot-marker eobp eolp eq equal eventp floatp framep
1165 get-largest-window get-lru-window
1167 identity ignore integerp integer-or-marker-p interactive-p
1168 invocation-directory invocation-name
1170 line-beginning-position line-end-position list listp
1171 make-marker mark mark-marker markerp memory-limit minibuffer-window
1173 natnump nlistp not null number-or-marker-p numberp
1174 one-window-p overlayp
1175 point point-marker point-min point-max processp
1176 recent-keys recursion-depth
1177 selected-frame selected-window sequencep stringp subrp symbolp
1178 standard-case-table standard-syntax-table syntax-table-p
1179 this-command-keys this-command-keys-vector this-single-command-keys
1180 this-single-command-raw-keys
1181 user-full-name user-login-name user-original-login-name
1182 user-real-login-name user-real-uid user-uid
1183 vector vectorp visible-frame-list
1184 window-configuration-p window-live-p windowp)))
1185 (while side-effect-free-fns
1186 (put (car side-effect-free-fns) 'side-effect-free t)
1187 (setq side-effect-free-fns (cdr side-effect-free-fns)))
1188 (while side-effect-and-error-free-fns
1189 (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free)
1190 (setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns)))
1194 (defun byte-compile-splice-in-already-compiled-code (form)
1195 ;; form is (byte-code "..." [...] n)
1196 (if (not (memq byte-optimize '(t lap)))
1197 (byte-compile-normal-call form)
1198 (byte-inline-lapcode
1199 (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t))
1200 (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form))
1201 byte-compile-maxdepth))
1202 (setq byte-compile-depth (1+ byte-compile-depth))))
1204 (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code)
1207 (defconst byte-constref-ops
1208 '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
1210 ;;; This function extracts the bitfields from variable-length opcodes.
1211 ;;; Originally defined in disass.el (which no longer uses it.)
1213 (defun disassemble-offset ()
1215 ;; fetch and return the offset for the current opcode.
1216 ;; return NIL if this opcode has no offset
1217 ;; OP, PTR and BYTES are used and set dynamically
1221 (cond ((< op byte-nth)
1222 (let ((tem (logand op 7)))
1223 (setq op (logand op 248))
1225 (setq ptr (1+ ptr)) ;offset in next byte
1228 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1230 (progn (setq ptr (1+ ptr))
1231 (lsh (aref bytes ptr) 8))))
1232 (t tem)))) ;offset was in opcode
1233 ((>= op byte-constant)
1234 (prog1 (- op byte-constant) ;offset in opcode
1235 (setq op byte-constant)))
1236 ((and (>= op byte-constant2)
1237 (<= op byte-goto-if-not-nil-else-pop))
1238 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1240 (progn (setq ptr (1+ ptr))
1241 (lsh (aref bytes ptr) 8))))
1242 ((and (>= op byte-listN)
1243 (<= op byte-insertN))
1244 (setq ptr (1+ ptr)) ;offset in next byte
1248 ;;; This de-compiler is used for inline expansion of compiled functions,
1249 ;;; and by the disassembler.
1251 ;;; This list contains numbers, which are pc values,
1252 ;;; before each instruction.
1253 (defun byte-decompile-bytecode (bytes constvec)
1254 "Turns BYTECODE into lapcode, referring to CONSTVEC."
1255 (let ((byte-compile-constants nil)
1256 (byte-compile-variables nil)
1257 (byte-compile-tag-number 0))
1258 (byte-decompile-bytecode-1 bytes constvec)))
1260 ;; As byte-decompile-bytecode, but updates
1261 ;; byte-compile-{constants, variables, tag-number}.
1262 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1263 ;; with `goto's destined for the end of the code.
1264 ;; That is for use by the compiler.
1265 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1266 ;; In that case, we put a pc value into the list
1267 ;; before each insn (or its label).
1268 (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
1269 (let ((length (length bytes))
1270 (ptr 0) optr tag tags op offset
1274 (while (not (= ptr length))
1276 (setq lap (cons ptr lap)))
1277 (setq op (aref bytes ptr)
1279 offset (disassemble-offset)) ; this does dynamic-scope magic
1280 (setq op (aref byte-code-vector op))
1281 (cond ((memq op byte-goto-ops)
1284 (cdr (or (assq offset tags)
1287 (byte-compile-make-tag))
1289 ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t)
1290 ((memq op byte-constref-ops)))
1291 (setq tmp (if (>= offset (length constvec))
1292 (list 'out-of-range offset)
1293 (aref constvec offset))
1294 offset (if (eq op 'byte-constant)
1295 (byte-compile-get-constant tmp)
1296 (or (assq tmp byte-compile-variables)
1297 (car (setq byte-compile-variables
1299 byte-compile-variables)))))))
1300 ((and make-spliceable
1301 (eq op 'byte-return))
1302 (if (= ptr (1- length))
1304 (setq offset (or endtag (setq endtag (byte-compile-make-tag)))
1306 ;; lap = ( [ (pc . (op . arg)) ]* )
1307 (setq lap (cons (cons optr (cons op (or offset 0)))
1309 (setq ptr (1+ ptr)))
1310 ;; take off the dummy nil op that we replaced a trailing "return" with.
1313 (cond ((numberp (car rest)))
1314 ((setq tmp (assq (car (car rest)) tags))
1315 ;; this addr is jumped to
1316 (setcdr rest (cons (cons nil (cdr tmp))
1318 (setq tags (delq tmp tags))
1319 (setq rest (cdr rest))))
1320 (setq rest (cdr rest))))
1321 (if tags (error "optimizer error: missed tags %s" tags))
1322 (if (null (car (cdr (car lap))))
1323 (setq lap (cdr lap)))
1325 (setq lap (cons (cons nil endtag) lap)))
1326 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1327 (mapcar (function (lambda (elt)
1334 ;;; peephole optimizer
1336 (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
1338 (defconst byte-conditional-ops
1339 '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
1340 byte-goto-if-not-nil-else-pop))
1342 (defconst byte-after-unbind-ops
1343 '(byte-constant byte-dup
1344 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1346 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1348 ;; How about other side-effect-free-ops? Is it safe to move an
1349 ;; error invocation (such as from nth) out of an unwind-protect?
1350 ;; No, it is not, because the unwind-protect forms can alter
1351 ;; the inside of the object to which nth would apply.
1352 ;; For the same reason, byte-equal was deleted from this list.
1353 "Byte-codes that can be moved past an unbind.")
1355 (defconst byte-compile-side-effect-and-error-free-ops
1356 '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
1357 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1358 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1359 byte-point-min byte-following-char byte-preceding-char
1360 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1361 byte-current-buffer byte-interactive-p))
1363 (defconst byte-compile-side-effect-free-ops
1365 '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
1366 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1367 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1368 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1369 byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
1370 byte-member byte-assq byte-quo byte-rem)
1371 byte-compile-side-effect-and-error-free-ops))
1373 ;;; This crock is because of the way DEFVAR_BOOL variables work.
1374 ;;; Consider the code
1376 ;;; (defun foo (flag)
1377 ;;; (let ((old-pop-ups pop-up-windows)
1378 ;;; (pop-up-windows flag))
1379 ;;; (cond ((not (eq pop-up-windows old-pop-ups))
1380 ;;; (setq old-pop-ups pop-up-windows)
1383 ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1384 ;;; something else. But if we optimize
1387 ;;; varbind pop-up-windows
1388 ;;; varref pop-up-windows
1393 ;;; varbind pop-up-windows
1396 ;;; we break the program, because it will appear that pop-up-windows and
1397 ;;; old-pop-ups are not EQ when really they are. So we have to know what
1398 ;;; the BOOL variables are, and not perform this optimization on them.
1400 ;;; The variable `byte-boolean-vars' is now primitive and updated
1401 ;;; automatically by DEFVAR_BOOL.
1403 (defun byte-optimize-lapcode (lap &optional for-effect)
1404 "Simple peephole optimizer. LAP is both modified and returned."
1408 (keep-going 'first-time)
1411 (side-effect-free (if byte-compile-delete-errors
1412 byte-compile-side-effect-free-ops
1413 byte-compile-side-effect-and-error-free-ops)))
1415 (or (eq keep-going 'first-time)
1416 (byte-compile-log-lap " ---- next pass"))
1420 (setq lap0 (car rest)
1424 ;; You may notice that sequences like "dup varset discard" are
1425 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1426 ;; You may be tempted to change this; resist that temptation.
1428 ;; <side-effect-free> pop --> <deleted>
1430 ;; const-X pop --> <deleted>
1431 ;; varref-X pop --> <deleted>
1432 ;; dup pop --> <deleted>
1434 ((and (eq 'byte-discard (car lap1))
1435 (memq (car lap0) side-effect-free))
1437 (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
1438 (setq rest (cdr rest))
1440 (byte-compile-log-lap
1441 " %s discard\t-->\t<deleted>" lap0)
1442 (setq lap (delq lap0 (delq lap1 lap))))
1444 (byte-compile-log-lap
1445 " %s discard\t-->\t<deleted> discard" lap0)
1446 (setq lap (delq lap0 lap)))
1448 (byte-compile-log-lap
1449 " %s discard\t-->\tdiscard discard" lap0)
1450 (setcar lap0 'byte-discard)
1452 ((error "Optimizer error: too much on the stack"))))
1454 ;; goto*-X X: --> X:
1456 ((and (memq (car lap0) byte-goto-ops)
1457 (eq (cdr lap0) lap1))
1458 (cond ((eq (car lap0) 'byte-goto)
1459 (setq lap (delq lap0 lap))
1460 (setq tmp "<deleted>"))
1461 ((memq (car lap0) byte-goto-always-pop-ops)
1462 (setcar lap0 (setq tmp 'byte-discard))
1464 ((error "Depth conflict at tag %d" (nth 2 lap0))))
1465 (and (memq byte-optimize-log '(t byte))
1466 (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
1467 (nth 1 lap1) (nth 1 lap1)
1469 (setq keep-going t))
1471 ;; varset-X varref-X --> dup varset-X
1472 ;; varbind-X varref-X --> dup varbind-X
1473 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1474 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1475 ;; The latter two can enable other optimizations.
1477 ((and (eq 'byte-varref (car lap2))
1478 (eq (cdr lap1) (cdr lap2))
1479 (memq (car lap1) '(byte-varset byte-varbind)))
1480 (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars))
1481 (not (eq (car lap0) 'byte-constant)))
1484 (if (memq (car lap0) '(byte-constant byte-dup))
1486 (setq tmp (if (or (not tmp)
1487 (memq (car (cdr lap0)) '(nil t)))
1489 (byte-compile-get-constant t)))
1490 (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
1491 lap0 lap1 lap2 lap0 lap1
1492 (cons (car lap0) tmp))
1493 (setcar lap2 (car lap0))
1495 (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
1496 (setcar lap2 (car lap1))
1497 (setcar lap1 'byte-dup)
1499 ;; The stack depth gets locally increased, so we will
1500 ;; increase maxdepth in case depth = maxdepth here.
1501 ;; This can cause the third argument to byte-code to
1502 ;; be larger than necessary.
1503 (setq add-depth 1))))
1505 ;; dup varset-X discard --> varset-X
1506 ;; dup varbind-X discard --> varbind-X
1507 ;; (the varbind variant can emerge from other optimizations)
1509 ((and (eq 'byte-dup (car lap0))
1510 (eq 'byte-discard (car lap2))
1511 (memq (car lap1) '(byte-varset byte-varbind)))
1512 (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
1515 (setq lap (delq lap0 (delq lap2 lap))))
1517 ;; not goto-X-if-nil --> goto-X-if-non-nil
1518 ;; not goto-X-if-non-nil --> goto-X-if-nil
1520 ;; it is wrong to do the same thing for the -else-pop variants.
1522 ((and (eq 'byte-not (car lap0))
1523 (or (eq 'byte-goto-if-nil (car lap1))
1524 (eq 'byte-goto-if-not-nil (car lap1))))
1525 (byte-compile-log-lap " not %s\t-->\t%s"
1528 (if (eq (car lap1) 'byte-goto-if-nil)
1529 'byte-goto-if-not-nil
1532 (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
1533 'byte-goto-if-not-nil
1535 (setq lap (delq lap0 lap))
1536 (setq keep-going t))
1538 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1539 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1541 ;; it is wrong to do the same thing for the -else-pop variants.
1543 ((and (or (eq 'byte-goto-if-nil (car lap0))
1544 (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX
1545 (eq 'byte-goto (car lap1)) ; gotoY
1546 (eq (cdr lap0) lap2)) ; TAG X
1547 (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
1548 'byte-goto-if-not-nil 'byte-goto-if-nil)))
1549 (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
1551 (cons inverse (cdr lap1)) lap2)
1552 (setq lap (delq lap0 lap))
1553 (setcar lap1 inverse)
1554 (setq keep-going t)))
1556 ;; const goto-if-* --> whatever
1558 ((and (eq 'byte-constant (car lap0))
1559 (memq (car lap1) byte-conditional-ops))
1560 (cond ((if (or (eq (car lap1) 'byte-goto-if-nil)
1561 (eq (car lap1) 'byte-goto-if-nil-else-pop))
1563 (not (car (cdr lap0))))
1564 (byte-compile-log-lap " %s %s\t-->\t<deleted>"
1566 (setq rest (cdr rest)
1567 lap (delq lap0 (delq lap1 lap))))
1569 (if (memq (car lap1) byte-goto-always-pop-ops)
1571 (byte-compile-log-lap " %s %s\t-->\t%s"
1572 lap0 lap1 (cons 'byte-goto (cdr lap1)))
1573 (setq lap (delq lap0 lap)))
1574 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1575 (cons 'byte-goto (cdr lap1))))
1576 (setcar lap1 'byte-goto)))
1577 (setq keep-going t))
1579 ;; varref-X varref-X --> varref-X dup
1580 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1581 ;; We don't optimize the const-X variations on this here,
1582 ;; because that would inhibit some goto optimizations; we
1583 ;; optimize the const-X case after all other optimizations.
1585 ((and (eq 'byte-varref (car lap0))
1587 (setq tmp (cdr rest))
1588 (while (eq (car (car tmp)) 'byte-dup)
1589 (setq tmp (cdr tmp)))
1591 (eq (cdr lap0) (cdr (car tmp)))
1592 (eq 'byte-varref (car (car tmp))))
1593 (if (memq byte-optimize-log '(t byte))
1595 (setq tmp2 (cdr rest))
1596 (while (not (eq tmp tmp2))
1597 (setq tmp2 (cdr tmp2)
1598 str (concat str " dup")))
1599 (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
1600 lap0 str lap0 lap0 str)))
1602 (setcar (car tmp) 'byte-dup)
1603 (setcdr (car tmp) 0)
1606 ;; TAG1: TAG2: --> TAG1: <deleted>
1607 ;; (and other references to TAG2 are replaced with TAG1)
1609 ((and (eq (car lap0) 'TAG)
1610 (eq (car lap1) 'TAG))
1611 (and (memq byte-optimize-log '(t byte))
1612 (byte-compile-log " adjacent tags %d and %d merged"
1613 (nth 1 lap1) (nth 1 lap0)))
1615 (while (setq tmp2 (rassq lap0 tmp3))
1617 (setq tmp3 (cdr (memq tmp2 tmp3))))
1618 (setq lap (delq lap0 lap)
1621 ;; unused-TAG: --> <deleted>
1623 ((and (eq 'TAG (car lap0))
1624 (not (rassq lap0 lap)))
1625 (and (memq byte-optimize-log '(t byte))
1626 (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
1627 (setq lap (delq lap0 lap)
1630 ;; goto ... --> goto <delete until TAG or end>
1631 ;; return ... --> return <delete until TAG or end>
1633 ((and (memq (car lap0) '(byte-goto byte-return))
1634 (not (memq (car lap1) '(TAG nil))))
1637 (opt-p (memq byte-optimize-log '(t lap)))
1639 (while (and (setq tmp (cdr tmp))
1640 (not (eq 'TAG (car (car tmp)))))
1641 (if opt-p (setq deleted (cons (car tmp) deleted)
1642 str (concat str " %s")
1646 (if (eq 'TAG (car (car tmp)))
1647 (format "%d:" (car (cdr (car tmp))))
1648 (or (car tmp) ""))))
1650 (apply 'byte-compile-log-lap-1
1652 " %s\t-->\t%s <deleted> %s")
1654 (nconc (nreverse deleted)
1655 (list tagstr lap0 tagstr)))
1656 (byte-compile-log-lap
1657 " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
1658 lap0 i (if (= i 1) "" "s")
1659 tagstr lap0 tagstr))))
1661 (setq keep-going t))
1663 ;; <safe-op> unbind --> unbind <safe-op>
1664 ;; (this may enable other optimizations.)
1666 ((and (eq 'byte-unbind (car lap1))
1667 (memq (car lap0) byte-after-unbind-ops))
1668 (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
1670 (setcar (cdr rest) lap0)
1671 (setq keep-going t))
1673 ;; varbind-X unbind-N --> discard unbind-(N-1)
1674 ;; save-excursion unbind-N --> unbind-(N-1)
1675 ;; save-restriction unbind-N --> unbind-(N-1)
1677 ((and (eq 'byte-unbind (car lap1))
1678 (memq (car lap0) '(byte-varbind byte-save-excursion
1679 byte-save-restriction))
1681 (if (zerop (setcdr lap1 (1- (cdr lap1))))
1683 (if (eq (car lap0) 'byte-varbind)
1684 (setcar rest (cons 'byte-discard 0))
1685 (setq lap (delq lap0 lap)))
1686 (byte-compile-log-lap " %s %s\t-->\t%s %s"
1687 lap0 (cons (car lap1) (1+ (cdr lap1)))
1688 (if (eq (car lap0) 'byte-varbind)
1691 (if (and (/= 0 (cdr lap1))
1692 (eq (car lap0) 'byte-varbind))
1695 (setq keep-going t))
1697 ;; goto*-X ... X: goto-Y --> goto*-Y
1698 ;; goto-X ... X: return --> return
1700 ((and (memq (car lap0) byte-goto-ops)
1701 (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
1702 '(byte-goto byte-return)))
1703 (cond ((and (not (eq tmp lap0))
1704 (or (eq (car lap0) 'byte-goto)
1705 (eq (car tmp) 'byte-goto)))
1706 (byte-compile-log-lap " %s [%s]\t-->\t%s"
1708 (if (eq (car tmp) 'byte-return)
1709 (setcar lap0 'byte-return))
1710 (setcdr lap0 (cdr tmp))
1711 (setq keep-going t))))
1713 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1714 ;; goto-*-else-pop X ... X: discard --> whatever
1716 ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
1717 byte-goto-if-not-nil-else-pop))
1718 (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
1720 (cons 'byte-discard byte-conditional-ops)))
1721 (not (eq lap0 (car tmp))))
1722 (setq tmp2 (car tmp))
1723 (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
1725 (byte-goto-if-not-nil-else-pop
1726 byte-goto-if-not-nil))))
1727 (if (memq (car tmp2) tmp3)
1728 (progn (setcar lap0 (car tmp2))
1729 (setcdr lap0 (cdr tmp2))
1730 (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
1731 (car lap0) tmp2 lap0))
1732 ;; Get rid of the -else-pop's and jump one step further.
1733 (or (eq 'TAG (car (nth 1 tmp)))
1734 (setcdr tmp (cons (byte-compile-make-tag)
1736 (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
1737 (car lap0) tmp2 (nth 1 tmp3))
1738 (setcar lap0 (nth 1 tmp3))
1739 (setcdr lap0 (nth 1 tmp)))
1740 (setq keep-going t))
1742 ;; const goto-X ... X: goto-if-* --> whatever
1743 ;; const goto-X ... X: discard --> whatever
1745 ((and (eq (car lap0) 'byte-constant)
1746 (eq (car lap1) 'byte-goto)
1747 (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
1749 (cons 'byte-discard byte-conditional-ops)))
1750 (not (eq lap1 (car tmp))))
1751 (setq tmp2 (car tmp))
1752 (cond ((memq (car tmp2)
1753 (if (null (car (cdr lap0)))
1754 '(byte-goto-if-nil byte-goto-if-nil-else-pop)
1755 '(byte-goto-if-not-nil
1756 byte-goto-if-not-nil-else-pop)))
1757 (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
1758 lap0 tmp2 lap0 tmp2)
1759 (setcar lap1 (car tmp2))
1760 (setcdr lap1 (cdr tmp2))
1761 ;; Let next step fix the (const,goto-if*) sequence.
1762 (setq rest (cons nil rest)))
1764 ;; Jump one step further
1765 (byte-compile-log-lap
1766 " %s goto [%s]\t-->\t<deleted> goto <skip>"
1768 (or (eq 'TAG (car (nth 1 tmp)))
1769 (setcdr tmp (cons (byte-compile-make-tag)
1771 (setcdr lap1 (car (cdr tmp)))
1772 (setq lap (delq lap0 lap))))
1773 (setq keep-going t))
1775 ;; X: varref-Y ... varset-Y goto-X -->
1776 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1777 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1778 ;; (This is so usual for while loops that it is worth handling).
1780 ((and (eq (car lap1) 'byte-varset)
1781 (eq (car lap2) 'byte-goto)
1782 (not (memq (cdr lap2) rest)) ;Backwards jump
1783 (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
1785 (eq (cdr (car tmp)) (cdr lap1))
1786 (not (memq (car (cdr lap1)) byte-boolean-vars)))
1787 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1788 (let ((newtag (byte-compile-make-tag)))
1789 (byte-compile-log-lap
1790 " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
1791 (nth 1 (cdr lap2)) (car tmp)
1793 (nth 1 (cdr lap2)) (car tmp)
1794 (nth 1 newtag) 'byte-dup lap1
1795 (cons 'byte-goto newtag)
1797 (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
1798 (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
1800 (setq keep-going t))
1802 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1803 ;; (This can pull the loop test to the end of the loop)
1805 ((and (eq (car lap0) 'byte-goto)
1806 (eq (car lap1) 'TAG)
1808 (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
1809 (memq (car (car tmp))
1810 '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
1811 byte-goto-if-nil-else-pop)))
1812 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1813 ;; lap0 lap1 (cdr lap0) (car tmp))
1814 (let ((newtag (byte-compile-make-tag)))
1815 (byte-compile-log-lap
1816 "%s %s: ... %s: %s\t-->\t%s ... %s:"
1817 lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
1818 (cons (cdr (assq (car (car tmp))
1819 '((byte-goto-if-nil . byte-goto-if-not-nil)
1820 (byte-goto-if-not-nil . byte-goto-if-nil)
1821 (byte-goto-if-nil-else-pop .
1822 byte-goto-if-not-nil-else-pop)
1823 (byte-goto-if-not-nil-else-pop .
1824 byte-goto-if-nil-else-pop))))
1829 (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
1830 (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
1831 ;; We can handle this case but not the -if-not-nil case,
1832 ;; because we won't know which non-nil constant to push.
1833 (setcdr rest (cons (cons 'byte-constant
1834 (byte-compile-get-constant nil))
1836 (setcar lap0 (nth 1 (memq (car (car tmp))
1837 '(byte-goto-if-nil-else-pop
1838 byte-goto-if-not-nil
1840 byte-goto-if-not-nil
1841 byte-goto byte-goto))))
1843 (setq keep-going t))
1845 (setq rest (cdr rest)))
1848 ;; Rebuild byte-compile-constants / byte-compile-variables.
1849 ;; Simple optimizations that would inhibit other optimizations if they
1850 ;; were done in the optimizing loop, and optimizations which there is no
1851 ;; need to do more than once.
1852 (setq byte-compile-constants nil
1853 byte-compile-variables nil)
1856 (setq lap0 (car rest)
1858 (if (memq (car lap0) byte-constref-ops)
1859 (if (not (eq (car lap0) 'byte-constant))
1860 (or (memq (cdr lap0) byte-compile-variables)
1861 (setq byte-compile-variables (cons (cdr lap0)
1862 byte-compile-variables)))
1863 (or (memq (cdr lap0) byte-compile-constants)
1864 (setq byte-compile-constants (cons (cdr lap0)
1865 byte-compile-constants)))))
1867 ;; const-C varset-X const-C --> const-C dup varset-X
1868 ;; const-C varbind-X const-C --> const-C dup varbind-X
1870 (and (eq (car lap0) 'byte-constant)
1871 (eq (car (nth 2 rest)) 'byte-constant)
1872 (eq (cdr lap0) (car (nth 2 rest)))
1873 (memq (car lap1) '(byte-varbind byte-varset)))
1874 (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
1875 lap0 lap1 lap0 lap0 lap1)
1876 (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
1877 (setcar (cdr rest) (cons 'byte-dup 0))
1880 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1881 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1883 ((memq (car lap0) '(byte-constant byte-varref))
1887 (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
1888 (and (eq (cdr lap0) (cdr (car tmp)))
1889 (eq (car lap0) (car (car tmp)))))
1890 (setcar tmp (cons 'byte-dup 0))
1893 (byte-compile-log-lap
1894 " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
1896 ;; unbind-N unbind-M --> unbind-(N+M)
1898 ((and (eq 'byte-unbind (car lap0))
1899 (eq 'byte-unbind (car lap1)))
1900 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1902 (+ (cdr lap0) (cdr lap1))))
1904 (setq lap (delq lap0 lap))
1905 (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
1907 (setq rest (cdr rest)))
1908 (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
1914 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
1915 ;; itself, compile some of its most used recursive functions (at load time).
1918 (or (byte-code-function-p (symbol-function 'byte-optimize-form))
1919 (assq 'byte-code (symbol-function 'byte-optimize-form))
1920 (let ((byte-optimize nil)
1921 (byte-compile-warnings nil))
1922 (mapcar '(lambda (x)
1923 (or noninteractive (message "compiling %s..." x))
1925 (or noninteractive (message "compiling %s...done" x)))
1926 '(byte-optimize-form
1928 byte-optimize-predicate
1929 byte-optimize-binary-predicate
1930 ;; Inserted some more than necessary, to speed it up.
1931 byte-optimize-form-code-walker
1932 byte-optimize-lapcode))))
1935 ;;; byte-opt.el ends here