1 ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler
3 ;;; Copyright (c) 1991, 1994, 2000, 2001 Free Software Foundation, Inc.
5 ;; Author: Jamie Zawinski <jwz@lucid.com>
6 ;; Hallvard Furuseth <hbf@ulrik.uio.no>
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software; you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation; either version 2, or (at your option)
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
25 ;; Boston, MA 02111-1307, USA.
29 ;; ========================================================================
30 ;; "No matter how hard you try, you can't make a racehorse out of a pig.
31 ;; You can, however, make a faster pig."
33 ;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code
34 ;; makes it be a VW Bug with fuel injection and a turbocharger... You're
35 ;; still not going to make it go faster than 70 mph, but it might be easier
41 ;; (apply (lambda (x &rest y) ...) 1 (foo))
43 ;; maintain a list of functions known not to access any global variables
44 ;; (actually, give them a 'dynamically-safe property) and then
45 ;; (let ( v1 v2 ... vM vN ) <...dynamically-safe...> ) ==>
46 ;; (let ( v1 v2 ... vM ) vN <...dynamically-safe...> )
47 ;; by recursing on this, we might be able to eliminate the entire let.
48 ;; However certain variables should never have their bindings optimized
49 ;; away, because they affect everything.
50 ;; (put 'debug-on-error 'binding-is-magic t)
51 ;; (put 'debug-on-abort 'binding-is-magic t)
52 ;; (put 'debug-on-next-call '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"
266 (when (and (consp fn) (eq (car fn) 'autoload))
268 (setq fn (or (and (fboundp name) (symbol-function name))
269 (cdr (assq name byte-compile-function-environment)))))
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))
343 ;; The following leads to infinite recursion when loading a
344 ;; file containing `(defsubst f () (f))', and then trying to
345 ;; byte-compile that file.
346 ;(setq body (mapcar 'byte-optimize-form body)))
350 (cons 'let (cons (nreverse bindings) body))
351 (cons 'progn body))))
352 (byte-compile-log " %s\t==>\t%s" form newform)
356 ;;; implementing source-level optimizers
358 (defun byte-optimize-form-code-walker (form for-effect)
360 ;; For normal function calls, We can just mapcar the optimizer the cdr. But
361 ;; we need to have special knowledge of the syntax of the special forms
362 ;; like let and defun (that's why they're special forms :-). (Actually,
363 ;; the important aspect is that they are subrs that don't evaluate all of
366 (let ((fn (car-safe form))
368 (cond ((not (consp form))
369 (if (not (and for-effect
370 (or byte-compile-delete-errors
376 (byte-compile-warn "malformed quote form: `%s'"
377 (prin1-to-string form)))
378 ;; map (quote nil) to nil to simplify optimizer logic.
379 ;; map quoted constants to nil if for-effect (just because).
383 ((or (byte-code-function-p fn)
384 (eq 'lambda (car-safe fn)))
385 (byte-compile-unfold-lambda form))
386 ((memq fn '(let let*))
387 ;; recursively enter the optimizer for the bindings and body
388 ;; of a let or let*. This for depth-firstness: forms that
389 ;; are more deeply nested are optimized first.
392 (mapcar (lambda (binding)
393 (if (symbolp binding)
395 (if (cdr (cdr binding))
396 (byte-compile-warn "malformed let binding: `%s'"
397 (prin1-to-string binding)))
399 (byte-optimize-form (nth 1 binding) nil))))
401 (byte-optimize-body (cdr (cdr form)) for-effect))))
404 (mapcar (lambda (clause)
407 (byte-optimize-form (car clause) nil)
408 (byte-optimize-body (cdr clause) for-effect))
409 (byte-compile-warn "malformed cond form: `%s'"
410 (prin1-to-string clause))
414 ;; as an extra added bonus, this simplifies (progn <x>) --> <x>
417 (setq tmp (byte-optimize-body (cdr form) for-effect))
418 (if (cdr tmp) (cons 'progn tmp) (car tmp)))
419 (byte-optimize-form (nth 1 form) for-effect)))
423 (cons (byte-optimize-form (nth 1 form) for-effect)
424 (byte-optimize-body (cdr (cdr form)) t)))
425 (byte-optimize-form (nth 1 form) for-effect)))
428 (cons (byte-optimize-form (nth 1 form) t)
429 (cons (byte-optimize-form (nth 2 form) for-effect)
430 (byte-optimize-body (cdr (cdr (cdr form))) t)))))
432 ((memq fn '(save-excursion save-restriction save-current-buffer))
433 ;; those subrs which have an implicit progn; it's not quite good
434 ;; enough to treat these like normal function calls.
435 ;; This can turn (save-excursion ...) into (save-excursion) which
436 ;; will be optimized away in the lap-optimize pass.
437 (cons fn (byte-optimize-body (cdr form) for-effect)))
439 ((eq fn 'with-output-to-temp-buffer)
440 ;; this is just like the above, except for the first argument.
443 (byte-optimize-form (nth 1 form) nil)
444 (byte-optimize-body (cdr (cdr form)) for-effect))))
447 (when (< (length form) 3)
448 (byte-compile-warn "too few arguments for `if'"))
450 (cons (byte-optimize-form (nth 1 form) nil)
452 (byte-optimize-form (nth 2 form) for-effect)
453 (byte-optimize-body (nthcdr 3 form) for-effect)))))
455 ((memq fn '(and or)) ; remember, and/or are control structures.
456 ;; take forms off the back until we can't any more.
457 ;; In the future it could conceivably be a problem that the
458 ;; subexpressions of these forms are optimized in the reverse
459 ;; order, but it's ok for now.
461 (let ((backwards (reverse (cdr form))))
462 (while (and backwards
463 (null (setcar backwards
464 (byte-optimize-form (car backwards)
466 (setq backwards (cdr backwards)))
467 (if (and (cdr form) (null backwards))
469 " all subforms of %s called for effect; deleted" form))
471 (cons fn (nreverse backwards))))
472 (cons fn (mapcar 'byte-optimize-form (cdr form)))))
474 ((eq fn 'interactive)
475 (byte-compile-warn "misplaced interactive spec: `%s'"
476 (prin1-to-string form))
479 ((memq fn '(defun defmacro function
480 condition-case save-window-excursion))
481 ;; These forms are compiled as constants or by breaking out
482 ;; all the subexpressions and compiling them separately.
485 ((eq fn 'unwind-protect)
486 ;; the "protected" part of an unwind-protect is compiled (and thus
487 ;; optimized) as a top-level form, so don't do it here. But the
488 ;; non-protected part has the same for-effect status as the
489 ;; unwind-protect itself. (The protected part is always for effect,
490 ;; but that isn't handled properly yet.)
492 (cons (byte-optimize-form (nth 1 form) for-effect)
496 ;; the body of a catch is compiled (and thus optimized) as a
497 ;; top-level form, so don't do it here. The tag is never
498 ;; for-effect. The body should have the same for-effect status
499 ;; as the catch form itself, but that isn't handled properly yet.
501 (cons (byte-optimize-form (nth 1 form) nil)
504 ;; If optimization is on, this is the only place that macros are
505 ;; expanded. If optimization is off, then macroexpansion happens
506 ;; in byte-compile-form. Otherwise, the macros are already expanded
507 ;; by the time that is reached.
509 (setq form (macroexpand form
510 byte-compile-macro-environment))))
511 (byte-optimize-form form for-effect))
513 ;; Support compiler macros as in cl.el.
514 ((and (fboundp 'compiler-macroexpand)
515 (symbolp (car-safe form))
516 (get (car-safe form) 'cl-compiler-macro)
518 (setq form (compiler-macroexpand form)))))
519 (byte-optimize-form form for-effect))
522 (byte-compile-warn "`%s' is a malformed function"
523 (prin1-to-string fn))
526 ((and for-effect (setq tmp (get fn 'side-effect-free))
527 (or byte-compile-delete-errors
530 (byte-compile-warn "`%s' called for effect"
531 (prin1-to-string form))
533 (byte-compile-log " %s called for effect; deleted" fn)
534 ;; appending a nil here might not be necessary, but it can't hurt.
536 (cons 'progn (append (cdr form) '(nil))) t))
539 ;; Otherwise, no args can be considered to be for-effect,
540 ;; even if the called function is for-effect, because we
541 ;; don't know anything about that function.
542 (cons fn (mapcar 'byte-optimize-form (cdr form)))))))
545 (defun byte-optimize-form (form &optional for-effect)
546 "The source-level pass of the optimizer."
548 ;; First, optimize all sub-forms of this one.
549 (setq form (byte-optimize-form-code-walker form for-effect))
551 ;; after optimizing all subforms, optimize this form until it doesn't
552 ;; optimize any further. This means that some forms will be passed through
553 ;; the optimizer many times, but that's necessary to make the for-effect
554 ;; processing do as much as possible.
557 (if (and (consp form)
560 ;; we don't have any of these yet, but we might.
561 (setq opt (get (car form) 'byte-for-effect-optimizer)))
562 (setq opt (get (car form) 'byte-optimizer)))
563 (not (eq form (setq new (funcall opt form)))))
565 ;; (if (equal form new) (error "bogus optimizer -- %s" opt))
566 (byte-compile-log " %s\t==>\t%s" form new)
567 (setq new (byte-optimize-form new for-effect))
572 (defun byte-optimize-body (forms all-for-effect)
573 ;; optimize the cdr of a progn or implicit progn; all forms is a list of
574 ;; forms, all but the last of which are optimized with the assumption that
575 ;; they are being called for effect. the last is for-effect as well if
576 ;; all-for-effect is true. returns a new list of forms.
581 (setq fe (or all-for-effect (cdr rest)))
582 (setq new (and (car rest) (byte-optimize-form (car rest) fe)))
583 (if (or new (not fe))
584 (setq result (cons new result)))
585 (setq rest (cdr rest)))
589 ;;; some source-level optimizers
591 ;;; when writing optimizers, be VERY careful that the optimizer returns
592 ;;; something not EQ to its argument if and ONLY if it has made a change.
593 ;;; This implies that you cannot simply destructively modify the list;
594 ;;; you must return something not EQ to it if you make an optimization.
596 ;;; It is now safe to optimize code such that it introduces new bindings.
598 ;; I'd like this to be a defsubst, but let's not be self-referential...
599 (defmacro byte-compile-trueconstp (form)
600 ;; Returns non-nil if FORM is a non-nil constant.
601 `(cond ((consp ,form) (eq (car ,form) 'quote))
602 ((not (symbolp ,form)))
606 ;; If the function is being called with constant numeric args,
607 ;; evaluate as much as possible at compile-time. This optimizer
608 ;; assumes that the function is associative, like + or *.
609 (defun byte-optimize-associative-math (form)
614 (if (numberp (car rest))
615 (setq constants (cons (car rest) constants))
616 (setq args (cons (car rest) args)))
617 (setq rest (cdr rest)))
621 (apply (car form) constants)
623 (cons (car form) (nreverse args))
625 (apply (car form) constants))
628 ;; If the function is being called with constant numeric args,
629 ;; evaluate as much as possible at compile-time. This optimizer
630 ;; assumes that the function satisfies
631 ;; (op x1 x2 ... xn) == (op ...(op (op x1 x2) x3) ...xn)
633 (defun byte-optimize-nonassociative-math (form)
634 (if (or (not (numberp (car (cdr form))))
635 (not (numberp (car (cdr (cdr form))))))
637 (let ((constant (car (cdr form)))
638 (rest (cdr (cdr form))))
639 (while (numberp (car rest))
640 (setq constant (funcall (car form) constant (car rest))
643 (cons (car form) (cons constant rest))
646 ;;(defun byte-optimize-associative-two-args-math (form)
647 ;; (setq form (byte-optimize-associative-math form))
649 ;; (byte-optimize-two-args-left form)
652 ;;(defun byte-optimize-nonassociative-two-args-math (form)
653 ;; (setq form (byte-optimize-nonassociative-math form))
655 ;; (byte-optimize-two-args-right form)
658 (defun byte-optimize-approx-equal (x y)
659 (<= (* (abs (- x y)) 100) (abs (+ x y))))
661 ;; Collect all the constants from FORM, after the STARTth arg,
662 ;; and apply FUN to them to make one argument at the end.
663 ;; For functions that can handle floats, that optimization
664 ;; can be incorrect because reordering can cause an overflow
665 ;; that would otherwise be avoided by encountering an arg that is a float.
666 ;; We avoid this problem by (1) not moving float constants and
667 ;; (2) not moving anything if it would cause an overflow.
668 (defun byte-optimize-delay-constants-math (form start fun)
669 ;; Merge all FORM's constants from number START, call FUN on them
670 ;; and put the result at the end.
671 (let ((rest (nthcdr (1- start) form))
673 ;; t means we must check for overflow.
674 (overflow (memq fun '(+ *))))
675 (while (cdr (setq rest (cdr rest)))
676 (if (integerp (car rest))
678 (setq form (copy-sequence form)
679 rest (nthcdr (1- start) form))
680 (while (setq rest (cdr rest))
681 (cond ((integerp (car rest))
682 (setq constants (cons (car rest) constants))
684 ;; If necessary, check now for overflow
685 ;; that might be caused by reordering.
687 ;; We have overflow if the result of doing the arithmetic
688 ;; on floats is not even close to the result
689 ;; of doing it on integers.
690 (not (byte-optimize-approx-equal
691 (apply fun (mapcar 'float constants))
692 (float (apply fun constants)))))
694 (setq form (nconc (delq nil form)
695 (list (apply fun (nreverse constants)))))))))
698 (defun byte-optimize-plus (form)
699 (setq form (byte-optimize-delay-constants-math form 1 '+))
700 (if (memq 0 form) (setq form (delq 0 (copy-sequence form))))
701 ;;(setq form (byte-optimize-associative-two-args-math form))
702 (cond ((null (cdr form))
706 ;;; It is not safe to delete the function entirely
707 ;;; (actually, it would be safe if we know the sole arg
708 ;;; is not a marker).
709 ;; ((null (cdr (cdr form))) (nth 1 form))
711 (if (numberp (nth 1 form))
714 ((and (null (nthcdr 3 form))
715 (or (memq (nth 1 form) '(1 -1))
716 (memq (nth 2 form) '(1 -1))))
717 ;; Optimize (+ x 1) into (1+ x) and (+ x -1) into (1- x).
719 (if (memq (nth 1 form) '(1 -1))
723 (if (memq (nth 1 form) '(1 -1))
726 (list (if (eq integer 1) '1+ '1-)
730 (defun byte-optimize-minus (form)
731 ;; Put constants at the end, except the last constant.
732 (setq form (byte-optimize-delay-constants-math form 2 '+))
733 ;; Now only first and last element can be a number.
734 (let ((last (car (reverse (nthcdr 3 form)))))
736 ;; (- x y ... 0) --> (- x y ...)
737 (setq form (copy-sequence form))
738 (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form))))
739 ((equal (nthcdr 2 form) '(1))
740 (setq form (list '1- (nth 1 form))))
741 ((equal (nthcdr 2 form) '(-1))
742 (setq form (list '1+ (nth 1 form))))
743 ;; If form is (- CONST foo... CONST), merge first and last.
744 ((and (numberp (nth 1 form))
746 (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
747 (delq last (copy-sequence (nthcdr 3 form))))))))
748 ;;; It is not safe to delete the function entirely
749 ;;; (actually, it would be safe if we know the sole arg
750 ;;; is not a marker).
751 ;;; (if (eq (nth 2 form) 0)
752 ;;; (nth 1 form) ; (- x 0) --> x
753 (byte-optimize-predicate
754 (if (and (null (cdr (cdr (cdr form))))
755 (eq (nth 1 form) 0)) ; (- 0 x) --> (- x)
756 (cons (car form) (cdr (cdr form)))
761 (defun byte-optimize-multiply (form)
762 (setq form (byte-optimize-delay-constants-math form 1 '*))
763 ;; If there is a constant in FORM, it is now the last element.
764 (cond ((null (cdr form)) 1)
765 ;;; It is not safe to delete the function entirely
766 ;;; (actually, it would be safe if we know the sole arg
767 ;;; is not a marker or if it appears in other arithmetic).
768 ;;; ((null (cdr (cdr form))) (nth 1 form))
769 ((let ((last (car (reverse form))))
770 (cond ((eq 0 last) (cons 'progn (cdr form)))
771 ((eq 1 last) (delq 1 (copy-sequence form)))
772 ((eq -1 last) (list '- (delq -1 (copy-sequence form))))
774 (memq t (mapcar 'symbolp (cdr form))))
775 (prog1 (setq form (delq 2 (copy-sequence form)))
776 (while (not (symbolp (car (setq form (cdr form))))))
777 (setcar form (list '+ (car form) (car form)))))
780 (defsubst byte-compile-butlast (form)
781 (nreverse (cdr (reverse form))))
783 (defun byte-optimize-divide (form)
784 (setq form (byte-optimize-delay-constants-math form 2 '*))
785 (let ((last (car (reverse (cdr (cdr form))))))
787 (cond ((= (length form) 3)
788 (if (and (numberp (nth 1 form))
791 (/ (nth 1 form) last)
793 (setq form (list 'progn (/ (nth 1 form) last)))))
795 (setq form (byte-compile-butlast form)))
796 ((numberp (nth 1 form))
797 (setq form (cons (car form)
798 (cons (/ (nth 1 form) last)
799 (byte-compile-butlast (cdr (cdr form)))))
802 ;;; ((null (cdr (cdr form)))
805 (append '(progn) (cdr (cdr form)) '(0)))
807 (list '- (if (nthcdr 3 form)
808 (byte-compile-butlast form)
812 (defun byte-optimize-logmumble (form)
813 (setq form (byte-optimize-delay-constants-math form 1 (car form)))
814 (byte-optimize-predicate
816 (setq form (if (eq (car form) 'logand)
817 (cons 'progn (cdr form))
818 (delq 0 (copy-sequence form)))))
819 ((and (eq (car-safe form) 'logior)
821 (cons 'progn (cdr form)))
825 (defun byte-optimize-binary-predicate (form)
826 (if (byte-compile-constp (nth 1 form))
827 (if (byte-compile-constp (nth 2 form))
829 (list 'quote (eval form))
831 ;; This can enable some lapcode optimizations.
832 (list (car form) (nth 2 form) (nth 1 form)))
835 (defun byte-optimize-predicate (form)
839 (setq ok (byte-compile-constp (car rest))
843 (list 'quote (eval form))
847 (defun byte-optimize-identity (form)
848 (if (and (cdr form) (null (cdr (cdr form))))
850 (byte-compile-warn "identity called with %d arg%s, but requires 1"
852 (if (= 1 (length (cdr form))) "" "s"))
855 (put 'identity 'byte-optimizer 'byte-optimize-identity)
857 (put '+ 'byte-optimizer 'byte-optimize-plus)
858 (put '* 'byte-optimizer 'byte-optimize-multiply)
859 (put '- 'byte-optimizer 'byte-optimize-minus)
860 (put '/ 'byte-optimizer 'byte-optimize-divide)
861 (put 'max 'byte-optimizer 'byte-optimize-associative-math)
862 (put 'min 'byte-optimizer 'byte-optimize-associative-math)
864 (put '= 'byte-optimizer 'byte-optimize-binary-predicate)
865 (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate)
866 (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate)
867 (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
868 (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)
870 (put '< 'byte-optimizer 'byte-optimize-predicate)
871 (put '> 'byte-optimizer 'byte-optimize-predicate)
872 (put '<= 'byte-optimizer 'byte-optimize-predicate)
873 (put '>= 'byte-optimizer 'byte-optimize-predicate)
874 (put '1+ 'byte-optimizer 'byte-optimize-predicate)
875 (put '1- 'byte-optimizer 'byte-optimize-predicate)
876 (put 'not 'byte-optimizer 'byte-optimize-predicate)
877 (put 'null 'byte-optimizer 'byte-optimize-predicate)
878 (put 'memq 'byte-optimizer 'byte-optimize-predicate)
879 (put 'consp 'byte-optimizer 'byte-optimize-predicate)
880 (put 'listp 'byte-optimizer 'byte-optimize-predicate)
881 (put 'symbolp 'byte-optimizer 'byte-optimize-predicate)
882 (put 'stringp 'byte-optimizer 'byte-optimize-predicate)
883 (put 'string< 'byte-optimizer 'byte-optimize-predicate)
884 (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate)
886 (put 'logand 'byte-optimizer 'byte-optimize-logmumble)
887 (put 'logior 'byte-optimizer 'byte-optimize-logmumble)
888 (put 'logxor 'byte-optimizer 'byte-optimize-logmumble)
889 (put 'lognot 'byte-optimizer 'byte-optimize-predicate)
891 (put 'car 'byte-optimizer 'byte-optimize-predicate)
892 (put 'cdr 'byte-optimizer 'byte-optimize-predicate)
893 (put 'car-safe 'byte-optimizer 'byte-optimize-predicate)
894 (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate)
897 ;; I'm not convinced that this is necessary. Doesn't the optimizer loop
898 ;; take care of this? - Jamie
899 ;; I think this may some times be necessary to reduce ie (quote 5) to 5,
900 ;; so arithmetic optimizers recognize the numeric constant. - Hallvard
901 (put 'quote 'byte-optimizer 'byte-optimize-quote)
902 (defun byte-optimize-quote (form)
903 (if (or (consp (nth 1 form))
904 (and (symbolp (nth 1 form))
905 (not (byte-compile-const-symbol-p form))))
909 (defun byte-optimize-zerop (form)
910 (cond ((numberp (nth 1 form))
912 (byte-compile-delete-errors
913 (list '= (nth 1 form) 0))
916 (put 'zerop 'byte-optimizer 'byte-optimize-zerop)
918 (defun byte-optimize-and (form)
919 ;; Simplify if less than 2 args.
920 ;; if there is a literal nil in the args to `and', throw it and following
921 ;; forms away, and surround the `and' with (progn ... nil).
922 (cond ((null (cdr form)))
926 (prog1 (setq form (copy-sequence form))
928 (setq form (cdr form)))
931 ((null (cdr (cdr form)))
933 ((byte-optimize-predicate form))))
935 (defun byte-optimize-or (form)
936 ;; Throw away nil's, and simplify if less than 2 args.
937 ;; If there is a literal non-nil constant in the args to `or', throw away all
940 (setq form (delq nil (copy-sequence form))))
942 (while (cdr (setq rest (cdr rest)))
943 (if (byte-compile-trueconstp (car rest))
944 (setq form (copy-sequence form)
945 rest (setcdr (memq (car rest) form) nil))))
947 (byte-optimize-predicate form)
950 (defun byte-optimize-cond (form)
951 ;; if any clauses have a literal nil as their test, throw them away.
952 ;; if any clause has a literal non-nil constant as its test, throw
953 ;; away all following clauses.
955 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...)
956 (while (setq rest (assq nil (cdr form)))
957 (setq form (delq rest (copy-sequence form))))
958 (if (memq nil (cdr form))
959 (setq form (delq nil (copy-sequence form))))
961 (while (setq rest (cdr rest))
962 (cond ((byte-compile-trueconstp (car-safe (car rest)))
963 (cond ((eq rest (cdr form))
966 (if (cdr (cdr (car rest)))
967 (cons 'progn (cdr (car rest)))
971 (setq form (copy-sequence form))
972 (setcdr (memq (car rest) form) nil)))
975 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... ))
976 (if (eq 'cond (car-safe form))
977 (let ((clauses (cdr form)))
978 (if (and (consp (car clauses))
979 (null (cdr (car clauses))))
980 (list 'or (car (car clauses))
982 (cons (car form) (cdr (cdr form)))))
986 (defun byte-optimize-if (form)
987 ;; (if <true-constant> <then> <else...>) ==> <then>
988 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>)
989 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>))
990 ;; (if <test> <then> nil) ==> (if <test> <then>)
991 (let ((clause (nth 1 form)))
992 (cond ((byte-compile-trueconstp clause)
996 (cons 'progn (nthcdr 3 form))
999 (if (equal '(nil) (nthcdr 3 form))
1000 (list 'if clause (nth 2 form))
1002 ((or (nth 3 form) (nthcdr 4 form))
1004 ;; Don't make a double negative;
1005 ;; instead, take away the one that is there.
1006 (if (and (consp clause) (memq (car clause) '(not null))
1007 (= (length clause) 2)) ; (not xxxx) or (not (xxxx))
1011 (cons 'progn (nthcdr 3 form))
1014 (list 'progn clause nil)))))
1016 (defun byte-optimize-while (form)
1017 (when (< (length form) 2)
1018 (byte-compile-warn "too few arguments for `while'"))
1022 (put 'and 'byte-optimizer 'byte-optimize-and)
1023 (put 'or 'byte-optimizer 'byte-optimize-or)
1024 (put 'cond 'byte-optimizer 'byte-optimize-cond)
1025 (put 'if 'byte-optimizer 'byte-optimize-if)
1026 (put 'while 'byte-optimizer 'byte-optimize-while)
1028 ;; byte-compile-negation-optimizer lives in bytecomp.el
1029 (put '/= 'byte-optimizer 'byte-compile-negation-optimizer)
1030 (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer)
1031 (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer)
1034 (defun byte-optimize-funcall (form)
1035 ;; (funcall (lambda ...) ...) ==> ((lambda ...) ...)
1036 ;; (funcall foo ...) ==> (foo ...)
1037 (let ((fn (nth 1 form)))
1038 (if (memq (car-safe fn) '(quote function))
1039 (cons (nth 1 fn) (cdr (cdr form)))
1042 (defun byte-optimize-apply (form)
1043 ;; If the last arg is a literal constant, turn this into a funcall.
1044 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...).
1045 (let ((fn (nth 1 form))
1046 (last (nth (1- (length form)) form))) ; I think this really is fastest
1047 (or (if (or (null last)
1048 (eq (car-safe last) 'quote))
1049 (if (listp (nth 1 last))
1050 (let ((butlast (nreverse (cdr (reverse (cdr (cdr form)))))))
1051 (nconc (list 'funcall fn) butlast
1052 (mapcar (lambda (x) (list 'quote x)) (nth 1 last))))
1054 "last arg to apply can't be a literal atom: `%s'"
1055 (prin1-to-string last))
1059 (put 'funcall 'byte-optimizer 'byte-optimize-funcall)
1060 (put 'apply 'byte-optimizer 'byte-optimize-apply)
1063 (put 'let 'byte-optimizer 'byte-optimize-letX)
1064 (put 'let* 'byte-optimizer 'byte-optimize-letX)
1065 (defun byte-optimize-letX (form)
1066 (cond ((null (nth 1 form))
1068 (cons 'progn (cdr (cdr form))))
1069 ((or (nth 2 form) (nthcdr 3 form))
1072 ((eq (car form) 'let)
1073 (append '(progn) (mapcar 'car-safe (mapcar 'cdr-safe (nth 1 form)))
1076 (let ((binds (reverse (nth 1 form))))
1077 (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil)))))
1080 (put 'nth 'byte-optimizer 'byte-optimize-nth)
1081 (defun byte-optimize-nth (form)
1082 (if (and (= (safe-length form) 3) (memq (nth 1 form) '(0 1)))
1083 (list 'car (if (zerop (nth 1 form))
1085 (list 'cdr (nth 2 form))))
1086 (byte-optimize-predicate form)))
1088 (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr)
1089 (defun byte-optimize-nthcdr (form)
1090 (if (and (= (safe-length form) 3) (not (memq (nth 1 form) '(0 1 2))))
1091 (byte-optimize-predicate form)
1092 (let ((count (nth 1 form)))
1093 (setq form (nth 2 form))
1094 (while (>= (setq count (1- count)) 0)
1095 (setq form (list 'cdr form)))
1098 (put 'concat 'byte-optimizer 'byte-optimize-concat)
1099 (defun byte-optimize-concat (form)
1100 (let ((args (cdr form))
1102 (while (and args constant)
1103 (or (byte-compile-constp (car args))
1104 (setq constant nil))
1105 (setq args (cdr args)))
1110 ;; Avoid having to write forward-... with a negative arg for speed.
1111 (put 'backward-char 'byte-optimizer 'byte-optimize-backward-char)
1112 (defun byte-optimize-backward-char (form)
1113 (cond ((and (= 2 (safe-length form))
1114 (numberp (nth 1 form)))
1115 (list 'forward-char (eval (- (nth 1 form)))))
1116 ((= 1 (safe-length form))
1120 (put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
1121 (defun byte-optimize-backward-word (form)
1122 (cond ((and (= 2 (safe-length form))
1123 (numberp (nth 1 form)))
1124 (list 'forward-word (eval (- (nth 1 form)))))
1125 ((= 1 (safe-length form))
1129 (put 'char-before 'byte-optimizer 'byte-optimize-char-before)
1130 (defun byte-optimize-char-before (form)
1131 (cond ((= 2 (safe-length form))
1132 `(char-after (1- ,(nth 1 form))))
1133 ((= 1 (safe-length form))
1134 '(char-after (1- (point))))
1137 ;;; enumerating those functions which need not be called if the returned
1138 ;;; value is not used. That is, something like
1139 ;;; (progn (list (something-with-side-effects) (yow))
1141 ;;; may safely be turned into
1142 ;;; (progn (progn (something-with-side-effects) (yow))
1144 ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
1146 ;;; I wonder if I missed any :-\)
1147 (let ((side-effect-free-fns
1148 '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
1150 boundp buffer-file-name buffer-local-variables buffer-modified-p
1152 capitalize car-less-than-car car cdr ceiling char-after char-before
1153 concat coordinates-in-window-p
1154 char-width copy-marker cos count-lines
1155 decode-char default-boundp default-value documentation downcase
1156 elt encode-char exp expt fboundp featurep
1157 file-directory-p file-exists-p file-locked-p file-name-absolute-p
1158 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
1159 float floor format frame-visible-p
1160 get gethash get-buffer get-buffer-window getenv get-file-buffer
1164 length local-variable-if-set-p local-variable-p log log10 logand
1165 logb logior lognot logxor lsh langinfo
1166 marker-buffer max member memq min mod multibyte-char-to-unibyte
1167 next-window nth nthcdr number-to-string
1168 parse-colon-path prefix-numeric-value previous-window propertize
1169 radians-to-degrees rassq regexp-quote reverse round
1170 sin sqrt string string< string= string-equal string-lessp string-to-char
1171 string-to-int string-to-number substring symbol-function symbol-plist
1172 symbol-value string-make-unibyte string-make-multibyte
1173 string-to-multibyte string-as-multibyte string-as-unibyte
1174 tan unibyte-char-to-multibyte upcase user-variable-p vconcat
1175 window-buffer window-dedicated-p window-edges window-height
1176 window-hscroll window-minibuffer-p window-width
1178 (side-effect-and-error-free-fns
1180 bobp bolp buffer-end buffer-list buffer-size buffer-string bufferp
1181 car-safe case-table-p cdr-safe char-or-string-p characterp
1182 charsetp commandp cons consp
1183 current-buffer current-global-map current-indentation
1184 current-local-map current-minor-mode-maps
1185 dot dot-marker eobp eolp eq equal eventp
1186 floatp following-char framep
1187 get-largest-window get-lru-window
1189 identity ignore integerp integer-or-marker-p interactive-p
1190 invocation-directory invocation-name
1192 line-beginning-position line-end-position list listp
1193 make-marker mark mark-marker markerp max-char memory-limit minibuffer-window
1195 natnump nlistp not null number-or-marker-p numberp
1196 one-window-p overlayp
1197 point point-marker point-min point-max preceding-char primary-charset
1199 recent-keys recursion-depth
1200 selected-frame selected-window sequencep stringp subrp symbolp
1201 standard-case-table standard-syntax-table syntax-table-p
1202 this-command-keys this-command-keys-vector this-single-command-keys
1203 this-single-command-raw-keys
1204 user-full-name user-login-name user-original-login-name
1205 user-real-login-name user-real-uid user-uid
1206 vector vectorp visible-frame-list
1207 window-configuration-p window-live-p windowp)))
1208 (while side-effect-free-fns
1209 (put (car side-effect-free-fns) 'side-effect-free t)
1210 (setq side-effect-free-fns (cdr side-effect-free-fns)))
1211 (while side-effect-and-error-free-fns
1212 (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free)
1213 (setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns)))
1217 (defun byte-compile-splice-in-already-compiled-code (form)
1218 ;; form is (byte-code "..." [...] n)
1219 (if (not (memq byte-optimize '(t lap)))
1220 (byte-compile-normal-call form)
1221 (byte-inline-lapcode
1222 (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t))
1223 (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form))
1224 byte-compile-maxdepth))
1225 (setq byte-compile-depth (1+ byte-compile-depth))))
1227 (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code)
1230 (defconst byte-constref-ops
1231 '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
1233 ;;; This function extracts the bitfields from variable-length opcodes.
1234 ;;; Originally defined in disass.el (which no longer uses it.)
1236 (defun disassemble-offset ()
1238 ;; fetch and return the offset for the current opcode.
1239 ;; return nil if this opcode has no offset
1240 ;; OP, PTR and BYTES are used and set dynamically
1244 (cond ((< op byte-nth)
1245 (let ((tem (logand op 7)))
1246 (setq op (logand op 248))
1248 (setq ptr (1+ ptr)) ;offset in next byte
1251 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1253 (progn (setq ptr (1+ ptr))
1254 (lsh (aref bytes ptr) 8))))
1255 (t tem)))) ;offset was in opcode
1256 ((>= op byte-constant)
1257 (prog1 (- op byte-constant) ;offset in opcode
1258 (setq op byte-constant)))
1259 ((and (>= op byte-constant2)
1260 (<= op byte-goto-if-not-nil-else-pop))
1261 (setq ptr (1+ ptr)) ;offset in next 2 bytes
1263 (progn (setq ptr (1+ ptr))
1264 (lsh (aref bytes ptr) 8))))
1265 ((and (>= op byte-listN)
1266 (<= op byte-insertN))
1267 (setq ptr (1+ ptr)) ;offset in next byte
1271 ;;; This de-compiler is used for inline expansion of compiled functions,
1272 ;;; and by the disassembler.
1274 ;;; This list contains numbers, which are pc values,
1275 ;;; before each instruction.
1276 (defun byte-decompile-bytecode (bytes constvec)
1277 "Turns BYTECODE into lapcode, referring to CONSTVEC."
1278 (let ((byte-compile-constants nil)
1279 (byte-compile-variables nil)
1280 (byte-compile-tag-number 0))
1281 (byte-decompile-bytecode-1 bytes constvec)))
1283 ;; As byte-decompile-bytecode, but updates
1284 ;; byte-compile-{constants, variables, tag-number}.
1285 ;; If MAKE-SPLICEABLE is true, then `return' opcodes are replaced
1286 ;; with `goto's destined for the end of the code.
1287 ;; That is for use by the compiler.
1288 ;; If MAKE-SPLICEABLE is nil, we are being called for the disassembler.
1289 ;; In that case, we put a pc value into the list
1290 ;; before each insn (or its label).
1291 (defun byte-decompile-bytecode-1 (bytes constvec &optional make-spliceable)
1292 (let ((length (length bytes))
1293 (ptr 0) optr tag tags op offset
1297 (while (not (= ptr length))
1299 (setq lap (cons ptr lap)))
1300 (setq op (aref bytes ptr)
1302 offset (disassemble-offset)) ; this does dynamic-scope magic
1303 (setq op (aref byte-code-vector op))
1304 (cond ((memq op byte-goto-ops)
1307 (cdr (or (assq offset tags)
1310 (byte-compile-make-tag))
1312 ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t)
1313 ((memq op byte-constref-ops)))
1314 (setq tmp (if (>= offset (length constvec))
1315 (list 'out-of-range offset)
1316 (aref constvec offset))
1317 offset (if (eq op 'byte-constant)
1318 (byte-compile-get-constant tmp)
1319 (or (assq tmp byte-compile-variables)
1320 (car (setq byte-compile-variables
1322 byte-compile-variables)))))))
1323 ((and make-spliceable
1324 (eq op 'byte-return))
1325 (if (= ptr (1- length))
1327 (setq offset (or endtag (setq endtag (byte-compile-make-tag)))
1329 ;; lap = ( [ (pc . (op . arg)) ]* )
1330 (setq lap (cons (cons optr (cons op (or offset 0)))
1332 (setq ptr (1+ ptr)))
1333 ;; take off the dummy nil op that we replaced a trailing "return" with.
1336 (cond ((numberp (car rest)))
1337 ((setq tmp (assq (car (car rest)) tags))
1338 ;; this addr is jumped to
1339 (setcdr rest (cons (cons nil (cdr tmp))
1341 (setq tags (delq tmp tags))
1342 (setq rest (cdr rest))))
1343 (setq rest (cdr rest))))
1344 (if tags (error "optimizer error: missed tags %s" tags))
1345 (if (null (car (cdr (car lap))))
1346 (setq lap (cdr lap)))
1348 (setq lap (cons (cons nil endtag) lap)))
1349 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* )
1350 (mapcar (function (lambda (elt)
1357 ;;; peephole optimizer
1359 (defconst byte-tagref-ops (cons 'TAG byte-goto-ops))
1361 (defconst byte-conditional-ops
1362 '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop
1363 byte-goto-if-not-nil-else-pop))
1365 (defconst byte-after-unbind-ops
1366 '(byte-constant byte-dup
1367 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp
1369 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4
1371 ;; How about other side-effect-free-ops? Is it safe to move an
1372 ;; error invocation (such as from nth) out of an unwind-protect?
1373 ;; No, it is not, because the unwind-protect forms can alter
1374 ;; the inside of the object to which nth would apply.
1375 ;; For the same reason, byte-equal was deleted from this list.
1376 "Byte-codes that can be moved past an unbind.")
1378 (defconst byte-compile-side-effect-and-error-free-ops
1379 '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp
1380 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe
1381 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max
1382 byte-point-min byte-following-char byte-preceding-char
1383 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp
1384 byte-current-buffer byte-interactive-p))
1386 (defconst byte-compile-side-effect-free-ops
1388 '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref
1389 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1
1390 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate
1391 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax
1392 byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt
1393 byte-member byte-assq byte-quo byte-rem)
1394 byte-compile-side-effect-and-error-free-ops))
1396 ;;; This crock is because of the way DEFVAR_BOOL variables work.
1397 ;;; Consider the code
1399 ;;; (defun foo (flag)
1400 ;;; (let ((old-pop-ups pop-up-windows)
1401 ;;; (pop-up-windows flag))
1402 ;;; (cond ((not (eq pop-up-windows old-pop-ups))
1403 ;;; (setq old-pop-ups pop-up-windows)
1406 ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
1407 ;;; something else. But if we optimize
1410 ;;; varbind pop-up-windows
1411 ;;; varref pop-up-windows
1416 ;;; varbind pop-up-windows
1419 ;;; we break the program, because it will appear that pop-up-windows and
1420 ;;; old-pop-ups are not EQ when really they are. So we have to know what
1421 ;;; the BOOL variables are, and not perform this optimization on them.
1423 ;;; The variable `byte-boolean-vars' is now primitive and updated
1424 ;;; automatically by DEFVAR_BOOL.
1426 (defun byte-optimize-lapcode (lap &optional for-effect)
1427 "Simple peephole optimizer. LAP is both modified and returned."
1431 (keep-going 'first-time)
1434 (side-effect-free (if byte-compile-delete-errors
1435 byte-compile-side-effect-free-ops
1436 byte-compile-side-effect-and-error-free-ops)))
1438 (or (eq keep-going 'first-time)
1439 (byte-compile-log-lap " ---- next pass"))
1443 (setq lap0 (car rest)
1447 ;; You may notice that sequences like "dup varset discard" are
1448 ;; optimized but sequences like "dup varset TAG1: discard" are not.
1449 ;; You may be tempted to change this; resist that temptation.
1451 ;; <side-effect-free> pop --> <deleted>
1453 ;; const-X pop --> <deleted>
1454 ;; varref-X pop --> <deleted>
1455 ;; dup pop --> <deleted>
1457 ((and (eq 'byte-discard (car lap1))
1458 (memq (car lap0) side-effect-free))
1460 (setq tmp (aref byte-stack+-info (symbol-value (car lap0))))
1461 (setq rest (cdr rest))
1463 (byte-compile-log-lap
1464 " %s discard\t-->\t<deleted>" lap0)
1465 (setq lap (delq lap0 (delq lap1 lap))))
1467 (byte-compile-log-lap
1468 " %s discard\t-->\t<deleted> discard" lap0)
1469 (setq lap (delq lap0 lap)))
1471 (byte-compile-log-lap
1472 " %s discard\t-->\tdiscard discard" lap0)
1473 (setcar lap0 'byte-discard)
1475 ((error "Optimizer error: too much on the stack"))))
1477 ;; goto*-X X: --> X:
1479 ((and (memq (car lap0) byte-goto-ops)
1480 (eq (cdr lap0) lap1))
1481 (cond ((eq (car lap0) 'byte-goto)
1482 (setq lap (delq lap0 lap))
1483 (setq tmp "<deleted>"))
1484 ((memq (car lap0) byte-goto-always-pop-ops)
1485 (setcar lap0 (setq tmp 'byte-discard))
1487 ((error "Depth conflict at tag %d" (nth 2 lap0))))
1488 (and (memq byte-optimize-log '(t byte))
1489 (byte-compile-log " (goto %s) %s:\t-->\t%s %s:"
1490 (nth 1 lap1) (nth 1 lap1)
1492 (setq keep-going t))
1494 ;; varset-X varref-X --> dup varset-X
1495 ;; varbind-X varref-X --> dup varbind-X
1496 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup
1497 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup
1498 ;; The latter two can enable other optimizations.
1500 ((and (eq 'byte-varref (car lap2))
1501 (eq (cdr lap1) (cdr lap2))
1502 (memq (car lap1) '(byte-varset byte-varbind)))
1503 (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars))
1504 (not (eq (car lap0) 'byte-constant)))
1507 (if (memq (car lap0) '(byte-constant byte-dup))
1509 (setq tmp (if (or (not tmp)
1510 (byte-compile-const-symbol-p
1513 (byte-compile-get-constant t)))
1514 (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s"
1515 lap0 lap1 lap2 lap0 lap1
1516 (cons (car lap0) tmp))
1517 (setcar lap2 (car lap0))
1519 (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1)
1520 (setcar lap2 (car lap1))
1521 (setcar lap1 'byte-dup)
1523 ;; The stack depth gets locally increased, so we will
1524 ;; increase maxdepth in case depth = maxdepth here.
1525 ;; This can cause the third argument to byte-code to
1526 ;; be larger than necessary.
1527 (setq add-depth 1))))
1529 ;; dup varset-X discard --> varset-X
1530 ;; dup varbind-X discard --> varbind-X
1531 ;; (the varbind variant can emerge from other optimizations)
1533 ((and (eq 'byte-dup (car lap0))
1534 (eq 'byte-discard (car lap2))
1535 (memq (car lap1) '(byte-varset byte-varbind)))
1536 (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1)
1539 (setq lap (delq lap0 (delq lap2 lap))))
1541 ;; not goto-X-if-nil --> goto-X-if-non-nil
1542 ;; not goto-X-if-non-nil --> goto-X-if-nil
1544 ;; it is wrong to do the same thing for the -else-pop variants.
1546 ((and (eq 'byte-not (car lap0))
1547 (or (eq 'byte-goto-if-nil (car lap1))
1548 (eq 'byte-goto-if-not-nil (car lap1))))
1549 (byte-compile-log-lap " not %s\t-->\t%s"
1552 (if (eq (car lap1) 'byte-goto-if-nil)
1553 'byte-goto-if-not-nil
1556 (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil)
1557 'byte-goto-if-not-nil
1559 (setq lap (delq lap0 lap))
1560 (setq keep-going t))
1562 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X:
1563 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X:
1565 ;; it is wrong to do the same thing for the -else-pop variants.
1567 ((and (or (eq 'byte-goto-if-nil (car lap0))
1568 (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX
1569 (eq 'byte-goto (car lap1)) ; gotoY
1570 (eq (cdr lap0) lap2)) ; TAG X
1571 (let ((inverse (if (eq 'byte-goto-if-nil (car lap0))
1572 'byte-goto-if-not-nil 'byte-goto-if-nil)))
1573 (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:"
1575 (cons inverse (cdr lap1)) lap2)
1576 (setq lap (delq lap0 lap))
1577 (setcar lap1 inverse)
1578 (setq keep-going t)))
1580 ;; const goto-if-* --> whatever
1582 ((and (eq 'byte-constant (car lap0))
1583 (memq (car lap1) byte-conditional-ops))
1584 (cond ((if (or (eq (car lap1) 'byte-goto-if-nil)
1585 (eq (car lap1) 'byte-goto-if-nil-else-pop))
1587 (not (car (cdr lap0))))
1588 (byte-compile-log-lap " %s %s\t-->\t<deleted>"
1590 (setq rest (cdr rest)
1591 lap (delq lap0 (delq lap1 lap))))
1593 (if (memq (car lap1) byte-goto-always-pop-ops)
1595 (byte-compile-log-lap " %s %s\t-->\t%s"
1596 lap0 lap1 (cons 'byte-goto (cdr lap1)))
1597 (setq lap (delq lap0 lap)))
1598 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1599 (cons 'byte-goto (cdr lap1))))
1600 (setcar lap1 'byte-goto)))
1601 (setq keep-going t))
1603 ;; varref-X varref-X --> varref-X dup
1604 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup
1605 ;; We don't optimize the const-X variations on this here,
1606 ;; because that would inhibit some goto optimizations; we
1607 ;; optimize the const-X case after all other optimizations.
1609 ((and (eq 'byte-varref (car lap0))
1611 (setq tmp (cdr rest))
1612 (while (eq (car (car tmp)) 'byte-dup)
1613 (setq tmp (cdr tmp)))
1615 (eq (cdr lap0) (cdr (car tmp)))
1616 (eq 'byte-varref (car (car tmp))))
1617 (if (memq byte-optimize-log '(t byte))
1619 (setq tmp2 (cdr rest))
1620 (while (not (eq tmp tmp2))
1621 (setq tmp2 (cdr tmp2)
1622 str (concat str " dup")))
1623 (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup"
1624 lap0 str lap0 lap0 str)))
1626 (setcar (car tmp) 'byte-dup)
1627 (setcdr (car tmp) 0)
1630 ;; TAG1: TAG2: --> TAG1: <deleted>
1631 ;; (and other references to TAG2 are replaced with TAG1)
1633 ((and (eq (car lap0) 'TAG)
1634 (eq (car lap1) 'TAG))
1635 (and (memq byte-optimize-log '(t byte))
1636 (byte-compile-log " adjacent tags %d and %d merged"
1637 (nth 1 lap1) (nth 1 lap0)))
1639 (while (setq tmp2 (rassq lap0 tmp3))
1641 (setq tmp3 (cdr (memq tmp2 tmp3))))
1642 (setq lap (delq lap0 lap)
1645 ;; unused-TAG: --> <deleted>
1647 ((and (eq 'TAG (car lap0))
1648 (not (rassq lap0 lap)))
1649 (and (memq byte-optimize-log '(t byte))
1650 (byte-compile-log " unused tag %d removed" (nth 1 lap0)))
1651 (setq lap (delq lap0 lap)
1654 ;; goto ... --> goto <delete until TAG or end>
1655 ;; return ... --> return <delete until TAG or end>
1657 ((and (memq (car lap0) '(byte-goto byte-return))
1658 (not (memq (car lap1) '(TAG nil))))
1661 (opt-p (memq byte-optimize-log '(t lap)))
1663 (while (and (setq tmp (cdr tmp))
1664 (not (eq 'TAG (car (car tmp)))))
1665 (if opt-p (setq deleted (cons (car tmp) deleted)
1666 str (concat str " %s")
1670 (if (eq 'TAG (car (car tmp)))
1671 (format "%d:" (car (cdr (car tmp))))
1672 (or (car tmp) ""))))
1674 (apply 'byte-compile-log-lap-1
1676 " %s\t-->\t%s <deleted> %s")
1678 (nconc (nreverse deleted)
1679 (list tagstr lap0 tagstr)))
1680 (byte-compile-log-lap
1681 " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s"
1682 lap0 i (if (= i 1) "" "s")
1683 tagstr lap0 tagstr))))
1685 (setq keep-going t))
1687 ;; <safe-op> unbind --> unbind <safe-op>
1688 ;; (this may enable other optimizations.)
1690 ((and (eq 'byte-unbind (car lap1))
1691 (memq (car lap0) byte-after-unbind-ops))
1692 (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0)
1694 (setcar (cdr rest) lap0)
1695 (setq keep-going t))
1697 ;; varbind-X unbind-N --> discard unbind-(N-1)
1698 ;; save-excursion unbind-N --> unbind-(N-1)
1699 ;; save-restriction unbind-N --> unbind-(N-1)
1701 ((and (eq 'byte-unbind (car lap1))
1702 (memq (car lap0) '(byte-varbind byte-save-excursion
1703 byte-save-restriction))
1705 (if (zerop (setcdr lap1 (1- (cdr lap1))))
1707 (if (eq (car lap0) 'byte-varbind)
1708 (setcar rest (cons 'byte-discard 0))
1709 (setq lap (delq lap0 lap)))
1710 (byte-compile-log-lap " %s %s\t-->\t%s %s"
1711 lap0 (cons (car lap1) (1+ (cdr lap1)))
1712 (if (eq (car lap0) 'byte-varbind)
1715 (if (and (/= 0 (cdr lap1))
1716 (eq (car lap0) 'byte-varbind))
1719 (setq keep-going t))
1721 ;; goto*-X ... X: goto-Y --> goto*-Y
1722 ;; goto-X ... X: return --> return
1724 ((and (memq (car lap0) byte-goto-ops)
1725 (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap))))
1726 '(byte-goto byte-return)))
1727 (cond ((and (not (eq tmp lap0))
1728 (or (eq (car lap0) 'byte-goto)
1729 (eq (car tmp) 'byte-goto)))
1730 (byte-compile-log-lap " %s [%s]\t-->\t%s"
1732 (if (eq (car tmp) 'byte-return)
1733 (setcar lap0 'byte-return))
1734 (setcdr lap0 (cdr tmp))
1735 (setq keep-going t))))
1737 ;; goto-*-else-pop X ... X: goto-if-* --> whatever
1738 ;; goto-*-else-pop X ... X: discard --> whatever
1740 ((and (memq (car lap0) '(byte-goto-if-nil-else-pop
1741 byte-goto-if-not-nil-else-pop))
1742 (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap)))))
1744 (cons 'byte-discard byte-conditional-ops)))
1745 (not (eq lap0 (car tmp))))
1746 (setq tmp2 (car tmp))
1747 (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop
1749 (byte-goto-if-not-nil-else-pop
1750 byte-goto-if-not-nil))))
1751 (if (memq (car tmp2) tmp3)
1752 (progn (setcar lap0 (car tmp2))
1753 (setcdr lap0 (cdr tmp2))
1754 (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s"
1755 (car lap0) tmp2 lap0))
1756 ;; Get rid of the -else-pop's and jump one step further.
1757 (or (eq 'TAG (car (nth 1 tmp)))
1758 (setcdr tmp (cons (byte-compile-make-tag)
1760 (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>"
1761 (car lap0) tmp2 (nth 1 tmp3))
1762 (setcar lap0 (nth 1 tmp3))
1763 (setcdr lap0 (nth 1 tmp)))
1764 (setq keep-going t))
1766 ;; const goto-X ... X: goto-if-* --> whatever
1767 ;; const goto-X ... X: discard --> whatever
1769 ((and (eq (car lap0) 'byte-constant)
1770 (eq (car lap1) 'byte-goto)
1771 (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap)))))
1773 (cons 'byte-discard byte-conditional-ops)))
1774 (not (eq lap1 (car tmp))))
1775 (setq tmp2 (car tmp))
1776 (cond ((memq (car tmp2)
1777 (if (null (car (cdr lap0)))
1778 '(byte-goto-if-nil byte-goto-if-nil-else-pop)
1779 '(byte-goto-if-not-nil
1780 byte-goto-if-not-nil-else-pop)))
1781 (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s"
1782 lap0 tmp2 lap0 tmp2)
1783 (setcar lap1 (car tmp2))
1784 (setcdr lap1 (cdr tmp2))
1785 ;; Let next step fix the (const,goto-if*) sequence.
1786 (setq rest (cons nil rest)))
1788 ;; Jump one step further
1789 (byte-compile-log-lap
1790 " %s goto [%s]\t-->\t<deleted> goto <skip>"
1792 (or (eq 'TAG (car (nth 1 tmp)))
1793 (setcdr tmp (cons (byte-compile-make-tag)
1795 (setcdr lap1 (car (cdr tmp)))
1796 (setq lap (delq lap0 lap))))
1797 (setq keep-going t))
1799 ;; X: varref-Y ... varset-Y goto-X -->
1800 ;; X: varref-Y Z: ... dup varset-Y goto-Z
1801 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.)
1802 ;; (This is so usual for while loops that it is worth handling).
1804 ((and (eq (car lap1) 'byte-varset)
1805 (eq (car lap2) 'byte-goto)
1806 (not (memq (cdr lap2) rest)) ;Backwards jump
1807 (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap)))))
1809 (eq (cdr (car tmp)) (cdr lap1))
1810 (not (memq (car (cdr lap1)) byte-boolean-vars)))
1811 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp))
1812 (let ((newtag (byte-compile-make-tag)))
1813 (byte-compile-log-lap
1814 " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s"
1815 (nth 1 (cdr lap2)) (car tmp)
1817 (nth 1 (cdr lap2)) (car tmp)
1818 (nth 1 newtag) 'byte-dup lap1
1819 (cons 'byte-goto newtag)
1821 (setcdr rest (cons (cons 'byte-dup 0) (cdr rest)))
1822 (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp))))
1824 (setq keep-going t))
1826 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y:
1827 ;; (This can pull the loop test to the end of the loop)
1829 ((and (eq (car lap0) 'byte-goto)
1830 (eq (car lap1) 'TAG)
1832 (cdr (car (setq tmp (cdr (memq (cdr lap0) lap))))))
1833 (memq (car (car tmp))
1834 '(byte-goto byte-goto-if-nil byte-goto-if-not-nil
1835 byte-goto-if-nil-else-pop)))
1836 ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional"
1837 ;; lap0 lap1 (cdr lap0) (car tmp))
1838 (let ((newtag (byte-compile-make-tag)))
1839 (byte-compile-log-lap
1840 "%s %s: ... %s: %s\t-->\t%s ... %s:"
1841 lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp)
1842 (cons (cdr (assq (car (car tmp))
1843 '((byte-goto-if-nil . byte-goto-if-not-nil)
1844 (byte-goto-if-not-nil . byte-goto-if-nil)
1845 (byte-goto-if-nil-else-pop .
1846 byte-goto-if-not-nil-else-pop)
1847 (byte-goto-if-not-nil-else-pop .
1848 byte-goto-if-nil-else-pop))))
1853 (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp)))
1854 (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop)
1855 ;; We can handle this case but not the -if-not-nil case,
1856 ;; because we won't know which non-nil constant to push.
1857 (setcdr rest (cons (cons 'byte-constant
1858 (byte-compile-get-constant nil))
1860 (setcar lap0 (nth 1 (memq (car (car tmp))
1861 '(byte-goto-if-nil-else-pop
1862 byte-goto-if-not-nil
1864 byte-goto-if-not-nil
1865 byte-goto byte-goto))))
1867 (setq keep-going t))
1869 (setq rest (cdr rest)))
1872 ;; Rebuild byte-compile-constants / byte-compile-variables.
1873 ;; Simple optimizations that would inhibit other optimizations if they
1874 ;; were done in the optimizing loop, and optimizations which there is no
1875 ;; need to do more than once.
1876 (setq byte-compile-constants nil
1877 byte-compile-variables nil)
1880 (setq lap0 (car rest)
1882 (if (memq (car lap0) byte-constref-ops)
1883 (if (or (eq (car lap0) 'byte-constant)
1884 (eq (car lap0) 'byte-constant2))
1885 (unless (memq (cdr lap0) byte-compile-constants)
1886 (setq byte-compile-constants (cons (cdr lap0)
1887 byte-compile-constants)))
1888 (unless (memq (cdr lap0) byte-compile-variables)
1889 (setq byte-compile-variables (cons (cdr lap0)
1890 byte-compile-variables)))))
1892 ;; const-C varset-X const-C --> const-C dup varset-X
1893 ;; const-C varbind-X const-C --> const-C dup varbind-X
1895 (and (eq (car lap0) 'byte-constant)
1896 (eq (car (nth 2 rest)) 'byte-constant)
1897 (eq (cdr lap0) (cdr (nth 2 rest)))
1898 (memq (car lap1) '(byte-varbind byte-varset)))
1899 (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s"
1900 lap0 lap1 lap0 lap0 lap1)
1901 (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1)))
1902 (setcar (cdr rest) (cons 'byte-dup 0))
1905 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup
1906 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup
1908 ((memq (car lap0) '(byte-constant byte-varref))
1912 (while (eq 'byte-dup (car (car (setq tmp (cdr tmp))))))
1913 (and (eq (cdr lap0) (cdr (car tmp)))
1914 (eq (car lap0) (car (car tmp)))))
1915 (setcar tmp (cons 'byte-dup 0))
1918 (byte-compile-log-lap
1919 " %s [dup/%s]...\t-->\t%s dup..." lap0 lap0 lap0)))
1921 ;; unbind-N unbind-M --> unbind-(N+M)
1923 ((and (eq 'byte-unbind (car lap0))
1924 (eq 'byte-unbind (car lap1)))
1925 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1
1927 (+ (cdr lap0) (cdr lap1))))
1929 (setq lap (delq lap0 lap))
1930 (setcdr lap1 (+ (cdr lap1) (cdr lap0))))
1932 (setq rest (cdr rest)))
1933 (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth)))
1939 ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles
1940 ;; itself, compile some of its most used recursive functions (at load time).
1943 (or (byte-code-function-p (symbol-function 'byte-optimize-form))
1944 (assq 'byte-code (symbol-function 'byte-optimize-form))
1945 (let ((byte-optimize nil)
1946 (byte-compile-warnings nil))
1948 (or noninteractive (message "compiling %s..." x))
1950 (or noninteractive (message "compiling %s...done" x)))
1951 '(byte-optimize-form
1953 byte-optimize-predicate
1954 byte-optimize-binary-predicate
1955 ;; Inserted some more than necessary, to speed it up.
1956 byte-optimize-form-code-walker
1957 byte-optimize-lapcode))))
1960 ;;; byte-opt.el ends here