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1 | ;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler. |
2 | ||
70e1dad8 | 3 | ;;; Copyright (c) 1991 Free Software Foundation, Inc. |
3eac9910 JB |
4 | |
5 | ;; Author: Jamie Zawinski <jwz@lucid.com> | |
6 | ;; Hallvard Furuseth <hbf@ulrik.uio.no> | |
7 | ;; Keywords: internal | |
1c393159 JB |
8 | |
9 | ;; This file is part of GNU Emacs. | |
10 | ||
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 | |
3eac9910 | 13 | ;; the Free Software Foundation; either version 2, or (at your option) |
1c393159 JB |
14 | ;; any later version. |
15 | ||
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. | |
20 | ||
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 | |
23 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
24 | ||
3eac9910 JB |
25 | ;;; Commentary: |
26 | ||
1c393159 JB |
27 | ;;; ======================================================================== |
28 | ;;; "No matter how hard you try, you can't make a racehorse out of a pig. | |
29 | ;;; you can, however, make a faster pig." | |
30 | ;;; | |
31 | ;;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code | |
32 | ;;; makes it be a VW Bug with fuel injection and a turbocharger... You're | |
33 | ;;; still not going to make it go faster than 70 mph, but it might be easier | |
34 | ;;; to get it there. | |
35 | ;;; | |
36 | ||
37 | ;;; TO DO: | |
38 | ;;; | |
39 | ;;; (apply '(lambda (x &rest y) ...) 1 (foo)) | |
40 | ;;; | |
41 | ;;; collapse common subexpressions | |
42 | ;;; | |
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 'inhibit-quit 'binding-is-magic t) | |
53 | ;;; (put 'quit-flag 'binding-is-magic t) | |
54 | ;;; others? | |
55 | ;;; | |
56 | ;;; Simple defsubsts often produce forms like | |
57 | ;;; (let ((v1 (f1)) (v2 (f2)) ...) | |
58 | ;;; (FN v1 v2 ...)) | |
59 | ;;; It would be nice if we could optimize this to | |
60 | ;;; (FN (f1) (f2) ...) | |
61 | ;;; but we can't unless FN is dynamically-safe (it might be dynamically | |
62 | ;;; referring to the bindings that the lambda arglist established.) | |
63 | ;;; One of the uncountable lossages introduced by dynamic scope... | |
64 | ;;; | |
65 | ;;; Maybe there should be a control-structure that says "turn on | |
66 | ;;; fast-and-loose type-assumptive optimizations here." Then when | |
67 | ;;; we see a form like (car foo) we can from then on assume that | |
68 | ;;; the variable foo is of type cons, and optimize based on that. | |
69 | ;;; But, this won't win much because of (you guessed it) dynamic | |
70 | ;;; scope. Anything down the stack could change the value. | |
71 | ;;; | |
72 | ;;; It would be nice if redundant sequences could be factored out as well, | |
73 | ;;; when they are known to have no side-effects: | |
74 | ;;; (list (+ a b c) (+ a b c)) --> a b add c add dup list-2 | |
75 | ;;; but beware of traps like | |
76 | ;;; (cons (list x y) (list x y)) | |
77 | ;;; | |
3eac9910 JB |
78 | ;;; Tail-recursion elimination is not really possible in Emacs Lisp. |
79 | ;;; Tail-recursion elimination is almost always impossible when all variables | |
80 | ;;; have dynamic scope, but given that the "return" byteop requires the | |
81 | ;;; binding stack to be empty (rather than emptying it itself), there can be | |
82 | ;;; no truly tail-recursive Emacs Lisp functions that take any arguments or | |
83 | ;;; make any bindings. | |
1c393159 | 84 | ;;; |
3eac9910 | 85 | ;;; Here is an example of an Emacs Lisp function which could safely be |
1c393159 JB |
86 | ;;; byte-compiled tail-recursively: |
87 | ;;; | |
88 | ;;; (defun tail-map (fn list) | |
89 | ;;; (cond (list | |
90 | ;;; (funcall fn (car list)) | |
91 | ;;; (tail-map fn (cdr list))))) | |
92 | ;;; | |
93 | ;;; However, if there was even a single let-binding around the COND, | |
94 | ;;; it could not be byte-compiled, because there would be an "unbind" | |
95 | ;;; byte-op between the final "call" and "return." Adding a | |
96 | ;;; Bunbind_all byteop would fix this. | |
97 | ;;; | |
98 | ;;; (defun foo (x y z) ... (foo a b c)) | |
99 | ;;; ... (const foo) (varref a) (varref b) (varref c) (call 3) END: (return) | |
100 | ;;; ... (varref a) (varbind x) (varref b) (varbind y) (varref c) (varbind z) (goto 0) END: (unbind-all) (return) | |
101 | ;;; ... (varref a) (varset x) (varref b) (varset y) (varref c) (varset z) (goto 0) END: (return) | |
102 | ;;; | |
103 | ;;; this also can be considered tail recursion: | |
104 | ;;; | |
105 | ;;; ... (const foo) (varref a) (call 1) (goto X) ... X: (return) | |
106 | ;;; could generalize this by doing the optimization | |
107 | ;;; (goto X) ... X: (return) --> (return) | |
108 | ;;; | |
109 | ;;; But this doesn't solve all of the problems: although by doing tail- | |
110 | ;;; recursion elimination in this way, the call-stack does not grow, the | |
111 | ;;; binding-stack would grow with each recursive step, and would eventually | |
112 | ;;; overflow. I don't believe there is any way around this without lexical | |
113 | ;;; scope. | |
114 | ;;; | |
3eac9910 | 115 | ;;; Wouldn't it be nice if Emacs Lisp had lexical scope. |
1c393159 JB |
116 | ;;; |
117 | ;;; Idea: the form (lexical-scope) in a file means that the file may be | |
118 | ;;; compiled lexically. This proclamation is file-local. Then, within | |
119 | ;;; that file, "let" would establish lexical bindings, and "let-dynamic" | |
120 | ;;; would do things the old way. (Or we could use CL "declare" forms.) | |
121 | ;;; We'd have to notice defvars and defconsts, since those variables should | |
122 | ;;; always be dynamic, and attempting to do a lexical binding of them | |
123 | ;;; should simply do a dynamic binding instead. | |
124 | ;;; But! We need to know about variables that were not necessarily defvarred | |
125 | ;;; in the file being compiled (doing a boundp check isn't good enough.) | |
126 | ;;; Fdefvar() would have to be modified to add something to the plist. | |
127 | ;;; | |
128 | ;;; A major disadvantage of this scheme is that the interpreter and compiler | |
129 | ;;; would have different semantics for files compiled with (dynamic-scope). | |
130 | ;;; Since this would be a file-local optimization, there would be no way to | |
131 | ;;; modify the interpreter to obey this (unless the loader was hacked | |
132 | ;;; in some grody way, but that's a really bad idea.) | |
133 | ;;; | |
134 | ;;; Really the Right Thing is to make lexical scope the default across | |
135 | ;;; the board, in the interpreter and compiler, and just FIX all of | |
136 | ;;; the code that relies on dynamic scope of non-defvarred variables. | |
137 | ||
3eac9910 | 138 | ;;; Code: |
1c393159 | 139 | |
1c393159 JB |
140 | (defun byte-compile-log-lap-1 (format &rest args) |
141 | (if (aref byte-code-vector 0) | |
142 | (error "The old version of the disassembler is loaded. Reload new-bytecomp as well.")) | |
143 | (byte-compile-log-1 | |
144 | (apply 'format format | |
145 | (let (c a) | |
146 | (mapcar '(lambda (arg) | |
147 | (if (not (consp arg)) | |
148 | (if (and (symbolp arg) | |
149 | (string-match "^byte-" (symbol-name arg))) | |
150 | (intern (substring (symbol-name arg) 5)) | |
151 | arg) | |
152 | (if (integerp (setq c (car arg))) | |
153 | (error "non-symbolic byte-op %s" c)) | |
154 | (if (eq c 'TAG) | |
155 | (setq c arg) | |
156 | (setq a (cond ((memq c byte-goto-ops) | |
157 | (car (cdr (cdr arg)))) | |
158 | ((memq c byte-constref-ops) | |
159 | (car (cdr arg))) | |
160 | (t (cdr arg)))) | |
161 | (setq c (symbol-name c)) | |
162 | (if (string-match "^byte-." c) | |
163 | (setq c (intern (substring c 5))))) | |
164 | (if (eq c 'constant) (setq c 'const)) | |
165 | (if (and (eq (cdr arg) 0) | |
166 | (not (memq c '(unbind call const)))) | |
167 | c | |
168 | (format "(%s %s)" c a)))) | |
169 | args))))) | |
170 | ||
171 | (defmacro byte-compile-log-lap (format-string &rest args) | |
172 | (list 'and | |
173 | '(memq byte-optimize-log '(t byte)) | |
174 | (cons 'byte-compile-log-lap-1 | |
175 | (cons format-string args)))) | |
176 | ||
177 | \f | |
178 | ;;; byte-compile optimizers to support inlining | |
179 | ||
180 | (put 'inline 'byte-optimizer 'byte-optimize-inline-handler) | |
181 | ||
182 | (defun byte-optimize-inline-handler (form) | |
183 | "byte-optimize-handler for the `inline' special-form." | |
184 | (cons 'progn | |
185 | (mapcar | |
186 | '(lambda (sexp) | |
187 | (let ((fn (car-safe sexp))) | |
188 | (if (and (symbolp fn) | |
189 | (or (cdr (assq fn byte-compile-function-environment)) | |
190 | (and (fboundp fn) | |
191 | (not (or (cdr (assq fn byte-compile-macro-environment)) | |
192 | (and (consp (setq fn (symbol-function fn))) | |
193 | (eq (car fn) 'macro)) | |
194 | (subrp fn)))))) | |
195 | (byte-compile-inline-expand sexp) | |
196 | sexp))) | |
197 | (cdr form)))) | |
198 | ||
199 | ||
70e1dad8 RS |
200 | ;; Splice the given lap code into the current instruction stream. |
201 | ;; If it has any labels in it, you're responsible for making sure there | |
202 | ;; are no collisions, and that byte-compile-tag-number is reasonable | |
203 | ;; after this is spliced in. The provided list is destroyed. | |
1c393159 | 204 | (defun byte-inline-lapcode (lap) |
1c393159 JB |
205 | (setq byte-compile-output (nconc (nreverse lap) byte-compile-output))) |
206 | ||
207 | ||
208 | (defun byte-compile-inline-expand (form) | |
209 | (let* ((name (car form)) | |
210 | (fn (or (cdr (assq name byte-compile-function-environment)) | |
211 | (and (fboundp name) (symbol-function name))))) | |
212 | (if (null fn) | |
213 | (progn | |
214 | (byte-compile-warn "attempt to inline %s before it was defined" name) | |
215 | form) | |
216 | ;; else | |
217 | (if (and (consp fn) (eq (car fn) 'autoload)) | |
218 | (load (nth 1 fn))) | |
219 | (if (and (consp fn) (eq (car fn) 'autoload)) | |
220 | (error "file \"%s\" didn't define \"%s\"" (nth 1 fn) name)) | |
221 | (if (symbolp fn) | |
222 | (byte-compile-inline-expand (cons fn (cdr form))) | |
223 | (if (compiled-function-p fn) | |
224 | (cons (list 'lambda (aref fn 0) | |
225 | (list 'byte-code (aref fn 1) (aref fn 2) (aref fn 3))) | |
226 | (cdr form)) | |
227 | (if (not (eq (car fn) 'lambda)) (error "%s is not a lambda" name)) | |
228 | (cons fn (cdr form))))))) | |
229 | ||
230 | ;;; ((lambda ...) ...) | |
231 | ;;; | |
232 | (defun byte-compile-unfold-lambda (form &optional name) | |
233 | (or name (setq name "anonymous lambda")) | |
234 | (let ((lambda (car form)) | |
235 | (values (cdr form))) | |
236 | (if (compiled-function-p lambda) | |
237 | (setq lambda (list 'lambda (nth 0 form) | |
238 | (list 'byte-code | |
239 | (nth 1 form) (nth 2 form) (nth 3 form))))) | |
240 | (let ((arglist (nth 1 lambda)) | |
241 | (body (cdr (cdr lambda))) | |
242 | optionalp restp | |
243 | bindings) | |
244 | (if (and (stringp (car body)) (cdr body)) | |
245 | (setq body (cdr body))) | |
246 | (if (and (consp (car body)) (eq 'interactive (car (car body)))) | |
247 | (setq body (cdr body))) | |
248 | (while arglist | |
249 | (cond ((eq (car arglist) '&optional) | |
250 | ;; ok, I'll let this slide because funcall_lambda() does... | |
251 | ;; (if optionalp (error "multiple &optional keywords in %s" name)) | |
252 | (if restp (error "&optional found after &rest in %s" name)) | |
253 | (if (null (cdr arglist)) | |
254 | (error "nothing after &optional in %s" name)) | |
255 | (setq optionalp t)) | |
256 | ((eq (car arglist) '&rest) | |
257 | ;; ...but it is by no stretch of the imagination a reasonable | |
258 | ;; thing that funcall_lambda() allows (&rest x y) and | |
259 | ;; (&rest x &optional y) in arglists. | |
260 | (if (null (cdr arglist)) | |
261 | (error "nothing after &rest in %s" name)) | |
262 | (if (cdr (cdr arglist)) | |
263 | (error "multiple vars after &rest in %s" name)) | |
264 | (setq restp t)) | |
265 | (restp | |
266 | (setq bindings (cons (list (car arglist) | |
267 | (and values (cons 'list values))) | |
268 | bindings) | |
269 | values nil)) | |
270 | ((and (not optionalp) (null values)) | |
271 | (byte-compile-warn "attempt to open-code %s with too few arguments" name) | |
272 | (setq arglist nil values 'too-few)) | |
273 | (t | |
274 | (setq bindings (cons (list (car arglist) (car values)) | |
275 | bindings) | |
276 | values (cdr values)))) | |
277 | (setq arglist (cdr arglist))) | |
278 | (if values | |
279 | (progn | |
280 | (or (eq values 'too-few) | |
281 | (byte-compile-warn | |
282 | "attempt to open-code %s with too many arguments" name)) | |
283 | form) | |
284 | (let ((newform | |
285 | (if bindings | |
286 | (cons 'let (cons (nreverse bindings) body)) | |
287 | (cons 'progn body)))) | |
288 | (byte-compile-log " %s\t==>\t%s" form newform) | |
289 | newform))))) | |
290 | ||
291 | \f | |
292 | ;;; implementing source-level optimizers | |
293 | ||
294 | (defun byte-optimize-form-code-walker (form for-effect) | |
295 | ;; | |
296 | ;; For normal function calls, We can just mapcar the optimizer the cdr. But | |
297 | ;; we need to have special knowledge of the syntax of the special forms | |
298 | ;; like let and defun (that's why they're special forms :-). (Actually, | |
299 | ;; the important aspect is that they are subrs that don't evaluate all of | |
300 | ;; their args.) | |
301 | ;; | |
302 | (let ((fn (car-safe form)) | |
303 | tmp) | |
304 | (cond ((not (consp form)) | |
305 | (if (not (and for-effect | |
306 | (or byte-compile-delete-errors | |
307 | (not (symbolp form)) | |
308 | (eq form t)))) | |
309 | form)) | |
310 | ((eq fn 'quote) | |
311 | (if (cdr (cdr form)) | |
312 | (byte-compile-warn "malformed quote form: %s" | |
313 | (prin1-to-string form))) | |
314 | ;; map (quote nil) to nil to simplify optimizer logic. | |
315 | ;; map quoted constants to nil if for-effect (just because). | |
316 | (and (nth 1 form) | |
317 | (not for-effect) | |
318 | form)) | |
319 | ((or (compiled-function-p fn) | |
320 | (eq 'lambda (car-safe fn))) | |
321 | (byte-compile-unfold-lambda form)) | |
322 | ((memq fn '(let let*)) | |
323 | ;; recursively enter the optimizer for the bindings and body | |
324 | ;; of a let or let*. This for depth-firstness: forms that | |
325 | ;; are more deeply nested are optimized first. | |
326 | (cons fn | |
327 | (cons | |
328 | (mapcar '(lambda (binding) | |
329 | (if (symbolp binding) | |
330 | binding | |
331 | (if (cdr (cdr binding)) | |
332 | (byte-compile-warn "malformed let binding: %s" | |
333 | (prin1-to-string binding))) | |
334 | (list (car binding) | |
335 | (byte-optimize-form (nth 1 binding) nil)))) | |
336 | (nth 1 form)) | |
337 | (byte-optimize-body (cdr (cdr form)) for-effect)))) | |
338 | ((eq fn 'cond) | |
339 | (cons fn | |
340 | (mapcar '(lambda (clause) | |
341 | (if (consp clause) | |
342 | (cons | |
343 | (byte-optimize-form (car clause) nil) | |
344 | (byte-optimize-body (cdr clause) for-effect)) | |
345 | (byte-compile-warn "malformed cond form: %s" | |
346 | (prin1-to-string clause)) | |
347 | clause)) | |
348 | (cdr form)))) | |
349 | ((eq fn 'progn) | |
350 | ;; as an extra added bonus, this simplifies (progn <x>) --> <x> | |
351 | (if (cdr (cdr form)) | |
352 | (progn | |
353 | (setq tmp (byte-optimize-body (cdr form) for-effect)) | |
354 | (if (cdr tmp) (cons 'progn tmp) (car tmp))) | |
355 | (byte-optimize-form (nth 1 form) for-effect))) | |
356 | ((eq fn 'prog1) | |
357 | (if (cdr (cdr form)) | |
358 | (cons 'prog1 | |
359 | (cons (byte-optimize-form (nth 1 form) for-effect) | |
360 | (byte-optimize-body (cdr (cdr form)) t))) | |
361 | (byte-optimize-form (nth 1 form) for-effect))) | |
362 | ((eq fn 'prog2) | |
363 | (cons 'prog2 | |
364 | (cons (byte-optimize-form (nth 1 form) t) | |
365 | (cons (byte-optimize-form (nth 2 form) for-effect) | |
366 | (byte-optimize-body (cdr (cdr (cdr form))) t))))) | |
367 | ||
368 | ((memq fn '(save-excursion save-restriction)) | |
369 | ;; those subrs which have an implicit progn; it's not quite good | |
370 | ;; enough to treat these like normal function calls. | |
371 | ;; This can turn (save-excursion ...) into (save-excursion) which | |
372 | ;; will be optimized away in the lap-optimize pass. | |
373 | (cons fn (byte-optimize-body (cdr form) for-effect))) | |
374 | ||
375 | ((eq fn 'with-output-to-temp-buffer) | |
376 | ;; this is just like the above, except for the first argument. | |
377 | (cons fn | |
378 | (cons | |
379 | (byte-optimize-form (nth 1 form) nil) | |
380 | (byte-optimize-body (cdr (cdr form)) for-effect)))) | |
381 | ||
382 | ((eq fn 'if) | |
383 | (cons fn | |
384 | (cons (byte-optimize-form (nth 1 form) nil) | |
385 | (cons | |
386 | (byte-optimize-form (nth 2 form) for-effect) | |
387 | (byte-optimize-body (nthcdr 3 form) for-effect))))) | |
388 | ||
389 | ((memq fn '(and or)) ; remember, and/or are control structures. | |
390 | ;; take forms off the back until we can't any more. | |
391 | ;; In the future it could concievably be a problem that the | |
392 | ;; subexpressions of these forms are optimized in the reverse | |
393 | ;; order, but it's ok for now. | |
394 | (if for-effect | |
395 | (let ((backwards (reverse (cdr form)))) | |
396 | (while (and backwards | |
397 | (null (setcar backwards | |
398 | (byte-optimize-form (car backwards) | |
399 | for-effect)))) | |
400 | (setq backwards (cdr backwards))) | |
401 | (if (and (cdr form) (null backwards)) | |
402 | (byte-compile-log | |
403 | " all subforms of %s called for effect; deleted" form)) | |
404 | (and backwards | |
405 | (cons fn (nreverse backwards)))) | |
406 | (cons fn (mapcar 'byte-optimize-form (cdr form))))) | |
407 | ||
408 | ((eq fn 'interactive) | |
409 | (byte-compile-warn "misplaced interactive spec: %s" | |
410 | (prin1-to-string form)) | |
411 | nil) | |
412 | ||
413 | ((memq fn '(defun defmacro function | |
414 | condition-case save-window-excursion)) | |
415 | ;; These forms are compiled as constants or by breaking out | |
416 | ;; all the subexpressions and compiling them separately. | |
417 | form) | |
418 | ||
419 | ((eq fn 'unwind-protect) | |
420 | ;; the "protected" part of an unwind-protect is compiled (and thus | |
421 | ;; optimized) as a top-level form, so don't do it here. But the | |
422 | ;; non-protected part has the same for-effect status as the | |
423 | ;; unwind-protect itself. (The protected part is always for effect, | |
424 | ;; but that isn't handled properly yet.) | |
425 | (cons fn | |
426 | (cons (byte-optimize-form (nth 1 form) for-effect) | |
427 | (cdr (cdr form))))) | |
428 | ||
429 | ((eq fn 'catch) | |
430 | ;; the body of a catch is compiled (and thus optimized) as a | |
431 | ;; top-level form, so don't do it here. The tag is never | |
432 | ;; for-effect. The body should have the same for-effect status | |
433 | ;; as the catch form itself, but that isn't handled properly yet. | |
434 | (cons fn | |
435 | (cons (byte-optimize-form (nth 1 form) nil) | |
436 | (cdr (cdr form))))) | |
437 | ||
438 | ;; If optimization is on, this is the only place that macros are | |
439 | ;; expanded. If optimization is off, then macroexpansion happens | |
440 | ;; in byte-compile-form. Otherwise, the macros are already expanded | |
441 | ;; by the time that is reached. | |
442 | ((not (eq form | |
443 | (setq form (macroexpand form | |
444 | byte-compile-macro-environment)))) | |
445 | (byte-optimize-form form for-effect)) | |
446 | ||
447 | ((not (symbolp fn)) | |
448 | (or (eq 'mocklisp (car-safe fn)) ; ha! | |
449 | (byte-compile-warn "%s is a malformed function" | |
450 | (prin1-to-string fn))) | |
451 | form) | |
452 | ||
453 | ((and for-effect (setq tmp (get fn 'side-effect-free)) | |
454 | (or byte-compile-delete-errors | |
455 | (eq tmp 'error-free) | |
456 | (progn | |
457 | (byte-compile-warn "%s called for effect" | |
458 | (prin1-to-string form)) | |
459 | nil))) | |
460 | (byte-compile-log " %s called for effect; deleted" fn) | |
461 | ;; appending a nil here might not be necessary, but it can't hurt. | |
462 | (byte-optimize-form | |
463 | (cons 'progn (append (cdr form) '(nil))) t)) | |
464 | ||
465 | (t | |
466 | ;; Otherwise, no args can be considered to be for-effect, | |
467 | ;; even if the called function is for-effect, because we | |
468 | ;; don't know anything about that function. | |
469 | (cons fn (mapcar 'byte-optimize-form (cdr form))))))) | |
470 | ||
471 | ||
472 | (defun byte-optimize-form (form &optional for-effect) | |
473 | "The source-level pass of the optimizer." | |
474 | ;; | |
475 | ;; First, optimize all sub-forms of this one. | |
476 | (setq form (byte-optimize-form-code-walker form for-effect)) | |
477 | ;; | |
478 | ;; after optimizing all subforms, optimize this form until it doesn't | |
479 | ;; optimize any further. This means that some forms will be passed through | |
480 | ;; the optimizer many times, but that's necessary to make the for-effect | |
481 | ;; processing do as much as possible. | |
482 | ;; | |
483 | (let (opt new) | |
484 | (if (and (consp form) | |
485 | (symbolp (car form)) | |
486 | (or (and for-effect | |
487 | ;; we don't have any of these yet, but we might. | |
488 | (setq opt (get (car form) 'byte-for-effect-optimizer))) | |
489 | (setq opt (get (car form) 'byte-optimizer))) | |
490 | (not (eq form (setq new (funcall opt form))))) | |
491 | (progn | |
492 | ;; (if (equal form new) (error "bogus optimizer -- %s" opt)) | |
493 | (byte-compile-log " %s\t==>\t%s" form new) | |
494 | (setq new (byte-optimize-form new for-effect)) | |
495 | new) | |
496 | form))) | |
497 | ||
498 | ||
499 | (defun byte-optimize-body (forms all-for-effect) | |
500 | ;; optimize the cdr of a progn or implicit progn; all forms is a list of | |
501 | ;; forms, all but the last of which are optimized with the assumption that | |
502 | ;; they are being called for effect. the last is for-effect as well if | |
503 | ;; all-for-effect is true. returns a new list of forms. | |
504 | (let ((rest forms) | |
505 | (result nil) | |
506 | fe new) | |
507 | (while rest | |
508 | (setq fe (or all-for-effect (cdr rest))) | |
509 | (setq new (and (car rest) (byte-optimize-form (car rest) fe))) | |
510 | (if (or new (not fe)) | |
511 | (setq result (cons new result))) | |
512 | (setq rest (cdr rest))) | |
513 | (nreverse result))) | |
514 | ||
515 | \f | |
516 | ;;; some source-level optimizers | |
517 | ;;; | |
518 | ;;; when writing optimizers, be VERY careful that the optimizer returns | |
519 | ;;; something not EQ to its argument if and ONLY if it has made a change. | |
520 | ;;; This implies that you cannot simply destructively modify the list; | |
521 | ;;; you must return something not EQ to it if you make an optimization. | |
522 | ;;; | |
523 | ;;; It is now safe to optimize code such that it introduces new bindings. | |
524 | ||
525 | ;; I'd like this to be a defsubst, but let's not be self-referental... | |
526 | (defmacro byte-compile-trueconstp (form) | |
527 | ;; Returns non-nil if FORM is a non-nil constant. | |
528 | (` (cond ((consp (, form)) (eq (car (, form)) 'quote)) | |
529 | ((not (symbolp (, form)))) | |
530 | ((eq (, form) t))))) | |
531 | ||
70e1dad8 RS |
532 | ;; If the function is being called with constant numeric args, |
533 | ;; evaluate as much as possible at compile-time. This optimizer | |
534 | ;; assumes that the function is associative, like + or *. | |
1c393159 | 535 | (defun byte-optimize-associative-math (form) |
1c393159 JB |
536 | (let ((args nil) |
537 | (constants nil) | |
538 | (rest (cdr form))) | |
539 | (while rest | |
540 | (if (numberp (car rest)) | |
541 | (setq constants (cons (car rest) constants)) | |
542 | (setq args (cons (car rest) args))) | |
543 | (setq rest (cdr rest))) | |
544 | (if (cdr constants) | |
545 | (if args | |
546 | (list (car form) | |
547 | (apply (car form) constants) | |
548 | (if (cdr args) | |
549 | (cons (car form) (nreverse args)) | |
550 | (car args))) | |
551 | (apply (car form) constants)) | |
552 | form))) | |
553 | ||
70e1dad8 RS |
554 | ;; If the function is being called with constant numeric args, |
555 | ;; evaluate as much as possible at compile-time. This optimizer | |
556 | ;; assumes that the function is nonassociative, like - or /. | |
1c393159 | 557 | (defun byte-optimize-nonassociative-math (form) |
1c393159 JB |
558 | (if (or (not (numberp (car (cdr form)))) |
559 | (not (numberp (car (cdr (cdr form)))))) | |
560 | form | |
561 | (let ((constant (car (cdr form))) | |
562 | (rest (cdr (cdr form)))) | |
563 | (while (numberp (car rest)) | |
564 | (setq constant (funcall (car form) constant (car rest)) | |
565 | rest (cdr rest))) | |
566 | (if rest | |
567 | (cons (car form) (cons constant rest)) | |
568 | constant)))) | |
569 | ||
570 | ;;(defun byte-optimize-associative-two-args-math (form) | |
571 | ;; (setq form (byte-optimize-associative-math form)) | |
572 | ;; (if (consp form) | |
573 | ;; (byte-optimize-two-args-left form) | |
574 | ;; form)) | |
575 | ||
576 | ;;(defun byte-optimize-nonassociative-two-args-math (form) | |
577 | ;; (setq form (byte-optimize-nonassociative-math form)) | |
578 | ;; (if (consp form) | |
579 | ;; (byte-optimize-two-args-right form) | |
580 | ;; form)) | |
581 | ||
582 | (defun byte-optimize-delay-constants-math (form start fun) | |
583 | ;; Merge all FORM's constants from number START, call FUN on them | |
584 | ;; and put the result at the end. | |
585 | (let ((rest (nthcdr (1- start) form))) | |
586 | (while (cdr (setq rest (cdr rest))) | |
587 | (if (numberp (car rest)) | |
588 | (let (constants) | |
589 | (setq form (copy-sequence form) | |
590 | rest (nthcdr (1- start) form)) | |
591 | (while (setq rest (cdr rest)) | |
592 | (cond ((numberp (car rest)) | |
593 | (setq constants (cons (car rest) constants)) | |
594 | (setcar rest nil)))) | |
595 | (setq form (nconc (delq nil form) | |
596 | (list (apply fun (nreverse constants)))))))) | |
597 | form)) | |
598 | ||
599 | (defun byte-optimize-plus (form) | |
600 | (setq form (byte-optimize-delay-constants-math form 1 '+)) | |
601 | (if (memq 0 form) (setq form (delq 0 (copy-sequence form)))) | |
602 | ;;(setq form (byte-optimize-associative-two-args-math form)) | |
603 | (cond ((null (cdr form)) | |
604 | (condition-case () | |
605 | (eval form) | |
606 | (error form))) | |
607 | ((null (cdr (cdr form))) (nth 1 form)) | |
608 | (t form))) | |
609 | ||
610 | (defun byte-optimize-minus (form) | |
611 | ;; Put constants at the end, except the last constant. | |
612 | (setq form (byte-optimize-delay-constants-math form 2 '+)) | |
613 | ;; Now only first and last element can be a number. | |
614 | (let ((last (car (reverse (nthcdr 3 form))))) | |
615 | (cond ((eq 0 last) | |
616 | ;; (- x y ... 0) --> (- x y ...) | |
617 | (setq form (copy-sequence form)) | |
618 | (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form)))) | |
619 | ;; If form is (- CONST foo... CONST), merge first and last. | |
620 | ((and (numberp (nth 1 form)) | |
621 | (numberp last)) | |
622 | (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form)) | |
623 | (delq last (copy-sequence (nthcdr 3 form)))))))) | |
624 | (if (eq (nth 2 form) 0) | |
625 | (nth 1 form) ; (- x 0) --> x | |
626 | (byte-optimize-predicate | |
627 | (if (and (null (cdr (cdr (cdr form)))) | |
628 | (eq (nth 1 form) 0)) ; (- 0 x) --> (- x) | |
629 | (cons (car form) (cdr (cdr form))) | |
630 | form)))) | |
631 | ||
632 | (defun byte-optimize-multiply (form) | |
633 | (setq form (byte-optimize-delay-constants-math form 1 '*)) | |
634 | ;; If there is a constant in FORM, it is now the last element. | |
635 | (cond ((null (cdr form)) 1) | |
636 | ((null (cdr (cdr form))) (nth 1 form)) | |
637 | ((let ((last (car (reverse form)))) | |
638 | (cond ((eq 0 last) (list 'progn (cdr form))) | |
639 | ((eq 1 last) (delq 1 (copy-sequence form))) | |
640 | ((eq -1 last) (list '- (delq -1 (copy-sequence form)))) | |
641 | ((and (eq 2 last) | |
642 | (memq t (mapcar 'symbolp (cdr form)))) | |
643 | (prog1 (setq form (delq 2 (copy-sequence form))) | |
644 | (while (not (symbolp (car (setq form (cdr form)))))) | |
645 | (setcar form (list '+ (car form) (car form))))) | |
646 | (form)))))) | |
647 | ||
648 | (defsubst byte-compile-butlast (form) | |
649 | (nreverse (cdr (reverse form)))) | |
650 | ||
651 | (defun byte-optimize-divide (form) | |
652 | (setq form (byte-optimize-delay-constants-math form 2 '*)) | |
653 | (let ((last (car (reverse (cdr (cdr form)))))) | |
654 | (if (numberp last) | |
655 | (cond ((= last 1) | |
656 | (setq form (byte-compile-butlast form))) | |
657 | ((numberp (nth 1 form)) | |
658 | (setq form (cons (car form) | |
659 | (cons (/ (nth 1 form) last) | |
660 | (byte-compile-butlast (cdr (cdr form))))) | |
661 | last nil)))) | |
662 | (cond ((null (cdr (cdr form))) | |
663 | (nth 1 form)) | |
664 | ((eq (nth 1 form) 0) | |
665 | (append '(progn) (cdr (cdr form)) '(0))) | |
666 | ((eq last -1) | |
667 | (list '- (if (nthcdr 3 form) | |
668 | (byte-compile-butlast form) | |
669 | (nth 1 form)))) | |
670 | (form)))) | |
671 | ||
672 | (defun byte-optimize-logmumble (form) | |
673 | (setq form (byte-optimize-delay-constants-math form 1 (car form))) | |
674 | (byte-optimize-predicate | |
675 | (cond ((memq 0 form) | |
676 | (setq form (if (eq (car form) 'logand) | |
677 | (cons 'progn (cdr form)) | |
678 | (delq 0 (copy-sequence form))))) | |
679 | ((and (eq (car-safe form) 'logior) | |
680 | (memq -1 form)) | |
681 | (delq -1 (copy-sequence form))) | |
682 | (form)))) | |
683 | ||
684 | ||
685 | (defun byte-optimize-binary-predicate (form) | |
686 | (if (byte-compile-constp (nth 1 form)) | |
687 | (if (byte-compile-constp (nth 2 form)) | |
688 | (condition-case () | |
689 | (list 'quote (eval form)) | |
690 | (error form)) | |
691 | ;; This can enable some lapcode optimizations. | |
692 | (list (car form) (nth 2 form) (nth 1 form))) | |
693 | form)) | |
694 | ||
695 | (defun byte-optimize-predicate (form) | |
696 | (let ((ok t) | |
697 | (rest (cdr form))) | |
698 | (while (and rest ok) | |
699 | (setq ok (byte-compile-constp (car rest)) | |
700 | rest (cdr rest))) | |
701 | (if ok | |
702 | (condition-case () | |
703 | (list 'quote (eval form)) | |
704 | (error form)) | |
705 | form))) | |
706 | ||
707 | (defun byte-optimize-identity (form) | |
708 | (if (and (cdr form) (null (cdr (cdr form)))) | |
709 | (nth 1 form) | |
710 | (byte-compile-warn "identity called with %d arg%s, but requires 1" | |
711 | (length (cdr form)) | |
712 | (if (= 1 (length (cdr form))) "" "s")) | |
713 | form)) | |
714 | ||
715 | (put 'identity 'byte-optimizer 'byte-optimize-identity) | |
716 | ||
717 | (put '+ 'byte-optimizer 'byte-optimize-plus) | |
718 | (put '* 'byte-optimizer 'byte-optimize-multiply) | |
719 | (put '- 'byte-optimizer 'byte-optimize-minus) | |
720 | (put '/ 'byte-optimizer 'byte-optimize-divide) | |
721 | (put 'max 'byte-optimizer 'byte-optimize-associative-math) | |
722 | (put 'min 'byte-optimizer 'byte-optimize-associative-math) | |
723 | ||
724 | (put '= 'byte-optimizer 'byte-optimize-binary-predicate) | |
725 | (put 'eq 'byte-optimizer 'byte-optimize-binary-predicate) | |
726 | (put 'eql 'byte-optimizer 'byte-optimize-binary-predicate) | |
727 | (put 'equal 'byte-optimizer 'byte-optimize-binary-predicate) | |
728 | (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate) | |
729 | (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate) | |
730 | ||
731 | (put '< 'byte-optimizer 'byte-optimize-predicate) | |
732 | (put '> 'byte-optimizer 'byte-optimize-predicate) | |
733 | (put '<= 'byte-optimizer 'byte-optimize-predicate) | |
734 | (put '>= 'byte-optimizer 'byte-optimize-predicate) | |
735 | (put '1+ 'byte-optimizer 'byte-optimize-predicate) | |
736 | (put '1- 'byte-optimizer 'byte-optimize-predicate) | |
737 | (put 'not 'byte-optimizer 'byte-optimize-predicate) | |
738 | (put 'null 'byte-optimizer 'byte-optimize-predicate) | |
739 | (put 'memq 'byte-optimizer 'byte-optimize-predicate) | |
740 | (put 'consp 'byte-optimizer 'byte-optimize-predicate) | |
741 | (put 'listp 'byte-optimizer 'byte-optimize-predicate) | |
742 | (put 'symbolp 'byte-optimizer 'byte-optimize-predicate) | |
743 | (put 'stringp 'byte-optimizer 'byte-optimize-predicate) | |
744 | (put 'string< 'byte-optimizer 'byte-optimize-predicate) | |
745 | (put 'string-lessp 'byte-optimizer 'byte-optimize-predicate) | |
746 | ||
747 | (put 'logand 'byte-optimizer 'byte-optimize-logmumble) | |
748 | (put 'logior 'byte-optimizer 'byte-optimize-logmumble) | |
749 | (put 'logxor 'byte-optimizer 'byte-optimize-logmumble) | |
750 | (put 'lognot 'byte-optimizer 'byte-optimize-predicate) | |
751 | ||
752 | (put 'car 'byte-optimizer 'byte-optimize-predicate) | |
753 | (put 'cdr 'byte-optimizer 'byte-optimize-predicate) | |
754 | (put 'car-safe 'byte-optimizer 'byte-optimize-predicate) | |
755 | (put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate) | |
756 | ||
757 | ||
758 | ;; I'm not convinced that this is necessary. Doesn't the optimizer loop | |
759 | ;; take care of this? - Jamie | |
760 | ;; I think this may some times be necessary to reduce ie (quote 5) to 5, | |
761 | ;; so arithmetic optimizers recognize the numerinc constant. - Hallvard | |
762 | (put 'quote 'byte-optimizer 'byte-optimize-quote) | |
763 | (defun byte-optimize-quote (form) | |
764 | (if (or (consp (nth 1 form)) | |
765 | (and (symbolp (nth 1 form)) | |
766 | (not (memq (nth 1 form) '(nil t))))) | |
767 | form | |
768 | (nth 1 form))) | |
769 | ||
770 | (defun byte-optimize-zerop (form) | |
771 | (cond ((numberp (nth 1 form)) | |
772 | (eval form)) | |
773 | (byte-compile-delete-errors | |
774 | (list '= (nth 1 form) 0)) | |
775 | (form))) | |
776 | ||
777 | (put 'zerop 'byte-optimizer 'byte-optimize-zerop) | |
778 | ||
779 | (defun byte-optimize-and (form) | |
780 | ;; Simplify if less than 2 args. | |
781 | ;; if there is a literal nil in the args to `and', throw it and following | |
782 | ;; forms away, and surround the `and' with (progn ... nil). | |
783 | (cond ((null (cdr form))) | |
784 | ((memq nil form) | |
785 | (list 'progn | |
786 | (byte-optimize-and | |
787 | (prog1 (setq form (copy-sequence form)) | |
788 | (while (nth 1 form) | |
789 | (setq form (cdr form))) | |
790 | (setcdr form nil))) | |
791 | nil)) | |
792 | ((null (cdr (cdr form))) | |
793 | (nth 1 form)) | |
794 | ((byte-optimize-predicate form)))) | |
795 | ||
796 | (defun byte-optimize-or (form) | |
797 | ;; Throw away nil's, and simplify if less than 2 args. | |
798 | ;; If there is a literal non-nil constant in the args to `or', throw away all | |
799 | ;; following forms. | |
800 | (if (memq nil form) | |
801 | (setq form (delq nil (copy-sequence form)))) | |
802 | (let ((rest form)) | |
803 | (while (cdr (setq rest (cdr rest))) | |
804 | (if (byte-compile-trueconstp (car rest)) | |
805 | (setq form (copy-sequence form) | |
806 | rest (setcdr (memq (car rest) form) nil)))) | |
807 | (if (cdr (cdr form)) | |
808 | (byte-optimize-predicate form) | |
809 | (nth 1 form)))) | |
810 | ||
811 | (defun byte-optimize-cond (form) | |
812 | ;; if any clauses have a literal nil as their test, throw them away. | |
813 | ;; if any clause has a literal non-nil constant as its test, throw | |
814 | ;; away all following clauses. | |
815 | (let (rest) | |
816 | ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...) | |
817 | (while (setq rest (assq nil (cdr form))) | |
818 | (setq form (delq rest (copy-sequence form)))) | |
819 | (if (memq nil (cdr form)) | |
820 | (setq form (delq nil (copy-sequence form)))) | |
821 | (setq rest form) | |
822 | (while (setq rest (cdr rest)) | |
823 | (cond ((byte-compile-trueconstp (car-safe (car rest))) | |
824 | (cond ((eq rest (cdr form)) | |
825 | (setq form | |
826 | (if (cdr (car rest)) | |
827 | (if (cdr (cdr (car rest))) | |
828 | (cons 'progn (cdr (car rest))) | |
829 | (nth 1 (car rest))) | |
830 | (car (car rest))))) | |
831 | ((cdr rest) | |
832 | (setq form (copy-sequence form)) | |
833 | (setcdr (memq (car rest) form) nil))) | |
834 | (setq rest nil))))) | |
835 | ;; | |
836 | ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... )) | |
837 | (if (eq 'cond (car-safe form)) | |
838 | (let ((clauses (cdr form))) | |
839 | (if (and (consp (car clauses)) | |
840 | (null (cdr (car clauses)))) | |
841 | (list 'or (car (car clauses)) | |
842 | (byte-optimize-cond | |
843 | (cons (car form) (cdr (cdr form))))) | |
844 | form)) | |
845 | form)) | |
846 | ||
847 | (defun byte-optimize-if (form) | |
848 | ;; (if <true-constant> <then> <else...>) ==> <then> | |
849 | ;; (if <false-constant> <then> <else...>) ==> (progn <else...>) | |
850 | ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>)) | |
851 | ;; (if <test> <then> nil) ==> (if <test> <then>) | |
852 | (let ((clause (nth 1 form))) | |
853 | (cond ((byte-compile-trueconstp clause) | |
854 | (nth 2 form)) | |
855 | ((null clause) | |
856 | (if (nthcdr 4 form) | |
857 | (cons 'progn (nthcdr 3 form)) | |
858 | (nth 3 form))) | |
859 | ((nth 2 form) | |
860 | (if (equal '(nil) (nthcdr 3 form)) | |
861 | (list 'if clause (nth 2 form)) | |
862 | form)) | |
863 | ((or (nth 3 form) (nthcdr 4 form)) | |
864 | (list 'if (list 'not clause) | |
865 | (if (nthcdr 4 form) | |
866 | (cons 'progn (nthcdr 3 form)) | |
867 | (nth 3 form)))) | |
868 | (t | |
869 | (list 'progn clause nil))))) | |
870 | ||
871 | (defun byte-optimize-while (form) | |
872 | (if (nth 1 form) | |
873 | form)) | |
874 | ||
875 | (put 'and 'byte-optimizer 'byte-optimize-and) | |
876 | (put 'or 'byte-optimizer 'byte-optimize-or) | |
877 | (put 'cond 'byte-optimizer 'byte-optimize-cond) | |
878 | (put 'if 'byte-optimizer 'byte-optimize-if) | |
879 | (put 'while 'byte-optimizer 'byte-optimize-while) | |
880 | ||
881 | ;; byte-compile-negation-optimizer lives in bytecomp.el | |
882 | (put '/= 'byte-optimizer 'byte-compile-negation-optimizer) | |
883 | (put 'atom 'byte-optimizer 'byte-compile-negation-optimizer) | |
884 | (put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer) | |
885 | ||
886 | ||
887 | (defun byte-optimize-funcall (form) | |
888 | ;; (funcall '(lambda ...) ...) ==> ((lambda ...) ...) | |
889 | ;; (funcall 'foo ...) ==> (foo ...) | |
890 | (let ((fn (nth 1 form))) | |
891 | (if (memq (car-safe fn) '(quote function)) | |
892 | (cons (nth 1 fn) (cdr (cdr form))) | |
893 | form))) | |
894 | ||
895 | (defun byte-optimize-apply (form) | |
896 | ;; If the last arg is a literal constant, turn this into a funcall. | |
897 | ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...). | |
898 | (let ((fn (nth 1 form)) | |
899 | (last (nth (1- (length form)) form))) ; I think this really is fastest | |
900 | (or (if (or (null last) | |
901 | (eq (car-safe last) 'quote)) | |
902 | (if (listp (nth 1 last)) | |
903 | (let ((butlast (nreverse (cdr (reverse (cdr (cdr form))))))) | |
904 | (nconc (list 'funcall fn) butlast (nth 1 last))) | |
905 | (byte-compile-warn | |
906 | "last arg to apply can't be a literal atom: %s" | |
907 | (prin1-to-string last)) | |
908 | nil)) | |
909 | form))) | |
910 | ||
911 | (put 'funcall 'byte-optimizer 'byte-optimize-funcall) | |
912 | (put 'apply 'byte-optimizer 'byte-optimize-apply) | |
913 | ||
914 | ||
915 | (put 'let 'byte-optimizer 'byte-optimize-letX) | |
916 | (put 'let* 'byte-optimizer 'byte-optimize-letX) | |
917 | (defun byte-optimize-letX (form) | |
918 | (cond ((null (nth 1 form)) | |
919 | ;; No bindings | |
920 | (cons 'progn (cdr (cdr form)))) | |
921 | ((or (nth 2 form) (nthcdr 3 form)) | |
922 | form) | |
923 | ;; The body is nil | |
924 | ((eq (car form) 'let) | |
925 | (append '(progn) (mapcar 'car (mapcar 'cdr (nth 1 form))) '(nil))) | |
926 | (t | |
927 | (let ((binds (reverse (nth 1 form)))) | |
928 | (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil))))) | |
929 | ||
930 | ||
931 | (put 'nth 'byte-optimizer 'byte-optimize-nth) | |
932 | (defun byte-optimize-nth (form) | |
933 | (if (memq (nth 1 form) '(0 1)) | |
934 | (list 'car (if (zerop (nth 1 form)) | |
935 | (nth 2 form) | |
936 | (list 'cdr (nth 2 form)))) | |
937 | (byte-optimize-predicate form))) | |
938 | ||
939 | (put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr) | |
940 | (defun byte-optimize-nthcdr (form) | |
941 | (let ((count (nth 1 form))) | |
942 | (if (not (memq count '(0 1 2))) | |
943 | (byte-optimize-predicate form) | |
944 | (setq form (nth 2 form)) | |
945 | (while (natnump (setq count (1- count))) | |
946 | (setq form (list 'cdr form))) | |
947 | form))) | |
948 | \f | |
949 | ;;; enumerating those functions which need not be called if the returned | |
950 | ;;; value is not used. That is, something like | |
951 | ;;; (progn (list (something-with-side-effects) (yow)) | |
952 | ;;; (foo)) | |
953 | ;;; may safely be turned into | |
954 | ;;; (progn (progn (something-with-side-effects) (yow)) | |
955 | ;;; (foo)) | |
956 | ;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo. | |
957 | ||
958 | ;;; I wonder if I missed any :-\) | |
959 | (let ((side-effect-free-fns | |
960 | '(% * + / /= 1+ < <= = > >= append aref ash assoc assq boundp | |
961 | buffer-file-name buffer-local-variables buffer-modified-p | |
962 | buffer-substring capitalize car cdr concat coordinates-in-window-p | |
963 | copy-marker count-lines documentation downcase elt fboundp featurep | |
964 | file-directory-p file-exists-p file-locked-p file-name-absolute-p | |
965 | file-newer-than-file-p file-readable-p file-symlink-p file-writable-p | |
966 | format get get-buffer get-buffer-window getenv get-file-buffer length | |
967 | logand logior lognot logxor lsh marker-buffer max member memq min mod | |
968 | next-window nth nthcdr previous-window rassq regexp-quote reverse | |
969 | string< string= string-lessp string-equal substring user-variable-p | |
970 | window-buffer window-edges window-height window-hscroll window-width | |
971 | zerop)) | |
972 | ;; could also add plusp, minusp, signum. If anyone ever defines | |
973 | ;; these, they will certainly be side-effect free. | |
974 | (side-effect-and-error-free-fns | |
975 | '(arrayp atom bobp bolp buffer-end buffer-list buffer-size | |
976 | buffer-string bufferp char-or-string-p commandp cons consp | |
977 | current-buffer dot dot-marker eobp eolp eq eql equal | |
978 | get-largest-window identity integerp integer-or-marker-p | |
979 | interactive-p keymapp list listp make-marker mark mark-marker | |
980 | markerp minibuffer-window natnump nlistp not null numberp | |
981 | one-window-p point point-marker processp selected-window sequencep | |
982 | stringp subrp symbolp syntax-table-p vector vectorp windowp))) | |
983 | (while side-effect-free-fns | |
984 | (put (car side-effect-free-fns) 'side-effect-free t) | |
985 | (setq side-effect-free-fns (cdr side-effect-free-fns))) | |
986 | (while side-effect-and-error-free-fns | |
987 | (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free) | |
988 | (setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns))) | |
989 | nil) | |
990 | ||
991 | ||
992 | (defun byte-compile-splice-in-already-compiled-code (form) | |
993 | ;; form is (byte-code "..." [...] n) | |
994 | (if (not (memq byte-optimize '(t lap))) | |
995 | (byte-compile-normal-call form) | |
996 | (byte-inline-lapcode | |
997 | (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t)) | |
998 | (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form)) | |
999 | byte-compile-maxdepth)) | |
1000 | (setq byte-compile-depth (1+ byte-compile-depth)))) | |
1001 | ||
1002 | (put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code) | |
1003 | ||
1004 | \f | |
1005 | (defconst byte-constref-ops | |
1006 | '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind)) | |
1007 | ||
1008 | ;;; This function extracts the bitfields from variable-length opcodes. | |
1009 | ;;; Originally defined in disass.el (which no longer uses it.) | |
1010 | ||
1011 | (defun disassemble-offset () | |
1012 | "Don't call this!" | |
1013 | ;; fetch and return the offset for the current opcode. | |
1014 | ;; return NIL if this opcode has no offset | |
1015 | ;; OP, PTR and BYTES are used and set dynamically | |
1016 | (defvar op) | |
1017 | (defvar ptr) | |
1018 | (defvar bytes) | |
1019 | (cond ((< op byte-nth) | |
1020 | (let ((tem (logand op 7))) | |
1021 | (setq op (logand op 248)) | |
1022 | (cond ((eq tem 6) | |
1023 | (setq ptr (1+ ptr)) ;offset in next byte | |
1024 | (aref bytes ptr)) | |
1025 | ((eq tem 7) | |
1026 | (setq ptr (1+ ptr)) ;offset in next 2 bytes | |
1027 | (+ (aref bytes ptr) | |
1028 | (progn (setq ptr (1+ ptr)) | |
1029 | (lsh (aref bytes ptr) 8)))) | |
1030 | (t tem)))) ;offset was in opcode | |
1031 | ((>= op byte-constant) | |
1032 | (prog1 (- op byte-constant) ;offset in opcode | |
1033 | (setq op byte-constant))) | |
1034 | ((and (>= op byte-constant2) | |
1035 | (<= op byte-goto-if-not-nil-else-pop)) | |
1036 | (setq ptr (1+ ptr)) ;offset in next 2 bytes | |
1037 | (+ (aref bytes ptr) | |
1038 | (progn (setq ptr (1+ ptr)) | |
1039 | (lsh (aref bytes ptr) 8)))) | |
3eac9910 | 1040 | ((and (>= op byte-listN) |
1c393159 JB |
1041 | (<= op byte-insertN)) |
1042 | (setq ptr (1+ ptr)) ;offset in next byte | |
1043 | (aref bytes ptr)))) | |
1044 | ||
1045 | ||
1046 | ;;; This de-compiler is used for inline expansion of compiled functions, | |
1047 | ;;; and by the disassembler. | |
1048 | ;;; | |
1049 | (defun byte-decompile-bytecode (bytes constvec) | |
1050 | "Turns BYTECODE into lapcode, refering to CONSTVEC." | |
1051 | (let ((byte-compile-constants nil) | |
1052 | (byte-compile-variables nil) | |
1053 | (byte-compile-tag-number 0)) | |
1054 | (byte-decompile-bytecode-1 bytes constvec))) | |
1055 | ||
70e1dad8 RS |
1056 | ;; As byte-decompile-bytecode, but updates |
1057 | ;; byte-compile-{constants, variables, tag-number}. | |
1058 | ;; If the optional 3rd arg is true, then `return' opcodes are replaced | |
1059 | ;; with `goto's destined for the end of the code. | |
1c393159 | 1060 | (defun byte-decompile-bytecode-1 (bytes constvec &optional make-splicable) |
1c393159 JB |
1061 | (let ((length (length bytes)) |
1062 | (ptr 0) optr tag tags op offset | |
1063 | lap tmp | |
1064 | endtag | |
1065 | (retcount 0)) | |
1066 | (while (not (= ptr length)) | |
1067 | (setq op (aref bytes ptr) | |
1068 | optr ptr | |
1069 | offset (disassemble-offset)) ; this does dynamic-scope magic | |
1070 | (setq op (aref byte-code-vector op)) | |
3eac9910 | 1071 | (cond ((memq op byte-goto-ops) |
1c393159 JB |
1072 | ;; it's a pc |
1073 | (setq offset | |
1074 | (cdr (or (assq offset tags) | |
1075 | (car (setq tags | |
1076 | (cons (cons offset | |
1077 | (byte-compile-make-tag)) | |
1078 | tags))))))) | |
1079 | ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t) | |
1080 | ((memq op byte-constref-ops))) | |
1081 | (setq tmp (aref constvec offset) | |
1082 | offset (if (eq op 'byte-constant) | |
1083 | (byte-compile-get-constant tmp) | |
1084 | (or (assq tmp byte-compile-variables) | |
1085 | (car (setq byte-compile-variables | |
1086 | (cons (list tmp) | |
1087 | byte-compile-variables))))))) | |
1088 | ((and make-splicable | |
1089 | (eq op 'byte-return)) | |
1090 | (if (= ptr (1- length)) | |
1091 | (setq op nil) | |
1092 | (setq offset (or endtag (setq endtag (byte-compile-make-tag))) | |
1093 | op 'byte-goto)))) | |
1094 | ;; lap = ( [ (pc . (op . arg)) ]* ) | |
1095 | (setq lap (cons (cons optr (cons op (or offset 0))) | |
1096 | lap)) | |
1097 | (setq ptr (1+ ptr))) | |
1098 | ;; take off the dummy nil op that we replaced a trailing "return" with. | |
1099 | (let ((rest lap)) | |
1100 | (while rest | |
1101 | (cond ((setq tmp (assq (car (car rest)) tags)) | |
1102 | ;; this addr is jumped to | |
1103 | (setcdr rest (cons (cons nil (cdr tmp)) | |
1104 | (cdr rest))) | |
1105 | (setq tags (delq tmp tags)) | |
1106 | (setq rest (cdr rest)))) | |
1107 | (setq rest (cdr rest)))) | |
1108 | (if tags (error "optimizer error: missed tags %s" tags)) | |
1109 | (if (null (car (cdr (car lap)))) | |
1110 | (setq lap (cdr lap))) | |
1111 | (if endtag | |
1112 | (setq lap (cons (cons nil endtag) lap))) | |
1113 | ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* ) | |
1114 | (mapcar 'cdr (nreverse lap)))) | |
1115 | ||
1116 | \f | |
1117 | ;;; peephole optimizer | |
1118 | ||
1119 | (defconst byte-tagref-ops (cons 'TAG byte-goto-ops)) | |
1120 | ||
1121 | (defconst byte-conditional-ops | |
1122 | '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop | |
1123 | byte-goto-if-not-nil-else-pop)) | |
1124 | ||
1125 | (defconst byte-after-unbind-ops | |
1126 | '(byte-constant byte-dup | |
1127 | byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp | |
1128 | byte-eq byte-equal byte-not | |
1129 | byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4 | |
1130 | byte-interactive-p | |
1131 | ;; How about other side-effect-free-ops? Is it safe to move an | |
1132 | ;; error invocation (such as from nth) out of an unwind-protect? | |
1133 | "Byte-codes that can be moved past an unbind.")) | |
1134 | ||
1135 | (defconst byte-compile-side-effect-and-error-free-ops | |
1136 | '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp | |
1137 | byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe | |
1138 | byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max | |
1139 | byte-point-min byte-following-char byte-preceding-char | |
1140 | byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp | |
1141 | byte-current-buffer byte-interactive-p)) | |
1142 | ||
1143 | (defconst byte-compile-side-effect-free-ops | |
1144 | (nconc | |
1145 | '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref | |
1146 | byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1 | |
1147 | byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate | |
1148 | byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax | |
1149 | byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt | |
1150 | byte-member byte-assq byte-quo byte-rem) | |
1151 | byte-compile-side-effect-and-error-free-ops)) | |
1152 | ||
1153 | ;;; This piece of shit is because of the way DEFVAR_BOOL() variables work. | |
1154 | ;;; Consider the code | |
1155 | ;;; | |
1156 | ;;; (defun foo (flag) | |
1157 | ;;; (let ((old-pop-ups pop-up-windows) | |
1158 | ;;; (pop-up-windows flag)) | |
1159 | ;;; (cond ((not (eq pop-up-windows old-pop-ups)) | |
1160 | ;;; (setq old-pop-ups pop-up-windows) | |
1161 | ;;; ...)))) | |
1162 | ;;; | |
1163 | ;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is | |
1164 | ;;; something else. But if we optimize | |
1165 | ;;; | |
1166 | ;;; varref flag | |
1167 | ;;; varbind pop-up-windows | |
1168 | ;;; varref pop-up-windows | |
1169 | ;;; not | |
1170 | ;;; to | |
1171 | ;;; varref flag | |
1172 | ;;; dup | |
1173 | ;;; varbind pop-up-windows | |
1174 | ;;; not | |
1175 | ;;; | |
1176 | ;;; we break the program, because it will appear that pop-up-windows and | |
1177 | ;;; old-pop-ups are not EQ when really they are. So we have to know what | |
1178 | ;;; the BOOL variables are, and not perform this optimization on them. | |
1179 | ;;; | |
1180 | (defconst byte-boolean-vars | |
3eac9910 JB |
1181 | '(abbrev-all-caps abbrevs-changed byte-metering-on |
1182 | check-protected-fields completion-auto-help completion-ignore-case | |
1183 | cursor-in-echo-area debug-on-next-call debug-on-quit | |
1184 | defining-kbd-macro delete-exited-processes | |
1185 | enable-recursive-minibuffers indent-tabs-mode | |
1186 | insert-default-directory inverse-video load-in-progress | |
1187 | menu-prompting mode-line-inverse-video no-redraw-on-reenter | |
1188 | noninteractive parse-sexp-ignore-comments pop-up-frames | |
1189 | pop-up-windows print-escape-newlines print-escape-newlines | |
1190 | truncate-partial-width-windows visible-bell vms-stmlf-recfm | |
1191 | words-include-escapes x-save-under) | |
1c393159 JB |
1192 | "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t. |
1193 | If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer | |
1194 | may generate incorrect code.") | |
1195 | ||
1196 | (defun byte-optimize-lapcode (lap &optional for-effect) | |
1197 | "Simple peephole optimizer. LAP is both modified and returned." | |
1198 | (let (lap0 off0 | |
1199 | lap1 off1 | |
1200 | lap2 off2 | |
1201 | (keep-going 'first-time) | |
1202 | (add-depth 0) | |
1203 | rest tmp tmp2 tmp3 | |
1204 | (side-effect-free (if byte-compile-delete-errors | |
1205 | byte-compile-side-effect-free-ops | |
1206 | byte-compile-side-effect-and-error-free-ops))) | |
1207 | (while keep-going | |
1208 | (or (eq keep-going 'first-time) | |
1209 | (byte-compile-log-lap " ---- next pass")) | |
1210 | (setq rest lap | |
1211 | keep-going nil) | |
1212 | (while rest | |
1213 | (setq lap0 (car rest) | |
1214 | lap1 (nth 1 rest) | |
1215 | lap2 (nth 2 rest)) | |
1216 | ||
1217 | ;; You may notice that sequences like "dup varset discard" are | |
1218 | ;; optimized but sequences like "dup varset TAG1: discard" are not. | |
1219 | ;; You may be tempted to change this; resist that temptation. | |
1220 | (cond ;; | |
1221 | ;; <side-effect-free> pop --> <deleted> | |
1222 | ;; ...including: | |
1223 | ;; const-X pop --> <deleted> | |
1224 | ;; varref-X pop --> <deleted> | |
1225 | ;; dup pop --> <deleted> | |
1226 | ;; | |
1227 | ((and (eq 'byte-discard (car lap1)) | |
1228 | (memq (car lap0) side-effect-free)) | |
1229 | (setq keep-going t) | |
1230 | (setq tmp (aref byte-stack+-info (symbol-value (car lap0)))) | |
1231 | (setq rest (cdr rest)) | |
1232 | (cond ((= tmp 1) | |
1233 | (byte-compile-log-lap | |
1234 | " %s discard\t-->\t<deleted>" lap0) | |
1235 | (setq lap (delq lap0 (delq lap1 lap)))) | |
1236 | ((= tmp 0) | |
1237 | (byte-compile-log-lap | |
1238 | " %s discard\t-->\t<deleted> discard" lap0) | |
1239 | (setq lap (delq lap0 lap))) | |
1240 | ((= tmp -1) | |
1241 | (byte-compile-log-lap | |
1242 | " %s discard\t-->\tdiscard discard" lap0) | |
1243 | (setcar lap0 'byte-discard) | |
1244 | (setcdr lap0 0)) | |
1245 | ((error "Optimizer error: too much on the stack")))) | |
1246 | ;; | |
1247 | ;; goto*-X X: --> X: | |
1248 | ;; | |
1249 | ((and (memq (car lap0) byte-goto-ops) | |
1250 | (eq (cdr lap0) lap1)) | |
1251 | (cond ((eq (car lap0) 'byte-goto) | |
1252 | (setq lap (delq lap0 lap)) | |
1253 | (setq tmp "<deleted>")) | |
1254 | ((memq (car lap0) byte-goto-always-pop-ops) | |
1255 | (setcar lap0 (setq tmp 'byte-discard)) | |
1256 | (setcdr lap0 0)) | |
1257 | ((error "Depth conflict at tag %d" (nth 2 lap0)))) | |
1258 | (and (memq byte-optimize-log '(t byte)) | |
1259 | (byte-compile-log " (goto %s) %s:\t-->\t%s %s:" | |
1260 | (nth 1 lap1) (nth 1 lap1) | |
1261 | tmp (nth 1 lap1))) | |
1262 | (setq keep-going t)) | |
1263 | ;; | |
1264 | ;; varset-X varref-X --> dup varset-X | |
1265 | ;; varbind-X varref-X --> dup varbind-X | |
1266 | ;; const/dup varset-X varref-X --> const/dup varset-X const/dup | |
1267 | ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup | |
1268 | ;; The latter two can enable other optimizations. | |
1269 | ;; | |
1270 | ((and (eq 'byte-varref (car lap2)) | |
1271 | (eq (cdr lap1) (cdr lap2)) | |
1272 | (memq (car lap1) '(byte-varset byte-varbind))) | |
1273 | (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars)) | |
1274 | (not (eq (car lap0) 'byte-constant))) | |
1275 | nil | |
1276 | (setq keep-going t) | |
1277 | (if (memq (car lap0) '(byte-constant byte-dup)) | |
1278 | (progn | |
1279 | (setq tmp (if (or (not tmp) | |
1280 | (memq (car (cdr lap0)) '(nil t))) | |
1281 | (cdr lap0) | |
1282 | (byte-compile-get-constant t))) | |
1283 | (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s" | |
1284 | lap0 lap1 lap2 lap0 lap1 | |
1285 | (cons (car lap0) tmp)) | |
1286 | (setcar lap2 (car lap0)) | |
1287 | (setcdr lap2 tmp)) | |
1288 | (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1) | |
1289 | (setcar lap2 (car lap1)) | |
1290 | (setcar lap1 'byte-dup) | |
1291 | (setcdr lap1 0) | |
1292 | ;; The stack depth gets locally increased, so we will | |
1293 | ;; increase maxdepth in case depth = maxdepth here. | |
1294 | ;; This can cause the third argument to byte-code to | |
1295 | ;; be larger than necessary. | |
1296 | (setq add-depth 1)))) | |
1297 | ;; | |
1298 | ;; dup varset-X discard --> varset-X | |
1299 | ;; dup varbind-X discard --> varbind-X | |
1300 | ;; (the varbind variant can emerge from other optimizations) | |
1301 | ;; | |
1302 | ((and (eq 'byte-dup (car lap0)) | |
1303 | (eq 'byte-discard (car lap2)) | |
1304 | (memq (car lap1) '(byte-varset byte-varbind))) | |
1305 | (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1) | |
1306 | (setq keep-going t | |
1307 | rest (cdr rest)) | |
1308 | (setq lap (delq lap0 (delq lap2 lap)))) | |
1309 | ;; | |
1310 | ;; not goto-X-if-nil --> goto-X-if-non-nil | |
1311 | ;; not goto-X-if-non-nil --> goto-X-if-nil | |
1312 | ;; | |
1313 | ;; it is wrong to do the same thing for the -else-pop variants. | |
1314 | ;; | |
1315 | ((and (eq 'byte-not (car lap0)) | |
1316 | (or (eq 'byte-goto-if-nil (car lap1)) | |
1317 | (eq 'byte-goto-if-not-nil (car lap1)))) | |
1318 | (byte-compile-log-lap " not %s\t-->\t%s" | |
1319 | lap1 | |
1320 | (cons | |
1321 | (if (eq (car lap1) 'byte-goto-if-nil) | |
1322 | 'byte-goto-if-not-nil | |
1323 | 'byte-goto-if-nil) | |
1324 | (cdr lap1))) | |
1325 | (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil) | |
1326 | 'byte-goto-if-not-nil | |
1327 | 'byte-goto-if-nil)) | |
1328 | (setq lap (delq lap0 lap)) | |
1329 | (setq keep-going t)) | |
1330 | ;; | |
1331 | ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X: | |
1332 | ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X: | |
1333 | ;; | |
1334 | ;; it is wrong to do the same thing for the -else-pop variants. | |
1335 | ;; | |
1336 | ((and (or (eq 'byte-goto-if-nil (car lap0)) | |
1337 | (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX | |
1338 | (eq 'byte-goto (car lap1)) ; gotoY | |
1339 | (eq (cdr lap0) lap2)) ; TAG X | |
1340 | (let ((inverse (if (eq 'byte-goto-if-nil (car lap0)) | |
1341 | 'byte-goto-if-not-nil 'byte-goto-if-nil))) | |
1342 | (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:" | |
1343 | lap0 lap1 lap2 | |
1344 | (cons inverse (cdr lap1)) lap2) | |
1345 | (setq lap (delq lap0 lap)) | |
1346 | (setcar lap1 inverse) | |
1347 | (setq keep-going t))) | |
1348 | ;; | |
1349 | ;; const goto-if-* --> whatever | |
1350 | ;; | |
1351 | ((and (eq 'byte-constant (car lap0)) | |
1352 | (memq (car lap1) byte-conditional-ops)) | |
1353 | (cond ((if (or (eq (car lap1) 'byte-goto-if-nil) | |
1354 | (eq (car lap1) 'byte-goto-if-nil-else-pop)) | |
1355 | (car (cdr lap0)) | |
1356 | (not (car (cdr lap0)))) | |
1357 | (byte-compile-log-lap " %s %s\t-->\t<deleted>" | |
1358 | lap0 lap1) | |
1359 | (setq rest (cdr rest) | |
1360 | lap (delq lap0 (delq lap1 lap)))) | |
1361 | (t | |
1362 | (if (memq (car lap1) byte-goto-always-pop-ops) | |
1363 | (progn | |
1364 | (byte-compile-log-lap " %s %s\t-->\t%s" | |
1365 | lap0 lap1 (cons 'byte-goto (cdr lap1))) | |
1366 | (setq lap (delq lap0 lap))) | |
1367 | (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 | |
1368 | (cons 'byte-goto (cdr lap1)))) | |
1369 | (setcar lap1 'byte-goto))) | |
1370 | (setq keep-going t)) | |
1371 | ;; | |
1372 | ;; varref-X varref-X --> varref-X dup | |
1373 | ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup | |
1374 | ;; We don't optimize the const-X variations on this here, | |
1375 | ;; because that would inhibit some goto optimizations; we | |
1376 | ;; optimize the const-X case after all other optimizations. | |
1377 | ;; | |
1378 | ((and (eq 'byte-varref (car lap0)) | |
1379 | (progn | |
1380 | (setq tmp (cdr rest)) | |
1381 | (while (eq (car (car tmp)) 'byte-dup) | |
1382 | (setq tmp (cdr tmp))) | |
1383 | t) | |
1384 | (eq (cdr lap0) (cdr (car tmp))) | |
1385 | (eq 'byte-varref (car (car tmp)))) | |
1386 | (if (memq byte-optimize-log '(t byte)) | |
1387 | (let ((str "")) | |
1388 | (setq tmp2 (cdr rest)) | |
1389 | (while (not (eq tmp tmp2)) | |
1390 | (setq tmp2 (cdr tmp2) | |
1391 | str (concat str " dup"))) | |
1392 | (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup" | |
1393 | lap0 str lap0 lap0 str))) | |
1394 | (setq keep-going t) | |
1395 | (setcar (car tmp) 'byte-dup) | |
1396 | (setcdr (car tmp) 0) | |
1397 | (setq rest tmp)) | |
1398 | ;; | |
1399 | ;; TAG1: TAG2: --> TAG1: <deleted> | |
1400 | ;; (and other references to TAG2 are replaced with TAG1) | |
1401 | ;; | |
1402 | ((and (eq (car lap0) 'TAG) | |
1403 | (eq (car lap1) 'TAG)) | |
1404 | (and (memq byte-optimize-log '(t byte)) | |
1405 | (byte-compile-log " adjascent tags %d and %d merged" | |
1406 | (nth 1 lap1) (nth 1 lap0))) | |
1407 | (setq tmp3 lap) | |
1408 | (while (setq tmp2 (rassq lap0 tmp3)) | |
1409 | (setcdr tmp2 lap1) | |
1410 | (setq tmp3 (cdr (memq tmp2 tmp3)))) | |
1411 | (setq lap (delq lap0 lap) | |
1412 | keep-going t)) | |
1413 | ;; | |
1414 | ;; unused-TAG: --> <deleted> | |
1415 | ;; | |
1416 | ((and (eq 'TAG (car lap0)) | |
1417 | (not (rassq lap0 lap))) | |
1418 | (and (memq byte-optimize-log '(t byte)) | |
1419 | (byte-compile-log " unused tag %d removed" (nth 1 lap0))) | |
1420 | (setq lap (delq lap0 lap) | |
1421 | keep-going t)) | |
1422 | ;; | |
1423 | ;; goto ... --> goto <delete until TAG or end> | |
1424 | ;; return ... --> return <delete until TAG or end> | |
1425 | ;; | |
1426 | ((and (memq (car lap0) '(byte-goto byte-return)) | |
1427 | (not (memq (car lap1) '(TAG nil)))) | |
1428 | (setq tmp rest) | |
1429 | (let ((i 0) | |
1430 | (opt-p (memq byte-optimize-log '(t lap))) | |
1431 | str deleted) | |
1432 | (while (and (setq tmp (cdr tmp)) | |
1433 | (not (eq 'TAG (car (car tmp))))) | |
1434 | (if opt-p (setq deleted (cons (car tmp) deleted) | |
1435 | str (concat str " %s") | |
1436 | i (1+ i)))) | |
1437 | (if opt-p | |
1438 | (let ((tagstr | |
1439 | (if (eq 'TAG (car (car tmp))) | |
1440 | (format "%d:" (cdr (car tmp))) | |
1441 | (or (car tmp) "")))) | |
1442 | (if (< i 6) | |
1443 | (apply 'byte-compile-log-lap-1 | |
1444 | (concat " %s" str | |
1445 | " %s\t-->\t%s <deleted> %s") | |
1446 | lap0 | |
1447 | (nconc (nreverse deleted) | |
1448 | (list tagstr lap0 tagstr))) | |
1449 | (byte-compile-log-lap | |
1450 | " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s" | |
1451 | lap0 i (if (= i 1) "" "s") | |
1452 | tagstr lap0 tagstr)))) | |
1453 | (rplacd rest tmp)) | |
1454 | (setq keep-going t)) | |
1455 | ;; | |
1456 | ;; <safe-op> unbind --> unbind <safe-op> | |
1457 | ;; (this may enable other optimizations.) | |
1458 | ;; | |
1459 | ((and (eq 'byte-unbind (car lap1)) | |
1460 | (memq (car lap0) byte-after-unbind-ops)) | |
1461 | (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0) | |
1462 | (setcar rest lap1) | |
1463 | (setcar (cdr rest) lap0) | |
1464 | (setq keep-going t)) | |
1465 | ;; | |
1466 | ;; varbind-X unbind-N --> discard unbind-(N-1) | |
1467 | ;; save-excursion unbind-N --> unbind-(N-1) | |
1468 | ;; save-restriction unbind-N --> unbind-(N-1) | |
1469 | ;; | |
1470 | ((and (eq 'byte-unbind (car lap1)) | |
1471 | (memq (car lap0) '(byte-varbind byte-save-excursion | |
1472 | byte-save-restriction)) | |
1473 | (< 0 (cdr lap1))) | |
1474 | (if (zerop (setcdr lap1 (1- (cdr lap1)))) | |
1475 | (delq lap1 rest)) | |
1476 | (if (eq (car lap0) 'byte-varbind) | |
1477 | (setcar rest (cons 'byte-discard 0)) | |
1478 | (setq lap (delq lap0 lap))) | |
1479 | (byte-compile-log-lap " %s %s\t-->\t%s %s" | |
1480 | lap0 (cons (car lap1) (1+ (cdr lap1))) | |
1481 | (if (eq (car lap0) 'byte-varbind) | |
1482 | (car rest) | |
1483 | (car (cdr rest))) | |
1484 | (if (and (/= 0 (cdr lap1)) | |
1485 | (eq (car lap0) 'byte-varbind)) | |
1486 | (car (cdr rest)) | |
1487 | "")) | |
1488 | (setq keep-going t)) | |
1489 | ;; | |
1490 | ;; goto*-X ... X: goto-Y --> goto*-Y | |
1491 | ;; goto-X ... X: return --> return | |
1492 | ;; | |
1493 | ((and (memq (car lap0) byte-goto-ops) | |
1494 | (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap)))) | |
1495 | '(byte-goto byte-return))) | |
1496 | (cond ((and (not (eq tmp lap0)) | |
1497 | (or (eq (car lap0) 'byte-goto) | |
1498 | (eq (car tmp) 'byte-goto))) | |
1499 | (byte-compile-log-lap " %s [%s]\t-->\t%s" | |
1500 | (car lap0) tmp tmp) | |
1501 | (if (eq (car tmp) 'byte-return) | |
1502 | (setcar lap0 'byte-return)) | |
1503 | (setcdr lap0 (cdr tmp)) | |
1504 | (setq keep-going t)))) | |
1505 | ;; | |
1506 | ;; goto-*-else-pop X ... X: goto-if-* --> whatever | |
1507 | ;; goto-*-else-pop X ... X: discard --> whatever | |
1508 | ;; | |
1509 | ((and (memq (car lap0) '(byte-goto-if-nil-else-pop | |
1510 | byte-goto-if-not-nil-else-pop)) | |
1511 | (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap))))) | |
1512 | (eval-when-compile | |
1513 | (cons 'byte-discard byte-conditional-ops))) | |
1514 | (not (eq lap0 (car tmp)))) | |
1515 | (setq tmp2 (car tmp)) | |
1516 | (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop | |
1517 | byte-goto-if-nil) | |
1518 | (byte-goto-if-not-nil-else-pop | |
1519 | byte-goto-if-not-nil)))) | |
1520 | (if (memq (car tmp2) tmp3) | |
1521 | (progn (setcar lap0 (car tmp2)) | |
1522 | (setcdr lap0 (cdr tmp2)) | |
1523 | (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s" | |
1524 | (car lap0) tmp2 lap0)) | |
1525 | ;; Get rid of the -else-pop's and jump one step further. | |
1526 | (or (eq 'TAG (car (nth 1 tmp))) | |
1527 | (setcdr tmp (cons (byte-compile-make-tag) | |
1528 | (cdr tmp)))) | |
1529 | (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>" | |
1530 | (car lap0) tmp2 (nth 1 tmp3)) | |
1531 | (setcar lap0 (nth 1 tmp3)) | |
1532 | (setcdr lap0 (nth 1 tmp))) | |
1533 | (setq keep-going t)) | |
1534 | ;; | |
1535 | ;; const goto-X ... X: goto-if-* --> whatever | |
1536 | ;; const goto-X ... X: discard --> whatever | |
1537 | ;; | |
1538 | ((and (eq (car lap0) 'byte-constant) | |
1539 | (eq (car lap1) 'byte-goto) | |
1540 | (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap))))) | |
1541 | (eval-when-compile | |
1542 | (cons 'byte-discard byte-conditional-ops))) | |
1543 | (not (eq lap1 (car tmp)))) | |
1544 | (setq tmp2 (car tmp)) | |
1545 | (cond ((memq (car tmp2) | |
1546 | (if (null (car (cdr lap0))) | |
1547 | '(byte-goto-if-nil byte-goto-if-nil-else-pop) | |
1548 | '(byte-goto-if-not-nil | |
1549 | byte-goto-if-not-nil-else-pop))) | |
1550 | (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s" | |
1551 | lap0 tmp2 lap0 tmp2) | |
1552 | (setcar lap1 (car tmp2)) | |
1553 | (setcdr lap1 (cdr tmp2)) | |
1554 | ;; Let next step fix the (const,goto-if*) sequence. | |
1555 | (setq rest (cons nil rest))) | |
1556 | (t | |
1557 | ;; Jump one step further | |
1558 | (byte-compile-log-lap | |
1559 | " %s goto [%s]\t-->\t<deleted> goto <skip>" | |
1560 | lap0 tmp2) | |
1561 | (or (eq 'TAG (car (nth 1 tmp))) | |
1562 | (setcdr tmp (cons (byte-compile-make-tag) | |
1563 | (cdr tmp)))) | |
1564 | (setcdr lap1 (car (cdr tmp))) | |
1565 | (setq lap (delq lap0 lap)))) | |
1566 | (setq keep-going t)) | |
1567 | ;; | |
1568 | ;; X: varref-Y ... varset-Y goto-X --> | |
1569 | ;; X: varref-Y Z: ... dup varset-Y goto-Z | |
1570 | ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.) | |
1571 | ;; (This is so usual for while loops that it is worth handling). | |
1572 | ;; | |
1573 | ((and (eq (car lap1) 'byte-varset) | |
1574 | (eq (car lap2) 'byte-goto) | |
1575 | (not (memq (cdr lap2) rest)) ;Backwards jump | |
1576 | (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap))))) | |
1577 | 'byte-varref) | |
1578 | (eq (cdr (car tmp)) (cdr lap1)) | |
1579 | (not (memq (car (cdr lap1)) byte-boolean-vars))) | |
1580 | ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp)) | |
1581 | (let ((newtag (byte-compile-make-tag))) | |
1582 | (byte-compile-log-lap | |
1583 | " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s" | |
1584 | (nth 1 (cdr lap2)) (car tmp) | |
1585 | lap1 lap2 | |
1586 | (nth 1 (cdr lap2)) (car tmp) | |
1587 | (nth 1 newtag) 'byte-dup lap1 | |
1588 | (cons 'byte-goto newtag) | |
1589 | ) | |
1590 | (setcdr rest (cons (cons 'byte-dup 0) (cdr rest))) | |
1591 | (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp)))) | |
1592 | (setq add-depth 1) | |
1593 | (setq keep-going t)) | |
1594 | ;; | |
1595 | ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y: | |
1596 | ;; (This can pull the loop test to the end of the loop) | |
1597 | ;; | |
1598 | ((and (eq (car lap0) 'byte-goto) | |
1599 | (eq (car lap1) 'TAG) | |
1600 | (eq lap1 | |
1601 | (cdr (car (setq tmp (cdr (memq (cdr lap0) lap)))))) | |
1602 | (memq (car (car tmp)) | |
1603 | '(byte-goto byte-goto-if-nil byte-goto-if-not-nil | |
1604 | byte-goto-if-nil-else-pop))) | |
1605 | ;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional" | |
1606 | ;; lap0 lap1 (cdr lap0) (car tmp)) | |
1607 | (let ((newtag (byte-compile-make-tag))) | |
1608 | (byte-compile-log-lap | |
1609 | "%s %s: ... %s: %s\t-->\t%s ... %s:" | |
1610 | lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp) | |
1611 | (cons (cdr (assq (car (car tmp)) | |
1612 | '((byte-goto-if-nil . byte-goto-if-not-nil) | |
1613 | (byte-goto-if-not-nil . byte-goto-if-nil) | |
1614 | (byte-goto-if-nil-else-pop . | |
1615 | byte-goto-if-not-nil-else-pop) | |
1616 | (byte-goto-if-not-nil-else-pop . | |
1617 | byte-goto-if-nil-else-pop)))) | |
1618 | newtag) | |
1619 | ||
1620 | (nth 1 newtag) | |
1621 | ) | |
1622 | (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp))) | |
1623 | (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop) | |
1624 | ;; We can handle this case but not the -if-not-nil case, | |
1625 | ;; because we won't know which non-nil constant to push. | |
1626 | (setcdr rest (cons (cons 'byte-constant | |
1627 | (byte-compile-get-constant nil)) | |
1628 | (cdr rest)))) | |
1629 | (setcar lap0 (nth 1 (memq (car (car tmp)) | |
1630 | '(byte-goto-if-nil-else-pop | |
1631 | byte-goto-if-not-nil | |
1632 | byte-goto-if-nil | |
1633 | byte-goto-if-not-nil | |
1634 | byte-goto byte-goto)))) | |
1635 | ) | |
1636 | (setq keep-going t)) | |
1637 | ) | |
1638 | (setq rest (cdr rest))) | |
1639 | ) | |
1640 | ;; Cleanup stage: | |
1641 | ;; Rebuild byte-compile-constants / byte-compile-variables. | |
1642 | ;; Simple optimizations that would inhibit other optimizations if they | |
1643 | ;; were done in the optimizing loop, and optimizations which there is no | |
1644 | ;; need to do more than once. | |
1645 | (setq byte-compile-constants nil | |
1646 | byte-compile-variables nil) | |
1647 | (setq rest lap) | |
1648 | (while rest | |
1649 | (setq lap0 (car rest) | |
1650 | lap1 (nth 1 rest)) | |
1651 | (if (memq (car lap0) byte-constref-ops) | |
1652 | (if (eq (cdr lap0) 'byte-constant) | |
1653 | (or (memq (cdr lap0) byte-compile-variables) | |
1654 | (setq byte-compile-variables (cons (cdr lap0) | |
1655 | byte-compile-variables))) | |
1656 | (or (memq (cdr lap0) byte-compile-constants) | |
1657 | (setq byte-compile-constants (cons (cdr lap0) | |
1658 | byte-compile-constants))))) | |
1659 | (cond (;; | |
1660 | ;; const-C varset-X const-C --> const-C dup varset-X | |
1661 | ;; const-C varbind-X const-C --> const-C dup varbind-X | |
1662 | ;; | |
1663 | (and (eq (car lap0) 'byte-constant) | |
1664 | (eq (car (nth 2 rest)) 'byte-constant) | |
1665 | (eq (cdr lap0) (car (nth 2 rest))) | |
1666 | (memq (car lap1) '(byte-varbind byte-varset))) | |
1667 | (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s" | |
1668 | lap0 lap1 lap0 lap0 lap1) | |
1669 | (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1))) | |
1670 | (setcar (cdr rest) (cons 'byte-dup 0)) | |
1671 | (setq add-depth 1)) | |
1672 | ;; | |
1673 | ;; const-X [dup/const-X ...] --> const-X [dup ...] dup | |
1674 | ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup | |
1675 | ;; | |
1676 | ((memq (car lap0) '(byte-constant byte-varref)) | |
1677 | (setq tmp rest | |
1678 | tmp2 nil) | |
1679 | (while (progn | |
1680 | (while (eq 'byte-dup (car (car (setq tmp (cdr tmp)))))) | |
1681 | (and (eq (cdr lap0) (cdr (car tmp))) | |
1682 | (eq (car lap0) (car (car tmp))))) | |
1683 | (setcar tmp (cons 'byte-dup 0)) | |
1684 | (setq tmp2 t)) | |
1685 | (if tmp2 | |
1686 | (byte-compile-log-lap | |
1687 | " %s [dup/%s]... %s\t-->\t%s dup..." lap0 lap0 lap0))) | |
1688 | ;; | |
1689 | ;; unbind-N unbind-M --> unbind-(N+M) | |
1690 | ;; | |
1691 | ((and (eq 'byte-unbind (car lap0)) | |
1692 | (eq 'byte-unbind (car lap1))) | |
1693 | (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 | |
1694 | (cons 'byte-unbind | |
1695 | (+ (cdr lap0) (cdr lap1)))) | |
1696 | (setq keep-going t) | |
1697 | (setq lap (delq lap0 lap)) | |
1698 | (setcdr lap1 (+ (cdr lap1) (cdr lap0)))) | |
1699 | ) | |
1700 | (setq rest (cdr rest))) | |
1701 | (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth))) | |
1702 | lap) | |
1703 | ||
1704 | (provide 'byte-optimize) | |
1705 | ||
1706 | \f | |
1707 | ;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles | |
1708 | ;; itself, compile some of its most used recursive functions (at load time). | |
1709 | ;; | |
1710 | (eval-when-compile | |
1711 | (or (compiled-function-p (symbol-function 'byte-optimize-form)) | |
1712 | (assq 'byte-code (symbol-function 'byte-optimize-form)) | |
1713 | (let ((byte-optimize nil) | |
1714 | (byte-compile-warnings nil)) | |
1715 | (mapcar '(lambda (x) | |
1716 | (or noninteractive (message "compiling %s..." x)) | |
1717 | (byte-compile x) | |
1718 | (or noninteractive (message "compiling %s...done" x))) | |
1719 | '(byte-optimize-form | |
1720 | byte-optimize-body | |
1721 | byte-optimize-predicate | |
1722 | byte-optimize-binary-predicate | |
1723 | ;; Inserted some more than necessary, to speed it up. | |
1724 | byte-optimize-form-code-walker | |
1725 | byte-optimize-lapcode)))) | |
1726 | nil) | |
3eac9910 JB |
1727 | |
1728 | ;;; byte-opt.el ends here |