1;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler. 2 3;;; Copyright (c) 1991, 1994 Free Software Foundation, Inc. 4 5;; Author: Jamie Zawinski <jwz@lucid.com> 6;; Hallvard Furuseth <hbf@ulrik.uio.no> 7;; Keywords: internal 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 13;; the Free Software Foundation; either version 2, or (at your option) 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 25;;; Commentary: 26 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;;; 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. 84;;; 85;;; Here is an example of an Emacs Lisp function which could safely be 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;;; 115;;; Wouldn't it be nice if Emacs Lisp had lexical scope. 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. 137 138;;; Code: 139 140(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)))) 176 177 178;;; 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)))) 198 199 200;; 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. 204(defun byte-inline-lapcode (lap) 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 (byte-code-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 (byte-code-function-p lambda) 237 (setq lambda (list 'lambda (aref lambda 0) 238 (list 'byte-code (aref lambda 1) 239 (aref lambda 2) (aref lambda 3))))) 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))))) 290 291 292;;; 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 (byte-code-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 conceivably 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))) 514 515 516;;; 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-referential... 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))))) 531 532;; 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 *. 535(defun byte-optimize-associative-math (form) 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))) 553 554;; 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 /. 557(defun byte-optimize-nonassociative-math (form) 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;;; It is not safe to delete the function entirely 608;;; (actually, it would be safe if we know the sole arg 609;;; is not a marker). 610;; ((null (cdr (cdr form))) (nth 1 form)) 611 (t form))) 612 613(defun byte-optimize-minus (form) 614 ;; Put constants at the end, except the last constant. 615 (setq form (byte-optimize-delay-constants-math form 2 '+)) 616 ;; Now only first and last element can be a number. 617 (let ((last (car (reverse (nthcdr 3 form))))) 618 (cond ((eq 0 last) 619 ;; (- x y ... 0) --> (- x y ...) 620 (setq form (copy-sequence form)) 621 (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form)))) 622 ;; If form is (- CONST foo... CONST), merge first and last. 623 ((and (numberp (nth 1 form)) 624 (numberp last)) 625 (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form)) 626 (delq last (copy-sequence (nthcdr 3 form)))))))) 627;;; It is not safe to delete the function entirely 628;;; (actually, it would be safe if we know the sole arg 629;;; is not a marker). 630;;; (if (eq (nth 2 form) 0) 631;;; (nth 1 form) ; (- x 0) --> x 632 (byte-optimize-predicate 633 (if (and (null (cdr (cdr (cdr form)))) 634 (eq (nth 1 form) 0)) ; (- 0 x) --> (- x) 635 (cons (car form) (cdr (cdr form))) 636 form)) 637;;; ) 638 ) 639 640(defun byte-optimize-multiply (form) 641 (setq form (byte-optimize-delay-constants-math form 1 '*)) 642 ;; If there is a constant in FORM, it is now the last element. 643 (cond ((null (cdr form)) 1) 644;;; It is not safe to delete the function entirely 645;;; (actually, it would be safe if we know the sole arg 646;;; is not a marker or if it appears in other arithmetic). 647;;; ((null (cdr (cdr form))) (nth 1 form)) 648 ((let ((last (car (reverse form)))) 649 (cond ((eq 0 last) (list 'progn (cdr form))) 650 ((eq 1 last) (delq 1 (copy-sequence form))) 651 ((eq -1 last) (list '- (delq -1 (copy-sequence form)))) 652 ((and (eq 2 last) 653 (memq t (mapcar 'symbolp (cdr form)))) 654 (prog1 (setq form (delq 2 (copy-sequence form))) 655 (while (not (symbolp (car (setq form (cdr form)))))) 656 (setcar form (list '+ (car form) (car form))))) 657 (form)))))) 658 659(defsubst byte-compile-butlast (form) 660 (nreverse (cdr (reverse form)))) 661 662(defun byte-optimize-divide (form) 663 (setq form (byte-optimize-delay-constants-math form 2 '*)) 664 (let ((last (car (reverse (cdr (cdr form)))))) 665 (if (numberp last) 666 (cond ((= (length form) 3) 667 ;; Don't shrink to less than two arguments--would get an error. 668 nil) 669 ((= last 1) 670 (setq form (byte-compile-butlast form))) 671 ((numberp (nth 1 form)) 672 (setq form (cons (car form) 673 (cons (/ (nth 1 form) last) 674 (byte-compile-butlast (cdr (cdr form))))) 675 last nil)))) 676 (cond 677;;; ((null (cdr (cdr form))) 678;;; (nth 1 form)) 679 ((eq (nth 1 form) 0) 680 (append '(progn) (cdr (cdr form)) '(0))) 681 ((eq last -1) 682 (list '- (if (nthcdr 3 form) 683 (byte-compile-butlast form) 684 (nth 1 form)))) 685 (form)))) 686 687(defun byte-optimize-logmumble (form) 688 (setq form (byte-optimize-delay-constants-math form 1 (car form))) 689 (byte-optimize-predicate 690 (cond ((memq 0 form) 691 (setq form (if (eq (car form) 'logand) 692 (cons 'progn (cdr form)) 693 (delq 0 (copy-sequence form))))) 694 ((and (eq (car-safe form) 'logior) 695 (memq -1 form)) 696 (delq -1 (copy-sequence form))) 697 (form)))) 698 699 700(defun byte-optimize-binary-predicate (form) 701 (if (byte-compile-constp (nth 1 form)) 702 (if (byte-compile-constp (nth 2 form)) 703 (condition-case () 704 (list 'quote (eval form)) 705 (error form)) 706 ;; This can enable some lapcode optimizations. 707 (list (car form) (nth 2 form) (nth 1 form))) 708 form)) 709 710(defun byte-optimize-predicate (form) 711 (let ((ok t) 712 (rest (cdr form))) 713 (while (and rest ok) 714 (setq ok (byte-compile-constp (car rest)) 715 rest (cdr rest))) 716 (if ok 717 (condition-case () 718 (list 'quote (eval form)) 719 (error form)) 720 form))) 721 722(defun byte-optimize-identity (form) 723 (if (and (cdr form) (null (cdr (cdr form)))) 724 (nth 1 form) 725 (byte-compile-warn "identity called with %d arg%s, but requires 1" 726 (length (cdr form)) 727 (if (= 1 (length (cdr form))) "" "s")) 728 form)) 729 730(put 'identity 'byte-optimizer 'byte-optimize-identity) 731 732(put '+ 'byte-optimizer 'byte-optimize-plus) 733(put '* 'byte-optimizer 'byte-optimize-multiply) 734(put '- 'byte-optimizer 'byte-optimize-minus) 735(put '/ 'byte-optimizer 'byte-optimize-divide) 736(put 'max 'byte-optimizer 'byte-optimize-associative-math) 737(put 'min 'byte-optimizer 'byte-optimize-associative-math) 738 739(put '= 'byte-optimizer 'byte-optimize-binary-predicate) 740(put 'eq 'byte-optimizer 'byte-optimize-binary-predicate) 741(put 'eql 'byte-optimizer 'byte-optimize-binary-predicate) 742(put 'equal 'byte-optimizer 'byte-optimize-binary-predicate) 743(put 'string= 'byte-optimizer 'byte-optimize-binary-predicate) 744(put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate) 745 746(put '< 'byte-optimizer 'byte-optimize-predicate) 747(put '> 'byte-optimizer 'byte-optimize-predicate) 748(put '<= 'byte-optimizer 'byte-optimize-predicate) 749(put '>= 'byte-optimizer 'byte-optimize-predicate) 750(put '1+ 'byte-optimizer 'byte-optimize-predicate) 751(put '1- 'byte-optimizer 'byte-optimize-predicate) 752(put 'not 'byte-optimizer 'byte-optimize-predicate) 753(put 'null 'byte-optimizer 'byte-optimize-predicate) 754(put 'memq 'byte-optimizer 'byte-optimize-predicate) 755(put 'consp 'byte-optimizer 'byte-optimize-predicate) 756(put 'listp 'byte-optimizer 'byte-optimize-predicate) 757(put 'symbolp 'byte-optimizer 'byte-optimize-predicate) 758(put 'stringp 'byte-optimizer 'byte-optimize-predicate) 759(put 'string< 'byte-optimizer 'byte-optimize-predicate) 760(put 'string-lessp 'byte-optimizer 'byte-optimize-predicate) 761 762(put 'logand 'byte-optimizer 'byte-optimize-logmumble) 763(put 'logior 'byte-optimizer 'byte-optimize-logmumble) 764(put 'logxor 'byte-optimizer 'byte-optimize-logmumble) 765(put 'lognot 'byte-optimizer 'byte-optimize-predicate) 766 767(put 'car 'byte-optimizer 'byte-optimize-predicate) 768(put 'cdr 'byte-optimizer 'byte-optimize-predicate) 769(put 'car-safe 'byte-optimizer 'byte-optimize-predicate) 770(put 'cdr-safe 'byte-optimizer 'byte-optimize-predicate) 771 772 773;; I'm not convinced that this is necessary. Doesn't the optimizer loop 774;; take care of this? - Jamie 775;; I think this may some times be necessary to reduce ie (quote 5) to 5, 776;; so arithmetic optimizers recognize the numeric constant. - Hallvard 777(put 'quote 'byte-optimizer 'byte-optimize-quote) 778(defun byte-optimize-quote (form) 779 (if (or (consp (nth 1 form)) 780 (and (symbolp (nth 1 form)) 781 (not (memq (nth 1 form) '(nil t))))) 782 form 783 (nth 1 form))) 784 785(defun byte-optimize-zerop (form) 786 (cond ((numberp (nth 1 form)) 787 (eval form)) 788 (byte-compile-delete-errors 789 (list '= (nth 1 form) 0)) 790 (form))) 791 792(put 'zerop 'byte-optimizer 'byte-optimize-zerop) 793 794(defun byte-optimize-and (form) 795 ;; Simplify if less than 2 args. 796 ;; if there is a literal nil in the args to `and', throw it and following 797 ;; forms away, and surround the `and' with (progn ... nil). 798 (cond ((null (cdr form))) 799 ((memq nil form) 800 (list 'progn 801 (byte-optimize-and 802 (prog1 (setq form (copy-sequence form)) 803 (while (nth 1 form) 804 (setq form (cdr form))) 805 (setcdr form nil))) 806 nil)) 807 ((null (cdr (cdr form))) 808 (nth 1 form)) 809 ((byte-optimize-predicate form)))) 810 811(defun byte-optimize-or (form) 812 ;; Throw away nil's, and simplify if less than 2 args. 813 ;; If there is a literal non-nil constant in the args to `or', throw away all 814 ;; following forms. 815 (if (memq nil form) 816 (setq form (delq nil (copy-sequence form)))) 817 (let ((rest form)) 818 (while (cdr (setq rest (cdr rest))) 819 (if (byte-compile-trueconstp (car rest)) 820 (setq form (copy-sequence form) 821 rest (setcdr (memq (car rest) form) nil)))) 822 (if (cdr (cdr form)) 823 (byte-optimize-predicate form) 824 (nth 1 form)))) 825 826(defun byte-optimize-cond (form) 827 ;; if any clauses have a literal nil as their test, throw them away. 828 ;; if any clause has a literal non-nil constant as its test, throw 829 ;; away all following clauses. 830 (let (rest) 831 ;; This must be first, to reduce (cond (t ...) (nil)) to (progn t ...) 832 (while (setq rest (assq nil (cdr form))) 833 (setq form (delq rest (copy-sequence form)))) 834 (if (memq nil (cdr form)) 835 (setq form (delq nil (copy-sequence form)))) 836 (setq rest form) 837 (while (setq rest (cdr rest)) 838 (cond ((byte-compile-trueconstp (car-safe (car rest))) 839 (cond ((eq rest (cdr form)) 840 (setq form 841 (if (cdr (car rest)) 842 (if (cdr (cdr (car rest))) 843 (cons 'progn (cdr (car rest))) 844 (nth 1 (car rest))) 845 (car (car rest))))) 846 ((cdr rest) 847 (setq form (copy-sequence form)) 848 (setcdr (memq (car rest) form) nil))) 849 (setq rest nil))))) 850 ;; 851 ;; Turn (cond (( <x> )) ... ) into (or <x> (cond ... )) 852 (if (eq 'cond (car-safe form)) 853 (let ((clauses (cdr form))) 854 (if (and (consp (car clauses)) 855 (null (cdr (car clauses)))) 856 (list 'or (car (car clauses)) 857 (byte-optimize-cond 858 (cons (car form) (cdr (cdr form))))) 859 form)) 860 form)) 861 862(defun byte-optimize-if (form) 863 ;; (if <true-constant> <then> <else...>) ==> <then> 864 ;; (if <false-constant> <then> <else...>) ==> (progn <else...>) 865 ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>)) 866 ;; (if <test> <then> nil) ==> (if <test> <then>) 867 (let ((clause (nth 1 form))) 868 (cond ((byte-compile-trueconstp clause) 869 (nth 2 form)) 870 ((null clause) 871 (if (nthcdr 4 form) 872 (cons 'progn (nthcdr 3 form)) 873 (nth 3 form))) 874 ((nth 2 form) 875 (if (equal '(nil) (nthcdr 3 form)) 876 (list 'if clause (nth 2 form)) 877 form)) 878 ((or (nth 3 form) (nthcdr 4 form)) 879 (list 'if (list 'not clause) 880 (if (nthcdr 4 form) 881 (cons 'progn (nthcdr 3 form)) 882 (nth 3 form)))) 883 (t 884 (list 'progn clause nil))))) 885 886(defun byte-optimize-while (form) 887 (if (nth 1 form) 888 form)) 889 890(put 'and 'byte-optimizer 'byte-optimize-and) 891(put 'or 'byte-optimizer 'byte-optimize-or) 892(put 'cond 'byte-optimizer 'byte-optimize-cond) 893(put 'if 'byte-optimizer 'byte-optimize-if) 894(put 'while 'byte-optimizer 'byte-optimize-while) 895 896;; byte-compile-negation-optimizer lives in bytecomp.el 897(put '/= 'byte-optimizer 'byte-compile-negation-optimizer) 898(put 'atom 'byte-optimizer 'byte-compile-negation-optimizer) 899(put 'nlistp 'byte-optimizer 'byte-compile-negation-optimizer) 900 901 902(defun byte-optimize-funcall (form) 903 ;; (funcall '(lambda ...) ...) ==> ((lambda ...) ...) 904 ;; (funcall 'foo ...) ==> (foo ...) 905 (let ((fn (nth 1 form))) 906 (if (memq (car-safe fn) '(quote function)) 907 (cons (nth 1 fn) (cdr (cdr form))) 908 form))) 909 910(defun byte-optimize-apply (form) 911 ;; If the last arg is a literal constant, turn this into a funcall. 912 ;; The funcall optimizer can then transform (funcall 'foo ...) -> (foo ...). 913 (let ((fn (nth 1 form)) 914 (last (nth (1- (length form)) form))) ; I think this really is fastest 915 (or (if (or (null last) 916 (eq (car-safe last) 'quote)) 917 (if (listp (nth 1 last)) 918 (let ((butlast (nreverse (cdr (reverse (cdr (cdr form))))))) 919 (nconc (list 'funcall fn) butlast 920 (mapcar '(lambda (x) (list 'quote x)) (nth 1 last)))) 921 (byte-compile-warn 922 "last arg to apply can't be a literal atom: %s" 923 (prin1-to-string last)) 924 nil)) 925 form))) 926 927(put 'funcall 'byte-optimizer 'byte-optimize-funcall) 928(put 'apply 'byte-optimizer 'byte-optimize-apply) 929 930 931(put 'let 'byte-optimizer 'byte-optimize-letX) 932(put 'let* 'byte-optimizer 'byte-optimize-letX) 933(defun byte-optimize-letX (form) 934 (cond ((null (nth 1 form)) 935 ;; No bindings 936 (cons 'progn (cdr (cdr form)))) 937 ((or (nth 2 form) (nthcdr 3 form)) 938 form) 939 ;; The body is nil 940 ((eq (car form) 'let) 941 (append '(progn) (mapcar 'car (mapcar 'cdr (nth 1 form))) '(nil))) 942 (t 943 (let ((binds (reverse (nth 1 form)))) 944 (list 'let* (reverse (cdr binds)) (nth 1 (car binds)) nil))))) 945 946 947(put 'nth 'byte-optimizer 'byte-optimize-nth) 948(defun byte-optimize-nth (form) 949 (if (memq (nth 1 form) '(0 1)) 950 (list 'car (if (zerop (nth 1 form)) 951 (nth 2 form) 952 (list 'cdr (nth 2 form)))) 953 (byte-optimize-predicate form))) 954 955(put 'nthcdr 'byte-optimizer 'byte-optimize-nthcdr) 956(defun byte-optimize-nthcdr (form) 957 (let ((count (nth 1 form))) 958 (if (not (memq count '(0 1 2))) 959 (byte-optimize-predicate form) 960 (setq form (nth 2 form)) 961 (while (natnump (setq count (1- count))) 962 (setq form (list 'cdr form))) 963 form))) 964 965;;; enumerating those functions which need not be called if the returned 966;;; value is not used. That is, something like 967;;; (progn (list (something-with-side-effects) (yow)) 968;;; (foo)) 969;;; may safely be turned into 970;;; (progn (progn (something-with-side-effects) (yow)) 971;;; (foo)) 972;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo. 973 974;;; I wonder if I missed any :-\) 975(let ((side-effect-free-fns 976 '(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan 977 assoc assq 978 boundp buffer-file-name buffer-local-variables buffer-modified-p 979 buffer-substring 980 capitalize car-less-than-car car cdr ceiling concat coordinates-in-window-p 981 copy-marker cos count-lines 982 default-boundp default-value documentation downcase 983 elt exp expt fboundp featurep 984 file-directory-p file-exists-p file-locked-p file-name-absolute-p 985 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p 986 float floor format 987 get get-buffer get-buffer-window getenv get-file-buffer 988 int-to-string 989 length log log10 logand logb logior lognot logxor lsh 990 marker-buffer max member memq min mod 991 next-window nth nthcdr number-to-string 992 parse-colon-path previous-window 993 radians-to-degrees rassq regexp-quote reverse round 994 sin sqrt string< string= string-equal string-lessp string-to-char 995 string-to-int string-to-number substring symbol-plist 996 tan upcase user-variable-p vconcat 997 window-buffer window-dedicated-p window-edges window-height 998 window-hscroll window-minibuffer-p window-width 999 zerop)) 1000 (side-effect-and-error-free-fns 1001 '(arrayp atom 1002 bobp bolp buffer-end buffer-list buffer-size buffer-string bufferp 1003 car-safe case-table-p cdr-safe char-or-string-p commandp cons consp 1004 current-buffer 1005 dot dot-marker eobp eolp eq eql equal eventp floatp framep 1006 get-largest-window get-lru-window 1007 identity ignore integerp integer-or-marker-p interactive-p 1008 invocation-directory invocation-name 1009 keymapp list listp 1010 make-marker mark mark-marker markerp memory-limit minibuffer-window 1011 mouse-movement-p 1012 natnump nlistp not null number-or-marker-p numberp 1013 one-window-p overlayp 1014 point point-marker point-min point-max processp 1015 selected-window sequencep stringp subrp symbolp syntax-table-p 1016 user-full-name user-login-name user-original-login-name 1017 user-real-login-name user-real-uid user-uid 1018 vector vectorp 1019 window-configuration-p window-live-p windowp))) 1020 (while side-effect-free-fns 1021 (put (car side-effect-free-fns) 'side-effect-free t) 1022 (setq side-effect-free-fns (cdr side-effect-free-fns))) 1023 (while side-effect-and-error-free-fns 1024 (put (car side-effect-and-error-free-fns) 'side-effect-free 'error-free) 1025 (setq side-effect-and-error-free-fns (cdr side-effect-and-error-free-fns))) 1026 nil) 1027 1028 1029(defun byte-compile-splice-in-already-compiled-code (form) 1030 ;; form is (byte-code "..." [...] n) 1031 (if (not (memq byte-optimize '(t lap))) 1032 (byte-compile-normal-call form) 1033 (byte-inline-lapcode 1034 (byte-decompile-bytecode-1 (nth 1 form) (nth 2 form) t)) 1035 (setq byte-compile-maxdepth (max (+ byte-compile-depth (nth 3 form)) 1036 byte-compile-maxdepth)) 1037 (setq byte-compile-depth (1+ byte-compile-depth)))) 1038 1039(put 'byte-code 'byte-compile 'byte-compile-splice-in-already-compiled-code) 1040 1041 1042(defconst byte-constref-ops 1043 '(byte-constant byte-constant2 byte-varref byte-varset byte-varbind)) 1044 1045;;; This function extracts the bitfields from variable-length opcodes. 1046;;; Originally defined in disass.el (which no longer uses it.) 1047 1048(defun disassemble-offset () 1049 "Don't call this!" 1050 ;; fetch and return the offset for the current opcode. 1051 ;; return NIL if this opcode has no offset 1052 ;; OP, PTR and BYTES are used and set dynamically 1053 (defvar op) 1054 (defvar ptr) 1055 (defvar bytes) 1056 (cond ((< op byte-nth) 1057 (let ((tem (logand op 7))) 1058 (setq op (logand op 248)) 1059 (cond ((eq tem 6) 1060 (setq ptr (1+ ptr)) ;offset in next byte 1061 (aref bytes ptr)) 1062 ((eq tem 7) 1063 (setq ptr (1+ ptr)) ;offset in next 2 bytes 1064 (+ (aref bytes ptr) 1065 (progn (setq ptr (1+ ptr)) 1066 (lsh (aref bytes ptr) 8)))) 1067 (t tem)))) ;offset was in opcode 1068 ((>= op byte-constant) 1069 (prog1 (- op byte-constant) ;offset in opcode 1070 (setq op byte-constant))) 1071 ((and (>= op byte-constant2) 1072 (<= op byte-goto-if-not-nil-else-pop)) 1073 (setq ptr (1+ ptr)) ;offset in next 2 bytes 1074 (+ (aref bytes ptr) 1075 (progn (setq ptr (1+ ptr)) 1076 (lsh (aref bytes ptr) 8)))) 1077 ((and (>= op byte-listN) 1078 (<= op byte-insertN)) 1079 (setq ptr (1+ ptr)) ;offset in next byte 1080 (aref bytes ptr)))) 1081 1082 1083;;; This de-compiler is used for inline expansion of compiled functions, 1084;;; and by the disassembler. 1085;;; 1086(defun byte-decompile-bytecode (bytes constvec) 1087 "Turns BYTECODE into lapcode, referring to CONSTVEC." 1088 (let ((byte-compile-constants nil) 1089 (byte-compile-variables nil) 1090 (byte-compile-tag-number 0)) 1091 (byte-decompile-bytecode-1 bytes constvec))) 1092 1093;; As byte-decompile-bytecode, but updates 1094;; byte-compile-{constants, variables, tag-number}. 1095;; If the optional 3rd arg is true, then `return' opcodes are replaced 1096;; with `goto's destined for the end of the code. 1097(defun byte-decompile-bytecode-1 (bytes constvec &optional make-splicable) 1098 (let ((length (length bytes)) 1099 (ptr 0) optr tag tags op offset 1100 lap tmp 1101 endtag 1102 (retcount 0)) 1103 (while (not (= ptr length)) 1104 (setq op (aref bytes ptr) 1105 optr ptr 1106 offset (disassemble-offset)) ; this does dynamic-scope magic 1107 (setq op (aref byte-code-vector op)) 1108 (cond ((memq op byte-goto-ops) 1109 ;; it's a pc 1110 (setq offset 1111 (cdr (or (assq offset tags) 1112 (car (setq tags 1113 (cons (cons offset 1114 (byte-compile-make-tag)) 1115 tags))))))) 1116 ((cond ((eq op 'byte-constant2) (setq op 'byte-constant) t) 1117 ((memq op byte-constref-ops))) 1118 (setq tmp (aref constvec offset) 1119 offset (if (eq op 'byte-constant) 1120 (byte-compile-get-constant tmp) 1121 (or (assq tmp byte-compile-variables) 1122 (car (setq byte-compile-variables 1123 (cons (list tmp) 1124 byte-compile-variables))))))) 1125 ((and make-splicable 1126 (eq op 'byte-return)) 1127 (if (= ptr (1- length)) 1128 (setq op nil) 1129 (setq offset (or endtag (setq endtag (byte-compile-make-tag))) 1130 op 'byte-goto)))) 1131 ;; lap = ( [ (pc . (op . arg)) ]* ) 1132 (setq lap (cons (cons optr (cons op (or offset 0))) 1133 lap)) 1134 (setq ptr (1+ ptr))) 1135 ;; take off the dummy nil op that we replaced a trailing "return" with. 1136 (let ((rest lap)) 1137 (while rest 1138 (cond ((setq tmp (assq (car (car rest)) tags)) 1139 ;; this addr is jumped to 1140 (setcdr rest (cons (cons nil (cdr tmp)) 1141 (cdr rest))) 1142 (setq tags (delq tmp tags)) 1143 (setq rest (cdr rest)))) 1144 (setq rest (cdr rest)))) 1145 (if tags (error "optimizer error: missed tags %s" tags)) 1146 (if (null (car (cdr (car lap)))) 1147 (setq lap (cdr lap))) 1148 (if endtag 1149 (setq lap (cons (cons nil endtag) lap))) 1150 ;; remove addrs, lap = ( [ (op . arg) | (TAG tagno) ]* ) 1151 (mapcar 'cdr (nreverse lap)))) 1152 1153 1154;;; peephole optimizer 1155 1156(defconst byte-tagref-ops (cons 'TAG byte-goto-ops)) 1157 1158(defconst byte-conditional-ops 1159 '(byte-goto-if-nil byte-goto-if-not-nil byte-goto-if-nil-else-pop 1160 byte-goto-if-not-nil-else-pop)) 1161 1162(defconst byte-after-unbind-ops 1163 '(byte-constant byte-dup 1164 byte-symbolp byte-consp byte-stringp byte-listp byte-numberp byte-integerp 1165 byte-eq byte-equal byte-not 1166 byte-cons byte-list1 byte-list2 ; byte-list3 byte-list4 1167 byte-interactive-p 1168 ;; How about other side-effect-free-ops? Is it safe to move an 1169 ;; error invocation (such as from nth) out of an unwind-protect? 1170 "Byte-codes that can be moved past an unbind.")) 1171 1172(defconst byte-compile-side-effect-and-error-free-ops 1173 '(byte-constant byte-dup byte-symbolp byte-consp byte-stringp byte-listp 1174 byte-integerp byte-numberp byte-eq byte-equal byte-not byte-car-safe 1175 byte-cdr-safe byte-cons byte-list1 byte-list2 byte-point byte-point-max 1176 byte-point-min byte-following-char byte-preceding-char 1177 byte-current-column byte-eolp byte-eobp byte-bolp byte-bobp 1178 byte-current-buffer byte-interactive-p)) 1179 1180(defconst byte-compile-side-effect-free-ops 1181 (nconc 1182 '(byte-varref byte-nth byte-memq byte-car byte-cdr byte-length byte-aref 1183 byte-symbol-value byte-get byte-concat2 byte-concat3 byte-sub1 byte-add1 1184 byte-eqlsign byte-gtr byte-lss byte-leq byte-geq byte-diff byte-negate 1185 byte-plus byte-max byte-min byte-mult byte-char-after byte-char-syntax 1186 byte-buffer-substring byte-string= byte-string< byte-nthcdr byte-elt 1187 byte-member byte-assq byte-quo byte-rem) 1188 byte-compile-side-effect-and-error-free-ops)) 1189 1190;;; This piece of shit is because of the way DEFVAR_BOOL() variables work. 1191;;; Consider the code 1192;;; 1193;;; (defun foo (flag) 1194;;; (let ((old-pop-ups pop-up-windows) 1195;;; (pop-up-windows flag)) 1196;;; (cond ((not (eq pop-up-windows old-pop-ups)) 1197;;; (setq old-pop-ups pop-up-windows) 1198;;; ...)))) 1199;;; 1200;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is 1201;;; something else. But if we optimize 1202;;; 1203;;; varref flag 1204;;; varbind pop-up-windows 1205;;; varref pop-up-windows 1206;;; not 1207;;; to 1208;;; varref flag 1209;;; dup 1210;;; varbind pop-up-windows 1211;;; not 1212;;; 1213;;; we break the program, because it will appear that pop-up-windows and 1214;;; old-pop-ups are not EQ when really they are. So we have to know what 1215;;; the BOOL variables are, and not perform this optimization on them. 1216;;; 1217(defconst byte-boolean-vars 1218 '(abbrev-all-caps abbrevs-changed byte-metering-on 1219 check-protected-fields completion-auto-help completion-ignore-case 1220 cursor-in-echo-area debug-on-next-call debug-on-quit 1221 defining-kbd-macro delete-exited-processes 1222 enable-recursive-minibuffers 1223 highlight-nonselected-windows indent-tabs-mode 1224 insert-default-directory inverse-video load-in-progress 1225 menu-prompting mode-line-inverse-video no-redraw-on-reenter 1226 noninteractive parse-sexp-ignore-comments pop-up-frames 1227 pop-up-windows print-escape-newlines print-escape-newlines 1228 truncate-partial-width-windows visible-bell vms-stmlf-recfm 1229 words-include-escapes x-save-under) 1230 "DEFVAR_BOOL variables. Giving these any non-nil value sets them to t. 1231If this does not enumerate all DEFVAR_BOOL variables, the byte-optimizer 1232may generate incorrect code.") 1233 1234(defun byte-optimize-lapcode (lap &optional for-effect) 1235 "Simple peephole optimizer. LAP is both modified and returned." 1236 (let (lap0 off0 1237 lap1 off1 1238 lap2 off2 1239 (keep-going 'first-time) 1240 (add-depth 0) 1241 rest tmp tmp2 tmp3 1242 (side-effect-free (if byte-compile-delete-errors 1243 byte-compile-side-effect-free-ops 1244 byte-compile-side-effect-and-error-free-ops))) 1245 (while keep-going 1246 (or (eq keep-going 'first-time) 1247 (byte-compile-log-lap " ---- next pass")) 1248 (setq rest lap 1249 keep-going nil) 1250 (while rest 1251 (setq lap0 (car rest) 1252 lap1 (nth 1 rest) 1253 lap2 (nth 2 rest)) 1254 1255 ;; You may notice that sequences like "dup varset discard" are 1256 ;; optimized but sequences like "dup varset TAG1: discard" are not. 1257 ;; You may be tempted to change this; resist that temptation. 1258 (cond ;; 1259 ;; <side-effect-free> pop --> <deleted> 1260 ;; ...including: 1261 ;; const-X pop --> <deleted> 1262 ;; varref-X pop --> <deleted> 1263 ;; dup pop --> <deleted> 1264 ;; 1265 ((and (eq 'byte-discard (car lap1)) 1266 (memq (car lap0) side-effect-free)) 1267 (setq keep-going t) 1268 (setq tmp (aref byte-stack+-info (symbol-value (car lap0)))) 1269 (setq rest (cdr rest)) 1270 (cond ((= tmp 1) 1271 (byte-compile-log-lap 1272 " %s discard\t-->\t<deleted>" lap0) 1273 (setq lap (delq lap0 (delq lap1 lap)))) 1274 ((= tmp 0) 1275 (byte-compile-log-lap 1276 " %s discard\t-->\t<deleted> discard" lap0) 1277 (setq lap (delq lap0 lap))) 1278 ((= tmp -1) 1279 (byte-compile-log-lap 1280 " %s discard\t-->\tdiscard discard" lap0) 1281 (setcar lap0 'byte-discard) 1282 (setcdr lap0 0)) 1283 ((error "Optimizer error: too much on the stack")))) 1284 ;; 1285 ;; goto*-X X: --> X: 1286 ;; 1287 ((and (memq (car lap0) byte-goto-ops) 1288 (eq (cdr lap0) lap1)) 1289 (cond ((eq (car lap0) 'byte-goto) 1290 (setq lap (delq lap0 lap)) 1291 (setq tmp "<deleted>")) 1292 ((memq (car lap0) byte-goto-always-pop-ops) 1293 (setcar lap0 (setq tmp 'byte-discard)) 1294 (setcdr lap0 0)) 1295 ((error "Depth conflict at tag %d" (nth 2 lap0)))) 1296 (and (memq byte-optimize-log '(t byte)) 1297 (byte-compile-log " (goto %s) %s:\t-->\t%s %s:" 1298 (nth 1 lap1) (nth 1 lap1) 1299 tmp (nth 1 lap1))) 1300 (setq keep-going t)) 1301 ;; 1302 ;; varset-X varref-X --> dup varset-X 1303 ;; varbind-X varref-X --> dup varbind-X 1304 ;; const/dup varset-X varref-X --> const/dup varset-X const/dup 1305 ;; const/dup varbind-X varref-X --> const/dup varbind-X const/dup 1306 ;; The latter two can enable other optimizations. 1307 ;; 1308 ((and (eq 'byte-varref (car lap2)) 1309 (eq (cdr lap1) (cdr lap2)) 1310 (memq (car lap1) '(byte-varset byte-varbind))) 1311 (if (and (setq tmp (memq (car (cdr lap2)) byte-boolean-vars)) 1312 (not (eq (car lap0) 'byte-constant))) 1313 nil 1314 (setq keep-going t) 1315 (if (memq (car lap0) '(byte-constant byte-dup)) 1316 (progn 1317 (setq tmp (if (or (not tmp) 1318 (memq (car (cdr lap0)) '(nil t))) 1319 (cdr lap0) 1320 (byte-compile-get-constant t))) 1321 (byte-compile-log-lap " %s %s %s\t-->\t%s %s %s" 1322 lap0 lap1 lap2 lap0 lap1 1323 (cons (car lap0) tmp)) 1324 (setcar lap2 (car lap0)) 1325 (setcdr lap2 tmp)) 1326 (byte-compile-log-lap " %s %s\t-->\tdup %s" lap1 lap2 lap1) 1327 (setcar lap2 (car lap1)) 1328 (setcar lap1 'byte-dup) 1329 (setcdr lap1 0) 1330 ;; The stack depth gets locally increased, so we will 1331 ;; increase maxdepth in case depth = maxdepth here. 1332 ;; This can cause the third argument to byte-code to 1333 ;; be larger than necessary. 1334 (setq add-depth 1)))) 1335 ;; 1336 ;; dup varset-X discard --> varset-X 1337 ;; dup varbind-X discard --> varbind-X 1338 ;; (the varbind variant can emerge from other optimizations) 1339 ;; 1340 ((and (eq 'byte-dup (car lap0)) 1341 (eq 'byte-discard (car lap2)) 1342 (memq (car lap1) '(byte-varset byte-varbind))) 1343 (byte-compile-log-lap " dup %s discard\t-->\t%s" lap1 lap1) 1344 (setq keep-going t 1345 rest (cdr rest)) 1346 (setq lap (delq lap0 (delq lap2 lap)))) 1347 ;; 1348 ;; not goto-X-if-nil --> goto-X-if-non-nil 1349 ;; not goto-X-if-non-nil --> goto-X-if-nil 1350 ;; 1351 ;; it is wrong to do the same thing for the -else-pop variants. 1352 ;; 1353 ((and (eq 'byte-not (car lap0)) 1354 (or (eq 'byte-goto-if-nil (car lap1)) 1355 (eq 'byte-goto-if-not-nil (car lap1)))) 1356 (byte-compile-log-lap " not %s\t-->\t%s" 1357 lap1 1358 (cons 1359 (if (eq (car lap1) 'byte-goto-if-nil) 1360 'byte-goto-if-not-nil 1361 'byte-goto-if-nil) 1362 (cdr lap1))) 1363 (setcar lap1 (if (eq (car lap1) 'byte-goto-if-nil) 1364 'byte-goto-if-not-nil 1365 'byte-goto-if-nil)) 1366 (setq lap (delq lap0 lap)) 1367 (setq keep-going t)) 1368 ;; 1369 ;; goto-X-if-nil goto-Y X: --> goto-Y-if-non-nil X: 1370 ;; goto-X-if-non-nil goto-Y X: --> goto-Y-if-nil X: 1371 ;; 1372 ;; it is wrong to do the same thing for the -else-pop variants. 1373 ;; 1374 ((and (or (eq 'byte-goto-if-nil (car lap0)) 1375 (eq 'byte-goto-if-not-nil (car lap0))) ; gotoX 1376 (eq 'byte-goto (car lap1)) ; gotoY 1377 (eq (cdr lap0) lap2)) ; TAG X 1378 (let ((inverse (if (eq 'byte-goto-if-nil (car lap0)) 1379 'byte-goto-if-not-nil 'byte-goto-if-nil))) 1380 (byte-compile-log-lap " %s %s %s:\t-->\t%s %s:" 1381 lap0 lap1 lap2 1382 (cons inverse (cdr lap1)) lap2) 1383 (setq lap (delq lap0 lap)) 1384 (setcar lap1 inverse) 1385 (setq keep-going t))) 1386 ;; 1387 ;; const goto-if-* --> whatever 1388 ;; 1389 ((and (eq 'byte-constant (car lap0)) 1390 (memq (car lap1) byte-conditional-ops)) 1391 (cond ((if (or (eq (car lap1) 'byte-goto-if-nil) 1392 (eq (car lap1) 'byte-goto-if-nil-else-pop)) 1393 (car (cdr lap0)) 1394 (not (car (cdr lap0)))) 1395 (byte-compile-log-lap " %s %s\t-->\t<deleted>" 1396 lap0 lap1) 1397 (setq rest (cdr rest) 1398 lap (delq lap0 (delq lap1 lap)))) 1399 (t 1400 (if (memq (car lap1) byte-goto-always-pop-ops) 1401 (progn 1402 (byte-compile-log-lap " %s %s\t-->\t%s" 1403 lap0 lap1 (cons 'byte-goto (cdr lap1))) 1404 (setq lap (delq lap0 lap))) 1405 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 1406 (cons 'byte-goto (cdr lap1)))) 1407 (setcar lap1 'byte-goto))) 1408 (setq keep-going t)) 1409 ;; 1410 ;; varref-X varref-X --> varref-X dup 1411 ;; varref-X [dup ...] varref-X --> varref-X [dup ...] dup 1412 ;; We don't optimize the const-X variations on this here, 1413 ;; because that would inhibit some goto optimizations; we 1414 ;; optimize the const-X case after all other optimizations. 1415 ;; 1416 ((and (eq 'byte-varref (car lap0)) 1417 (progn 1418 (setq tmp (cdr rest)) 1419 (while (eq (car (car tmp)) 'byte-dup) 1420 (setq tmp (cdr tmp))) 1421 t) 1422 (eq (cdr lap0) (cdr (car tmp))) 1423 (eq 'byte-varref (car (car tmp)))) 1424 (if (memq byte-optimize-log '(t byte)) 1425 (let ((str "")) 1426 (setq tmp2 (cdr rest)) 1427 (while (not (eq tmp tmp2)) 1428 (setq tmp2 (cdr tmp2) 1429 str (concat str " dup"))) 1430 (byte-compile-log-lap " %s%s %s\t-->\t%s%s dup" 1431 lap0 str lap0 lap0 str))) 1432 (setq keep-going t) 1433 (setcar (car tmp) 'byte-dup) 1434 (setcdr (car tmp) 0) 1435 (setq rest tmp)) 1436 ;; 1437 ;; TAG1: TAG2: --> TAG1: <deleted> 1438 ;; (and other references to TAG2 are replaced with TAG1) 1439 ;; 1440 ((and (eq (car lap0) 'TAG) 1441 (eq (car lap1) 'TAG)) 1442 (and (memq byte-optimize-log '(t byte)) 1443 (byte-compile-log " adjacent tags %d and %d merged" 1444 (nth 1 lap1) (nth 1 lap0))) 1445 (setq tmp3 lap) 1446 (while (setq tmp2 (rassq lap0 tmp3)) 1447 (setcdr tmp2 lap1) 1448 (setq tmp3 (cdr (memq tmp2 tmp3)))) 1449 (setq lap (delq lap0 lap) 1450 keep-going t)) 1451 ;; 1452 ;; unused-TAG: --> <deleted> 1453 ;; 1454 ((and (eq 'TAG (car lap0)) 1455 (not (rassq lap0 lap))) 1456 (and (memq byte-optimize-log '(t byte)) 1457 (byte-compile-log " unused tag %d removed" (nth 1 lap0))) 1458 (setq lap (delq lap0 lap) 1459 keep-going t)) 1460 ;; 1461 ;; goto ... --> goto <delete until TAG or end> 1462 ;; return ... --> return <delete until TAG or end> 1463 ;; 1464 ((and (memq (car lap0) '(byte-goto byte-return)) 1465 (not (memq (car lap1) '(TAG nil)))) 1466 (setq tmp rest) 1467 (let ((i 0) 1468 (opt-p (memq byte-optimize-log '(t lap))) 1469 str deleted) 1470 (while (and (setq tmp (cdr tmp)) 1471 (not (eq 'TAG (car (car tmp))))) 1472 (if opt-p (setq deleted (cons (car tmp) deleted) 1473 str (concat str " %s") 1474 i (1+ i)))) 1475 (if opt-p 1476 (let ((tagstr 1477 (if (eq 'TAG (car (car tmp))) 1478 (format "%d:" (cdr (car tmp))) 1479 (or (car tmp) "")))) 1480 (if (< i 6) 1481 (apply 'byte-compile-log-lap-1 1482 (concat " %s" str 1483 " %s\t-->\t%s <deleted> %s") 1484 lap0 1485 (nconc (nreverse deleted) 1486 (list tagstr lap0 tagstr))) 1487 (byte-compile-log-lap 1488 " %s <%d unreachable op%s> %s\t-->\t%s <deleted> %s" 1489 lap0 i (if (= i 1) "" "s") 1490 tagstr lap0 tagstr)))) 1491 (rplacd rest tmp)) 1492 (setq keep-going t)) 1493 ;; 1494 ;; <safe-op> unbind --> unbind <safe-op> 1495 ;; (this may enable other optimizations.) 1496 ;; 1497 ((and (eq 'byte-unbind (car lap1)) 1498 (memq (car lap0) byte-after-unbind-ops)) 1499 (byte-compile-log-lap " %s %s\t-->\t%s %s" lap0 lap1 lap1 lap0) 1500 (setcar rest lap1) 1501 (setcar (cdr rest) lap0) 1502 (setq keep-going t)) 1503 ;; 1504 ;; varbind-X unbind-N --> discard unbind-(N-1) 1505 ;; save-excursion unbind-N --> unbind-(N-1) 1506 ;; save-restriction unbind-N --> unbind-(N-1) 1507 ;; 1508 ((and (eq 'byte-unbind (car lap1)) 1509 (memq (car lap0) '(byte-varbind byte-save-excursion 1510 byte-save-restriction)) 1511 (< 0 (cdr lap1))) 1512 (if (zerop (setcdr lap1 (1- (cdr lap1)))) 1513 (delq lap1 rest)) 1514 (if (eq (car lap0) 'byte-varbind) 1515 (setcar rest (cons 'byte-discard 0)) 1516 (setq lap (delq lap0 lap))) 1517 (byte-compile-log-lap " %s %s\t-->\t%s %s" 1518 lap0 (cons (car lap1) (1+ (cdr lap1))) 1519 (if (eq (car lap0) 'byte-varbind) 1520 (car rest) 1521 (car (cdr rest))) 1522 (if (and (/= 0 (cdr lap1)) 1523 (eq (car lap0) 'byte-varbind)) 1524 (car (cdr rest)) 1525 "")) 1526 (setq keep-going t)) 1527 ;; 1528 ;; goto*-X ... X: goto-Y --> goto*-Y 1529 ;; goto-X ... X: return --> return 1530 ;; 1531 ((and (memq (car lap0) byte-goto-ops) 1532 (memq (car (setq tmp (nth 1 (memq (cdr lap0) lap)))) 1533 '(byte-goto byte-return))) 1534 (cond ((and (not (eq tmp lap0)) 1535 (or (eq (car lap0) 'byte-goto) 1536 (eq (car tmp) 'byte-goto))) 1537 (byte-compile-log-lap " %s [%s]\t-->\t%s" 1538 (car lap0) tmp tmp) 1539 (if (eq (car tmp) 'byte-return) 1540 (setcar lap0 'byte-return)) 1541 (setcdr lap0 (cdr tmp)) 1542 (setq keep-going t)))) 1543 ;; 1544 ;; goto-*-else-pop X ... X: goto-if-* --> whatever 1545 ;; goto-*-else-pop X ... X: discard --> whatever 1546 ;; 1547 ((and (memq (car lap0) '(byte-goto-if-nil-else-pop 1548 byte-goto-if-not-nil-else-pop)) 1549 (memq (car (car (setq tmp (cdr (memq (cdr lap0) lap))))) 1550 (eval-when-compile 1551 (cons 'byte-discard byte-conditional-ops))) 1552 (not (eq lap0 (car tmp)))) 1553 (setq tmp2 (car tmp)) 1554 (setq tmp3 (assq (car lap0) '((byte-goto-if-nil-else-pop 1555 byte-goto-if-nil) 1556 (byte-goto-if-not-nil-else-pop 1557 byte-goto-if-not-nil)))) 1558 (if (memq (car tmp2) tmp3) 1559 (progn (setcar lap0 (car tmp2)) 1560 (setcdr lap0 (cdr tmp2)) 1561 (byte-compile-log-lap " %s-else-pop [%s]\t-->\t%s" 1562 (car lap0) tmp2 lap0)) 1563 ;; Get rid of the -else-pop's and jump one step further. 1564 (or (eq 'TAG (car (nth 1 tmp))) 1565 (setcdr tmp (cons (byte-compile-make-tag) 1566 (cdr tmp)))) 1567 (byte-compile-log-lap " %s [%s]\t-->\t%s <skip>" 1568 (car lap0) tmp2 (nth 1 tmp3)) 1569 (setcar lap0 (nth 1 tmp3)) 1570 (setcdr lap0 (nth 1 tmp))) 1571 (setq keep-going t)) 1572 ;; 1573 ;; const goto-X ... X: goto-if-* --> whatever 1574 ;; const goto-X ... X: discard --> whatever 1575 ;; 1576 ((and (eq (car lap0) 'byte-constant) 1577 (eq (car lap1) 'byte-goto) 1578 (memq (car (car (setq tmp (cdr (memq (cdr lap1) lap))))) 1579 (eval-when-compile 1580 (cons 'byte-discard byte-conditional-ops))) 1581 (not (eq lap1 (car tmp)))) 1582 (setq tmp2 (car tmp)) 1583 (cond ((memq (car tmp2) 1584 (if (null (car (cdr lap0))) 1585 '(byte-goto-if-nil byte-goto-if-nil-else-pop) 1586 '(byte-goto-if-not-nil 1587 byte-goto-if-not-nil-else-pop))) 1588 (byte-compile-log-lap " %s goto [%s]\t-->\t%s %s" 1589 lap0 tmp2 lap0 tmp2) 1590 (setcar lap1 (car tmp2)) 1591 (setcdr lap1 (cdr tmp2)) 1592 ;; Let next step fix the (const,goto-if*) sequence. 1593 (setq rest (cons nil rest))) 1594 (t 1595 ;; Jump one step further 1596 (byte-compile-log-lap 1597 " %s goto [%s]\t-->\t<deleted> goto <skip>" 1598 lap0 tmp2) 1599 (or (eq 'TAG (car (nth 1 tmp))) 1600 (setcdr tmp (cons (byte-compile-make-tag) 1601 (cdr tmp)))) 1602 (setcdr lap1 (car (cdr tmp))) 1603 (setq lap (delq lap0 lap)))) 1604 (setq keep-going t)) 1605 ;; 1606 ;; X: varref-Y ... varset-Y goto-X --> 1607 ;; X: varref-Y Z: ... dup varset-Y goto-Z 1608 ;; (varset-X goto-BACK, BACK: varref-X --> copy the varref down.) 1609 ;; (This is so usual for while loops that it is worth handling). 1610 ;; 1611 ((and (eq (car lap1) 'byte-varset) 1612 (eq (car lap2) 'byte-goto) 1613 (not (memq (cdr lap2) rest)) ;Backwards jump 1614 (eq (car (car (setq tmp (cdr (memq (cdr lap2) lap))))) 1615 'byte-varref) 1616 (eq (cdr (car tmp)) (cdr lap1)) 1617 (not (memq (car (cdr lap1)) byte-boolean-vars))) 1618 ;;(byte-compile-log-lap " Pulled %s to end of loop" (car tmp)) 1619 (let ((newtag (byte-compile-make-tag))) 1620 (byte-compile-log-lap 1621 " %s: %s ... %s %s\t-->\t%s: %s %s: ... %s %s %s" 1622 (nth 1 (cdr lap2)) (car tmp) 1623 lap1 lap2 1624 (nth 1 (cdr lap2)) (car tmp) 1625 (nth 1 newtag) 'byte-dup lap1 1626 (cons 'byte-goto newtag) 1627 ) 1628 (setcdr rest (cons (cons 'byte-dup 0) (cdr rest))) 1629 (setcdr tmp (cons (setcdr lap2 newtag) (cdr tmp)))) 1630 (setq add-depth 1) 1631 (setq keep-going t)) 1632 ;; 1633 ;; goto-X Y: ... X: goto-if*-Y --> goto-if-not-*-X+1 Y: 1634 ;; (This can pull the loop test to the end of the loop) 1635 ;; 1636 ((and (eq (car lap0) 'byte-goto) 1637 (eq (car lap1) 'TAG) 1638 (eq lap1 1639 (cdr (car (setq tmp (cdr (memq (cdr lap0) lap)))))) 1640 (memq (car (car tmp)) 1641 '(byte-goto byte-goto-if-nil byte-goto-if-not-nil 1642 byte-goto-if-nil-else-pop))) 1643;; (byte-compile-log-lap " %s %s, %s %s --> moved conditional" 1644;; lap0 lap1 (cdr lap0) (car tmp)) 1645 (let ((newtag (byte-compile-make-tag))) 1646 (byte-compile-log-lap 1647 "%s %s: ... %s: %s\t-->\t%s ... %s:" 1648 lap0 (nth 1 lap1) (nth 1 (cdr lap0)) (car tmp) 1649 (cons (cdr (assq (car (car tmp)) 1650 '((byte-goto-if-nil . byte-goto-if-not-nil) 1651 (byte-goto-if-not-nil . byte-goto-if-nil) 1652 (byte-goto-if-nil-else-pop . 1653 byte-goto-if-not-nil-else-pop) 1654 (byte-goto-if-not-nil-else-pop . 1655 byte-goto-if-nil-else-pop)))) 1656 newtag) 1657 1658 (nth 1 newtag) 1659 ) 1660 (setcdr tmp (cons (setcdr lap0 newtag) (cdr tmp))) 1661 (if (eq (car (car tmp)) 'byte-goto-if-nil-else-pop) 1662 ;; We can handle this case but not the -if-not-nil case, 1663 ;; because we won't know which non-nil constant to push. 1664 (setcdr rest (cons (cons 'byte-constant 1665 (byte-compile-get-constant nil)) 1666 (cdr rest)))) 1667 (setcar lap0 (nth 1 (memq (car (car tmp)) 1668 '(byte-goto-if-nil-else-pop 1669 byte-goto-if-not-nil 1670 byte-goto-if-nil 1671 byte-goto-if-not-nil 1672 byte-goto byte-goto)))) 1673 ) 1674 (setq keep-going t)) 1675 ) 1676 (setq rest (cdr rest))) 1677 ) 1678 ;; Cleanup stage: 1679 ;; Rebuild byte-compile-constants / byte-compile-variables. 1680 ;; Simple optimizations that would inhibit other optimizations if they 1681 ;; were done in the optimizing loop, and optimizations which there is no 1682 ;; need to do more than once. 1683 (setq byte-compile-constants nil 1684 byte-compile-variables nil) 1685 (setq rest lap) 1686 (while rest 1687 (setq lap0 (car rest) 1688 lap1 (nth 1 rest)) 1689 (if (memq (car lap0) byte-constref-ops) 1690 (if (eq (cdr lap0) 'byte-constant) 1691 (or (memq (cdr lap0) byte-compile-variables) 1692 (setq byte-compile-variables (cons (cdr lap0) 1693 byte-compile-variables))) 1694 (or (memq (cdr lap0) byte-compile-constants) 1695 (setq byte-compile-constants (cons (cdr lap0) 1696 byte-compile-constants))))) 1697 (cond (;; 1698 ;; const-C varset-X const-C --> const-C dup varset-X 1699 ;; const-C varbind-X const-C --> const-C dup varbind-X 1700 ;; 1701 (and (eq (car lap0) 'byte-constant) 1702 (eq (car (nth 2 rest)) 'byte-constant) 1703 (eq (cdr lap0) (car (nth 2 rest))) 1704 (memq (car lap1) '(byte-varbind byte-varset))) 1705 (byte-compile-log-lap " %s %s %s\t-->\t%s dup %s" 1706 lap0 lap1 lap0 lap0 lap1) 1707 (setcar (cdr (cdr rest)) (cons (car lap1) (cdr lap1))) 1708 (setcar (cdr rest) (cons 'byte-dup 0)) 1709 (setq add-depth 1)) 1710 ;; 1711 ;; const-X [dup/const-X ...] --> const-X [dup ...] dup 1712 ;; varref-X [dup/varref-X ...] --> varref-X [dup ...] dup 1713 ;; 1714 ((memq (car lap0) '(byte-constant byte-varref)) 1715 (setq tmp rest 1716 tmp2 nil) 1717 (while (progn 1718 (while (eq 'byte-dup (car (car (setq tmp (cdr tmp)))))) 1719 (and (eq (cdr lap0) (cdr (car tmp))) 1720 (eq (car lap0) (car (car tmp))))) 1721 (setcar tmp (cons 'byte-dup 0)) 1722 (setq tmp2 t)) 1723 (if tmp2 1724 (byte-compile-log-lap 1725 " %s [dup/%s]... %s\t-->\t%s dup..." lap0 lap0 lap0))) 1726 ;; 1727 ;; unbind-N unbind-M --> unbind-(N+M) 1728 ;; 1729 ((and (eq 'byte-unbind (car lap0)) 1730 (eq 'byte-unbind (car lap1))) 1731 (byte-compile-log-lap " %s %s\t-->\t%s" lap0 lap1 1732 (cons 'byte-unbind 1733 (+ (cdr lap0) (cdr lap1)))) 1734 (setq keep-going t) 1735 (setq lap (delq lap0 lap)) 1736 (setcdr lap1 (+ (cdr lap1) (cdr lap0)))) 1737 ) 1738 (setq rest (cdr rest))) 1739 (setq byte-compile-maxdepth (+ byte-compile-maxdepth add-depth))) 1740 lap) 1741 1742(provide 'byte-optimize) 1743 1744 1745;; To avoid "lisp nesting exceeds max-lisp-eval-depth" when this file compiles 1746;; itself, compile some of its most used recursive functions (at load time). 1747;; 1748(eval-when-compile 1749 (or (byte-code-function-p (symbol-function 'byte-optimize-form)) 1750 (assq 'byte-code (symbol-function 'byte-optimize-form)) 1751 (let ((byte-optimize nil) 1752 (byte-compile-warnings nil)) 1753 (mapcar '(lambda (x) 1754 (or noninteractive (message "compiling %s..." x)) 1755 (byte-compile x) 1756 (or noninteractive (message "compiling %s...done" x))) 1757 '(byte-optimize-form 1758 byte-optimize-body 1759 byte-optimize-predicate 1760 byte-optimize-binary-predicate 1761 ;; Inserted some more than necessary, to speed it up. 1762 byte-optimize-form-code-walker 1763 byte-optimize-lapcode)))) 1764 nil) 1765 1766;;; byte-opt.el ends here 1767