/[cmucl]/src/compiler/ir1opt.lisp
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Contents of /src/compiler/ir1opt.lisp

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Revision 1.78 - (show annotations)
Sun Oct 5 12:34:35 2003 UTC (10 years, 6 months ago) by gerd
Branch: MAIN
Changes since 1.77: +6 -4 lines
	(compile nil
	 '(lambda (a b c)
		  (declare (notinline logandc2 not))
		  (declare (optimize (safety 3)))
		  (declare (optimize (speed 0)))
		  (declare (optimize (debug 0)))
		  (let ((v10
			 (let ((v5 (if (not nil) -4 (logandc2 68392 c))))
			      c)))
		       a)))
	 => assertion failure, (not (block-delete-p block))

	* src/compiler/ir1opt.lisp (recognize-known-call): Treat
	:inline and :maybe-inline like :notinline if byte-compiling
	or converting for interpreter.  Reported by Paul Dietz.
1 ;;; -*- Package: C; Log: C.Log -*-
2 ;;;
3 ;;; **********************************************************************
4 ;;; This code was written as part of the CMU Common Lisp project at
5 ;;; Carnegie Mellon University, and has been placed in the public domain.
6 ;;;
7 (ext:file-comment
8 "$Header: /tiger/var/lib/cvsroots/cmucl/src/compiler/ir1opt.lisp,v 1.78 2003/10/05 12:34:35 gerd Exp $")
9 ;;;
10 ;;; **********************************************************************
11 ;;;
12 ;;; This file implements the IR1 optimization phase of the compiler. IR1
13 ;;; optimization is a grab-bag of optimizations that don't make major changes
14 ;;; to the block-level control flow and don't use flow analysis. These
15 ;;; optimizations can mostly be classified as "meta-evaluation", but there is a
16 ;;; sizable top-down component as well.
17 ;;;
18 ;;; Written by Rob MacLachlan
19 ;;;
20 (in-package :c)
21
22
23 ;;;; Interface for obtaining results of constant folding:
24
25 ;;; Constant-Continuation-P -- Interface
26 ;;;
27 ;;; Return true if the sole use of Cont is a reference to a constant leaf.
28 ;;;
29 (defun constant-continuation-p (cont)
30 (declare (type continuation cont) (values boolean))
31 (let ((use (continuation-use cont)))
32 (and (ref-p use)
33 (constant-p (ref-leaf use)))))
34
35
36 ;;; Continuation-Value -- Interface
37 ;;;
38 ;;; Return the constant value for a continuation whose only use is a
39 ;;; constant node.
40 ;;;
41 (defun continuation-value (cont)
42 (declare (type continuation cont))
43 (assert (constant-continuation-p cont))
44 (constant-value (ref-leaf (continuation-use cont))))
45
46
47 ;;;; Interface for obtaining results of type inference:
48
49 ;;; CONTINUATION-PROVEN-TYPE -- Interface
50 ;;;
51 ;;; Return a (possibly values) type that describes what we have proven about
52 ;;; the type of Cont without taking any type assertions into consideration.
53 ;;; This is just the union of the NODE-DERIVED-TYPE of all the uses. Most
54 ;;; often people use CONTINUATION-DERIVED-TYPE or CONTINUATION-TYPE instead of
55 ;;; using this function directly.
56 ;;;
57 (defun continuation-proven-type (cont)
58 (declare (type continuation cont))
59 (ecase (continuation-kind cont)
60 ((:block-start :deleted-block-start)
61 (let ((uses (block-start-uses (continuation-block cont))))
62 (if uses
63 (do ((res (node-derived-type (first uses))
64 (values-type-union (node-derived-type (first current))
65 res))
66 (current (rest uses) (rest current)))
67 ((null current) res))
68 *empty-type*)))
69 (:inside-block
70 (node-derived-type (continuation-use cont)))))
71
72
73 ;;; Continuation-Derived-Type -- Interface
74 ;;;
75 ;;; Our best guess for the type of this continuation's value. Note that
76 ;;; this may be Values or Function type, which cannot be passed as an argument
77 ;;; to the normal type operations. See Continuation-Type. This may be called
78 ;;; on deleted continuations, always returning *.
79 ;;;
80 ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the result
81 ;;; is a subtype of the assertion. If so, return the proven type and set
82 ;;; TYPE-CHECK to nil. Otherwise, return the intersection of the asserted and
83 ;;; proven types, and set TYPE-CHECK T. If TYPE-CHECK already has a non-null
84 ;;; value, then preserve it. Only in the somewhat unusual circumstance of
85 ;;; a newly discovered assertion will we change TYPE-CHECK from NIL to T.
86 ;;;
87 ;;; The result value is cached in the Continuation-%Derived-Type. If the
88 ;;; slot is true, just return that value, otherwise recompute and stash the
89 ;;; value there.
90 ;;;
91 (declaim (inline continuation-derived-type))
92 (defun continuation-derived-type (cont)
93 (declare (type continuation cont))
94 (or (continuation-%derived-type cont)
95 (%continuation-derived-type cont)))
96 ;;;
97 (defun %continuation-derived-type (cont)
98 (declare (type continuation cont))
99 (let ((proven (continuation-proven-type cont))
100 (asserted (continuation-asserted-type cont)))
101 (cond ((values-subtypep proven asserted)
102 (setf (continuation-%type-check cont) nil)
103 (setf (continuation-%derived-type cont) proven))
104 (t
105 (unless (or (continuation-%type-check cont)
106 (not (continuation-dest cont))
107 (eq asserted *universal-type*))
108 (setf (continuation-%type-check cont) t))
109
110 (setf (continuation-%derived-type cont)
111 (values-type-intersection asserted proven))))))
112
113
114 ;;; CONTINUATION-TYPE-CHECK -- Interface
115 ;;;
116 ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to date, then
117 ;;; return it.
118 ;;;
119 (declaim (inline continuation-type-check))
120 (defun continuation-type-check (cont)
121 (declare (type continuation cont))
122 (continuation-derived-type cont)
123 (continuation-%type-check cont))
124
125
126 ;;; Continuation-Type -- Interface
127 ;;;
128 ;;; Return the derived type for Cont's first value. This is guaranteed not
129 ;;; to be a Values or Function type.
130 ;;;
131 (defun continuation-type (cont)
132 (declare (type continuation cont) (values ctype))
133 (single-value-type (continuation-derived-type cont)))
134
135
136 ;;;; Interface routines used by optimizers:
137
138 ;;; Reoptimize-Continuation -- Interface
139 ;;;
140 ;;; This function is called by optimizers to indicate that something
141 ;;; interesting has happened to the value of Cont. Optimizers must make sure
142 ;;; that they don't call for reoptimization when nothing has happened, since
143 ;;; optimization will fail to terminate.
144 ;;;
145 ;;; We clear any cached type for the continuation and set the reoptimize
146 ;;; flags on everything in sight, unless the continuation is deleted (in which
147 ;;; case we do nothing.)
148 ;;;
149 ;;; Since this can get called curing IR1 conversion, we have to be careful
150 ;;; not to fly into space when the Dest's Prev is missing.
151 ;;;
152 (defun reoptimize-continuation (cont)
153 (declare (type continuation cont))
154 (unless (member (continuation-kind cont) '(:deleted :unused))
155 (setf (continuation-%derived-type cont) nil)
156 (let ((dest (continuation-dest cont)))
157 (when dest
158 (setf (continuation-reoptimize cont) t)
159 (setf (node-reoptimize dest) t)
160 (let ((prev (node-prev dest)))
161 (when prev
162 (let* ((block (continuation-block prev))
163 (component (block-component block)))
164 (when (typep dest 'cif)
165 (setf (block-test-modified block) t))
166 (setf (block-reoptimize block) t)
167 (setf (component-reoptimize component) t))))))
168 (do-uses (node cont)
169 (setf (block-type-check (node-block node)) t)))
170 (undefined-value))
171
172
173 ;;; Derive-Node-Type -- Interface
174 ;;;
175 ;;; Annotate Node to indicate that its result has been proven to be typep to
176 ;;; RType. After IR1 conversion has happened, this is the only correct way to
177 ;;; supply information discovered about a node's type. If you fuck with the
178 ;;; Node-Derived-Type directly, then information may be lost and reoptimization
179 ;;; may not happen.
180 ;;;
181 ;;; What we do is intersect Rtype with Node's Derived-Type. If the
182 ;;; intersection is different from the old type, then we do a
183 ;;; Reoptimize-Continuation on the Node-Cont.
184 ;;;
185 (defun derive-node-type (node rtype)
186 (declare (type node node) (type ctype rtype))
187 (let ((node-type (node-derived-type node)))
188 (unless (eq node-type rtype)
189 (let ((int (values-type-intersection node-type rtype)))
190 (when (type/= node-type int)
191 (when (and *check-consistency*
192 (eq int *empty-type*)
193 (not (eq rtype *empty-type*)))
194 (let ((*compiler-error-context* node))
195 (compiler-warning
196 "New inferred type ~S conflicts with old type:~
197 ~% ~S~%*** Bug?"
198 (type-specifier rtype) (type-specifier node-type))))
199 (setf (node-derived-type node) int)
200 (reoptimize-continuation (node-cont node))))))
201 (undefined-value))
202
203 (declaim (start-block assert-continuation-type
204 assert-continuation-optional-type assert-call-type))
205
206 ;;; Assert-Continuation-Type -- Interface
207 ;;;
208 ;;; Similar to Derive-Node-Type, but asserts that it is an error for Cont's
209 ;;; value not to be typep to Type. If we improve the assertion, we set
210 ;;; TYPE-CHECK and TYPE-ASSERTED to guarantee that the new assertion will be
211 ;;; checked.
212 ;;;
213 (defun assert-continuation-type (cont type)
214 (declare (type continuation cont) (type ctype type))
215 (let ((cont-type (continuation-asserted-type cont)))
216 (unless (eq cont-type type)
217 (let ((int (values-type-intersection cont-type type)))
218 (when (type/= cont-type int)
219 (setf (continuation-asserted-type cont) int)
220 (do-uses (node cont)
221 (setf (block-attributep (block-flags (node-block node))
222 type-check type-asserted)
223 t))
224 (reoptimize-continuation cont)))))
225 (undefined-value))
226
227
228 ;;; Assert-continuation-optional-type -- Interface
229 ;;;
230 ;;; Similar to Assert-Continuation-Type, but asserts that the type is
231 ;;; for an optional argument and that other arguments may be received.
232 ;;;
233 (defun assert-continuation-optional-type (cont type)
234 (declare (type continuation cont) (type ctype type))
235 (let ((opt-type (make-values-type :optional (list type)
236 :rest *universal-type*)))
237 (assert-continuation-type cont opt-type)))
238
239
240 ;;; Assert-Call-Type -- Interface
241 ;;;
242 ;;; Assert that Call is to a function of the specified Type. It is assumed
243 ;;; that the call is legal and has only constants in the keyword positions.
244 ;;;
245 (defun assert-call-type (call type)
246 (declare (type combination call) (type function-type type))
247 (derive-node-type call (function-type-returns type))
248 (let ((args (combination-args call)))
249 (dolist (req (function-type-required type))
250 (when (null args) (return-from assert-call-type))
251 (let ((arg (pop args)))
252 (assert-continuation-optional-type arg req)))
253 (dolist (opt (function-type-optional type))
254 (when (null args) (return-from assert-call-type))
255 (let ((arg (pop args)))
256 (assert-continuation-optional-type arg opt)))
257
258 (let ((rest (function-type-rest type)))
259 (when rest
260 (dolist (arg args)
261 (assert-continuation-optional-type arg rest))))
262
263 (dolist (key (function-type-keywords type))
264 (let ((name (key-info-name key)))
265 (do ((arg args (cddr arg)))
266 ((null arg))
267 (when (eq (continuation-value (first arg)) name)
268 (assert-continuation-optional-type
269 (second arg) (key-info-type key)))))))
270 (undefined-value))
271
272
273 ;;;; IR1-OPTIMIZE:
274
275 (declaim (start-block ir1-optimize))
276
277 ;;; IR1-Optimize -- Interface
278 ;;;
279 ;;; Do one forward pass over Component, deleting unreachable blocks and
280 ;;; doing IR1 optimizations. We can ignore all blocks that don't have the
281 ;;; Reoptimize flag set. If Component-Reoptimize is true when we are done,
282 ;;; then another iteration would be beneficial.
283 ;;;
284 ;;; We delete blocks when there is either no predecessor or the block is in
285 ;;; a lambda that has been deleted. These blocks would eventually be deleted
286 ;;; by DFO recomputation, but doing it here immediately makes the effect
287 ;;; avaliable to IR1 optimization.
288 ;;;
289 (defun ir1-optimize (component)
290 (declare (type component component))
291 (setf (component-reoptimize component) nil)
292 (do-blocks (block component)
293 (cond
294 ((or (block-delete-p block)
295 (null (block-pred block))
296 (eq (functional-kind (block-home-lambda block)) :deleted))
297 (delete-block block))
298 (t
299 (loop
300 (let ((succ (block-succ block)))
301 (unless (and succ (null (rest succ)))
302 (return)))
303
304 (let ((last (block-last block)))
305 (typecase last
306 (cif
307 ;;
308 ;; Don't flush an if-test if it requires a type check.
309 (cond ((memq (continuation-type-check (if-test last))
310 '(nil :deleted))
311 (flush-dest (if-test last))
312 (when (unlink-node last) (return)))
313 (t
314 (return))))
315 (exit
316 (when (maybe-delete-exit last) (return)))))
317
318 (unless (join-successor-if-possible block)
319 (return)))
320
321 (when (and (block-reoptimize block) (block-component block))
322 (assert (not (block-delete-p block)))
323 (ir1-optimize-block block))
324
325 (when (and (block-flush-p block) (block-component block))
326 (assert (not (block-delete-p block)))
327 (flush-dead-code block)))))
328
329 (undefined-value))
330
331
332 ;;; IR1-Optimize-Block -- Internal
333 ;;;
334 ;;; Loop over the nodes in Block, looking for stuff that needs to be
335 ;;; optimized. We dispatch off of the type of each node with its reoptimize
336 ;;; flag set:
337 ;;; -- With a combination, we call Propagate-Function-Change whenever the
338 ;;; function changes, and call IR1-Optimize-Combination if any argument
339 ;;; changes.
340 ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
341 ;;; propagate Cont's assertion to the Value, since if we did, this would
342 ;;; move the checking of Cont's assertion to the exit. This wouldn't work
343 ;;; with Catch and UWP, where the Exit node is just a placeholder for the
344 ;;; actual unknown exit.
345 ;;;
346 ;;; Note that we clear the node & block reoptimize flags *before* doing the
347 ;;; optimization. This ensures that the node or block will be reoptimized if
348 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
349 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
350 ;;;
351 (defun ir1-optimize-block (block)
352 (declare (type cblock block))
353 (setf (block-reoptimize block) nil)
354 (do-nodes (node cont block :restart-p t)
355 (when (node-reoptimize node)
356 (setf (node-reoptimize node) nil)
357 (typecase node
358 (ref)
359 (combination
360 (ir1-optimize-combination node))
361 (cif
362 (ir1-optimize-if node))
363 (creturn
364 (setf (node-reoptimize node) t)
365 (ir1-optimize-return node))
366 (mv-combination
367 (ir1-optimize-mv-combination node))
368 (exit
369 (let ((value (exit-value node)))
370 (when value
371 (derive-node-type node (continuation-derived-type value)))))
372 (cset
373 (ir1-optimize-set node)))))
374 (undefined-value))
375
376
377 ;;; Join-Successor-If-Possible -- Internal
378 ;;;
379 ;;; We cannot combine with a successor block if:
380 ;;; 1] The successor has more than one predecessor.
381 ;;; 2] The last node's Cont is also used somewhere else.
382 ;;; 3] The successor is the current block (infinite loop).
383 ;;; 4] The next block has a different cleanup, and thus we may want to insert
384 ;;; cleanup code between the two blocks at some point.
385 ;;; 5] The next block has a different home lambda, and thus the control
386 ;;; transfer is a non-local exit.
387 ;;;
388 ;;; If we succeed, we return true, otherwise false.
389 ;;;
390 ;;; Joining is easy when the successor's Start continuation is the same from
391 ;;; our Last's Cont. If they differ, then we can still join when the last
392 ;;; continuation has no next and the next continuation has no uses. In this
393 ;;; case, we replace the next continuation with the last before joining the
394 ;;; blocks.
395 ;;;
396 (defun join-successor-if-possible (block)
397 (declare (type cblock block))
398 (let ((next (first (block-succ block))))
399 (when (block-start next)
400 (let* ((last (block-last block))
401 (last-cont (node-cont last))
402 (next-cont (block-start next)))
403 (cond ((or (rest (block-pred next))
404 (not (eq (continuation-use last-cont) last))
405 (eq next block)
406 (not (eq (block-end-cleanup block)
407 (block-start-cleanup next)))
408 (not (eq (block-home-lambda block)
409 (block-home-lambda next))))
410 nil)
411 ((eq last-cont next-cont)
412 (join-blocks block next)
413 t)
414 ((and (null (block-start-uses next))
415 (eq (continuation-kind last-cont) :inside-block))
416 (let ((next-node (continuation-next next-cont)))
417 ;;
418 ;; If next-cont does have a dest, it must be unreachable,
419 ;; since there are no uses. DELETE-CONTINUATION will mark the
420 ;; dest block as delete-p [and also this block, unless it is
421 ;; no longer backward reachable from the dest block.]
422 (delete-continuation next-cont)
423 (setf (node-prev next-node) last-cont)
424 (setf (continuation-next last-cont) next-node)
425 (setf (block-start next) last-cont)
426 (join-blocks block next))
427 t)
428 (t
429 nil))))))
430
431
432 ;;; Join-Blocks -- Internal
433 ;;;
434 ;;; Join together two blocks which have the same ending/starting
435 ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
436 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
437 ;;; that any indicated optimization gets done.
438 ;;;
439 (defun join-blocks (block1 block2)
440 (declare (type cblock block1 block2))
441 (let* ((last (block-last block2))
442 (last-cont (node-cont last))
443 (succ (block-succ block2))
444 (start2 (block-start block2)))
445 (do ((cont start2 (node-cont (continuation-next cont))))
446 ((eq cont last-cont)
447 (when (eq (continuation-kind last-cont) :inside-block)
448 (setf (continuation-block last-cont) block1)))
449 (setf (continuation-block cont) block1))
450
451 (unlink-blocks block1 block2)
452 (dolist (block succ)
453 (unlink-blocks block2 block)
454 (link-blocks block1 block))
455
456 (setf (block-last block1) last)
457 (setf (continuation-kind start2) :inside-block))
458
459 (setf (block-flags block1)
460 (attributes-union (block-flags block1)
461 (block-flags block2)
462 (block-attributes type-asserted test-modified)))
463
464 (let ((next (block-next block2))
465 (prev (block-prev block2)))
466 (setf (block-next prev) next)
467 (setf (block-prev next) prev))
468
469 (undefined-value))
470
471 ;;; Flush-Dead-Code -- Internal
472 ;;;
473 ;;; Delete any nodes in Block whose value is unused and have no
474 ;;; side-effects. We can delete sets of lexical variables when the set
475 ;;; variable has no references.
476 ;;;
477 ;;; [### For now, don't delete potentially flushable calls when they have the
478 ;;; Call attribute. Someday we should look at the funcitonal args to determine
479 ;;; if they have any side-effects.]
480 ;;;
481 (defun flush-dead-code (block)
482 (declare (type cblock block))
483 (do-nodes-backwards (node cont block)
484 (unless (continuation-dest cont)
485 (typecase node
486 (ref
487 (delete-ref node)
488 (unlink-node node))
489 (combination
490 (let ((info (combination-kind node)))
491 (when (function-info-p info)
492 (let ((attr (function-info-attributes info)))
493 (when (and (ir1-attributep attr flushable)
494 (not (ir1-attributep attr call)))
495 (if (policy node (= safety 3))
496 ;; Don't flush calls to flushable functions if
497 ;; their value is unused in safe code, because
498 ;; this means something like (PROGN (FBOUNDP 42)
499 ;; T) won't signal an error. KLUDGE: The right
500 ;; thing to do here is probably teaching
501 ;; MAYBE-NEGATE-CHECK and friends to accept nil
502 ;; continuation-dests instead of faking one.
503 ;; Can't be bothered at present.
504 ;; Gerd, 2003-04-26.
505 (setf (continuation-dest cont)
506 (continuation-next cont))
507 (progn
508 (flush-dest (combination-fun node))
509 (dolist (arg (combination-args node))
510 (flush-dest arg))
511 (unlink-node node))))))))
512 (mv-combination
513 (when (eq (basic-combination-kind node) :local)
514 (let ((fun (combination-lambda node)))
515 (when (dolist (var (lambda-vars fun) t)
516 (when (or (leaf-refs var)
517 (lambda-var-sets var))
518 (return nil)))
519 (flush-dest (first (basic-combination-args node)))
520 (delete-let fun)))))
521 (exit
522 (let ((value (exit-value node)))
523 (when value
524 (flush-dest value)
525 (setf (exit-value node) nil))))
526 (cset
527 (let ((var (set-var node)))
528 (when (and (lambda-var-p var)
529 (null (leaf-refs var)))
530 (flush-dest (set-value node))
531 (setf (basic-var-sets var)
532 (delete node (basic-var-sets var)))
533 (unlink-node node)))))))
534
535 (setf (block-flush-p block) nil)
536 (undefined-value))
537
538 (declaim (end-block))
539
540
541 ;;;; Local call return type propagation:
542
543 ;;; Find-Result-Type -- Internal
544 ;;;
545 ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
546 ;;; set. It iterates over the uses of the RESULT, looking for interesting
547 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
548 ;;; its type together with the types of other such uses. We assign to the
549 ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
550 ;;; type. We can make this intersection now (potentially before type checking)
551 ;;; because this assertion on the result will eventually be checked (if
552 ;;; appropriate.)
553 ;;;
554 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
555 ;;; which may change the succesor of the call to be the called function, and if
556 ;;; so, checks if the call can become an assignment. If we convert to an
557 ;;; assignment, we abort, since the RETURN has been deleted.
558 ;;;
559 (defun find-result-type (node)
560 (declare (type creturn node))
561 (let ((result (return-result node)))
562 (collect ((use-union *empty-type* values-type-union))
563 (do-uses (use result)
564 (cond ((and (basic-combination-p use)
565 (eq (basic-combination-kind use) :local))
566 (assert (eq (lambda-tail-set (node-home-lambda use))
567 (lambda-tail-set (combination-lambda use))))
568 (when (combination-p use)
569 (when (nth-value 1 (maybe-convert-tail-local-call use))
570 (return-from find-result-type (undefined-value)))))
571 (t
572 (use-union (node-derived-type use)))))
573 (let ((int (values-type-intersection (continuation-asserted-type result)
574 (use-union))))
575 (setf (return-result-type node) int))))
576 (undefined-value))
577
578
579 ;;; IR1-Optimize-Return -- Internal
580 ;;;
581 ;;; Do stuff to realize that something has changed about the value delivered
582 ;;; to a return node. Since we consider the return values of all functions in
583 ;;; the tail set to be equivalent, this amounts to bringing the entire tail set
584 ;;; up to date. We iterate over the returns for all the functions in the tail
585 ;;; set, reanalyzing them all (not treating Node specially.)
586 ;;;
587 ;;; When we are done, we check if the new type is different from the old
588 ;;; TAIL-SET-TYPE. If so, we set the type and also reoptimize all the
589 ;;; continuations for references to functions in the tail set. This will
590 ;;; cause IR1-OPTIMIZE-COMBINATION to derive the new type as the results of the
591 ;;; calls.
592 ;;;
593 (defun ir1-optimize-return (node)
594 (declare (type creturn node))
595 (let* ((tails (lambda-tail-set (return-lambda node)))
596 (funs (tail-set-functions tails)))
597 (collect ((res *empty-type* values-type-union))
598 (dolist (fun funs)
599 (let ((return (lambda-return fun)))
600 (when return
601 (when (node-reoptimize return)
602 (setf (node-reoptimize return) nil)
603 (find-result-type return))
604 (res (return-result-type return)))))
605
606 (when (type/= (res) (tail-set-type tails))
607 (setf (tail-set-type tails) (res))
608 (dolist (fun (tail-set-functions tails))
609 (dolist (ref (leaf-refs fun))
610 (reoptimize-continuation (node-cont ref)))))))
611
612 (undefined-value))
613
614
615 ;;; IF optimization:
616
617 (declaim (start-block ir1-optimize-if))
618
619 ;;; IR1-Optimize-If -- Internal
620 ;;;
621 ;;; If the test has multiple uses, replicate the node when possible. Also
622 ;;; check if the predicate is known to be true or false, deleting the IF node
623 ;;; in favor of the appropriate branch when this is the case.
624 ;;;
625 (defun ir1-optimize-if (node)
626 (declare (type cif node))
627 (let ((test (if-test node))
628 (block (node-block node)))
629
630 (when (and (eq (block-start block) test)
631 (eq (continuation-next test) node)
632 (rest (block-start-uses block)))
633 (do-uses (use test)
634 (when (immediately-used-p test use)
635 (convert-if-if use node)
636 (when (continuation-use test) (return)))))
637 ;;
638 ;; Don't flush if-tests when they require a type check.
639 (when (memq (continuation-type-check test) '(nil :deleted))
640 (let* ((type (continuation-type test))
641 (victim
642 (cond ((constant-continuation-p test)
643 (if (continuation-value test)
644 (if-alternative node)
645 (if-consequent node)))
646 ((not (types-intersect type *null-type*))
647 (if-alternative node))
648 ((type= type *null-type*)
649 (if-consequent node)))))
650 (when victim
651 (flush-dest test)
652 (when (rest (block-succ block))
653 (unlink-blocks block victim))
654 (setf (component-reanalyze (block-component (node-block node))) t)
655 (unlink-node node)))))
656 (undefined-value))
657
658
659 ;;; Convert-If-If -- Internal
660 ;;;
661 ;;; Create a new copy of an IF Node that tests the value of the node Use.
662 ;;; The test must have >1 use, and must be immediately used by Use. Node must
663 ;;; be the only node in its block (implying that block-start = if-test).
664 ;;;
665 ;;; This optimization has an effect semantically similar to the
666 ;;; source-to-source transformation:
667 ;;; (IF (IF A B C) D E) ==>
668 ;;; (IF A (IF B D E) (IF C D E))
669 ;;;
670 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new node so
671 ;;; that dead code deletion notes will definitely not consider either node to
672 ;;; be part of the original source. One node might become unreachable,
673 ;;; resulting in a spurious note.
674 ;;;
675 (defun convert-if-if (use node)
676 (declare (type node use) (type cif node))
677 (with-ir1-environment node
678 (let* ((block (node-block node))
679 (test (if-test node))
680 (cblock (if-consequent node))
681 (ablock (if-alternative node))
682 (use-block (node-block use))
683 (dummy-cont (make-continuation))
684 (new-cont (make-continuation))
685 (new-node (make-if :test new-cont
686 :consequent cblock :alternative ablock))
687 (new-block (continuation-starts-block new-cont)))
688 (prev-link new-node new-cont)
689 (setf (continuation-dest new-cont) new-node)
690 (add-continuation-use new-node dummy-cont)
691 (setf (block-last new-block) new-node)
692
693 (unlink-blocks use-block block)
694 (delete-continuation-use use)
695 (add-continuation-use use new-cont)
696 (link-blocks use-block new-block)
697
698 (link-blocks new-block cblock)
699 (link-blocks new-block ablock)
700
701 (push "<IF Duplication>" (node-source-path node))
702 (push "<IF Duplication>" (node-source-path new-node))
703
704 (reoptimize-continuation test)
705 (reoptimize-continuation new-cont)
706 (setf (component-reanalyze *current-component*) t)))
707 (undefined-value))
708
709 (declaim (end-block))
710
711
712 ;;;; Exit IR1 optimization:
713
714 ;;; Maybe-Delete-Exit -- Interface
715 ;;;
716 ;;; This function attempts to delete an exit node, returning true if it
717 ;;; deletes the block as a consequence:
718 ;;; -- If the exit is degenerate (has no Entry), then we don't do anything,
719 ;;; since there is nothing to be done.
720 ;;; -- If the exit node and its Entry have the same home lambda then we know
721 ;;; the exit is local, and can delete the exit. We change uses of the
722 ;;; Exit-Value to be uses of the original continuation, then unlink the
723 ;;; node. If the exit is to a TR context, then we must do MERGE-TAIL-SETS
724 ;;; on any local calls which delivered their value to this exit.
725 ;;; -- If there is no value (as in a GO), then we skip the value semantics.
726 ;;;
727 ;;; This function is also called by environment analysis, since it wants all
728 ;;; exits to be optimized even if normal optimization was omitted.
729 ;;;
730 (defun maybe-delete-exit (node)
731 (declare (type exit node))
732 (let ((value (exit-value node))
733 (entry (exit-entry node))
734 (cont (node-cont node)))
735 (when (and entry
736 (eq (node-home-lambda node) (node-home-lambda entry)))
737 (setf (entry-exits entry) (delete node (entry-exits entry)))
738 (prog1
739 (unlink-node node)
740 (when value
741 (collect ((merges))
742 (when (return-p (continuation-dest cont))
743 (do-uses (use value)
744 (when (and (basic-combination-p use)
745 (eq (basic-combination-kind use) :local))
746 (merges use))))
747 (substitute-continuation-uses cont value)
748 (dolist (merge (merges))
749 (merge-tail-sets merge))))))))
750
751
752 ;;;; Combination IR1 optimization:
753
754 (declaim (start-block ir1-optimize-combination maybe-terminate-block
755 validate-call-type))
756
757 ;;; Ir1-Optimize-Combination -- Internal
758 ;;;
759 ;;; Do IR1 optimizations on a Combination node.
760 ;;;
761 (defun ir1-optimize-combination (node)
762 (declare (type combination node))
763 (when (continuation-reoptimize (basic-combination-fun node))
764 (propagate-function-change node))
765 (let ((args (basic-combination-args node))
766 (kind (basic-combination-kind node)))
767 (case kind
768 (:local
769 (let ((fun (combination-lambda node)))
770 (if (eq (functional-kind fun) :let)
771 (propagate-let-args node fun)
772 (propagate-local-call-args node fun))))
773 ((:full :error)
774 (dolist (arg args)
775 (when arg
776 (setf (continuation-reoptimize arg) nil))))
777 (t
778 (dolist (arg args)
779 (when arg
780 (setf (continuation-reoptimize arg) nil)))
781
782 (let ((attr (function-info-attributes kind)))
783 (when (and (ir1-attributep attr foldable)
784 (not (ir1-attributep attr call))
785 (every #'constant-continuation-p args)
786 (continuation-dest (node-cont node)))
787 (constant-fold-call node)
788 (return-from ir1-optimize-combination)))
789
790 (let ((fun (function-info-derive-type kind)))
791 (when fun
792 (let ((res (funcall fun node)))
793 (when res
794 (derive-node-type node res)
795 (maybe-terminate-block node nil)))))
796
797 (let ((fun (function-info-optimizer kind)))
798 (unless (and fun (funcall fun node))
799 (dolist (x (function-info-transforms kind))
800 (unless (ir1-transform node x)
801 (return))))))))
802
803 (undefined-value))
804
805
806 ;;; MAYBE-TERMINATE-BLOCK -- Interface
807 ;;;
808 ;;; If Call is to a function that doesn't return (type NIL), then terminate
809 ;;; the block there, and link it to the component tail. We also change the
810 ;;; call's CONT to be a dummy continuation to prevent the use from confusing
811 ;;; things.
812 ;;;
813 ;;; Except when called during IR1, we delete the continuation if it has no
814 ;;; other uses. (If it does have other uses, we reoptimize.)
815 ;;;
816 ;;; Termination on the basis of a continuation type assertion is inhibited
817 ;;; when:
818 ;;; -- The continuation is deleted (hence the assertion is spurious), or
819 ;;; -- We are in IR1 conversion (where THE assertions are subject to
820 ;;; weakening.)
821 ;;;
822 (defun maybe-terminate-block (call ir1-p)
823 (declare (type basic-combination call))
824 (let* ((block (node-block call))
825 (cont (node-cont call))
826 (tail (component-tail (block-component block)))
827 (succ (first (block-succ block))))
828 (unless (or (and (eq call (block-last block)) (eq succ tail))
829 (block-delete-p block)
830 *converting-for-interpreter*)
831 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
832 (not (or ir1-p (eq (continuation-kind cont) :deleted))))
833 (eq (node-derived-type call) *empty-type*))
834 (cond (ir1-p
835 (delete-continuation-use call)
836 (cond
837 ((block-last block)
838 (assert (and (eq (block-last block) call)
839 (eq (continuation-kind cont) :block-start))))
840 (t
841 (setf (block-last block) call)
842 (link-blocks block (continuation-starts-block cont)))))
843 (t
844 (node-ends-block call)
845 (delete-continuation-use call)
846 (if (eq (continuation-kind cont) :unused)
847 (delete-continuation cont)
848 (reoptimize-continuation cont))))
849
850 (unlink-blocks block (first (block-succ block)))
851 (setf (component-reanalyze (block-component block)) t)
852 (assert (not (block-succ block)))
853 (link-blocks block tail)
854 (add-continuation-use call (make-continuation))
855 t))))
856
857
858 ;;; Recognize-Known-Call -- Interface
859 ;;;
860 ;;; Called both by IR1 conversion and IR1 optimization when they have
861 ;;; verified the type signature for the call, and are wondering if something
862 ;;; should be done to special-case the call. If Call is a call to a global
863 ;;; function, then see if it defined or known:
864 ;;; -- If a DEFINED-FUNCTION should be inline expanded, then convert the
865 ;;; expansion and change the call to call it. Expansion is enabled if
866 ;;; :INLINE or if space=0. If the FUNCTIONAL slot is true, we never expand,
867 ;;; since this function has already been converted. Local call analysis
868 ;;; will duplicate the definition if necessary. We claim that the parent
869 ;;; form is LABELS for context declarations, since we don't want it to be
870 ;;; considered a real global function.
871 ;;; -- In addition to a direct check for the function name in the table, we
872 ;;; also must check for slot accessors. If the function is a slot accessor,
873 ;;; then we set the combination kind to the function info of %Slot-Setter or
874 ;;; %Slot-Accessor, as appropriate.
875 ;;; -- If it is a known function, mark it as such by setting the Kind.
876 ;;;
877 ;;; We return the leaf referenced (NIL if not a leaf) and the function-info
878 ;;; assigned.
879 ;;;
880 (defun recognize-known-call (call ir1-p)
881 (declare (type combination call))
882 (let* ((ref (continuation-use (basic-combination-fun call)))
883 (leaf (when (ref-p ref) (ref-leaf ref)))
884 (inlinep (if (defined-function-p leaf)
885 (defined-function-inlinep leaf)
886 :no-chance)))
887 (when (and (or (byte-compiling)
888 *converting-for-interpreter*)
889 (member inlinep '(:inline :maybe-inline)))
890 (setq inlinep :notinline))
891 (cond
892 ((eq inlinep :notinline) (values nil nil))
893 ((not (and (global-var-p leaf)
894 (eq (global-var-kind leaf) :global-function)))
895 (values leaf nil))
896 ((and (ecase inlinep
897 (:inline t)
898 (:no-chance nil)
899 ((nil :maybe-inline) (policy call (zerop space))))
900 (defined-function-inline-expansion leaf)
901 (let ((fun (defined-function-functional leaf)))
902 (or (not fun)
903 (and (eq inlinep :inline) (functional-kind fun))))
904 (inline-expansion-ok call))
905 (flet ((frob ()
906 (let ((res (ir1-convert-lambda-for-defun
907 (defined-function-inline-expansion leaf)
908 leaf t
909 #'ir1-convert-inline-lambda
910 'labels)))
911 (setf (defined-function-functional leaf) res)
912 (change-ref-leaf ref res))))
913 (if ir1-p
914 (frob)
915 (with-ir1-environment call
916 (frob)
917 (local-call-analyze *current-component*))))
918
919 (values (ref-leaf (continuation-use (basic-combination-fun call)))
920 nil))
921 (t
922 (let* ((name (leaf-name leaf))
923 (info (info function info
924 (if (slot-accessor-p leaf)
925 (if (consp name)
926 '%slot-setter
927 '%slot-accessor)
928 name))))
929 (if info
930 (values leaf (setf (basic-combination-kind call) info))
931 (values leaf nil)))))))
932
933
934 ;;; VALIDATE-CALL-TYPE -- Internal
935 ;;;
936 ;;; Check if Call satisfies Type. If so, apply the type to the call, and do
937 ;;; MAYBE-TERMINATE-BLOCK and return the values of RECOGNIZE-KNOWN-CALL. If an
938 ;;; error, set the combination kind and return NIL, NIL. If the type is just
939 ;;; FUNCTION, then skip the syntax check, arg/result type processing, but still
940 ;;; call RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda, and
941 ;;; that checking is done by local call analysis.
942 ;;;
943 (defun validate-call-type (call type ir1-p)
944 (declare (type combination call) (type ctype type))
945 (cond ((not (function-type-p type))
946 (assert (multiple-value-bind
947 (val win)
948 (csubtypep type (specifier-type 'function))
949 (or val (not win))))
950 (recognize-known-call call ir1-p))
951 ((valid-function-use call type
952 :argument-test #'always-subtypep
953 :result-test #'always-subtypep
954 :error-function #'compiler-warning
955 :warning-function #'compiler-note)
956 (assert-call-type call type)
957 (maybe-terminate-block call ir1-p)
958 (recognize-known-call call ir1-p))
959 (t
960 (setf (combination-kind call) :error)
961 (values nil nil))))
962
963
964 ;;; Propagate-Function-Change -- Internal
965 ;;;
966 ;;; Called by Ir1-Optimize when the function for a call has changed.
967 ;;; If the call is local, we try to let-convert it, and derive the result type.
968 ;;; If it is a :FULL call, we validate it against the type, which recognizes
969 ;;; known calls, does inline expansion, etc. If a call to a predicate in a
970 ;;; non-conditional position or to a function with a source transform, then we
971 ;;; reconvert the form to give IR1 another chance.
972 ;;;
973 (defun propagate-function-change (call)
974 (declare (type combination call))
975 (let ((*compiler-error-context* call)
976 (fun-cont (basic-combination-fun call)))
977 (setf (continuation-reoptimize fun-cont) nil)
978 (case (combination-kind call)
979 (:local
980 (let ((fun (combination-lambda call)))
981 (maybe-let-convert fun)
982 (unless (member (functional-kind fun) '(:let :assignment :deleted))
983 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
984 (:full
985 (multiple-value-bind
986 (leaf info)
987 (validate-call-type call (continuation-type fun-cont) nil)
988 (cond ((functional-p leaf)
989 (convert-call-if-possible
990 (continuation-use (basic-combination-fun call))
991 call))
992 ((not leaf))
993 ((or (info function source-transform (leaf-name leaf))
994 (and info
995 (ir1-attributep (function-info-attributes info)
996 predicate)
997 (let ((dest (continuation-dest (node-cont call))))
998 (and dest (not (if-p dest))))))
999 (let ((name (leaf-name leaf)))
1000 (when (symbolp name)
1001 (let ((dums (loop repeat (length (combination-args call))
1002 collect (gensym))))
1003 (transform-call call
1004 `(lambda ,dums
1005 (,name ,@dums))))))))))))
1006 (undefined-value))
1007
1008
1009 ;;;; Known function optimization:
1010
1011
1012 ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
1013 ;;;
1014 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for Node, Fun
1015 ;;; and Args. If there is already a note for Node and Transform, replace it,
1016 ;;; otherwise add a new one.
1017 ;;;
1018 (defun record-optimization-failure (node transform args)
1019 (declare (type combination node) (type transform transform)
1020 (type (or function-type list) args))
1021 (let* ((table (component-failed-optimizations *compile-component*))
1022 (found (assoc transform (gethash node table))))
1023 (if found
1024 (setf (cdr found) args)
1025 (push (cons transform args) (gethash node table))))
1026 (undefined-value))
1027
1028
1029 ;;; IR1-Transform -- Internal
1030 ;;;
1031 ;;; Attempt to transform Node using Function, subject to the call type
1032 ;;; constraint Type. If we are inhibited from doing the transform for some
1033 ;;; reason and Flame is true, then we make a note of the message in
1034 ;;; FAILED-OPTIMIZATIONS for IR1 finalize to pick up. We return true if
1035 ;;; the transform failed, and thus further transformation should be
1036 ;;; attempted. We return false if either the transform suceeded or was
1037 ;;; aborted.
1038 ;;;
1039 (defun ir1-transform (node transform)
1040 (declare (type combination node) (type transform transform))
1041 (let* ((type (transform-type transform))
1042 (fun (transform-function transform))
1043 (constrained (function-type-p type))
1044 (table (component-failed-optimizations *compile-component*))
1045 (flame
1046 (if (transform-important transform)
1047 (policy node (>= speed brevity))
1048 (policy node (> speed brevity))))
1049 (*compiler-error-context* node))
1050 (cond ((let ((when (transform-when transform)))
1051 (not (or (eq when :both)
1052 (eq when (if *byte-compiling* :byte :native)))))
1053 t)
1054 ((or (not constrained)
1055 (valid-function-use node type :strict-result t))
1056 (multiple-value-bind
1057 (severity args)
1058 (catch 'give-up
1059 (transform-call node (funcall fun node))
1060 (values :none nil))
1061 (ecase severity
1062 (:none
1063 (remhash node table)
1064 nil)
1065 (:aborted
1066 (setf (combination-kind node) :error)
1067 (when args
1068 (apply #'compiler-warning args))
1069 (remhash node table)
1070 nil)
1071 (:failure
1072 (if args
1073 (when flame
1074 (record-optimization-failure node transform args))
1075 (setf (gethash node table)
1076 (remove transform (gethash node table) :key #'car)))
1077 t)
1078 (:delayed
1079 (remhash node table)
1080 nil))))
1081 ((and flame
1082 (valid-function-use node type
1083 :argument-test #'types-intersect
1084 :result-test #'values-types-intersect))
1085 (record-optimization-failure node transform type)
1086 t)
1087 (t
1088 t))))
1089
1090 (declaim (end-block))
1091
1092 ;;; give-up, abort-transform -- Interface
1093 ;;;
1094 ;;; Just throw the severity and args...
1095 ;;;
1096 (defun give-up (&rest args)
1097 "This function is used to throw out of an IR1 transform, aborting this
1098 attempt to transform the call, but admitting the possibility that this or
1099 some other transform will later suceed. If arguments are supplied, they are
1100 format arguments for an efficiency note."
1101 (values nil)
1102 (throw 'give-up (values :failure args)))
1103 ;;;
1104 (defun abort-transform (&rest args)
1105 "This function is used to throw out of an IR1 transform and force a normal
1106 call to the function at run time. No further optimizations will be
1107 attempted."
1108 (throw 'give-up (values :aborted args)))
1109
1110 (defvar *delayed-transforms*)
1111
1112 ;;; delay-transform -- Interface
1113 ;;;
1114 (defun delay-transform (node &rest reasons)
1115 "This function is used to throw out of an IR1 transform, and delay the
1116 transform on the node until later. The reasons specifies when the transform
1117 will be later retried. The :optimize reason causes the transform to be
1118 delayed until after the current IR1 optimization pass. The :constraint
1119 reason causes the transform to be delayed until after constraint
1120 propagation."
1121 (let ((assoc (assoc node *delayed-transforms*)))
1122 (cond ((not assoc)
1123 (setf *delayed-transforms*
1124 (acons node reasons *delayed-transforms*))
1125 (throw 'give-up :delayed))
1126 ((cdr assoc)
1127 (dolist (reason reasons)
1128 (pushnew reason (cdr assoc)))
1129 (throw 'give-up :delayed)))))
1130
1131 ;;; retry-delayed-transforms -- Interface.
1132 ;;;
1133 ;;; Clear any delayed transform with no reasons - these should have been tried
1134 ;;; in the last pass. Then remove the reason from the delayed transform
1135 ;;; reasons, and if any become empty then set reoptimize flags for the
1136 ;;; node. Returns true if any transforms are to be retried.
1137 ;;;
1138 (defun retry-delayed-transforms (reason)
1139 (setf *delayed-transforms* (remove-if-not #'cdr *delayed-transforms*))
1140 (let ((reoptimize nil))
1141 (dolist (assoc *delayed-transforms*)
1142 (let ((reasons (remove reason (cdr assoc))))
1143 (setf (cdr assoc) reasons)
1144 (unless reasons
1145 (let ((node (car assoc)))
1146 (unless (node-deleted node)
1147 (setf reoptimize t)
1148 (setf (node-reoptimize node) t)
1149 (let ((block (node-block node)))
1150 (setf (block-reoptimize block) t)
1151 (setf (component-reoptimize (block-component block)) t)))))))
1152 reoptimize))
1153
1154
1155 ;;; Transform-Call -- Internal
1156 ;;;
1157 ;;; Take the lambda-expression Res, IR1 convert it in the proper
1158 ;;; environment, and then install it as the function for the call Node. We do
1159 ;;; local call analysis so that the new function is integrated into the control
1160 ;;; flow.
1161 ;;;
1162 (defun transform-call (node res)
1163 (declare (type combination node) (list res))
1164 (with-ir1-environment node
1165 (let ((new-fun (ir1-convert-inline-lambda res))
1166 (ref (continuation-use (combination-fun node))))
1167 (change-ref-leaf ref new-fun)
1168 (setf (combination-kind node) :full)
1169 (local-call-analyze *current-component*)))
1170 (undefined-value))
1171
1172 ;;; Constant-Fold-Call -- Internal
1173 ;;;
1174 ;;; Replace a call to a foldable function of constant arguments with the
1175 ;;; result of evaluating the form. We insert the resulting constant node after
1176 ;;; the call, stealing the call's continuation. We give the call a
1177 ;;; continuation with no Dest, which should cause it and its arguments to go
1178 ;;; away. If there is an error during the evaluation, we give a warning and
1179 ;;; leave the call alone, making the call a :ERROR call.
1180 ;;;
1181 ;;; If there is more than one value, then we transform the call into a
1182 ;;; values form.
1183 ;;;
1184 (defun constant-fold-call (call)
1185 (declare (type combination call))
1186 (let* ((args (mapcar #'continuation-value (combination-args call)))
1187 (ref (continuation-use (combination-fun call)))
1188 (fun (leaf-name (ref-leaf ref))))
1189
1190 (multiple-value-bind (values win)
1191 (careful-call fun args call "constant folding")
1192 (cond ((not win)
1193 (setf (combination-kind call) :error))
1194 ;;
1195 ;; Don't constand-fold a call if one of its arguments
1196 ;; requires a type check.
1197 ((or (policy call (< safety 3))
1198 (loop for arg in (basic-combination-args call)
1199 as check = (continuation-type-check arg)
1200 always (member check '(nil :deleted))))
1201 (let ((dummies (loop repeat (length args) collect (gensym))))
1202 (transform-call
1203 call
1204 `(lambda ,dummies
1205 (declare (ignore ,@dummies))
1206 (values ,@(mapcar (lambda (x) `',x) values)))))))))
1207 (values))
1208
1209
1210 ;;;; Local call optimization:
1211
1212 (declaim (start-block ir1-optimize-set constant-reference-p delete-let
1213 propagate-let-args propagate-local-call-args
1214 propagate-to-refs propagate-from-sets
1215 ir1-optimize-mv-combination))
1216
1217 ;;; Propagate-To-Refs -- Internal
1218 ;;;
1219 ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1220 ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1221 ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1222 ;;;
1223 (defun propagate-to-refs (leaf type)
1224 (declare (type leaf leaf) (type ctype type))
1225 (let ((var-type (leaf-type leaf)))
1226 (unless (function-type-p var-type)
1227 (let ((int (type-intersection var-type type)))
1228 (when (type/= int var-type)
1229 (setf (leaf-type leaf) int)
1230 (dolist (ref (leaf-refs leaf))
1231 (derive-node-type ref int))))
1232 (undefined-value))))
1233
1234
1235 ;;; PROPAGATE-FROM-SETS -- Internal
1236 ;;;
1237 ;;; Figure out the type of a LET variable that has sets. We compute the
1238 ;;; union of the initial value Type and the types of all the set values and to
1239 ;;; a PROPAGATE-TO-REFS with this type.
1240 ;;;
1241 (defun propagate-from-sets (var type)
1242 (collect ((res type type-union))
1243 (dolist (set (basic-var-sets var))
1244 (res (continuation-type (set-value set)))
1245 (setf (node-reoptimize set) nil))
1246 (propagate-to-refs var (res)))
1247 (undefined-value))
1248
1249
1250 ;;; IR1-OPTIMIZE-SET -- Internal
1251 ;;;
1252 ;;; If a let variable, find the initial value's type and do
1253 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1254 ;;;
1255 (defun ir1-optimize-set (node)
1256 (declare (type cset node))
1257 (let ((var (set-var node)))
1258 (when (and (lambda-var-p var) (leaf-refs var))
1259 (let ((home (lambda-var-home var)))
1260 (when (eq (functional-kind home) :let)
1261 (let ((iv (let-var-initial-value var)))
1262 (setf (continuation-reoptimize iv) nil)
1263 (propagate-from-sets var (continuation-type iv)))))))
1264
1265 (derive-node-type node (continuation-type (set-value node)))
1266 (undefined-value))
1267
1268
1269 ;;; CONSTANT-REFERENCE-P -- Interface
1270 ;;;
1271 ;;; Return true if the value of Ref will always be the same (and is thus
1272 ;;; legal to substitute.)
1273 ;;;
1274 (defun constant-reference-p (ref)
1275 (declare (type ref ref))
1276 (let ((leaf (ref-leaf ref)))
1277 (typecase leaf
1278 ((or constant functional) t)
1279 (lambda-var
1280 (null (lambda-var-sets leaf)))
1281 (defined-function
1282 (not (eq (defined-function-inlinep leaf) :notinline)))
1283 (global-var
1284 (case (global-var-kind leaf)
1285 (:global-function t)
1286 (:constant t))))))
1287
1288
1289 ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1290 ;;;
1291 ;;; If we have a non-set let var with a single use, then (if possible)
1292 ;;; replace the variable reference's CONT with the arg continuation. This is
1293 ;;; inhibited when:
1294 ;;; -- CONT has other uses, or
1295 ;;; -- CONT receives multiple values, or
1296 ;;; -- the reference is in a different environment from the variable, or
1297 ;;; -- either continuation has a funky TYPE-CHECK annotation.
1298 ;;; -- the continuations have incompatible assertions, so the new asserted type
1299 ;;; would be NIL.
1300 ;;; -- CONT's assertion is incompatbile with the proven type of ARG's, such as
1301 ;;; when ARG returns multiple values and CONT has a single value assertion.
1302 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1303 ;;;
1304 ;;; We change the Ref to be a reference to NIL with unused value, and let it
1305 ;;; be flushed as dead code. A side-effect of this substitution is to delete
1306 ;;; the variable.
1307 ;;;
1308 (defun substitute-single-use-continuation (arg var)
1309 (declare (type continuation arg) (type lambda-var var))
1310 (let* ((ref (first (leaf-refs var)))
1311 (cont (node-cont ref))
1312 (cont-atype (continuation-asserted-type cont))
1313 (dest (continuation-dest cont)))
1314 (when (and (eq (continuation-use cont) ref)
1315 dest
1316 (not (typep dest '(or creturn exit mv-combination)))
1317 (eq (node-home-lambda ref)
1318 (lambda-home (lambda-var-home var)))
1319 (member (continuation-type-check arg) '(t nil))
1320 (member (continuation-type-check cont) '(t nil))
1321 (not (eq (values-type-intersection
1322 cont-atype (continuation-asserted-type arg))
1323 *empty-type*))
1324 (not (eq (values-type-intersection
1325 cont-atype (continuation-proven-type arg))
1326 *empty-type*))
1327 (eq (lexenv-cookie (node-lexenv dest))
1328 (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1329 (assert (member (continuation-kind arg)
1330 '(:block-start :deleted-block-start :inside-block)))
1331 (assert-continuation-type arg cont-atype)
1332 (setf (node-derived-type ref) *wild-type*)
1333 (change-ref-leaf ref (find-constant nil))
1334 (substitute-continuation arg cont)
1335 (reoptimize-continuation arg)
1336 t)))
1337
1338
1339 ;;; DELETE-LET -- Interface
1340 ;;;
1341 ;;; Delete a Let, removing the call and bind nodes, and warning about any
1342 ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1343 ;;; away and delete the REF and then the lambda, since we flush the FUN
1344 ;;; continuation.
1345 ;;;
1346 (defun delete-let (fun)
1347 (declare (type clambda fun))
1348 (assert (member (functional-kind fun) '(:let :mv-let)))
1349 (note-unreferenced-vars fun)
1350 (let ((call (let-combination fun)))
1351 (flush-dest (basic-combination-fun call))
1352 (unlink-node call)
1353 (unlink-node (lambda-bind fun))
1354 (setf (lambda-bind fun) nil))
1355 (undefined-value))
1356
1357
1358 ;;; Propagate-Let-Args -- Internal
1359 ;;;
1360 ;;; This function is called when one of the arguments to a LET changes. We
1361 ;;; look at each changed argument. If the corresponding variable is set, then
1362 ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1363 ;;; variable, and also propagate derived-type information for the arg to all
1364 ;;; the Var's refs.
1365 ;;;
1366 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1367 ;;; subtype of the argument's asserted type. This prevents type checking from
1368 ;;; being defeated, and also ensures that the best representation for the
1369 ;;; variable can be used.
1370 ;;;
1371 ;;; Substitution of individual references is inhibited if the reference is
1372 ;;; in a different component from the home. This can only happen with closures
1373 ;;; over top-level lambda vars. In such cases, the references may have already
1374 ;;; been compiled, and thus can't be retroactively modified.
1375 ;;;
1376 ;;; If all of the variables are deleted (have no references) when we are
1377 ;;; done, then we delete the let.
1378 ;;;
1379 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1380 ;;; flags.
1381 ;;;
1382 (defun propagate-let-args (call fun)
1383 (declare (type combination call) (type clambda fun))
1384 (loop for arg in (combination-args call)
1385 and var in (lambda-vars fun) do
1386 (when (and arg (continuation-reoptimize arg))
1387 (setf (continuation-reoptimize arg) nil)
1388 (cond
1389 ((lambda-var-sets var)
1390 (propagate-from-sets var (continuation-type arg)))
1391 ((let ((use (continuation-use arg)))
1392 (when (ref-p use)
1393 (let ((leaf (ref-leaf use)))
1394 (when (and (constant-reference-p use)
1395 (values-subtypep (leaf-type leaf)
1396 (continuation-asserted-type arg)))
1397 (propagate-to-refs var (continuation-type arg))
1398 (let ((this-comp (block-component (node-block use))))
1399 (substitute-leaf-if
1400 #'(lambda (ref)
1401 (cond ((eq (block-component (node-block ref))
1402 this-comp)
1403 t)
1404 (t
1405 (assert (eq (functional-kind (lambda-home fun))
1406 :top-level))
1407 nil)))
1408 leaf var))
1409 t)))))
1410 ((and (null (rest (leaf-refs var)))
1411 (not *byte-compiling*)
1412 (substitute-single-use-continuation arg var)))
1413 (t
1414 (propagate-to-refs var (continuation-type arg))))))
1415
1416 (when (every #'null (combination-args call))
1417 (delete-let fun))
1418
1419 (undefined-value))
1420
1421
1422 ;;; Propagate-Local-Call-Args -- Internal
1423 ;;;
1424 ;;; This function is called when one of the args to a non-let local call
1425 ;;; changes. For each changed argument corresponding to an unset variable, we
1426 ;;; compute the union of the types across all calls and propagate this type
1427 ;;; information to the var's refs.
1428 ;;;
1429 ;;; If the function has an XEP, then we don't do anything, since we won't
1430 ;;; discover anything.
1431 ;;;
1432 ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1433 ;;; corresponding to changed arguments in Call, since the only use in IR1
1434 ;;; optimization of the Reoptimize flag for local call args is right here.
1435 ;;;
1436 (defun propagate-local-call-args (call fun)
1437 (declare (type combination call) (type clambda fun))
1438
1439 (unless (or (functional-entry-function fun)
1440 (lambda-optional-dispatch fun))
1441 (let* ((vars (lambda-vars fun))
1442 (union (mapcar #'(lambda (arg var)
1443 (when (and arg
1444 (continuation-reoptimize arg)
1445 (null (basic-var-sets var)))
1446 (continuation-type arg)))
1447 (basic-combination-args call)
1448 vars))
1449 (this-ref (continuation-use (basic-combination-fun call))))
1450
1451 (dolist (arg (basic-combination-args call))
1452 (when arg
1453 (setf (continuation-reoptimize arg) nil)))
1454
1455 (dolist (ref (leaf-refs fun))
1456 (let ((dest (continuation-dest (node-cont ref))))
1457 (unless (or (eq ref this-ref) (not dest))
1458 (setq union
1459 (mapcar #'(lambda (this-arg old)
1460 (when old
1461 (setf (continuation-reoptimize this-arg) nil)
1462 (type-union (continuation-type this-arg) old)))
1463 (basic-combination-args dest)
1464 union)))))
1465
1466 (mapc #'(lambda (var type)
1467 (when type
1468 (propagate-to-refs var type)))
1469 vars union)))
1470
1471 (undefined-value))
1472
1473 (declaim (end-block))
1474
1475
1476 ;;;; Multiple values optimization:
1477
1478 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1479 ;;;
1480 ;;; Do stuff to notice a change to a MV combination node. There are two
1481 ;;; main branches here:
1482 ;;; -- If the call is local, then it is already a MV let, or should become one.
1483 ;;; Note that although all :LOCAL MV calls must eventually be converted to
1484 ;;; :MV-LETs, there can be a window when the call is local, but has not
1485 ;;; been let converted yet. This is because the entry-point lambdas may
1486 ;;; have stray references (in other entry points) that have not been
1487 ;;; deleted yet.
1488 ;;; -- The call is full. This case is somewhat similar to the non-MV
1489 ;;; combination optimization: we propagate return type information and
1490 ;;; notice non-returning calls. We also have an optimization
1491 ;;; which tries to convert MV-CALLs into MV-binds.
1492 ;;;
1493 (defun ir1-optimize-mv-combination (node)
1494 (ecase (basic-combination-kind node)
1495 (:local
1496 (let ((fun-cont (basic-combination-fun node)))
1497 (when (continuation-reoptimize fun-cont)
1498 (setf (continuation-reoptimize fun-cont) nil)
1499 (maybe-let-convert (combination-lambda node))))
1500 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1501 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1502 (unless (convert-mv-bind-to-let node)
1503 (ir1-optimize-mv-bind node))))
1504 (:full
1505 (let* ((fun (basic-combination-fun node))
1506 (fun-changed (continuation-reoptimize fun))
1507 (args (basic-combination-args node)))
1508 (when fun-changed
1509 (setf (continuation-reoptimize fun) nil)
1510 (let ((type (continuation-type fun)))
1511 (when (function-type-p type)
1512 (derive-node-type node (function-type-returns type))))
1513 (maybe-terminate-block node nil)
1514 (let ((use (continuation-use fun)))
1515 (when (and (ref-p use) (functional-p (ref-leaf use)))
1516 (convert-call-if-possible use node)
1517 (when (eq (basic-combination-kind node) :local)
1518 (maybe-let-convert (ref-leaf use))))))
1519 (unless (or (eq (basic-combination-kind node) :local)
1520 (eq (continuation-function-name fun) '%throw))
1521 (ir1-optimize-mv-call node))
1522 (dolist (arg args)
1523 (setf (continuation-reoptimize arg) nil))))
1524 (:error))
1525 (undefined-value))
1526
1527
1528 ;;; Values-types-defaulted -- Internal
1529 ;;;
1530 ;;; Like values-types, but returns the types of the given number of
1531 ;;; arguments. If optional of rest values must be used then the union
1532 ;;; with the null type is computed in case of defaulting, and if no
1533 ;;; values are available then they are defaulted to the null type.
1534 ;;;
1535 (defun values-types-defaulted (type count)
1536 (declare (type ctype type) (type index count))
1537 (cond ((eq type *wild-type*)
1538 (let ((types nil))
1539 (dotimes (i count types)
1540 (push *universal-type* types))))
1541 ((not (values-type-p type))
1542 (let ((types nil))
1543 (dotimes (i (1- count))
1544 (push *null-type* types))
1545 (push type types)))
1546 (t
1547 (let ((required (args-type-required type))
1548 (optional (args-type-optional type))
1549 (keyp-allowp (or (args-type-keyp type) (args-type-allowp type)))
1550 (rest (args-type-rest type)))
1551 (collect ((types))
1552 (dotimes (i count)
1553 (types (cond (required (single-value-type (pop required)))
1554 (optional (values-type-union
1555 (single-value-type (pop optional))
1556 *null-type*))
1557 (keyp-allowp *universal-type*)
1558 (rest (values-type-union (single-value-type rest)
1559 *null-type*))
1560 (t *null-type*))))
1561 (types))))))
1562
1563
1564 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1565 ;;;
1566 ;;; Propagate derived type info from the values continuation to the vars.
1567 ;;;
1568 (defun ir1-optimize-mv-bind (node)
1569 (declare (type mv-combination node))
1570 (let ((arg (first (basic-combination-args node)))
1571 (vars (lambda-vars (combination-lambda node))))
1572 (let ((types (values-types-defaulted (continuation-derived-type arg)
1573 (length vars))))
1574 (mapc #'(lambda (var type)
1575 (if (basic-var-sets var)
1576 (propagate-from-sets var type)
1577 (propagate-to-refs var type)))
1578 vars types))
1579
1580 (setf (continuation-reoptimize arg) nil))
1581 (undefined-value))
1582
1583
1584 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1585 ;;;
1586 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1587 ;;; if:
1588 ;;; -- The call has only one argument, and
1589 ;;; -- The function has a known fixed number of arguments, or
1590 ;;; -- The argument yields a known fixed number of values.
1591 ;;;
1592 ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1593 ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1594 ;;; this call can be converted (the next time around.) This new lambda just
1595 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1596 ;;; that this new MV bind is not let-converted immediately, as there are going
1597 ;;; to be stray references from the entry-point functions until they get
1598 ;;; deleted.
1599 ;;;
1600 ;;; In order to avoid loss of argument count checking, we only do the
1601 ;;; transformation according to a known number of expected argument if safety
1602 ;;; is unimportant. We can always convert if we know the number of actual
1603 ;;; values, since the normal call that we build will still do any appropriate
1604 ;;; argument count checking.
1605 ;;;
1606 ;;; We only attempt the transformation if the called function is a constant
1607 ;;; reference. This allows us to just splice the leaf into the new function,
1608 ;;; instead of trying to somehow bind the function expression. The leaf must
1609 ;;; be constant because we are evaluating it again in a different place. This
1610 ;;; also has the effect of squelching multiple warnings when there is an
1611 ;;; argument count error.
1612 ;;;
1613 (defun ir1-optimize-mv-call (node)
1614 (let ((fun (basic-combination-fun node))
1615 (*compiler-error-context* node)
1616 (ref (continuation-use (basic-combination-fun node)))
1617 (args (basic-combination-args node)))
1618
1619 (unless (and (ref-p ref) (constant-reference-p ref)
1620 args (null (rest args)))
1621 (return-from ir1-optimize-mv-call))
1622
1623 (multiple-value-bind (min max)
1624 (function-type-nargs (continuation-type fun))
1625 (let ((total-nvals
1626 (multiple-value-bind
1627 (types nvals)
1628 (values-types (continuation-derived-type (first args)))
1629 (declare (ignore types))
1630 (if (eq nvals :unknown) nil nvals))))
1631
1632 (when total-nvals
1633 (when (and min (< total-nvals min))
1634 (compiler-warning
1635 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1636 at least ~R."
1637 total-nvals min)
1638 (setf (basic-combination-kind node) :error)
1639 (return-from ir1-optimize-mv-call))
1640 (when (and max (> total-nvals max))
1641 (compiler-warning
1642 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1643 at most ~R."
1644 total-nvals max)
1645 (setf (basic-combination-kind node) :error)
1646 (return-from ir1-optimize-mv-call)))
1647
1648 (let ((count (cond (total-nvals)
1649 ((and (policy node (zerop safety)) (eql min max))
1650 min)
1651 (t nil))))
1652 (when count
1653 (with-ir1-environment node
1654 (let* ((dums (loop repeat count collect (gensym)))
1655 (ignore (gensym))
1656 (fun (ir1-convert-lambda
1657 `(lambda (&optional ,@dums &rest ,ignore)
1658 (declare (ignore ,ignore))
1659 (funcall ,(ref-leaf ref) ,@dums)))))
1660 (change-ref-leaf ref fun)
1661 (assert (eq (basic-combination-kind node) :full))
1662 (local-call-analyze *current-component*)
1663 (assert (eq (basic-combination-kind node) :local)))))))))
1664 (undefined-value))
1665
1666
1667 ;;; CONVERT-MV-BIND-TO-LET -- Internal
1668 ;;;
1669 ;;; If we see:
1670 ;;; (multiple-value-bind (x y)
1671 ;;; (values xx yy)
1672 ;;; ...)
1673 ;;; Convert to:
1674 ;;; (let ((x xx)
1675 ;;; (y yy))
1676 ;;; ...)
1677 ;;;
1678 ;;; What we actually do is convert the VALUES combination into a normal let
1679 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1680 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1681 ;;; args, insert references to NIL.
1682 ;;;
1683 (defun convert-mv-bind-to-let (call)
1684 (declare (type mv-combination call))
1685 (let* ((arg (first (basic-combination-args call)))
1686 (use (continuation-use arg)))
1687 (when (and (combination-p use)
1688 (eq (continuation-function-name (combination-fun use))
1689 'values))
1690 (let* ((fun (combination-lambda call))
1691 (vars (lambda-vars fun))
1692 (vals (combination-args use))
1693 (nvars (length vars))
1694 (nvals (length vals)))
1695 (cond ((> nvals nvars)
1696 (mapc #'flush-dest (subseq vals nvars))
1697 (setq vals (subseq vals 0 nvars)))
1698 ((< nvals nvars)
1699 (with-ir1-environment use
1700 (let ((node-prev (node-prev use)))
1701 (setf (node-prev use) nil)
1702 (setf (continuation-next node-prev) nil)
1703 (collect ((res vals))
1704 (loop as cont = (make-continuation use)
1705 and prev = node-prev then cont
1706 repeat (- nvars nvals)
1707 do (reference-constant prev cont nil)
1708 (res cont))
1709 (setq vals (res)))
1710 (prev-link use (car (last vals)))))))
1711 (setf (combination-args use) vals)
1712 (flush-dest (combination-fun use))
1713 (let ((fun-cont (basic-combination-fun call)))
1714 (setf (continuation-dest fun-cont) use)
1715 (setf (combination-fun use) fun-cont))
1716 (setf (combination-kind use) :local)
1717 (setf (functional-kind fun) :let)
1718 (flush-dest (first (basic-combination-args call)))
1719 (unlink-node call)
1720 (when vals
1721 (reoptimize-continuation (first vals)))
1722 (propagate-to-args use fun))
1723 t)))
1724
1725
1726 ;;; VALUES-LIST IR1 optimizer -- Internal
1727 ;;;
1728 ;;; If we see:
1729 ;;; (values-list (list x y z))
1730 ;;;
1731 ;;; Convert to:
1732 ;;; (values x y z)
1733 ;;;
1734 ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1735 ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1736 ;;; the old argument continuation (allowing the LIST to be flushed.)
1737 ;;;
1738 (defoptimizer (values-list optimizer) ((list) node)
1739 (let ((use (continuation-use list)))
1740 (when (and (combination-p use)
1741 (eq (continuation-function-name (combination-fun use))
1742 'list))
1743 (change-ref-leaf (continuation-use (combination-fun node))
1744 (find-free-function 'values "in a strange place"))
1745 (setf (combination-kind node) :full)
1746 (let ((args (combination-args use)))
1747 (dolist (arg args)
1748 (setf (continuation-dest arg) node))
1749 (setf (combination-args use) nil)
1750 (flush-dest list)
1751 (setf (combination-args node) args))
1752 t)))
1753
1754
1755 ;;; VALUES IR1 transform -- Internal
1756 ;;;
1757 ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1758 ;;; PROG1. This allows the computation of the additional values to become dead
1759 ;;; code. Some attempt is made to correct the node derived type, setting it to
1760 ;;; the received single-value-type. The node continuation asserted type must
1761 ;;; also be adjusted, taking care when the continuation has multiple uses.
1762 ;;;
1763 (deftransform values ((&rest vals) * * :node node)
1764 (let ((cont (node-cont node)))
1765 (when (typep (continuation-dest cont) '(or creturn exit mv-combination))
1766 (give-up))
1767 (flet ((first-value-type (type)
1768 (declare (type ctype type))
1769 (cond ((values-type-p type)
1770 (let ((required (args-type-required type)))
1771 (if required
1772 (first required)
1773 (let ((otype (args-type-optional type)))
1774 (cond (otype (first otype))
1775 ((or (args-type-keyp type)
1776 (args-type-allowp type))
1777 *universal-type*)
1778 ((args-type-rest type))
1779 (t *null-type*))))))
1780 ((eq type *wild-type*)
1781 *universal-type*)
1782 (t
1783 type))))
1784 (cond ((= (length (find-uses cont)) 1)
1785 (setf (node-derived-type node)
1786 (single-value-type (node-derived-type node)))
1787 (setf (continuation-asserted-type cont)
1788 (first-value-type (continuation-asserted-type cont))))
1789 (t
1790 (setf (node-derived-type node)
1791 (single-value-type (node-derived-type node)))
1792 (setf (continuation-asserted-type cont)
1793 (values-type-union (continuation-asserted-type cont)
1794 (first-value-type
1795 (continuation-asserted-type cont)))))))
1796 (reoptimize-continuation cont)
1797 (if vals
1798 (let ((dummies (loop repeat (1- (length vals))
1799 collect (gensym))))
1800 `(lambda (val ,@dummies)
1801 (declare (ignore ,@dummies))
1802 val))
1803 'nil)))

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