/[cmucl]/src/compiler/ir1opt.lisp
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Revision 1.74 - (show annotations)
Sun Mar 4 20:12:17 2001 UTC (13 years, 1 month ago) by pw
Branch: MAIN
CVS Tags: release-18e-base, LINKAGE_TABLE, PRE_LINKAGE_TABLE, release-18e-pre2, cold-pcl-base, UNICODE-BASE, release-18e, release-18e-pre1
Branch point for: UNICODE-BRANCH, release-18e-branch, cold-pcl
Changes since 1.73: +3 -3 lines
Change most PROCLAIMs to DECLAIMs.
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 1.74 2001/03/04 20:12:17 pw 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 (flush-dest (if-test last))
308 (when (unlink-node last) (return)))
309 (exit
310 (when (maybe-delete-exit last) (return)))))
311
312 (unless (join-successor-if-possible block)
313 (return)))
314
315 (when (and (block-reoptimize block) (block-component block))
316 (assert (not (block-delete-p block)))
317 (ir1-optimize-block block))
318
319 (when (and (block-flush-p block) (block-component block))
320 (assert (not (block-delete-p block)))
321 (flush-dead-code block)))))
322
323 (undefined-value))
324
325
326 ;;; IR1-Optimize-Block -- Internal
327 ;;;
328 ;;; Loop over the nodes in Block, looking for stuff that needs to be
329 ;;; optimized. We dispatch off of the type of each node with its reoptimize
330 ;;; flag set:
331 ;;; -- With a combination, we call Propagate-Function-Change whenever the
332 ;;; function changes, and call IR1-Optimize-Combination if any argument
333 ;;; changes.
334 ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
335 ;;; propagate Cont's assertion to the Value, since if we did, this would
336 ;;; move the checking of Cont's assertion to the exit. This wouldn't work
337 ;;; with Catch and UWP, where the Exit node is just a placeholder for the
338 ;;; actual unknown exit.
339 ;;;
340 ;;; Note that we clear the node & block reoptimize flags *before* doing the
341 ;;; optimization. This ensures that the node or block will be reoptimized if
342 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
343 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
344 ;;;
345 (defun ir1-optimize-block (block)
346 (declare (type cblock block))
347 (setf (block-reoptimize block) nil)
348 (do-nodes (node cont block :restart-p t)
349 (when (node-reoptimize node)
350 (setf (node-reoptimize node) nil)
351 (typecase node
352 (ref)
353 (combination
354 (ir1-optimize-combination node))
355 (cif
356 (ir1-optimize-if node))
357 (creturn
358 (setf (node-reoptimize node) t)
359 (ir1-optimize-return node))
360 (mv-combination
361 (ir1-optimize-mv-combination node))
362 (exit
363 (let ((value (exit-value node)))
364 (when value
365 (derive-node-type node (continuation-derived-type value)))))
366 (cset
367 (ir1-optimize-set node)))))
368 (undefined-value))
369
370
371 ;;; Join-Successor-If-Possible -- Internal
372 ;;;
373 ;;; We cannot combine with a successor block if:
374 ;;; 1] The successor has more than one predecessor.
375 ;;; 2] The last node's Cont is also used somewhere else.
376 ;;; 3] The successor is the current block (infinite loop).
377 ;;; 4] The next block has a different cleanup, and thus we may want to insert
378 ;;; cleanup code between the two blocks at some point.
379 ;;; 5] The next block has a different home lambda, and thus the control
380 ;;; transfer is a non-local exit.
381 ;;;
382 ;;; If we succeed, we return true, otherwise false.
383 ;;;
384 ;;; Joining is easy when the successor's Start continuation is the same from
385 ;;; our Last's Cont. If they differ, then we can still join when the last
386 ;;; continuation has no next and the next continuation has no uses. In this
387 ;;; case, we replace the next continuation with the last before joining the
388 ;;; blocks.
389 ;;;
390 (defun join-successor-if-possible (block)
391 (declare (type cblock block))
392 (let ((next (first (block-succ block))))
393 (when (block-start next)
394 (let* ((last (block-last block))
395 (last-cont (node-cont last))
396 (next-cont (block-start next)))
397 (cond ((or (rest (block-pred next))
398 (not (eq (continuation-use last-cont) last))
399 (eq next block)
400 (not (eq (block-end-cleanup block)
401 (block-start-cleanup next)))
402 (not (eq (block-home-lambda block)
403 (block-home-lambda next))))
404 nil)
405 ((eq last-cont next-cont)
406 (join-blocks block next)
407 t)
408 ((and (null (block-start-uses next))
409 (eq (continuation-kind last-cont) :inside-block))
410 (let ((next-node (continuation-next next-cont)))
411 ;;
412 ;; If next-cont does have a dest, it must be unreachable,
413 ;; since there are no uses. DELETE-CONTINUATION will mark the
414 ;; dest block as delete-p [and also this block, unless it is
415 ;; no longer backward reachable from the dest block.]
416 (delete-continuation next-cont)
417 (setf (node-prev next-node) last-cont)
418 (setf (continuation-next last-cont) next-node)
419 (setf (block-start next) last-cont)
420 (join-blocks block next))
421 t)
422 (t
423 nil))))))
424
425
426 ;;; Join-Blocks -- Internal
427 ;;;
428 ;;; Join together two blocks which have the same ending/starting
429 ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
430 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
431 ;;; that any indicated optimization gets done.
432 ;;;
433 (defun join-blocks (block1 block2)
434 (declare (type cblock block1 block2))
435 (let* ((last (block-last block2))
436 (last-cont (node-cont last))
437 (succ (block-succ block2))
438 (start2 (block-start block2)))
439 (do ((cont start2 (node-cont (continuation-next cont))))
440 ((eq cont last-cont)
441 (when (eq (continuation-kind last-cont) :inside-block)
442 (setf (continuation-block last-cont) block1)))
443 (setf (continuation-block cont) block1))
444
445 (unlink-blocks block1 block2)
446 (dolist (block succ)
447 (unlink-blocks block2 block)
448 (link-blocks block1 block))
449
450 (setf (block-last block1) last)
451 (setf (continuation-kind start2) :inside-block))
452
453 (setf (block-flags block1)
454 (attributes-union (block-flags block1)
455 (block-flags block2)
456 (block-attributes type-asserted test-modified)))
457
458 (let ((next (block-next block2))
459 (prev (block-prev block2)))
460 (setf (block-next prev) next)
461 (setf (block-prev next) prev))
462
463 (undefined-value))
464
465 ;;; Flush-Dead-Code -- Internal
466 ;;;
467 ;;; Delete any nodes in Block whose value is unused and have no
468 ;;; side-effects. We can delete sets of lexical variables when the set
469 ;;; variable has no references.
470 ;;;
471 ;;; [### For now, don't delete potentially flushable calls when they have the
472 ;;; Call attribute. Someday we should look at the funcitonal args to determine
473 ;;; if they have any side-effects.]
474 ;;;
475 (defun flush-dead-code (block)
476 (declare (type cblock block))
477 (do-nodes-backwards (node cont block)
478 (unless (continuation-dest cont)
479 (typecase node
480 (ref
481 (delete-ref node)
482 (unlink-node node))
483 (combination
484 (let ((info (combination-kind node)))
485 (when (function-info-p info)
486 (let ((attr (function-info-attributes info)))
487 (when (and (ir1-attributep attr flushable)
488 (not (ir1-attributep attr call)))
489 (flush-dest (combination-fun node))
490 (dolist (arg (combination-args node))
491 (flush-dest arg))
492 (unlink-node node))))))
493 (mv-combination
494 (when (eq (basic-combination-kind node) :local)
495 (let ((fun (combination-lambda node)))
496 (when (dolist (var (lambda-vars fun) t)
497 (when (or (leaf-refs var)
498 (lambda-var-sets var))
499 (return nil)))
500 (flush-dest (first (basic-combination-args node)))
501 (delete-let fun)))))
502 (exit
503 (let ((value (exit-value node)))
504 (when value
505 (flush-dest value)
506 (setf (exit-value node) nil))))
507 (cset
508 (let ((var (set-var node)))
509 (when (and (lambda-var-p var)
510 (null (leaf-refs var)))
511 (flush-dest (set-value node))
512 (setf (basic-var-sets var)
513 (delete node (basic-var-sets var)))
514 (unlink-node node)))))))
515
516 (setf (block-flush-p block) nil)
517 (undefined-value))
518
519 (declaim (end-block))
520
521
522 ;;;; Local call return type propagation:
523
524 ;;; Find-Result-Type -- Internal
525 ;;;
526 ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
527 ;;; set. It iterates over the uses of the RESULT, looking for interesting
528 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
529 ;;; its type together with the types of other such uses. We assign to the
530 ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
531 ;;; type. We can make this intersection now (potentially before type checking)
532 ;;; because this assertion on the result will eventually be checked (if
533 ;;; appropriate.)
534 ;;;
535 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
536 ;;; which may change the succesor of the call to be the called function, and if
537 ;;; so, checks if the call can become an assignment. If we convert to an
538 ;;; assignment, we abort, since the RETURN has been deleted.
539 ;;;
540 (defun find-result-type (node)
541 (declare (type creturn node))
542 (let ((result (return-result node)))
543 (collect ((use-union *empty-type* values-type-union))
544 (do-uses (use result)
545 (cond ((and (basic-combination-p use)
546 (eq (basic-combination-kind use) :local))
547 (assert (eq (lambda-tail-set (node-home-lambda use))
548 (lambda-tail-set (combination-lambda use))))
549 (when (combination-p use)
550 (when (nth-value 1 (maybe-convert-tail-local-call use))
551 (return-from find-result-type (undefined-value)))))
552 (t
553 (use-union (node-derived-type use)))))
554 (let ((int (values-type-intersection (continuation-asserted-type result)
555 (use-union))))
556 (setf (return-result-type node) int))))
557 (undefined-value))
558
559
560 ;;; IR1-Optimize-Return -- Internal
561 ;;;
562 ;;; Do stuff to realize that something has changed about the value delivered
563 ;;; to a return node. Since we consider the return values of all functions in
564 ;;; the tail set to be equivalent, this amounts to bringing the entire tail set
565 ;;; up to date. We iterate over the returns for all the functions in the tail
566 ;;; set, reanalyzing them all (not treating Node specially.)
567 ;;;
568 ;;; When we are done, we check if the new type is different from the old
569 ;;; TAIL-SET-TYPE. If so, we set the type and also reoptimize all the
570 ;;; continuations for references to functions in the tail set. This will
571 ;;; cause IR1-OPTIMIZE-COMBINATION to derive the new type as the results of the
572 ;;; calls.
573 ;;;
574 (defun ir1-optimize-return (node)
575 (declare (type creturn node))
576 (let* ((tails (lambda-tail-set (return-lambda node)))
577 (funs (tail-set-functions tails)))
578 (collect ((res *empty-type* values-type-union))
579 (dolist (fun funs)
580 (let ((return (lambda-return fun)))
581 (when return
582 (when (node-reoptimize return)
583 (setf (node-reoptimize return) nil)
584 (find-result-type return))
585 (res (return-result-type return)))))
586
587 (when (type/= (res) (tail-set-type tails))
588 (setf (tail-set-type tails) (res))
589 (dolist (fun (tail-set-functions tails))
590 (dolist (ref (leaf-refs fun))
591 (reoptimize-continuation (node-cont ref)))))))
592
593 (undefined-value))
594
595
596 ;;; IF optimization:
597
598 (declaim (start-block ir1-optimize-if))
599
600 ;;; IR1-Optimize-If -- Internal
601 ;;;
602 ;;; If the test has multiple uses, replicate the node when possible. Also
603 ;;; check if the predicate is known to be true or false, deleting the IF node
604 ;;; in favor of the appropriate branch when this is the case.
605 ;;;
606 (defun ir1-optimize-if (node)
607 (declare (type cif node))
608 (let ((test (if-test node))
609 (block (node-block node)))
610
611 (when (and (eq (block-start block) test)
612 (eq (continuation-next test) node)
613 (rest (block-start-uses block)))
614 (do-uses (use test)
615 (when (immediately-used-p test use)
616 (convert-if-if use node)
617 (when (continuation-use test) (return)))))
618
619 (let* ((type (continuation-type test))
620 (victim
621 (cond ((constant-continuation-p test)
622 (if (continuation-value test)
623 (if-alternative node)
624 (if-consequent node)))
625 ((not (types-intersect type *null-type*))
626 (if-alternative node))
627 ((type= type *null-type*)
628 (if-consequent node)))))
629 (when victim
630 (flush-dest test)
631 (when (rest (block-succ block))
632 (unlink-blocks block victim))
633 (setf (component-reanalyze (block-component (node-block node))) t)
634 (unlink-node node))))
635 (undefined-value))
636
637
638 ;;; Convert-If-If -- Internal
639 ;;;
640 ;;; Create a new copy of an IF Node that tests the value of the node Use.
641 ;;; The test must have >1 use, and must be immediately used by Use. Node must
642 ;;; be the only node in its block (implying that block-start = if-test).
643 ;;;
644 ;;; This optimization has an effect semantically similar to the
645 ;;; source-to-source transformation:
646 ;;; (IF (IF A B C) D E) ==>
647 ;;; (IF A (IF B D E) (IF C D E))
648 ;;;
649 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new node so
650 ;;; that dead code deletion notes will definitely not consider either node to
651 ;;; be part of the original source. One node might become unreachable,
652 ;;; resulting in a spurious note.
653 ;;;
654 (defun convert-if-if (use node)
655 (declare (type node use) (type cif node))
656 (with-ir1-environment node
657 (let* ((block (node-block node))
658 (test (if-test node))
659 (cblock (if-consequent node))
660 (ablock (if-alternative node))
661 (use-block (node-block use))
662 (dummy-cont (make-continuation))
663 (new-cont (make-continuation))
664 (new-node (make-if :test new-cont
665 :consequent cblock :alternative ablock))
666 (new-block (continuation-starts-block new-cont)))
667 (prev-link new-node new-cont)
668 (setf (continuation-dest new-cont) new-node)
669 (add-continuation-use new-node dummy-cont)
670 (setf (block-last new-block) new-node)
671
672 (unlink-blocks use-block block)
673 (delete-continuation-use use)
674 (add-continuation-use use new-cont)
675 (link-blocks use-block new-block)
676
677 (link-blocks new-block cblock)
678 (link-blocks new-block ablock)
679
680 (push "<IF Duplication>" (node-source-path node))
681 (push "<IF Duplication>" (node-source-path new-node))
682
683 (reoptimize-continuation test)
684 (reoptimize-continuation new-cont)
685 (setf (component-reanalyze *current-component*) t)))
686 (undefined-value))
687
688 (declaim (end-block))
689
690
691 ;;;; Exit IR1 optimization:
692
693 ;;; Maybe-Delete-Exit -- Interface
694 ;;;
695 ;;; This function attempts to delete an exit node, returning true if it
696 ;;; deletes the block as a consequence:
697 ;;; -- If the exit is degenerate (has no Entry), then we don't do anything,
698 ;;; since there is nothing to be done.
699 ;;; -- If the exit node and its Entry have the same home lambda then we know
700 ;;; the exit is local, and can delete the exit. We change uses of the
701 ;;; Exit-Value to be uses of the original continuation, then unlink the
702 ;;; node. If the exit is to a TR context, then we must do MERGE-TAIL-SETS
703 ;;; on any local calls which delivered their value to this exit.
704 ;;; -- If there is no value (as in a GO), then we skip the value semantics.
705 ;;;
706 ;;; This function is also called by environment analysis, since it wants all
707 ;;; exits to be optimized even if normal optimization was omitted.
708 ;;;
709 (defun maybe-delete-exit (node)
710 (declare (type exit node))
711 (let ((value (exit-value node))
712 (entry (exit-entry node))
713 (cont (node-cont node)))
714 (when (and entry
715 (eq (node-home-lambda node) (node-home-lambda entry)))
716 (setf (entry-exits entry) (delete node (entry-exits entry)))
717 (prog1
718 (unlink-node node)
719 (when value
720 (collect ((merges))
721 (when (return-p (continuation-dest cont))
722 (do-uses (use value)
723 (when (and (basic-combination-p use)
724 (eq (basic-combination-kind use) :local))
725 (merges use))))
726 (substitute-continuation-uses cont value)
727 (dolist (merge (merges))
728 (merge-tail-sets merge))))))))
729
730
731 ;;;; Combination IR1 optimization:
732
733 (declaim (start-block ir1-optimize-combination maybe-terminate-block
734 validate-call-type))
735
736 ;;; Ir1-Optimize-Combination -- Internal
737 ;;;
738 ;;; Do IR1 optimizations on a Combination node.
739 ;;;
740 (defun ir1-optimize-combination (node)
741 (declare (type combination node))
742 (when (continuation-reoptimize (basic-combination-fun node))
743 (propagate-function-change node))
744 (let ((args (basic-combination-args node))
745 (kind (basic-combination-kind node)))
746 (case kind
747 (:local
748 (let ((fun (combination-lambda node)))
749 (if (eq (functional-kind fun) :let)
750 (propagate-let-args node fun)
751 (propagate-local-call-args node fun))))
752 ((:full :error)
753 (dolist (arg args)
754 (when arg
755 (setf (continuation-reoptimize arg) nil))))
756 (t
757 (dolist (arg args)
758 (when arg
759 (setf (continuation-reoptimize arg) nil)))
760
761 (let ((attr (function-info-attributes kind)))
762 (when (and (ir1-attributep attr foldable)
763 (not (ir1-attributep attr call))
764 (every #'constant-continuation-p args)
765 (continuation-dest (node-cont node)))
766 (constant-fold-call node)
767 (return-from ir1-optimize-combination)))
768
769 (let ((fun (function-info-derive-type kind)))
770 (when fun
771 (let ((res (funcall fun node)))
772 (when res
773 (derive-node-type node res)
774 (maybe-terminate-block node nil)))))
775
776 (let ((fun (function-info-optimizer kind)))
777 (unless (and fun (funcall fun node))
778 (dolist (x (function-info-transforms kind))
779 (unless (ir1-transform node x)
780 (return))))))))
781
782 (undefined-value))
783
784
785 ;;; MAYBE-TERMINATE-BLOCK -- Interface
786 ;;;
787 ;;; If Call is to a function that doesn't return (type NIL), then terminate
788 ;;; the block there, and link it to the component tail. We also change the
789 ;;; call's CONT to be a dummy continuation to prevent the use from confusing
790 ;;; things.
791 ;;;
792 ;;; Except when called during IR1, we delete the continuation if it has no
793 ;;; other uses. (If it does have other uses, we reoptimize.)
794 ;;;
795 ;;; Termination on the basis of a continuation type assertion is inhibited
796 ;;; when:
797 ;;; -- The continuation is deleted (hence the assertion is spurious), or
798 ;;; -- We are in IR1 conversion (where THE assertions are subject to
799 ;;; weakening.)
800 ;;;
801 (defun maybe-terminate-block (call ir1-p)
802 (declare (type basic-combination call))
803 (let* ((block (node-block call))
804 (cont (node-cont call))
805 (tail (component-tail (block-component block)))
806 (succ (first (block-succ block))))
807 (unless (or (and (eq call (block-last block)) (eq succ tail))
808 (block-delete-p block)
809 *converting-for-interpreter*)
810 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
811 (not (or ir1-p (eq (continuation-kind cont) :deleted))))
812 (eq (node-derived-type call) *empty-type*))
813 (cond (ir1-p
814 (delete-continuation-use call)
815 (cond
816 ((block-last block)
817 (assert (and (eq (block-last block) call)
818 (eq (continuation-kind cont) :block-start))))
819 (t
820 (setf (block-last block) call)
821 (link-blocks block (continuation-starts-block cont)))))
822 (t
823 (node-ends-block call)
824 (delete-continuation-use call)
825 (if (eq (continuation-kind cont) :unused)
826 (delete-continuation cont)
827 (reoptimize-continuation cont))))
828
829 (unlink-blocks block (first (block-succ block)))
830 (setf (component-reanalyze (block-component block)) t)
831 (assert (not (block-succ block)))
832 (link-blocks block tail)
833 (add-continuation-use call (make-continuation))
834 t))))
835
836
837 ;;; Recognize-Known-Call -- Interface
838 ;;;
839 ;;; Called both by IR1 conversion and IR1 optimization when they have
840 ;;; verified the type signature for the call, and are wondering if something
841 ;;; should be done to special-case the call. If Call is a call to a global
842 ;;; function, then see if it defined or known:
843 ;;; -- If a DEFINED-FUNCTION should be inline expanded, then convert the
844 ;;; expansion and change the call to call it. Expansion is enabled if
845 ;;; :INLINE or if space=0. If the FUNCTIONAL slot is true, we never expand,
846 ;;; since this function has already been converted. Local call analysis
847 ;;; will duplicate the definition if necessary. We claim that the parent
848 ;;; form is LABELS for context declarations, since we don't want it to be
849 ;;; considered a real global function.
850 ;;; -- In addition to a direct check for the function name in the table, we
851 ;;; also must check for slot accessors. If the function is a slot accessor,
852 ;;; then we set the combination kind to the function info of %Slot-Setter or
853 ;;; %Slot-Accessor, as appropriate.
854 ;;; -- If it is a known function, mark it as such by setting the Kind.
855 ;;;
856 ;;; We return the leaf referenced (NIL if not a leaf) and the function-info
857 ;;; assigned.
858 ;;;
859 (defun recognize-known-call (call ir1-p)
860 (declare (type combination call))
861 (let* ((ref (continuation-use (basic-combination-fun call)))
862 (leaf (when (ref-p ref) (ref-leaf ref)))
863 (inlinep (if (and (defined-function-p leaf)
864 (not (byte-compiling)))
865 (defined-function-inlinep leaf)
866 :no-chance)))
867 (cond
868 ((eq inlinep :notinline) (values nil nil))
869 ((not (and (global-var-p leaf)
870 (eq (global-var-kind leaf) :global-function)))
871 (values leaf nil))
872 ((and (ecase inlinep
873 (:inline t)
874 (:no-chance nil)
875 ((nil :maybe-inline) (policy call (zerop space))))
876 (defined-function-inline-expansion leaf)
877 (let ((fun (defined-function-functional leaf)))
878 (or (not fun)
879 (and (eq inlinep :inline) (functional-kind fun))))
880 (inline-expansion-ok call))
881 (flet ((frob ()
882 (let ((res (ir1-convert-lambda-for-defun
883 (defined-function-inline-expansion leaf)
884 leaf t
885 #'ir1-convert-inline-lambda
886 'labels)))
887 (setf (defined-function-functional leaf) res)
888 (change-ref-leaf ref res))))
889 (if ir1-p
890 (frob)
891 (with-ir1-environment call
892 (frob)
893 (local-call-analyze *current-component*))))
894
895 (values (ref-leaf (continuation-use (basic-combination-fun call)))
896 nil))
897 (t
898 (let* ((name (leaf-name leaf))
899 (info (info function info
900 (if (slot-accessor-p leaf)
901 (if (consp name)
902 '%slot-setter
903 '%slot-accessor)
904 name))))
905 (if info
906 (values leaf (setf (basic-combination-kind call) info))
907 (values leaf nil)))))))
908
909
910 ;;; VALIDATE-CALL-TYPE -- Internal
911 ;;;
912 ;;; Check if Call satisfies Type. If so, apply the type to the call, and do
913 ;;; MAYBE-TERMINATE-BLOCK and return the values of RECOGNIZE-KNOWN-CALL. If an
914 ;;; error, set the combination kind and return NIL, NIL. If the type is just
915 ;;; FUNCTION, then skip the syntax check, arg/result type processing, but still
916 ;;; call RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda, and
917 ;;; that checking is done by local call analysis.
918 ;;;
919 (defun validate-call-type (call type ir1-p)
920 (declare (type combination call) (type ctype type))
921 (cond ((not (function-type-p type))
922 (assert (multiple-value-bind
923 (val win)
924 (csubtypep type (specifier-type 'function))
925 (or val (not win))))
926 (recognize-known-call call ir1-p))
927 ((valid-function-use call type
928 :argument-test #'always-subtypep
929 :result-test #'always-subtypep
930 :error-function #'compiler-warning
931 :warning-function #'compiler-note)
932 (assert-call-type call type)
933 (maybe-terminate-block call ir1-p)
934 (recognize-known-call call ir1-p))
935 (t
936 (setf (combination-kind call) :error)
937 (values nil nil))))
938
939
940 ;;; Propagate-Function-Change -- Internal
941 ;;;
942 ;;; Called by Ir1-Optimize when the function for a call has changed.
943 ;;; If the call is local, we try to let-convert it, and derive the result type.
944 ;;; If it is a :FULL call, we validate it against the type, which recognizes
945 ;;; known calls, does inline expansion, etc. If a call to a predicate in a
946 ;;; non-conditional position or to a function with a source transform, then we
947 ;;; reconvert the form to give IR1 another chance.
948 ;;;
949 (defun propagate-function-change (call)
950 (declare (type combination call))
951 (let ((*compiler-error-context* call)
952 (fun-cont (basic-combination-fun call)))
953 (setf (continuation-reoptimize fun-cont) nil)
954 (case (combination-kind call)
955 (:local
956 (let ((fun (combination-lambda call)))
957 (maybe-let-convert fun)
958 (unless (member (functional-kind fun) '(:let :assignment :deleted))
959 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
960 (:full
961 (multiple-value-bind
962 (leaf info)
963 (validate-call-type call (continuation-type fun-cont) nil)
964 (cond ((functional-p leaf)
965 (convert-call-if-possible
966 (continuation-use (basic-combination-fun call))
967 call))
968 ((not leaf))
969 ((or (info function source-transform (leaf-name leaf))
970 (and info
971 (ir1-attributep (function-info-attributes info)
972 predicate)
973 (let ((dest (continuation-dest (node-cont call))))
974 (and dest (not (if-p dest))))))
975 (let ((name (leaf-name leaf)))
976 (when (symbolp name)
977 (let ((dums (loop repeat (length (combination-args call))
978 collect (gensym))))
979 (transform-call call
980 `(lambda ,dums
981 (,name ,@dums))))))))))))
982 (undefined-value))
983
984
985 ;;;; Known function optimization:
986
987
988 ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
989 ;;;
990 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for Node, Fun
991 ;;; and Args. If there is already a note for Node and Transform, replace it,
992 ;;; otherwise add a new one.
993 ;;;
994 (defun record-optimization-failure (node transform args)
995 (declare (type combination node) (type transform transform)
996 (type (or function-type list) args))
997 (let* ((table (component-failed-optimizations *compile-component*))
998 (found (assoc transform (gethash node table))))
999 (if found
1000 (setf (cdr found) args)
1001 (push (cons transform args) (gethash node table))))
1002 (undefined-value))
1003
1004
1005 ;;; IR1-Transform -- Internal
1006 ;;;
1007 ;;; Attempt to transform Node using Function, subject to the call type
1008 ;;; constraint Type. If we are inhibited from doing the transform for some
1009 ;;; reason and Flame is true, then we make a note of the message in
1010 ;;; FAILED-OPTIMIZATIONS for IR1 finalize to pick up. We return true if
1011 ;;; the transform failed, and thus further transformation should be
1012 ;;; attempted. We return false if either the transform suceeded or was
1013 ;;; aborted.
1014 ;;;
1015 (defun ir1-transform (node transform)
1016 (declare (type combination node) (type transform transform))
1017 (let* ((type (transform-type transform))
1018 (fun (transform-function transform))
1019 (constrained (function-type-p type))
1020 (table (component-failed-optimizations *compile-component*))
1021 (flame
1022 (if (transform-important transform)
1023 (policy node (>= speed brevity))
1024 (policy node (> speed brevity))))
1025 (*compiler-error-context* node))
1026 (cond ((let ((when (transform-when transform)))
1027 (not (or (eq when :both)
1028 (eq when (if *byte-compiling* :byte :native)))))
1029 t)
1030 ((or (not constrained)
1031 (valid-function-use node type :strict-result t))
1032 (multiple-value-bind
1033 (severity args)
1034 (catch 'give-up
1035 (transform-call node (funcall fun node))
1036 (values :none nil))
1037 (ecase severity
1038 (:none
1039 (remhash node table)
1040 nil)
1041 (:aborted
1042 (setf (combination-kind node) :error)
1043 (when args
1044 (apply #'compiler-warning args))
1045 (remhash node table)
1046 nil)
1047 (:failure
1048 (if args
1049 (when flame
1050 (record-optimization-failure node transform args))
1051 (setf (gethash node table)
1052 (remove transform (gethash node table) :key #'car)))
1053 t)
1054 (:delayed
1055 (remhash node table)
1056 nil))))
1057 ((and flame
1058 (valid-function-use node type
1059 :argument-test #'types-intersect
1060 :result-test #'values-types-intersect))
1061 (record-optimization-failure node transform type)
1062 t)
1063 (t
1064 t))))
1065
1066 (declaim (end-block))
1067
1068 ;;; give-up, abort-transform -- Interface
1069 ;;;
1070 ;;; Just throw the severity and args...
1071 ;;;
1072 (defun give-up (&rest args)
1073 "This function is used to throw out of an IR1 transform, aborting this
1074 attempt to transform the call, but admitting the possibility that this or
1075 some other transform will later suceed. If arguments are supplied, they are
1076 format arguments for an efficiency note."
1077 (values nil)
1078 (throw 'give-up (values :failure args)))
1079 ;;;
1080 (defun abort-transform (&rest args)
1081 "This function is used to throw out of an IR1 transform and force a normal
1082 call to the function at run time. No further optimizations will be
1083 attempted."
1084 (throw 'give-up (values :aborted args)))
1085
1086 (defvar *delayed-transforms*)
1087
1088 ;;; delay-transform -- Interface
1089 ;;;
1090 (defun delay-transform (node &rest reasons)
1091 "This function is used to throw out of an IR1 transform, and delay the
1092 transform on the node until later. The reasons specifies when the transform
1093 will be later retried. The :optimize reason causes the transform to be
1094 delayed until after the current IR1 optimization pass. The :constraint
1095 reason causes the transform to be delayed until after constraint
1096 propagation."
1097 (let ((assoc (assoc node *delayed-transforms*)))
1098 (cond ((not assoc)
1099 (setf *delayed-transforms*
1100 (acons node reasons *delayed-transforms*))
1101 (throw 'give-up :delayed))
1102 ((cdr assoc)
1103 (dolist (reason reasons)
1104 (pushnew reason (cdr assoc)))
1105 (throw 'give-up :delayed)))))
1106
1107 ;;; retry-delayed-transforms -- Interface.
1108 ;;;
1109 ;;; Clear any delayed transform with no reasons - these should have been tried
1110 ;;; in the last pass. Then remove the reason from the delayed transform
1111 ;;; reasons, and if any become empty then set reoptimize flags for the
1112 ;;; node. Returns true if any transforms are to be retried.
1113 ;;;
1114 (defun retry-delayed-transforms (reason)
1115 (setf *delayed-transforms* (remove-if-not #'cdr *delayed-transforms*))
1116 (let ((reoptimize nil))
1117 (dolist (assoc *delayed-transforms*)
1118 (let ((reasons (remove reason (cdr assoc))))
1119 (setf (cdr assoc) reasons)
1120 (unless reasons
1121 (let ((node (car assoc)))
1122 (unless (node-deleted node)
1123 (setf reoptimize t)
1124 (setf (node-reoptimize node) t)
1125 (let ((block (node-block node)))
1126 (setf (block-reoptimize block) t)
1127 (setf (component-reoptimize (block-component block)) t)))))))
1128 reoptimize))
1129
1130
1131 ;;; Transform-Call -- Internal
1132 ;;;
1133 ;;; Take the lambda-expression Res, IR1 convert it in the proper
1134 ;;; environment, and then install it as the function for the call Node. We do
1135 ;;; local call analysis so that the new function is integrated into the control
1136 ;;; flow.
1137 ;;;
1138 (defun transform-call (node res)
1139 (declare (type combination node) (list res))
1140 (with-ir1-environment node
1141 (let ((new-fun (ir1-convert-inline-lambda res))
1142 (ref (continuation-use (combination-fun node))))
1143 (change-ref-leaf ref new-fun)
1144 (setf (combination-kind node) :full)
1145 (local-call-analyze *current-component*)))
1146 (undefined-value))
1147
1148
1149 ;;; Constant-Fold-Call -- Internal
1150 ;;;
1151 ;;; Replace a call to a foldable function of constant arguments with the
1152 ;;; result of evaluating the form. We insert the resulting constant node after
1153 ;;; the call, stealing the call's continuation. We give the call a
1154 ;;; continuation with no Dest, which should cause it and its arguments to go
1155 ;;; away. If there is an error during the evaluation, we give a warning and
1156 ;;; leave the call alone, making the call a :ERROR call.
1157 ;;;
1158 ;;; If there is more than one value, then we transform the call into a
1159 ;;; values form.
1160 ;;;
1161 (defun constant-fold-call (call)
1162 (declare (type combination call))
1163 (let* ((args (mapcar #'continuation-value (combination-args call)))
1164 (ref (continuation-use (combination-fun call)))
1165 (fun (leaf-name (ref-leaf ref))))
1166
1167 (multiple-value-bind (values win)
1168 (careful-call fun args call "constant folding")
1169 (cond
1170 ((not win)
1171 (setf (combination-kind call) :error))
1172 ;; X Always transform the call below so that non-flushable
1173 ;; functions get flushed if the constant folding works.
1174 #+nil
1175 ((= (length values) 1)
1176 (with-ir1-environment call
1177 (when (producing-fasl-file)
1178 (maybe-emit-make-load-forms (first values)))
1179 (let* ((leaf (find-constant (first values)))
1180 (node (make-ref (leaf-type leaf) leaf))
1181 (dummy (make-continuation))
1182 (cont (node-cont call))
1183 (block (node-block call))
1184 (next (continuation-next cont)))
1185 (push node (leaf-refs leaf))
1186 (setf (leaf-ever-used leaf) t)
1187
1188 (delete-continuation-use call)
1189 (add-continuation-use call dummy)
1190 (prev-link node dummy)
1191 (add-continuation-use node cont)
1192 (setf (continuation-next cont) next)
1193 (when (eq call (block-last block))
1194 (setf (block-last block) node))
1195 (reoptimize-continuation cont))))
1196 (t
1197 (let ((dummies (loop repeat (length args)
1198 collect (gensym))))
1199 (transform-call
1200 call
1201 `(lambda ,dummies
1202 (declare (ignore ,@dummies))
1203 (values ,@(mapcar #'(lambda (x) `',x) values)))))))))
1204
1205 (undefined-value))
1206
1207
1208 ;;;; Local call optimization:
1209
1210 (declaim (start-block ir1-optimize-set constant-reference-p delete-let
1211 propagate-let-args propagate-local-call-args
1212 propagate-to-refs propagate-from-sets
1213 ir1-optimize-mv-combination))
1214
1215 ;;; Propagate-To-Refs -- Internal
1216 ;;;
1217 ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1218 ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1219 ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1220 ;;;
1221 (defun propagate-to-refs (leaf type)
1222 (declare (type leaf leaf) (type ctype type))
1223 (let ((var-type (leaf-type leaf)))
1224 (unless (function-type-p var-type)
1225 (let ((int (type-intersection var-type type)))
1226 (when (type/= int var-type)
1227 (setf (leaf-type leaf) int)
1228 (dolist (ref (leaf-refs leaf))
1229 (derive-node-type ref int))))
1230 (undefined-value))))
1231
1232
1233 ;;; PROPAGATE-FROM-SETS -- Internal
1234 ;;;
1235 ;;; Figure out the type of a LET variable that has sets. We compute the
1236 ;;; union of the initial value Type and the types of all the set values and to
1237 ;;; a PROPAGATE-TO-REFS with this type.
1238 ;;;
1239 (defun propagate-from-sets (var type)
1240 (collect ((res type type-union))
1241 (dolist (set (basic-var-sets var))
1242 (res (continuation-type (set-value set)))
1243 (setf (node-reoptimize set) nil))
1244 (propagate-to-refs var (res)))
1245 (undefined-value))
1246
1247
1248 ;;; IR1-OPTIMIZE-SET -- Internal
1249 ;;;
1250 ;;; If a let variable, find the initial value's type and do
1251 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1252 ;;;
1253 (defun ir1-optimize-set (node)
1254 (declare (type cset node))
1255 (let ((var (set-var node)))
1256 (when (and (lambda-var-p var) (leaf-refs var))
1257 (let ((home (lambda-var-home var)))
1258 (when (eq (functional-kind home) :let)
1259 (let ((iv (let-var-initial-value var)))
1260 (setf (continuation-reoptimize iv) nil)
1261 (propagate-from-sets var (continuation-type iv)))))))
1262
1263 (derive-node-type node (continuation-type (set-value node)))
1264 (undefined-value))
1265
1266
1267 ;;; CONSTANT-REFERENCE-P -- Interface
1268 ;;;
1269 ;;; Return true if the value of Ref will always be the same (and is thus
1270 ;;; legal to substitute.)
1271 ;;;
1272 (defun constant-reference-p (ref)
1273 (declare (type ref ref))
1274 (let ((leaf (ref-leaf ref)))
1275 (typecase leaf
1276 ((or constant functional) t)
1277 (lambda-var
1278 (null (lambda-var-sets leaf)))
1279 (defined-function
1280 (not (eq (defined-function-inlinep leaf) :notinline)))
1281 (global-var
1282 (case (global-var-kind leaf)
1283 (:global-function t)
1284 (:constant t))))))
1285
1286
1287 ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1288 ;;;
1289 ;;; If we have a non-set let var with a single use, then (if possible)
1290 ;;; replace the variable reference's CONT with the arg continuation. This is
1291 ;;; inhibited when:
1292 ;;; -- CONT has other uses, or
1293 ;;; -- CONT receives multiple values, or
1294 ;;; -- the reference is in a different environment from the variable, or
1295 ;;; -- either continuation has a funky TYPE-CHECK annotation.
1296 ;;; -- the continuations have incompatible assertions, so the new asserted type
1297 ;;; would be NIL.
1298 ;;; -- CONT's assertion is incompatbile with the proven type of ARG's, such as
1299 ;;; when ARG returns multiple values and CONT has a single value assertion.
1300 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1301 ;;;
1302 ;;; We change the Ref to be a reference to NIL with unused value, and let it
1303 ;;; be flushed as dead code. A side-effect of this substitution is to delete
1304 ;;; the variable.
1305 ;;;
1306 (defun substitute-single-use-continuation (arg var)
1307 (declare (type continuation arg) (type lambda-var var))
1308 (let* ((ref (first (leaf-refs var)))
1309 (cont (node-cont ref))
1310 (cont-atype (continuation-asserted-type cont))
1311 (dest (continuation-dest cont)))
1312 (when (and (eq (continuation-use cont) ref)
1313 dest
1314 (not (typep dest '(or creturn exit mv-combination)))
1315 (eq (node-home-lambda ref)
1316 (lambda-home (lambda-var-home var)))
1317 (member (continuation-type-check arg) '(t nil))
1318 (member (continuation-type-check cont) '(t nil))
1319 (not (eq (values-type-intersection
1320 cont-atype (continuation-asserted-type arg))
1321 *empty-type*))
1322 (not (eq (values-type-intersection
1323 cont-atype (continuation-proven-type arg))
1324 *empty-type*))
1325 (eq (lexenv-cookie (node-lexenv dest))
1326 (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1327 (assert (member (continuation-kind arg)
1328 '(:block-start :deleted-block-start :inside-block)))
1329 (assert-continuation-type arg cont-atype)
1330 (setf (node-derived-type ref) *wild-type*)
1331 (change-ref-leaf ref (find-constant nil))
1332 (substitute-continuation arg cont)
1333 (reoptimize-continuation arg)
1334 t)))
1335
1336
1337 ;;; DELETE-LET -- Interface
1338 ;;;
1339 ;;; Delete a Let, removing the call and bind nodes, and warning about any
1340 ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1341 ;;; away and delete the REF and then the lambda, since we flush the FUN
1342 ;;; continuation.
1343 ;;;
1344 (defun delete-let (fun)
1345 (declare (type clambda fun))
1346 (assert (member (functional-kind fun) '(:let :mv-let)))
1347 (note-unreferenced-vars fun)
1348 (let ((call (let-combination fun)))
1349 (flush-dest (basic-combination-fun call))
1350 (unlink-node call)
1351 (unlink-node (lambda-bind fun))
1352 (setf (lambda-bind fun) nil))
1353 (undefined-value))
1354
1355
1356 ;;; Propagate-Let-Args -- Internal
1357 ;;;
1358 ;;; This function is called when one of the arguments to a LET changes. We
1359 ;;; look at each changed argument. If the corresponding variable is set, then
1360 ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1361 ;;; variable, and also propagate derived-type information for the arg to all
1362 ;;; the Var's refs.
1363 ;;;
1364 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1365 ;;; subtype of the argument's asserted type. This prevents type checking from
1366 ;;; being defeated, and also ensures that the best representation for the
1367 ;;; variable can be used.
1368 ;;;
1369 ;;; Substitution of individual references is inhibited if the reference is
1370 ;;; in a different component from the home. This can only happen with closures
1371 ;;; over top-level lambda vars. In such cases, the references may have already
1372 ;;; been compiled, and thus can't be retroactively modified.
1373 ;;;
1374 ;;; If all of the variables are deleted (have no references) when we are
1375 ;;; done, then we delete the let.
1376 ;;;
1377 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1378 ;;; flags.
1379 ;;;
1380 (defun propagate-let-args (call fun)
1381 (declare (type combination call) (type clambda fun))
1382 (loop for arg in (combination-args call)
1383 and var in (lambda-vars fun) do
1384 (when (and arg (continuation-reoptimize arg))
1385 (setf (continuation-reoptimize arg) nil)
1386 (cond
1387 ((lambda-var-sets var)
1388 (propagate-from-sets var (continuation-type arg)))
1389 ((let ((use (continuation-use arg)))
1390 (when (ref-p use)
1391 (let ((leaf (ref-leaf use)))
1392 (when (and (constant-reference-p use)
1393 (values-subtypep (leaf-type leaf)
1394 (continuation-asserted-type arg)))
1395 (propagate-to-refs var (continuation-type arg))
1396 (let ((this-comp (block-component (node-block use))))
1397 (substitute-leaf-if
1398 #'(lambda (ref)
1399 (cond ((eq (block-component (node-block ref))
1400 this-comp)
1401 t)
1402 (t
1403 (assert (eq (functional-kind (lambda-home fun))
1404 :top-level))
1405 nil)))
1406 leaf var))
1407 t)))))
1408 ((and (null (rest (leaf-refs var)))
1409 (not *byte-compiling*)
1410 (substitute-single-use-continuation arg var)))
1411 (t
1412 (propagate-to-refs var (continuation-type arg))))))
1413
1414 (when (every #'null (combination-args call))
1415 (delete-let fun))
1416
1417 (undefined-value))
1418
1419
1420 ;;; Propagate-Local-Call-Args -- Internal
1421 ;;;
1422 ;;; This function is called when one of the args to a non-let local call
1423 ;;; changes. For each changed argument corresponding to an unset variable, we
1424 ;;; compute the union of the types across all calls and propagate this type
1425 ;;; information to the var's refs.
1426 ;;;
1427 ;;; If the function has an XEP, then we don't do anything, since we won't
1428 ;;; discover anything.
1429 ;;;
1430 ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1431 ;;; corresponding to changed arguments in Call, since the only use in IR1
1432 ;;; optimization of the Reoptimize flag for local call args is right here.
1433 ;;;
1434 (defun propagate-local-call-args (call fun)
1435 (declare (type combination call) (type clambda fun))
1436
1437 (unless (or (functional-entry-function fun)
1438 (lambda-optional-dispatch fun))
1439 (let* ((vars (lambda-vars fun))
1440 (union (mapcar #'(lambda (arg var)
1441 (when (and arg
1442 (continuation-reoptimize arg)
1443 (null (basic-var-sets var)))
1444 (continuation-type arg)))
1445 (basic-combination-args call)
1446 vars))
1447 (this-ref (continuation-use (basic-combination-fun call))))
1448
1449 (dolist (arg (basic-combination-args call))
1450 (when arg
1451 (setf (continuation-reoptimize arg) nil)))
1452
1453 (dolist (ref (leaf-refs fun))
1454 (let ((dest (continuation-dest (node-cont ref))))
1455 (unless (or (eq ref this-ref) (not dest))
1456 (setq union
1457 (mapcar #'(lambda (this-arg old)
1458 (when old
1459 (setf (continuation-reoptimize this-arg) nil)
1460 (type-union (continuation-type this-arg) old)))
1461 (basic-combination-args dest)
1462 union)))))
1463
1464 (mapc #'(lambda (var type)
1465 (when type
1466 (propagate-to-refs var type)))
1467 vars union)))
1468
1469 (undefined-value))
1470
1471 (declaim (end-block))
1472
1473
1474 ;;;; Multiple values optimization:
1475
1476 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1477 ;;;
1478 ;;; Do stuff to notice a change to a MV combination node. There are two
1479 ;;; main branches here:
1480 ;;; -- If the call is local, then it is already a MV let, or should become one.
1481 ;;; Note that although all :LOCAL MV calls must eventually be converted to
1482 ;;; :MV-LETs, there can be a window when the call is local, but has not
1483 ;;; been let converted yet. This is because the entry-point lambdas may
1484 ;;; have stray references (in other entry points) that have not been
1485 ;;; deleted yet.
1486 ;;; -- The call is full. This case is somewhat similar to the non-MV
1487 ;;; combination optimization: we propagate return type information and
1488 ;;; notice non-returning calls. We also have an optimization
1489 ;;; which tries to convert MV-CALLs into MV-binds.
1490 ;;;
1491 (defun ir1-optimize-mv-combination (node)
1492 (ecase (basic-combination-kind node)
1493 (:local
1494 (let ((fun-cont (basic-combination-fun node)))
1495 (when (continuation-reoptimize fun-cont)
1496 (setf (continuation-reoptimize fun-cont) nil)
1497 (maybe-let-convert (combination-lambda node))))
1498 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1499 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1500 (unless (convert-mv-bind-to-let node)
1501 (ir1-optimize-mv-bind node))))
1502 (:full
1503 (let* ((fun (basic-combination-fun node))
1504 (fun-changed (continuation-reoptimize fun))
1505 (args (basic-combination-args node)))
1506 (when fun-changed
1507 (setf (continuation-reoptimize fun) nil)
1508 (let ((type (continuation-type fun)))
1509 (when (function-type-p type)
1510 (derive-node-type node (function-type-returns type))))
1511 (maybe-terminate-block node nil)
1512 (let ((use (continuation-use fun)))
1513 (when (and (ref-p use) (functional-p (ref-leaf use)))
1514 (convert-call-if-possible use node)
1515 (when (eq (basic-combination-kind node) :local)
1516 (maybe-let-convert (ref-leaf use))))))
1517 (unless (or (eq (basic-combination-kind node) :local)
1518 (eq (continuation-function-name fun) '%throw))
1519 (ir1-optimize-mv-call node))
1520 (dolist (arg args)
1521 (setf (continuation-reoptimize arg) nil))))
1522 (:error))
1523 (undefined-value))
1524
1525
1526 ;;; Values-types-defaulted -- Internal
1527 ;;;
1528 ;;; Like values-types, but returns the types of the given number of
1529 ;;; arguments. If optional of rest values must be used then the union
1530 ;;; with the null type is computed in case of defaulting, and if no
1531 ;;; values are available then they are defaulted to the null type.
1532 ;;;
1533 (defun values-types-defaulted (type count)
1534 (declare (type ctype type) (type index count))
1535 (cond ((eq type *wild-type*)
1536 (let ((types nil))
1537 (dotimes (i count types)
1538 (push *universal-type* types))))
1539 ((not (values-type-p type))
1540 (let ((types nil))
1541 (dotimes (i (1- count))
1542 (push *null-type* types))
1543 (push type types)))
1544 (t
1545 (let ((required (args-type-required type))
1546 (optional (args-type-optional type))
1547 (keyp-allowp (or (args-type-keyp type) (args-type-allowp type)))
1548 (rest (args-type-rest type)))
1549 (collect ((types))
1550 (dotimes (i count)
1551 (types (cond (required (single-value-type (pop required)))
1552 (optional (values-type-union
1553 (single-value-type (pop optional))
1554 *null-type*))
1555 (keyp-allowp *universal-type*)
1556 (rest (values-type-union (single-value-type rest)
1557 *null-type*))
1558 (t *null-type*))))
1559 (types))))))
1560
1561
1562 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1563 ;;;
1564 ;;; Propagate derived type info from the values continuation to the vars.
1565 ;;;
1566 (defun ir1-optimize-mv-bind (node)
1567 (declare (type mv-combination node))
1568 (let ((arg (first (basic-combination-args node)))
1569 (vars (lambda-vars (combination-lambda node))))
1570 (let ((types (values-types-defaulted (continuation-derived-type arg)
1571 (length vars))))
1572 (mapc #'(lambda (var type)
1573 (if (basic-var-sets var)
1574 (propagate-from-sets var type)
1575 (propagate-to-refs var type)))
1576 vars types))
1577
1578 (setf (continuation-reoptimize arg) nil))
1579 (undefined-value))
1580
1581
1582 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1583 ;;;
1584 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1585 ;;; if:
1586 ;;; -- The call has only one argument, and
1587 ;;; -- The function has a known fixed number of arguments, or
1588 ;;; -- The argument yields a known fixed number of values.
1589 ;;;
1590 ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1591 ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1592 ;;; this call can be converted (the next time around.) This new lambda just
1593 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1594 ;;; that this new MV bind is not let-converted immediately, as there are going
1595 ;;; to be stray references from the entry-point functions until they get
1596 ;;; deleted.
1597 ;;;
1598 ;;; In order to avoid loss of argument count checking, we only do the
1599 ;;; transformation according to a known number of expected argument if safety
1600 ;;; is unimportant. We can always convert if we know the number of actual
1601 ;;; values, since the normal call that we build will still do any appropriate
1602 ;;; argument count checking.
1603 ;;;
1604 ;;; We only attempt the transformation if the called function is a constant
1605 ;;; reference. This allows us to just splice the leaf into the new function,
1606 ;;; instead of trying to somehow bind the function expression. The leaf must
1607 ;;; be constant because we are evaluating it again in a different place. This
1608 ;;; also has the effect of squelching multiple warnings when there is an
1609 ;;; argument count error.
1610 ;;;
1611 (defun ir1-optimize-mv-call (node)
1612 (let ((fun (basic-combination-fun node))
1613 (*compiler-error-context* node)
1614 (ref (continuation-use (basic-combination-fun node)))
1615 (args (basic-combination-args node)))
1616
1617 (unless (and (ref-p ref) (constant-reference-p ref)
1618 args (null (rest args)))
1619 (return-from ir1-optimize-mv-call))
1620
1621 (multiple-value-bind (min max)
1622 (function-type-nargs (continuation-type fun))
1623 (let ((total-nvals
1624 (multiple-value-bind
1625 (types nvals)
1626 (values-types (continuation-derived-type (first args)))
1627 (declare (ignore types))
1628 (if (eq nvals :unknown) nil nvals))))
1629
1630 (when total-nvals
1631 (when (and min (< total-nvals min))
1632 (compiler-warning
1633 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1634 at least ~R."
1635 total-nvals min)
1636 (setf (basic-combination-kind node) :error)
1637 (return-from ir1-optimize-mv-call))
1638 (when (and max (> total-nvals max))
1639 (compiler-warning
1640 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1641 at most ~R."
1642 total-nvals max)
1643 (setf (basic-combination-kind node) :error)
1644 (return-from ir1-optimize-mv-call)))
1645
1646 (let ((count (cond (total-nvals)
1647 ((and (policy node (zerop safety)) (eql min max))
1648 min)
1649 (t nil))))
1650 (when count
1651 (with-ir1-environment node
1652 (let* ((dums (loop repeat count collect (gensym)))
1653 (ignore (gensym))
1654 (fun (ir1-convert-lambda
1655 `(lambda (&optional ,@dums &rest ,ignore)
1656 (declare (ignore ,ignore))
1657 (funcall ,(ref-leaf ref) ,@dums)))))
1658 (change-ref-leaf ref fun)
1659 (assert (eq (basic-combination-kind node) :full))
1660 (local-call-analyze *current-component*)
1661 (assert (eq (basic-combination-kind node) :local)))))))))
1662 (undefined-value))
1663
1664
1665 ;;; CONVERT-MV-BIND-TO-LET -- Internal
1666 ;;;
1667 ;;; If we see:
1668 ;;; (multiple-value-bind (x y)
1669 ;;; (values xx yy)
1670 ;;; ...)
1671 ;;; Convert to:
1672 ;;; (let ((x xx)
1673 ;;; (y yy))
1674 ;;; ...)
1675 ;;;
1676 ;;; What we actually do is convert the VALUES combination into a normal let
1677 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1678 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1679 ;;; args, insert references to NIL.
1680 ;;;
1681 (defun convert-mv-bind-to-let (call)
1682 (declare (type mv-combination call))
1683 (let* ((arg (first (basic-combination-args call)))
1684 (use (continuation-use arg)))
1685 (when (and (combination-p use)
1686 (eq (continuation-function-name (combination-fun use))
1687 'values))
1688 (let* ((fun (combination-lambda call))
1689 (vars (lambda-vars fun))
1690 (vals (combination-args use))
1691 (nvars (length vars))
1692 (nvals (length vals)))
1693 (cond ((> nvals nvars)
1694 (mapc #'flush-dest (subseq vals nvars))
1695 (setq vals (subseq vals 0 nvars)))
1696 ((< nvals nvars)
1697 (with-ir1-environment use
1698 (let ((node-prev (node-prev use)))
1699 (setf (node-prev use) nil)
1700 (setf (continuation-next node-prev) nil)
1701 (collect ((res vals))
1702 (loop as cont = (make-continuation use)
1703 and prev = node-prev then cont
1704 repeat (- nvars nvals)
1705 do (reference-constant prev cont nil)
1706 (res cont))
1707 (setq vals (res)))
1708 (prev-link use (car (last vals)))))))
1709 (setf (combination-args use) vals)
1710 (flush-dest (combination-fun use))
1711 (let ((fun-cont (basic-combination-fun call)))
1712 (setf (continuation-dest fun-cont) use)
1713 (setf (combination-fun use) fun-cont))
1714 (setf (combination-kind use) :local)
1715 (setf (functional-kind fun) :let)
1716 (flush-dest (first (basic-combination-args call)))
1717 (unlink-node call)
1718 (when vals
1719 (reoptimize-continuation (first vals)))
1720 (propagate-to-args use fun))
1721 t)))
1722
1723
1724 ;;; VALUES-LIST IR1 optimizer -- Internal
1725 ;;;
1726 ;;; If we see:
1727 ;;; (values-list (list x y z))
1728 ;;;
1729 ;;; Convert to:
1730 ;;; (values x y z)
1731 ;;;
1732 ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1733 ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1734 ;;; the old argument continuation (allowing the LIST to be flushed.)
1735 ;;;
1736 (defoptimizer (values-list optimizer) ((list) node)
1737 (let ((use (continuation-use list)))
1738 (when (and (combination-p use)
1739 (eq (continuation-function-name (combination-fun use))
1740 'list))
1741 (change-ref-leaf (continuation-use (combination-fun node))
1742 (find-free-function 'values "in a strange place"))
1743 (setf (combination-kind node) :full)
1744 (let ((args (combination-args use)))
1745 (dolist (arg args)
1746 (setf (continuation-dest arg) node))
1747 (setf (combination-args use) nil)
1748 (flush-dest list)
1749 (setf (combination-args node) args))
1750 t)))
1751
1752
1753 ;;; VALUES IR1 transform -- Internal
1754 ;;;
1755 ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1756 ;;; PROG1. This allows the computation of the additional values to become dead
1757 ;;; code. Some attempt is made to correct the node derived type, setting it to
1758 ;;; the received single-value-type. The node continuation asserted type must
1759 ;;; also be adjusted, taking care when the continuation has multiple uses.
1760 ;;;
1761 (deftransform values ((&rest vals) * * :node node)
1762 (let ((cont (node-cont node)))
1763 (when (typep (continuation-dest cont) '(or creturn exit mv-combination))
1764 (give-up))
1765 (flet ((first-value-type (type)
1766 (declare (type ctype type))
1767 (cond ((values-type-p type)
1768 (let ((required (args-type-required type)))
1769 (if required
1770 (first required)
1771 (let ((otype (args-type-optional type)))
1772 (cond (otype (first otype))
1773 ((or (args-type-keyp type)
1774 (args-type-allowp type))
1775 *universal-type*)
1776 ((args-type-rest type))
1777 (t *null-type*))))))
1778 ((eq type *wild-type*)
1779 *universal-type*)
1780 (t
1781 type))))
1782 (cond ((= (length (find-uses cont)) 1)
1783 (setf (node-derived-type node)
1784 (single-value-type (node-derived-type node)))
1785 (setf (continuation-asserted-type cont)
1786 (first-value-type (continuation-asserted-type cont))))
1787 (t
1788 (setf (node-derived-type node)
1789 (single-value-type (node-derived-type node)))
1790 (setf (continuation-asserted-type cont)
1791 (values-type-union (continuation-asserted-type cont)
1792 (first-value-type
1793 (continuation-asserted-type cont)))))))
1794 (reoptimize-continuation cont)
1795 (if vals
1796 (let ((dummies (loop repeat (1- (length vals))
1797 collect (gensym))))
1798 `(lambda (val ,@dummies)
1799 (declare (ignore ,@dummies))
1800 val))
1801 'nil)))

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