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Revision 1.64 - (show annotations)
Thu Jan 6 18:04:03 1994 UTC (20 years, 3 months ago) by ram
Branch: MAIN
Changes since 1.63: +3 -2 lines
In propagate-local-call-args, don't do anything if there is an
optional-dispatch specified.  The last fixed entry point won't be referenced by
the XEP, so we can't count on that providing a T type input.
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 ;;; If you want to use this code or any part of CMU Common Lisp, please contact
7 ;;; Scott Fahlman or slisp-group@cs.cmu.edu.
8 ;;;
9 (ext:file-comment
10 "$Header: /tiger/var/lib/cvsroots/cmucl/src/compiler/ir1opt.lisp,v 1.64 1994/01/06 18:04:03 ram Exp $")
11 ;;;
12 ;;; **********************************************************************
13 ;;;
14 ;;; This file implements the IR1 optimization phase of the compiler. IR1
15 ;;; optimization is a grab-bag of optimizations that don't make major changes
16 ;;; to the block-level control flow and don't use flow analysis. These
17 ;;; optimizations can mostly be classified as "meta-evaluation", but there is a
18 ;;; sizable top-down component as well.
19 ;;;
20 ;;; Written by Rob MacLachlan
21 ;;;
22 (in-package :c)
23
24
25 ;;;; Interface for obtaining results of constant folding:
26
27 ;;; Constant-Continuation-P -- Interface
28 ;;;
29 ;;; Return true if the sole use of Cont is a reference to a constant leaf.
30 ;;;
31 (proclaim '(function constant-continuation-p (continuation) boolean))
32 (defun constant-continuation-p (cont)
33 (let ((use (continuation-use cont)))
34 (and (ref-p use)
35 (constant-p (ref-leaf use)))))
36
37
38 ;;; Continuation-Value -- Interface
39 ;;;
40 ;;; Return the constant value for a continuation whose only use is a
41 ;;; constant node.
42 ;;;
43 (proclaim '(function continuation-value (continuation) t))
44 (defun continuation-value (cont)
45 (assert (constant-continuation-p cont))
46 (constant-value (ref-leaf (continuation-use cont))))
47
48
49 ;;;; Interface for obtaining results of type inference:
50
51 ;;; CONTINUATION-PROVEN-TYPE -- Interface
52 ;;;
53 ;;; Return a (possibly values) type that describes what we have proven about
54 ;;; the type of Cont without taking any type assertions into consideration.
55 ;;; This is just the union of the NODE-DERIVED-TYPE of all the uses. Most
56 ;;; often people use CONTINUATION-DERIVED-TYPE or CONTINUATION-TYPE instead of
57 ;;; using this function directly.
58 ;;;
59 (defun continuation-proven-type (cont)
60 (declare (type continuation cont))
61 (ecase (continuation-kind cont)
62 ((:block-start :deleted-block-start)
63 (let ((uses (block-start-uses (continuation-block cont))))
64 (if uses
65 (do ((res (node-derived-type (first uses))
66 (values-type-union (node-derived-type (first current))
67 res))
68 (current (rest uses) (rest current)))
69 ((null current) res))
70 *empty-type*)))
71 (:inside-block
72 (node-derived-type (continuation-use cont)))))
73
74
75 ;;; Continuation-Derived-Type -- Interface
76 ;;;
77 ;;; Our best guess for the type of this continuation's value. Note that
78 ;;; this may be Values or Function type, which cannot be passed as an argument
79 ;;; to the normal type operations. See Continuation-Type. This may be called
80 ;;; on deleted continuations, always returning *.
81 ;;;
82 ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the result
83 ;;; is a subtype of the assertion. If so, return the proven type and set
84 ;;; TYPE-CHECK to nil. Otherwise, return the intersection of the asserted and
85 ;;; proven types, and set TYPE-CHECK T. If TYPE-CHECK already has a non-null
86 ;;; value, then preserve it. Only in the somewhat unusual circumstance of
87 ;;; a newly discovered assertion will we change TYPE-CHECK from NIL to T.
88 ;;;
89 ;;; The result value is cached in the Continuation-%Derived-Type. If the
90 ;;; slot is true, just return that value, otherwise recompute and stash the
91 ;;; value there.
92 ;;;
93 (proclaim '(inline continuation-derived-type))
94 (defun continuation-derived-type (cont)
95 (declare (type continuation cont))
96 (or (continuation-%derived-type cont)
97 (%continuation-derived-type cont)))
98 ;;;
99 (defun %continuation-derived-type (cont)
100 (declare (type continuation cont))
101 (let ((proven (continuation-proven-type cont))
102 (asserted (continuation-asserted-type cont)))
103 (cond ((values-subtypep proven asserted)
104 (setf (continuation-%type-check cont) nil)
105 (setf (continuation-%derived-type cont) proven))
106 (t
107 (unless (or (continuation-%type-check cont)
108 (not (continuation-dest cont))
109 (eq asserted *universal-type*))
110 (setf (continuation-%type-check cont) t))
111
112 (setf (continuation-%derived-type cont)
113 (values-type-intersection asserted proven))))))
114
115
116 ;;; CONTINUATION-TYPE-CHECK -- Interface
117 ;;;
118 ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to date, then
119 ;;; return it.
120 ;;;
121 (proclaim '(inline continuation-type-check))
122 (defun continuation-type-check (cont)
123 (declare (type continuation cont))
124 (continuation-derived-type cont)
125 (continuation-%type-check cont))
126
127
128 ;;; Continuation-Type -- Interface
129 ;;;
130 ;;; Return the derived type for Cont's first value. This is guaranteed not
131 ;;; to be a Values or Function type.
132 ;;;
133 (proclaim '(function continuation-type (continuation) ctype))
134 (defun continuation-type (cont)
135 (single-value-type (continuation-derived-type cont)))
136
137
138 ;;;; Interface routines used by optimizers:
139
140 ;;; Reoptimize-Continuation -- Interface
141 ;;;
142 ;;; This function is called by optimizers to indicate that something
143 ;;; interesting has happened to the value of Cont. Optimizers must make sure
144 ;;; that they don't call for reoptimization when nothing has happened, since
145 ;;; optimization will fail to terminate.
146 ;;;
147 ;;; We clear any cached type for the continuation and set the reoptimize
148 ;;; flags on everything in sight, unless the continuation is deleted (in which
149 ;;; case we do nothing.)
150 ;;;
151 ;;; Since this can get called curing IR1 conversion, we have to be careful
152 ;;; not to fly into space when the Dest's Prev is missing.
153 ;;;
154 (defun reoptimize-continuation (cont)
155 (declare (type continuation cont))
156 (unless (member (continuation-kind cont) '(:deleted :unused))
157 (setf (continuation-%derived-type cont) nil)
158 (let ((dest (continuation-dest cont)))
159 (when dest
160 (setf (continuation-reoptimize cont) t)
161 (setf (node-reoptimize dest) t)
162 (let ((prev (node-prev dest)))
163 (when prev
164 (let* ((block (continuation-block prev))
165 (component (block-component block)))
166 (when (typep dest 'cif)
167 (setf (block-test-modified block) t))
168 (setf (block-reoptimize block) t)
169 (setf (component-reoptimize component) t))))))
170 (do-uses (node cont)
171 (setf (block-type-check (node-block node)) t)))
172 (undefined-value))
173
174
175 ;;; Derive-Node-Type -- Interface
176 ;;;
177 ;;; Annotate Node to indicate that its result has been proven to be typep to
178 ;;; RType. After IR1 conversion has happened, this is the only correct way to
179 ;;; supply information discovered about a node's type. If you fuck with the
180 ;;; Node-Derived-Type directly, then information may be lost and reoptimization
181 ;;; may not happen.
182 ;;;
183 ;;; What we do is intersect Rtype with Node's Derived-Type. If the
184 ;;; intersection is different from the old type, then we do a
185 ;;; Reoptimize-Continuation on the Node-Cont.
186 ;;;
187 (defun derive-node-type (node rtype)
188 (declare (type node node) (type ctype rtype))
189 (let ((node-type (node-derived-type node)))
190 (unless (eq node-type rtype)
191 (let ((int (values-type-intersection node-type rtype)))
192 (when (type/= node-type int)
193 (when (and *check-consistency*
194 (eq int *empty-type*)
195 (not (eq rtype *empty-type*)))
196 (let ((*compiler-error-context* node))
197 (compiler-warning
198 "New inferred type ~S conflicts with old type:~
199 ~% ~S~%*** Bug?"
200 (type-specifier rtype) (type-specifier node-type))))
201 (setf (node-derived-type node) int)
202 (reoptimize-continuation (node-cont node))))))
203 (undefined-value))
204
205 (declaim (start-block assert-continuation-type assert-call-type))
206
207 ;;; Assert-Continuation-Type -- Interface
208 ;;;
209 ;;; Similar to Derive-Node-Type, but asserts that it is an error for Cont's
210 ;;; value not to be typep to Type. If we improve the assertion, we set
211 ;;; TYPE-CHECK and TYPE-ASSERTED to guarantee that the new assertion will be
212 ;;; checked.
213 ;;;
214 (defun assert-continuation-type (cont type)
215 (declare (type continuation cont) (type ctype type))
216 (let ((cont-type (continuation-asserted-type cont)))
217 (unless (eq cont-type type)
218 (let ((int (values-type-intersection cont-type type)))
219 (when (type/= cont-type int)
220 (setf (continuation-asserted-type cont) int)
221 (do-uses (node cont)
222 (setf (block-attributep (block-flags (node-block node))
223 type-check type-asserted)
224 t))
225 (reoptimize-continuation cont)))))
226 (undefined-value))
227
228
229 ;;; Assert-Call-Type -- Interface
230 ;;;
231 ;;; Assert that Call is to a function of the specified Type. It is assumed
232 ;;; that the call is legal and has only constants in the keyword positions.
233 ;;;
234 (defun assert-call-type (call type)
235 (declare (type combination call) (type function-type type))
236 (derive-node-type call (function-type-returns type))
237 (let ((args (combination-args call)))
238 (dolist (req (function-type-required type))
239 (when (null args) (return-from assert-call-type))
240 (let ((arg (pop args)))
241 (assert-continuation-type arg req)))
242 (dolist (opt (function-type-optional type))
243 (when (null args) (return-from assert-call-type))
244 (let ((arg (pop args)))
245 (assert-continuation-type arg opt)))
246
247 (let ((rest (function-type-rest type)))
248 (when rest
249 (dolist (arg args)
250 (assert-continuation-type arg rest))))
251
252 (dolist (key (function-type-keywords type))
253 (let ((name (key-info-name key)))
254 (do ((arg args (cddr arg)))
255 ((null arg))
256 (when (eq (continuation-value (first arg)) name)
257 (assert-continuation-type
258 (second arg) (key-info-type key)))))))
259 (undefined-value))
260
261
262 ;;;; IR1-OPTIMIZE:
263
264 (declaim (start-block ir1-optimize))
265
266 ;;; IR1-Optimize -- Interface
267 ;;;
268 ;;; Do one forward pass over Component, deleting unreachable blocks and
269 ;;; doing IR1 optimizations. We can ignore all blocks that don't have the
270 ;;; Reoptimize flag set. If Component-Reoptimize is true when we are done,
271 ;;; then another iteration would be beneficial.
272 ;;;
273 ;;; We delete blocks when there is either no predecessor or the block is in
274 ;;; a lambda that has been deleted. These blocks would eventually be deleted
275 ;;; by DFO recomputation, but doing it here immediately makes the effect
276 ;;; avaliable to IR1 optimization.
277 ;;;
278 (defun ir1-optimize (component)
279 (declare (type component component))
280 (setf (component-reoptimize component) nil)
281 (do-blocks (block component)
282 (cond
283 ((or (block-delete-p block)
284 (null (block-pred block))
285 (eq (functional-kind (block-home-lambda block)) :deleted))
286 (delete-block block))
287 (t
288 (loop
289 (let ((succ (block-succ block)))
290 (unless (and succ (null (rest succ)))
291 (return)))
292
293 (let ((last (block-last block)))
294 (typecase last
295 (cif
296 (flush-dest (if-test last))
297 (when (unlink-node last) (return)))
298 (exit
299 (when (maybe-delete-exit last) (return)))))
300
301 (unless (join-successor-if-possible block)
302 (return)))
303
304 (when (and (block-reoptimize block) (block-component block))
305 (assert (not (block-delete-p block)))
306 (ir1-optimize-block block))
307
308 (when (and (block-flush-p block) (block-component block))
309 (assert (not (block-delete-p block)))
310 (flush-dead-code block)))))
311
312 (undefined-value))
313
314
315 ;;; IR1-Optimize-Block -- Internal
316 ;;;
317 ;;; Loop over the nodes in Block, looking for stuff that needs to be
318 ;;; optimized. We dispatch off of the type of each node with its reoptimize
319 ;;; flag set:
320 ;;; -- With a combination, we call Propagate-Function-Change whenever the
321 ;;; function changes, and call IR1-Optimize-Combination if any argument
322 ;;; changes.
323 ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
324 ;;; propagate Cont's assertion to the Value, since if we did, this would
325 ;;; move the checking of Cont's assertion to the exit. This wouldn't work
326 ;;; with Catch and UWP, where the Exit node is just a placeholder for the
327 ;;; actual unknown exit.
328 ;;;
329 ;;; Note that we clear the node & block reoptimize flags *before* doing the
330 ;;; optimization. This ensures that the node or block will be reoptimized if
331 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
332 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
333 ;;;
334 (defun ir1-optimize-block (block)
335 (declare (type cblock block))
336 (setf (block-reoptimize block) nil)
337 (do-nodes (node cont block :restart-p t)
338 (when (node-reoptimize node)
339 (setf (node-reoptimize node) nil)
340 (typecase node
341 (ref)
342 (combination
343 (ir1-optimize-combination node))
344 (cif
345 (ir1-optimize-if node))
346 (creturn
347 (setf (node-reoptimize node) t)
348 (ir1-optimize-return node))
349 (mv-combination
350 (ir1-optimize-mv-combination node))
351 (exit
352 (let ((value (exit-value node)))
353 (when value
354 (derive-node-type node (continuation-derived-type value)))))
355 (cset
356 (ir1-optimize-set node)))))
357 (undefined-value))
358
359
360 ;;; Join-Successor-If-Possible -- Internal
361 ;;;
362 ;;; We cannot combine with a successor block if:
363 ;;; 1] The successor has more than one predecessor.
364 ;;; 2] The last node's Cont is also used somewhere else.
365 ;;; 3] The successor is the current block (infinite loop).
366 ;;; 4] The next block has a different cleanup, and thus we may want to insert
367 ;;; cleanup code between the two blocks at some point.
368 ;;; 5] The next block has a different home lambda, and thus the control
369 ;;; transfer is a non-local exit.
370 ;;;
371 ;;; If we succeed, we return true, otherwise false.
372 ;;;
373 ;;; Joining is easy when the successor's Start continuation is the same from
374 ;;; our Last's Cont. If they differ, then we can still join when the last
375 ;;; continuation has no next and the next continuation has no uses. In this
376 ;;; case, we replace the next continuation with the last before joining the
377 ;;; blocks.
378 ;;;
379 (defun join-successor-if-possible (block)
380 (declare (type cblock block))
381 (let ((next (first (block-succ block))))
382 (when (block-start next)
383 (let* ((last (block-last block))
384 (last-cont (node-cont last))
385 (next-cont (block-start next)))
386 (cond ((or (rest (block-pred next))
387 (not (eq (continuation-use last-cont) last))
388 (eq next block)
389 (not (eq (block-end-cleanup block)
390 (block-start-cleanup next)))
391 (not (eq (block-home-lambda block)
392 (block-home-lambda next))))
393 nil)
394 ((eq last-cont next-cont)
395 (join-blocks block next)
396 t)
397 ((and (null (block-start-uses next))
398 (eq (continuation-kind last-cont) :inside-block))
399 (let ((next-node (continuation-next next-cont)))
400 ;;
401 ;; If next-cont does have a dest, it must be unreachable,
402 ;; since there are no uses. DELETE-CONTINUATION will mark the
403 ;; dest block as delete-p [and also this block, unless it is
404 ;; no longer backward reachable from the dest block.]
405 (delete-continuation next-cont)
406 (setf (node-prev next-node) last-cont)
407 (setf (continuation-next last-cont) next-node)
408 (setf (block-start next) last-cont)
409 (join-blocks block next))
410 t)
411 (t
412 nil))))))
413
414
415 ;;; Join-Blocks -- Internal
416 ;;;
417 ;;; Join together two blocks which have the same ending/starting
418 ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
419 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
420 ;;; that any indicated optimization gets done.
421 ;;;
422 (defun join-blocks (block1 block2)
423 (declare (type cblock block1 block2))
424 (let* ((last (block-last block2))
425 (last-cont (node-cont last))
426 (succ (block-succ block2))
427 (start2 (block-start block2)))
428 (do ((cont start2 (node-cont (continuation-next cont))))
429 ((eq cont last-cont)
430 (when (eq (continuation-kind last-cont) :inside-block)
431 (setf (continuation-block last-cont) block1)))
432 (setf (continuation-block cont) block1))
433
434 (unlink-blocks block1 block2)
435 (dolist (block succ)
436 (unlink-blocks block2 block)
437 (link-blocks block1 block))
438
439 (setf (block-last block1) last)
440 (setf (continuation-kind start2) :inside-block))
441
442 (setf (block-flags block1)
443 (attributes-union (block-flags block1)
444 (block-flags block2)
445 (block-attributes type-asserted test-modified)))
446
447 (let ((next (block-next block2))
448 (prev (block-prev block2)))
449 (setf (block-next prev) next)
450 (setf (block-prev next) prev))
451
452 (undefined-value))
453
454 ;;; Flush-Dead-Code -- Internal
455 ;;;
456 ;;; Delete any nodes in Block whose value is unused and have no
457 ;;; side-effects. We can delete sets of lexical variables when the set
458 ;;; variable has no references.
459 ;;;
460 ;;; [### For now, don't delete potentially flushable calls when they have the
461 ;;; Call attribute. Someday we should look at the funcitonal args to determine
462 ;;; if they have any side-effects.]
463 ;;;
464 (defun flush-dead-code (block)
465 (declare (type cblock block))
466 (do-nodes-backwards (node cont block)
467 (unless (continuation-dest cont)
468 (typecase node
469 (ref
470 (delete-ref node)
471 (unlink-node node))
472 (combination
473 (let ((info (combination-kind node)))
474 (when (function-info-p info)
475 (let ((attr (function-info-attributes info)))
476 (when (and (ir1-attributep attr flushable)
477 (not (ir1-attributep attr call)))
478 (flush-dest (combination-fun node))
479 (dolist (arg (combination-args node))
480 (flush-dest arg))
481 (unlink-node node))))))
482 (mv-combination
483 (when (eq (basic-combination-kind node) :local)
484 (let ((fun (combination-lambda node)))
485 (when (dolist (var (lambda-vars fun) t)
486 (when (or (leaf-refs var)
487 (lambda-var-sets var))
488 (return nil)))
489 (flush-dest (first (basic-combination-args node)))
490 (delete-let fun)))))
491 (exit
492 (let ((value (exit-value node)))
493 (when value
494 (flush-dest value)
495 (setf (exit-value node) nil))))
496 (cset
497 (let ((var (set-var node)))
498 (when (and (lambda-var-p var)
499 (null (leaf-refs var)))
500 (flush-dest (set-value node))
501 (setf (basic-var-sets var)
502 (delete node (basic-var-sets var)))
503 (unlink-node node)))))))
504
505 (setf (block-flush-p block) nil)
506 (undefined-value))
507
508 (declaim (end-block))
509
510
511 ;;;; Local call return type propagation:
512
513 ;;; Find-Result-Type -- Internal
514 ;;;
515 ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
516 ;;; set. It iterates over the uses of the RESULT, looking for interesting
517 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
518 ;;; its type together with the types of other such uses. We assign to the
519 ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
520 ;;; type. We can make this intersection now (potentially before type checking)
521 ;;; because this assertion on the result will eventually be checked (if
522 ;;; appropriate.)
523 ;;;
524 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
525 ;;; which may change the succesor of the call to be the called function, and if
526 ;;; so, checks if the call can become an assignment. If we convert to an
527 ;;; assignment, we abort, since the RETURN has been deleted.
528 ;;;
529 (defun find-result-type (node)
530 (declare (type creturn node))
531 (let ((result (return-result node)))
532 (collect ((use-union *empty-type* values-type-union))
533 (do-uses (use result)
534 (cond ((and (basic-combination-p use)
535 (eq (basic-combination-kind use) :local))
536 (assert (eq (lambda-tail-set (node-home-lambda use))
537 (lambda-tail-set (combination-lambda use))))
538 (when (combination-p use)
539 (when (nth-value 1 (maybe-convert-tail-local-call use))
540 (return-from find-result-type (undefined-value)))))
541 (t
542 (use-union (node-derived-type use)))))
543 (let ((int (values-type-intersection
544 (continuation-asserted-type result)
545 (use-union))))
546 (setf (return-result-type node) int))))
547 (undefined-value))
548
549
550 ;;; IR1-Optimize-Return -- Internal
551 ;;;
552 ;;; Do stuff to realize that something has changed about the value delivered
553 ;;; to a return node. Since we consider the return values of all functions in
554 ;;; the tail set to be equivalent, this amounts to bringing the entire tail set
555 ;;; up to date. We iterate over the returns for all the functions in the tail
556 ;;; set, reanalyzing them all (not treating Node specially.)
557 ;;;
558 ;;; When we are done, we check if the new type is different from the old
559 ;;; TAIL-SET-TYPE. If so, we set the type and also reoptimize all the
560 ;;; continuations for references to functions in the tail set. This will
561 ;;; cause IR1-OPTIMIZE-COMBINATION to derive the new type as the results of the
562 ;;; calls.
563 ;;;
564 (defun ir1-optimize-return (node)
565 (declare (type creturn node))
566 (let* ((tails (lambda-tail-set (return-lambda node)))
567 (funs (tail-set-functions tails)))
568 (collect ((res *empty-type* values-type-union))
569 (dolist (fun funs)
570 (let ((return (lambda-return fun)))
571 (when return
572 (when (node-reoptimize return)
573 (setf (node-reoptimize return) nil)
574 (find-result-type return))
575 (res (return-result-type return)))))
576
577 (when (type/= (res) (tail-set-type tails))
578 (setf (tail-set-type tails) (res))
579 (dolist (fun (tail-set-functions tails))
580 (dolist (ref (leaf-refs fun))
581 (reoptimize-continuation (node-cont ref)))))))
582
583 (undefined-value))
584
585
586 ;;; IF optimization:
587
588 (declaim (start-block ir1-optimize-if))
589
590 ;;; IR1-Optimize-If -- Internal
591 ;;;
592 ;;; If the test has multiple uses, replicate the node when possible. Also
593 ;;; check if the predicate is known to be true or false, deleting the IF node
594 ;;; in favor of the appropriate branch when this is the case.
595 ;;;
596 (defun ir1-optimize-if (node)
597 (declare (type cif node))
598 (let ((test (if-test node))
599 (block (node-block node)))
600
601 (when (and (eq (block-start block) test)
602 (eq (continuation-next test) node)
603 (rest (block-start-uses block)))
604 (do-uses (use test)
605 (when (immediately-used-p test use)
606 (convert-if-if use node)
607 (when (continuation-use test) (return)))))
608
609 (let* ((type (continuation-type test))
610 (victim
611 (cond ((constant-continuation-p test)
612 (if (continuation-value test)
613 (if-alternative node)
614 (if-consequent node)))
615 ((not (types-intersect type *null-type*))
616 (if-alternative node))
617 ((type= type *null-type*)
618 (if-consequent node)))))
619 (when victim
620 (flush-dest test)
621 (when (rest (block-succ block))
622 (unlink-blocks block victim))
623 (setf (component-reanalyze (block-component (node-block node))) t)
624 (unlink-node node))))
625 (undefined-value))
626
627
628 ;;; Convert-If-If -- Internal
629 ;;;
630 ;;; Create a new copy of an IF Node that tests the value of the node Use.
631 ;;; The test must have >1 use, and must be immediately used by Use. Node must
632 ;;; be the only node in its block (implying that block-start = if-test).
633 ;;;
634 ;;; This optimization has an effect semantically similar to the
635 ;;; source-to-source transformation:
636 ;;; (IF (IF A B C) D E) ==>
637 ;;; (IF A (IF B D E) (IF C D E))
638 ;;;
639 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new node so
640 ;;; that dead code deletion notes will definitely not consider either node to
641 ;;; be part of the original source. One node might become unreachable,
642 ;;; resulting in a spurious note.
643 ;;;
644 (defun convert-if-if (use node)
645 (declare (type node use) (type cif node))
646 (with-ir1-environment node
647 (let* ((block (node-block node))
648 (test (if-test node))
649 (cblock (if-consequent node))
650 (ablock (if-alternative node))
651 (use-block (node-block use))
652 (dummy-cont (make-continuation))
653 (new-cont (make-continuation))
654 (new-node (make-if :test new-cont
655 :consequent cblock :alternative ablock))
656 (new-block (continuation-starts-block new-cont)))
657 (prev-link new-node new-cont)
658 (setf (continuation-dest new-cont) new-node)
659 (add-continuation-use new-node dummy-cont)
660 (setf (block-last new-block) new-node)
661
662 (unlink-blocks use-block block)
663 (delete-continuation-use use)
664 (add-continuation-use use new-cont)
665 (link-blocks use-block new-block)
666
667 (link-blocks new-block cblock)
668 (link-blocks new-block ablock)
669
670 (push "<IF Duplication>" (node-source-path node))
671 (push "<IF Duplication>" (node-source-path new-node))
672
673 (reoptimize-continuation test)
674 (reoptimize-continuation new-cont)
675 (setf (component-reanalyze *current-component*) t)))
676 (undefined-value))
677
678 (declaim (end-block))
679
680
681 ;;;; Exit IR1 optimization:
682
683 ;;; Maybe-Delete-Exit -- Interface
684 ;;;
685 ;;; This function attempts to delete an exit node, returning true if it
686 ;;; deletes the block as a consequence:
687 ;;; -- If the exit is degenerate (has no Entry), then we don't do anything,
688 ;;; since there is nothing to be done.
689 ;;; -- If the exit node and its Entry have the same home lambda then we know
690 ;;; the exit is local, and can delete the exit. We change uses of the
691 ;;; Exit-Value to be uses of the original continuation, then unlink the
692 ;;; node. If the exit is to a TR context, then we must do MERGE-TAIL-SETS
693 ;;; on any local calls which delivered their value to this exit.
694 ;;; -- If there is no value (as in a GO), then we skip the value semantics.
695 ;;;
696 ;;; This function is also called by environment analysis, since it wants all
697 ;;; exits to be optimized even if normal optimization was omitted.
698 ;;;
699 (defun maybe-delete-exit (node)
700 (declare (type exit node))
701 (let ((value (exit-value node))
702 (entry (exit-entry node))
703 (cont (node-cont node)))
704 (when (and entry
705 (eq (node-home-lambda node) (node-home-lambda entry)))
706 (setf (entry-exits entry) (delete node (entry-exits entry)))
707 (prog1
708 (unlink-node node)
709 (when value
710 (collect ((merges))
711 (when (return-p (continuation-dest cont))
712 (do-uses (use value)
713 (when (and (basic-combination-p use)
714 (eq (basic-combination-kind use) :local))
715 (merges use))))
716 (substitute-continuation-uses cont value)
717 (dolist (merge (merges))
718 (merge-tail-sets merge))))))))
719
720
721 ;;;; Combination IR1 optimization:
722
723 (declaim (start-block ir1-optimize-combination maybe-terminate-block
724 validate-call-type))
725
726 ;;; Ir1-Optimize-Combination -- Internal
727 ;;;
728 ;;; Do IR1 optimizations on a Combination node.
729 ;;;
730 (proclaim '(function ir1-optimize-combination (combination) void))
731 (defun ir1-optimize-combination (node)
732 (when (continuation-reoptimize (basic-combination-fun node))
733 (propagate-function-change node))
734 (let ((args (basic-combination-args node))
735 (kind (basic-combination-kind node)))
736 (case kind
737 (:local
738 (let ((fun (combination-lambda node)))
739 (if (eq (functional-kind fun) :let)
740 (propagate-let-args node fun)
741 (propagate-local-call-args node fun))))
742 ((:full :error)
743 (dolist (arg args)
744 (when arg
745 (setf (continuation-reoptimize arg) nil))))
746 (t
747 (dolist (arg args)
748 (when arg
749 (setf (continuation-reoptimize arg) nil)))
750
751 (let ((attr (function-info-attributes kind)))
752 (when (and (ir1-attributep attr foldable)
753 (not (ir1-attributep attr call))
754 (every #'constant-continuation-p args)
755 (continuation-dest (node-cont node)))
756 (constant-fold-call node)
757 (return-from ir1-optimize-combination)))
758
759 (let ((fun (function-info-derive-type kind)))
760 (when fun
761 (let ((res (funcall fun node)))
762 (when res
763 (derive-node-type node res)
764 (maybe-terminate-block node nil)))))
765
766 (let ((fun (function-info-optimizer kind)))
767 (unless (and fun (funcall fun node))
768 (dolist (x (function-info-transforms kind))
769 (unless (ir1-transform node x)
770 (return))))))))
771
772 (undefined-value))
773
774
775 ;;; MAYBE-TERMINATE-BLOCK -- Interface
776 ;;;
777 ;;; If Call is to a function that doesn't return (type NIL), then terminate
778 ;;; the block there, and link it to the component tail. We also change the
779 ;;; call's CONT to be a dummy continuation to prevent the use from confusing
780 ;;; things.
781 ;;;
782 ;;; Except when called during IR1, we delete the continuation if it has no
783 ;;; other uses. (If it does have other uses, we reoptimize.)
784 ;;;
785 ;;; Termination on the basis of a continuation type assertion is inhibited
786 ;;; when:
787 ;;; -- The continuation is deleted (hence the assertion is spurious), or
788 ;;; -- We are in IR1 conversion (where THE assertions are subject to
789 ;;; weakening.)
790 ;;;
791 (defun maybe-terminate-block (call ir1-p)
792 (declare (type basic-combination call))
793 (let* ((block (node-block call))
794 (cont (node-cont call))
795 (tail (component-tail (block-component block)))
796 (succ (first (block-succ block))))
797 (unless (or (and (eq call (block-last block)) (eq succ tail))
798 (block-delete-p block)
799 *converting-for-interpreter*)
800 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
801 (not (or ir1-p (eq (continuation-kind cont) :deleted))))
802 (eq (node-derived-type call) *empty-type*))
803 (cond (ir1-p
804 (delete-continuation-use call)
805 (cond
806 ((block-last block)
807 (assert (and (eq (block-last block) call)
808 (eq (continuation-kind cont) :block-start))))
809 (t
810 (setf (block-last block) call)
811 (link-blocks block (continuation-starts-block cont)))))
812 (t
813 (node-ends-block call)
814 (delete-continuation-use call)
815 (if (eq (continuation-kind cont) :unused)
816 (delete-continuation cont)
817 (reoptimize-continuation cont))))
818
819 (unlink-blocks block (first (block-succ block)))
820 (setf (component-reanalyze (block-component block)) t)
821 (assert (not (block-succ block)))
822 (link-blocks block tail)
823 (add-continuation-use call (make-continuation))
824 t))))
825
826
827 ;;; Recognize-Known-Call -- Interface
828 ;;;
829 ;;; Called both by IR1 conversion and IR1 optimization when they have
830 ;;; verified the type signature for the call, and are wondering if something
831 ;;; should be done to special-case the call. If Call is a call to a global
832 ;;; function, then see if it defined or known:
833 ;;; -- If a DEFINED-FUNCTION should be inline expanded, then convert the
834 ;;; expansion and change the call to call it. Expansion is enabled if
835 ;;; :INLINE or if space=0. If the FUNCTIONAL slot is true, we never expand,
836 ;;; since this function has already been converted. Local call analysis
837 ;;; will duplicate the definition if necessary. We claim that the parent
838 ;;; form is LABELS for context declarations, since we don't want it to be
839 ;;; considered a real global function.
840 ;;; -- In addition to a direct check for the function name in the table, we
841 ;;; also must check for slot accessors. If the function is a slot accessor,
842 ;;; then we set the combination kind to the function info of %Slot-Setter or
843 ;;; %Slot-Accessor, as appropriate.
844 ;;; -- If it is a known function, mark it as such by setting the Kind.
845 ;;;
846 ;;; We return the leaf referenced (NIL if not a leaf) and the function-info
847 ;;; assigned.
848 ;;;
849 (defun recognize-known-call (call ir1-p)
850 (declare (type combination call))
851 (let* ((ref (continuation-use (basic-combination-fun call)))
852 (leaf (when (ref-p ref) (ref-leaf ref)))
853 (inlinep (if (and (defined-function-p leaf)
854 (not (byte-compiling)))
855 (defined-function-inlinep leaf)
856 :no-chance)))
857 (cond
858 ((eq inlinep :notinline) (values nil nil))
859 ((not (and (global-var-p leaf)
860 (eq (global-var-kind leaf) :global-function)))
861 (values leaf nil))
862 ((and (ecase inlinep
863 (:inline t)
864 (:no-chance nil)
865 ((nil :maybe-inline) (policy call (zerop space))))
866 (defined-function-inline-expansion leaf)
867 (let ((fun (defined-function-functional leaf)))
868 (or (not fun)
869 (and (eq inlinep :inline) (functional-kind fun))))
870 (inline-expansion-ok call))
871 (flet ((frob ()
872 (let ((res (ir1-convert-lambda-for-defun
873 (defined-function-inline-expansion leaf)
874 leaf t
875 #'ir1-convert-inline-lambda
876 'labels)))
877 (setf (defined-function-functional leaf) res)
878 (change-ref-leaf ref res))))
879 (if ir1-p
880 (frob)
881 (with-ir1-environment call
882 (frob)
883 (local-call-analyze *current-component*))))
884
885 (values (ref-leaf (continuation-use (basic-combination-fun call)))
886 nil))
887 (t
888 (let* ((name (leaf-name leaf))
889 (info (if (dylan-function-var-p leaf)
890 (dylan-function-var-function-info leaf)
891 (info function info
892 (if (slot-accessor-p leaf)
893 (if (consp name)
894 '%slot-setter
895 '%slot-accessor)
896 name)))))
897 (if info
898 (values leaf (setf (basic-combination-kind call) info))
899 (values leaf nil)))))))
900
901
902 ;;; VALIDATE-CALL-TYPE -- Internal
903 ;;;
904 ;;; Check if Call satisfies Type. If so, apply the type to the call, and do
905 ;;; MAYBE-TERMINATE-BLOCK and return the values of RECOGNIZE-KNOWN-CALL. If an
906 ;;; error, set the combination kind and return NIL, NIL. If the type is just
907 ;;; FUNCTION, then skip the syntax check, arg/result type processing, but still
908 ;;; call RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda, and
909 ;;; that checking is done by local call analysis.
910 ;;;
911 (defun validate-call-type (call type ir1-p)
912 (declare (type combination call) (type ctype type))
913 (cond ((not (function-type-p type))
914 (assert (multiple-value-bind
915 (val win)
916 (csubtypep type (specifier-type 'function))
917 (or val (not win))))
918 (recognize-known-call call ir1-p))
919 ((valid-function-use call type
920 :argument-test #'always-subtypep
921 :result-test #'always-subtypep
922 :error-function #'compiler-warning
923 :warning-function #'compiler-note)
924 (assert-call-type call type)
925 (maybe-terminate-block call ir1-p)
926 (recognize-known-call call ir1-p))
927 (t
928 (setf (combination-kind call) :error)
929 (values nil nil))))
930
931
932 ;;; Propagate-Function-Change -- Internal
933 ;;;
934 ;;; Called by Ir1-Optimize when the function for a call has changed.
935 ;;; If the call is local, we try to let-convert it, and derive the result type.
936 ;;; If it is a :FULL call, we validate it against the type, which recognizes
937 ;;; known calls, does inline expansion, etc. If a call to a predicate in a
938 ;;; non-conditional position or to a function with a source transform, then we
939 ;;; reconvert the form to give IR1 another chance.
940 ;;;
941 (defun propagate-function-change (call)
942 (declare (type combination call))
943 (let ((*compiler-error-context* call)
944 (fun-cont (basic-combination-fun call)))
945 (setf (continuation-reoptimize fun-cont) nil)
946 (case (combination-kind call)
947 (:local
948 (let ((fun (combination-lambda call)))
949 (maybe-let-convert fun)
950 (unless (member (functional-kind fun) '(:let :assignment :deleted))
951 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
952 (:full
953 (multiple-value-bind
954 (leaf info)
955 (validate-call-type call (continuation-type fun-cont) nil)
956 (cond ((functional-p leaf)
957 (convert-call-if-possible
958 (continuation-use (basic-combination-fun call))
959 call))
960 ((not leaf))
961 ((or (info function source-transform (leaf-name leaf))
962 (and info
963 (ir1-attributep (function-info-attributes info)
964 predicate)
965 (let ((dest (continuation-dest (node-cont call))))
966 (and dest (not (if-p dest))))))
967 (let ((name (leaf-name leaf)))
968 (when (symbolp name)
969 (let ((dums (loop repeat (length (combination-args call))
970 collect (gensym))))
971 (transform-call call
972 `(lambda ,dums
973 (,name ,@dums))))))))))))
974 (undefined-value))
975
976
977 ;;;; Known function optimization:
978
979
980 ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
981 ;;;
982 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for Node, Fun
983 ;;; and Args. If there is already a note for Node and Transform, replace it,
984 ;;; otherwise add a new one.
985 ;;;
986 (defun record-optimization-failure (node transform args)
987 (declare (type combination node) (type transform transform)
988 (type (or function-type list) args))
989 (let* ((table (component-failed-optimizations *compile-component*))
990 (found (assoc transform (gethash node table))))
991 (if found
992 (setf (cdr found) args)
993 (push (cons transform args) (gethash node table))))
994 (undefined-value))
995
996
997 ;;; IR1-Transform -- Internal
998 ;;;
999 ;;; Attempt to transform Node using Function, subject to the call type
1000 ;;; constraint Type. If we are inhibited from doing the transform for some
1001 ;;; reason and Flame is true, then we make a note of the message in
1002 ;;; FAILED-OPTIMIZATIONS for IR1 finalize to pick up. We return true if
1003 ;;; the transform failed, and thus further transformation should be
1004 ;;; attempted. We return false if either the transform suceeded or was
1005 ;;; aborted.
1006 ;;;
1007 (defun ir1-transform (node transform)
1008 (declare (type combination node) (type transform transform))
1009 (let* ((type (transform-type transform))
1010 (fun (transform-function transform))
1011 (constrained (function-type-p type))
1012 (table (component-failed-optimizations *compile-component*))
1013 (flame
1014 (if (transform-important transform)
1015 (policy node (>= speed brevity))
1016 (policy node (> speed brevity))))
1017 (*compiler-error-context* node))
1018 (cond ((let ((when (transform-when transform)))
1019 (not (or (eq when :both)
1020 (eq when (if *byte-compiling* :byte :native)))))
1021 t)
1022 ((or (not constrained)
1023 (valid-function-use node type :strict-result t))
1024 (multiple-value-bind
1025 (severity args)
1026 (catch 'give-up
1027 (transform-call node (funcall fun node))
1028 (values :none nil))
1029 (ecase severity
1030 (:none
1031 (remhash node table)
1032 nil)
1033 (:aborted
1034 (setf (combination-kind node) :error)
1035 (when args
1036 (apply #'compiler-warning args))
1037 (remhash node table)
1038 nil)
1039 (:failure
1040 (if args
1041 (when flame
1042 (record-optimization-failure node transform args))
1043 (setf (gethash node table)
1044 (remove transform (gethash node table) :key #'car)))
1045 t))))
1046 ((and flame
1047 (valid-function-use node type
1048 :argument-test #'types-intersect
1049 :result-test #'values-types-intersect))
1050 (record-optimization-failure node transform type)
1051 t)
1052 (t
1053 t))))
1054
1055 (declaim (end-block))
1056
1057 ;;; GIVE-UP, ABORT-TRANSFORM -- Interface
1058 ;;;
1059 ;;; Just throw the severity and args...
1060 ;;;
1061 (proclaim '(function give-up (&rest t) nil))
1062 (defun give-up (&rest args)
1063 "This function is used to throw out of an IR1 transform, aborting this
1064 attempt to transform the call, but admitting the possibility that this or
1065 some other transform will later suceed. If arguments are supplied, they are
1066 format arguments for an efficiency note."
1067 (throw 'give-up (values :failure args)))
1068 ;;;
1069 (defun abort-transform (&rest args)
1070 "This function is used to throw out of an IR1 transform and force a normal
1071 call to the function at run time. No further optimizations will be
1072 attempted."
1073 (throw 'give-up (values :aborted args)))
1074
1075
1076 ;;; Transform-Call -- Internal
1077 ;;;
1078 ;;; Take the lambda-expression Res, IR1 convert it in the proper
1079 ;;; environment, and then install it as the function for the call Node. We do
1080 ;;; local call analysis so that the new function is integrated into the control
1081 ;;; flow.
1082 ;;;
1083 (defun transform-call (node res)
1084 (declare (type combination node) (list res))
1085 (with-ir1-environment node
1086 (let ((new-fun (ir1-convert-inline-lambda res))
1087 (ref (continuation-use (combination-fun node))))
1088 (change-ref-leaf ref new-fun)
1089 (setf (combination-kind node) :full)
1090 (local-call-analyze *current-component*)))
1091 (undefined-value))
1092
1093
1094 ;;; Constant-Fold-Call -- Internal
1095 ;;;
1096 ;;; Replace a call to a foldable function of constant arguments with the
1097 ;;; result of evaluating the form. We insert the resulting constant node after
1098 ;;; the call, stealing the call's continuation. We give the call a
1099 ;;; continuation with no Dest, which should cause it and its arguments to go
1100 ;;; away. If there is an error during the evaluation, we give a warning and
1101 ;;; leave the call alone, making the call a :ERROR call.
1102 ;;;
1103 ;;; If there is more than one value, then we transform the call into a
1104 ;;; values form.
1105 ;;;
1106 (defun constant-fold-call (call)
1107 (declare (type combination call))
1108 (let* ((args (mapcar #'continuation-value (combination-args call)))
1109 (ref (continuation-use (combination-fun call)))
1110 (fun (leaf-name (ref-leaf ref))))
1111
1112 (multiple-value-bind (values win)
1113 (careful-call fun args call "constant folding")
1114 (cond
1115 ((not win)
1116 (setf (combination-kind call) :error))
1117 ((= (length values) 1)
1118 (with-ir1-environment call
1119 (when (producing-fasl-file)
1120 (maybe-emit-make-load-forms (first values)))
1121 (let* ((leaf (find-constant (first values)))
1122 (node (make-ref (leaf-type leaf) leaf))
1123 (dummy (make-continuation))
1124 (cont (node-cont call))
1125 (block (node-block call))
1126 (next (continuation-next cont)))
1127 (push node (leaf-refs leaf))
1128 (setf (leaf-ever-used leaf) t)
1129
1130 (delete-continuation-use call)
1131 (add-continuation-use call dummy)
1132 (prev-link node dummy)
1133 (add-continuation-use node cont)
1134 (setf (continuation-next cont) next)
1135 (when (eq call (block-last block))
1136 (setf (block-last block) node))
1137 (reoptimize-continuation cont))))
1138 (t
1139 (let ((dummies (loop repeat (length args)
1140 collect (gensym))))
1141 (transform-call
1142 call
1143 `(lambda ,dummies
1144 (declare (ignore ,@dummies))
1145 (values ,@(mapcar #'(lambda (x) `',x) values)))))))))
1146
1147 (undefined-value))
1148
1149
1150 ;;;; Local call optimization:
1151
1152 (declaim (start-block ir1-optimize-set constant-reference-p delete-let
1153 propagate-let-args propagate-local-call-args
1154 propagate-to-refs propagate-from-sets
1155 ir1-optimize-mv-combination))
1156
1157 ;;; Propagate-To-Refs -- Internal
1158 ;;;
1159 ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1160 ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1161 ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1162 ;;;
1163 (defun propagate-to-refs (leaf type)
1164 (declare (type leaf leaf) (type ctype type))
1165 (let ((var-type (leaf-type leaf)))
1166 (unless (function-type-p var-type)
1167 (let ((int (type-intersection var-type type)))
1168 (when (type/= int var-type)
1169 (setf (leaf-type leaf) int)
1170 (dolist (ref (leaf-refs leaf))
1171 (derive-node-type ref int))))
1172 (undefined-value))))
1173
1174
1175 ;;; PROPAGATE-FROM-SETS -- Internal
1176 ;;;
1177 ;;; Figure out the type of a LET variable that has sets. We compute the
1178 ;;; union of the initial value Type and the types of all the set values and to
1179 ;;; a PROPAGATE-TO-REFS with this type.
1180 ;;;
1181 (defun propagate-from-sets (var type)
1182 (collect ((res type type-union))
1183 (dolist (set (basic-var-sets var))
1184 (res (continuation-type (set-value set)))
1185 (setf (node-reoptimize set) nil))
1186 (propagate-to-refs var (res)))
1187 (undefined-value))
1188
1189
1190 ;;; IR1-OPTIMIZE-SET -- Internal
1191 ;;;
1192 ;;; If a let variable, find the initial value's type and do
1193 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1194 ;;;
1195 (defun ir1-optimize-set (node)
1196 (declare (type cset node))
1197 (let ((var (set-var node)))
1198 (when (and (lambda-var-p var) (leaf-refs var))
1199 (let ((home (lambda-var-home var)))
1200 (when (eq (functional-kind home) :let)
1201 (let ((iv (let-var-initial-value var)))
1202 (setf (continuation-reoptimize iv) nil)
1203 (propagate-from-sets var (continuation-type iv)))))))
1204
1205 (derive-node-type node (continuation-type (set-value node)))
1206 (undefined-value))
1207
1208
1209 ;;; CONSTANT-REFERENCE-P -- Interface
1210 ;;;
1211 ;;; Return true if the value of Ref will always be the same (and is thus
1212 ;;; legal to substitute.)
1213 ;;;
1214 (defun constant-reference-p (ref)
1215 (declare (type ref ref))
1216 (let ((leaf (ref-leaf ref)))
1217 (typecase leaf
1218 ((or constant functional) t)
1219 (lambda-var
1220 (null (lambda-var-sets leaf)))
1221 (defined-function
1222 (not (eq (defined-function-inlinep leaf) :notinline)))
1223 (global-var
1224 (case (global-var-kind leaf)
1225 (:global-function t)
1226 (:constant t))))))
1227
1228
1229 ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1230 ;;;
1231 ;;; If we have a non-set let var with a single use, then (if possible)
1232 ;;; replace the variable reference's CONT with the arg continuation. This is
1233 ;;; inhibited when:
1234 ;;; -- CONT has other uses, or
1235 ;;; -- CONT receives multiple values, or
1236 ;;; -- the reference is in a different environment from the variable, or
1237 ;;; -- either continuation has a funky TYPE-CHECK annotation.
1238 ;;; -- the continuations have incompatible assertions, so the new asserted type
1239 ;;; would be NIL.
1240 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1241 ;;;
1242 ;;; We change the Ref to be a reference to NIL with unused value, and let it
1243 ;;; be flushed as dead code. A side-effect of this substitution is to delete
1244 ;;; the variable.
1245 ;;;
1246 (defun substitute-single-use-continuation (arg var)
1247 (declare (type continuation arg) (type lambda-var var))
1248 (let* ((ref (first (leaf-refs var)))
1249 (cont (node-cont ref))
1250 (cont-atype (continuation-asserted-type cont))
1251 (dest (continuation-dest cont)))
1252 (when (and (eq (continuation-use cont) ref)
1253 dest
1254 (not (typep dest '(or creturn exit mv-combination)))
1255 (eq (node-home-lambda ref)
1256 (lambda-home (lambda-var-home var)))
1257 (member (continuation-type-check arg) '(t nil))
1258 (member (continuation-type-check cont) '(t nil))
1259 (not (eq (values-type-intersection
1260 cont-atype
1261 (continuation-asserted-type arg))
1262 *empty-type*))
1263 (eq (lexenv-cookie (node-lexenv dest))
1264 (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1265 (assert (member (continuation-kind arg)
1266 '(:block-start :deleted-block-start :inside-block)))
1267 (assert-continuation-type arg cont-atype)
1268 (setf (node-derived-type ref) *wild-type*)
1269 (change-ref-leaf ref (find-constant nil))
1270 (substitute-continuation arg cont)
1271 (reoptimize-continuation arg)
1272 t)))
1273
1274
1275 ;;; DELETE-LET -- Interface
1276 ;;;
1277 ;;; Delete a Let, removing the call and bind nodes, and warning about any
1278 ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1279 ;;; away and delete the REF and then the lambda, since we flush the FUN
1280 ;;; continuation.
1281 ;;;
1282 (defun delete-let (fun)
1283 (declare (type clambda fun))
1284 (assert (member (functional-kind fun) '(:let :mv-let)))
1285 (note-unreferenced-vars fun)
1286 (let ((call (let-combination fun)))
1287 (flush-dest (basic-combination-fun call))
1288 (unlink-node call)
1289 (unlink-node (lambda-bind fun))
1290 (setf (lambda-bind fun) nil))
1291 (undefined-value))
1292
1293
1294 ;;; Propagate-Let-Args -- Internal
1295 ;;;
1296 ;;; This function is called when one of the arguments to a LET changes. We
1297 ;;; look at each changed argument. If the corresponding variable is set, then
1298 ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1299 ;;; variable, and also propagate derived-type information for the arg to all
1300 ;;; the Var's refs.
1301 ;;;
1302 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1303 ;;; subtype of the argument's asserted type. This prevents type checking from
1304 ;;; being defeated, and also ensures that the best representation for the
1305 ;;; variable can be used.
1306 ;;;
1307 ;;; Substitution of individual references is inhibited if the reference is
1308 ;;; in a different component from the home. This can only happen with closures
1309 ;;; over top-level lambda vars. In such cases, the references may have already
1310 ;;; been compiled, and thus can't be retroactively modified.
1311 ;;;
1312 ;;; If all of the variables are deleted (have no references) when we are
1313 ;;; done, then we delete the let.
1314 ;;;
1315 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1316 ;;; flags.
1317 ;;;
1318 (defun propagate-let-args (call fun)
1319 (declare (type combination call) (type clambda fun))
1320 (loop for arg in (combination-args call)
1321 and var in (lambda-vars fun) do
1322 (when (and arg (continuation-reoptimize arg))
1323 (setf (continuation-reoptimize arg) nil)
1324 (cond
1325 ((lambda-var-sets var)
1326 (propagate-from-sets var (continuation-type arg)))
1327 ((let ((use (continuation-use arg)))
1328 (when (ref-p use)
1329 (let ((leaf (ref-leaf use)))
1330 (when (and (constant-reference-p use)
1331 (values-subtypep (leaf-type leaf)
1332 (continuation-asserted-type arg)))
1333 (propagate-to-refs var (continuation-type arg))
1334 (let ((this-comp (block-component (node-block use))))
1335 (substitute-leaf-if
1336 #'(lambda (ref)
1337 (cond ((eq (block-component (node-block ref))
1338 this-comp)
1339 t)
1340 (t
1341 (assert (eq (functional-kind (lambda-home fun))
1342 :top-level))
1343 nil)))
1344 leaf var))
1345 t)))))
1346 ((and (null (rest (leaf-refs var)))
1347 (not *byte-compiling*)
1348 (substitute-single-use-continuation arg var)))
1349 (t
1350 (propagate-to-refs var (continuation-type arg))))))
1351
1352 (when (every #'null (combination-args call))
1353 (delete-let fun))
1354
1355 (undefined-value))
1356
1357
1358 ;;; Propagate-Local-Call-Args -- Internal
1359 ;;;
1360 ;;; This function is called when one of the args to a non-let local call
1361 ;;; changes. For each changed argument corresponding to an unset variable, we
1362 ;;; compute the union of the types across all calls and propagate this type
1363 ;;; information to the var's refs.
1364 ;;;
1365 ;;; If the function has an XEP, then we don't do anything, since we won't
1366 ;;; discover anything.
1367 ;;;
1368 ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1369 ;;; corresponding to changed arguments in Call, since the only use in IR1
1370 ;;; optimization of the Reoptimize flag for local call args is right here.
1371 ;;;
1372 (defun propagate-local-call-args (call fun)
1373 (declare (type combination call) (type clambda fun))
1374
1375 (unless (or (functional-entry-function fun)
1376 (lambda-optional-dispatch fun))
1377 (let* ((vars (lambda-vars fun))
1378 (union (mapcar #'(lambda (arg var)
1379 (when (and arg
1380 (continuation-reoptimize arg)
1381 (null (basic-var-sets var)))
1382 (continuation-type arg)))
1383 (basic-combination-args call)
1384 vars))
1385 (this-ref (continuation-use (basic-combination-fun call))))
1386
1387 (dolist (arg (basic-combination-args call))
1388 (when arg
1389 (setf (continuation-reoptimize arg) nil)))
1390
1391 (dolist (ref (leaf-refs fun))
1392 (let ((dest (continuation-dest (node-cont ref))))
1393 (unless (or (eq ref this-ref) (not dest))
1394 (setq union
1395 (mapcar #'(lambda (this-arg old)
1396 (when old
1397 (setf (continuation-reoptimize this-arg) nil)
1398 (type-union (continuation-type this-arg) old)))
1399 (basic-combination-args dest)
1400 union)))))
1401
1402 (mapc #'(lambda (var type)
1403 (when type
1404 (propagate-to-refs var type)))
1405 vars union)))
1406
1407 (undefined-value))
1408
1409 (declaim (end-block))
1410
1411
1412 ;;;; Multiple values optimization:
1413
1414 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1415 ;;;
1416 ;;; Do stuff to notice a change to a MV combination node. There are two
1417 ;;; main branches here:
1418 ;;; -- If the call is local, then it is already a MV let, or should become one.
1419 ;;; Note that although all :LOCAL MV calls must eventually be converted to
1420 ;;; :MV-LETs, there can be a window when the call is local, but has not
1421 ;;; been let converted yet. This is because the entry-point lambdas may
1422 ;;; have stray references (in other entry points) that have not been
1423 ;;; deleted yet.
1424 ;;; -- The call is full. This case is somewhat similar to the non-MV
1425 ;;; combination optimization: we propagate return type information and
1426 ;;; notice non-returning calls. We also have an optimization
1427 ;;; which tries to convert MV-CALLs into MV-binds.
1428 ;;;
1429 (defun ir1-optimize-mv-combination (node)
1430 (ecase (basic-combination-kind node)
1431 (:local
1432 (let ((fun-cont (basic-combination-fun node)))
1433 (when (continuation-reoptimize fun-cont)
1434 (setf (continuation-reoptimize fun-cont) nil)
1435 (maybe-let-convert (combination-lambda node))))
1436 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1437 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1438 (unless (convert-mv-bind-to-let node)
1439 (ir1-optimize-mv-bind node))))
1440 (:full
1441 (let* ((fun (basic-combination-fun node))
1442 (fun-changed (continuation-reoptimize fun))
1443 (args (basic-combination-args node)))
1444 (when fun-changed
1445 (setf (continuation-reoptimize fun) nil)
1446 (let ((type (continuation-type fun)))
1447 (when (function-type-p type)
1448 (derive-node-type node (function-type-returns type))))
1449 (maybe-terminate-block node nil)
1450 (let ((use (continuation-use fun)))
1451 (when (and (ref-p use) (functional-p (ref-leaf use)))
1452 (convert-call-if-possible use node)
1453 (when (eq (basic-combination-kind node) :local)
1454 (maybe-let-convert (ref-leaf use))))))
1455 (unless (or (eq (basic-combination-kind node) :local)
1456 (eq (continuation-function-name fun) '%throw))
1457 (ir1-optimize-mv-call node))
1458 (dolist (arg args)
1459 (setf (continuation-reoptimize arg) nil))))
1460 (:error))
1461 (undefined-value))
1462
1463
1464 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1465 ;;;
1466 ;;; Propagate derived type info from the values continuation to the vars.
1467 ;;;
1468 (defun ir1-optimize-mv-bind (node)
1469 (declare (type mv-combination node))
1470 (let ((arg (first (basic-combination-args node)))
1471 (vars (lambda-vars (combination-lambda node))))
1472 (multiple-value-bind (types nvals)
1473 (values-types (continuation-derived-type arg))
1474 (unless (eq nvals :unknown)
1475 (mapc #'(lambda (var type)
1476 (if (basic-var-sets var)
1477 (propagate-from-sets var type)
1478 (propagate-to-refs var type)))
1479 vars
1480 (append types
1481 (make-list (max (- (length vars) nvals) 0)
1482 :initial-element *null-type*)))))
1483
1484 (setf (continuation-reoptimize arg) nil))
1485 (undefined-value))
1486
1487
1488 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1489 ;;;
1490 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1491 ;;; if:
1492 ;;; -- The call has only one argument, and
1493 ;;; -- The function has a known fixed number of arguments, or
1494 ;;; -- The argument yields a known fixed number of values.
1495 ;;;
1496 ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1497 ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1498 ;;; this call can be converted (the next time around.) This new lambda just
1499 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1500 ;;; that this new MV bind is not let-converted immediately, as there are going
1501 ;;; to be stray references from the entry-point functions until they get
1502 ;;; deleted.
1503 ;;;
1504 ;;; In order to avoid loss of argument count checking, we only do the
1505 ;;; transformation according to a known number of expected argument if safety
1506 ;;; is unimportant. We can always convert if we know the number of actual
1507 ;;; values, since the normal call that we build will still do any appropriate
1508 ;;; argument count checking.
1509 ;;;
1510 ;;; We only attempt the transformation if the called function is a constant
1511 ;;; reference. This allows us to just splice the leaf into the new function,
1512 ;;; instead of trying to somehow bind the function expression. The leaf must
1513 ;;; be constant because we are evaluating it again in a different place. This
1514 ;;; also has the effect of squelching multiple warnings when there is an
1515 ;;; argument count error.
1516 ;;;
1517 (defun ir1-optimize-mv-call (node)
1518 (let ((fun (basic-combination-fun node))
1519 (*compiler-error-context* node)
1520 (ref (continuation-use (basic-combination-fun node)))
1521 (args (basic-combination-args node)))
1522
1523 (unless (and (ref-p ref) (constant-reference-p ref)
1524 args (null (rest args)))
1525 (return-from ir1-optimize-mv-call))
1526
1527 (multiple-value-bind (min max)
1528 (function-type-nargs (continuation-type fun))
1529 (let ((total-nvals
1530 (multiple-value-bind
1531 (types nvals)
1532 (values-types (continuation-derived-type (first args)))
1533 (declare (ignore types))
1534 (if (eq nvals :unknown) nil nvals))))
1535
1536 (when total-nvals
1537 (when (and min (< total-nvals min))
1538 (compiler-warning
1539 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1540 at least ~R."
1541 total-nvals min)
1542 (setf (basic-combination-kind node) :error)
1543 (return-from ir1-optimize-mv-call))
1544 (when (and max (> total-nvals max))
1545 (compiler-warning
1546 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1547 at most ~R."
1548 total-nvals max)
1549 (setf (basic-combination-kind node) :error)
1550 (return-from ir1-optimize-mv-call)))
1551
1552 (let ((count (cond (total-nvals)
1553 ((and (policy node (zerop safety)) (eql min max))
1554 min)
1555 (t nil))))
1556 (when count
1557 (with-ir1-environment node
1558 (let* ((dums (loop repeat count collect (gensym)))
1559 (ignore (gensym))
1560 (fun (ir1-convert-lambda
1561 `(lambda (&optional ,@dums &rest ,ignore)
1562 (declare (ignore ,ignore))
1563 (funcall ,(ref-leaf ref) ,@dums)))))
1564 (change-ref-leaf ref fun)
1565 (assert (eq (basic-combination-kind node) :full))
1566 (local-call-analyze *current-component*)
1567 (assert (eq (basic-combination-kind node) :local)))))))))
1568 (undefined-value))
1569
1570
1571 ;;; CONVERT-MV-BIND-TO-LET -- Internal
1572 ;;;
1573 ;;; If we see:
1574 ;;; (multiple-value-bind (x y)
1575 ;;; (values xx yy)
1576 ;;; ...)
1577 ;;; Convert to:
1578 ;;; (let ((x xx)
1579 ;;; (y yy))
1580 ;;; ...)
1581 ;;;
1582 ;;; What we actually do is convert the VALUES combination into a normal let
1583 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1584 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1585 ;;; args, insert references to NIL.
1586 ;;;
1587 (defun convert-mv-bind-to-let (call)
1588 (declare (type mv-combination call))
1589 (let* ((arg (first (basic-combination-args call)))
1590 (use (continuation-use arg)))
1591 (when (and (combination-p use)
1592 (eq (continuation-function-name (combination-fun use))
1593 'values))
1594 (let* ((fun (combination-lambda call))
1595 (vars (lambda-vars fun))
1596 (vals (combination-args use))
1597 (nvars (length vars))
1598 (nvals (length vals)))
1599 (cond ((> nvals nvars)
1600 (mapc #'flush-dest (subseq vals nvars))
1601 (setq vals (subseq vals 0 nvars)))
1602 ((< nvals nvars)
1603 (with-ir1-environment use
1604 (let ((node-prev (node-prev use)))
1605 (setf (node-prev use) nil)
1606 (setf (continuation-next node-prev) nil)
1607 (collect ((res vals))
1608 (loop as cont = (make-continuation use)
1609 and prev = node-prev then cont
1610 repeat (- nvars nvals)
1611 do (reference-constant prev cont nil)
1612 (res cont))
1613 (setq vals (res)))
1614 (prev-link use (car (last vals)))))))
1615 (setf (combination-args use) vals)
1616 (flush-dest (combination-fun use))
1617 (let ((fun-cont (basic-combination-fun call)))
1618 (setf (continuation-dest fun-cont) use)
1619 (setf (combination-fun use) fun-cont))
1620 (setf (combination-kind use) :local)
1621 (setf (functional-kind fun) :let)
1622 (flush-dest (first (basic-combination-args call)))
1623 (unlink-node call)
1624 (when vals
1625 (reoptimize-continuation (first vals)))
1626 (propagate-to-args use fun))
1627 t)))
1628
1629
1630 ;;; VALUES-LIST IR1 optimizer -- Internal
1631 ;;;
1632 ;;; If we see:
1633 ;;; (values-list (list x y z))
1634 ;;;
1635 ;;; Convert to:
1636 ;;; (values x y z)
1637 ;;;
1638 ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1639 ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1640 ;;; the old argument continuation (allowing the LIST to be flushed.)
1641 ;;;
1642 (defoptimizer (values-list optimizer) ((list) node)
1643 (let ((use (continuation-use list)))
1644 (when (and (combination-p use)
1645 (eq (continuation-function-name (combination-fun use))
1646 'list))
1647 (change-ref-leaf (continuation-use (combination-fun node))
1648 (find-free-function 'values "in a strange place"))
1649 (setf (combination-kind node) :full)
1650 (let ((args (combination-args use)))
1651 (dolist (arg args)
1652 (setf (continuation-dest arg) node))
1653 (setf (combination-args use) nil)
1654 (flush-dest list)
1655 (setf (combination-args node) args))
1656 t)))
1657
1658
1659 ;;; VALUES IR1 transform -- Internal
1660 ;;;
1661 ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1662 ;;; PROG1. This allows the computation of the additional values to become dead
1663 ;;; code.
1664 ;;;
1665 (deftransform values ((&rest vals) * * :node node)
1666 (when (typep (continuation-dest (node-cont node))
1667 '(or creturn exit mv-combination))
1668 (give-up))
1669 (setf (node-derived-type node) *wild-type*)
1670 (if vals
1671 (let ((dummies (loop repeat (1- (length vals))
1672 collect (gensym))))
1673 `(lambda (val ,@dummies)
1674 (declare (ignore ,@dummies))
1675 val))
1676 'nil))

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