1 ;;;; This file implements the IR1 optimization phase of the compiler.
2 ;;;; IR1 optimization is a grab-bag of optimizations that don't make
3 ;;;; major changes to the block-level control flow and don't use flow
4 ;;;; analysis. These optimizations can mostly be classified as
5 ;;;; "meta-evaluation", but there is a sizable top-down component as
8 ;;;; This software is part of the SBCL system. See the README file for
11 ;;;; This software is derived from the CMU CL system, which was
12 ;;;; written at Carnegie Mellon University and released into the
13 ;;;; public domain. The software is in the public domain and is
14 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
15 ;;;; files for more information.
19 ;;;; interface for obtaining results of constant folding
21 ;;; Return true for a CONTINUATION whose sole use is a reference to a
23 (defun constant-continuation-p (thing)
24 (and (continuation-p thing)
25 (let ((use (continuation-use thing)))
27 (constant-p (ref-leaf use))))))
29 ;;; Return the constant value for a continuation whose only use is a
31 (declaim (ftype (function (continuation) t) continuation-value))
32 (defun continuation-value (cont)
33 (aver (constant-continuation-p cont))
34 (constant-value (ref-leaf (continuation-use cont))))
36 ;;;; interface for obtaining results of type inference
38 ;;; Return a (possibly values) type that describes what we have proven
39 ;;; about the type of Cont without taking any type assertions into
40 ;;; consideration. This is just the union of the NODE-DERIVED-TYPE of
41 ;;; all the uses. Most often people use CONTINUATION-DERIVED-TYPE or
42 ;;; CONTINUATION-TYPE instead of using this function directly.
43 (defun continuation-proven-type (cont)
44 (declare (type continuation cont))
45 (ecase (continuation-kind cont)
46 ((:block-start :deleted-block-start)
47 (let ((uses (block-start-uses (continuation-block cont))))
49 (do ((res (node-derived-type (first uses))
50 (values-type-union (node-derived-type (first current))
52 (current (rest uses) (rest current)))
56 (node-derived-type (continuation-use cont)))))
58 ;;; Our best guess for the type of this continuation's value. Note
59 ;;; that this may be Values or Function type, which cannot be passed
60 ;;; as an argument to the normal type operations. See
61 ;;; Continuation-Type. This may be called on deleted continuations,
62 ;;; always returning *.
64 ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the
65 ;;; result is a subtype of the assertion. If so, return the proven
66 ;;; type and set TYPE-CHECK to nil. Otherwise, return the intersection
67 ;;; of the asserted and proven types, and set TYPE-CHECK T. If
68 ;;; TYPE-CHECK already has a non-null value, then preserve it. Only in
69 ;;; the somewhat unusual circumstance of a newly discovered assertion
70 ;;; will we change TYPE-CHECK from NIL to T.
72 ;;; The result value is cached in the CONTINUATION-%DERIVED-TYPE slot.
73 ;;; If the slot is true, just return that value, otherwise recompute
74 ;;; and stash the value there.
75 #!-sb-fluid (declaim (inline continuation-derived-type))
76 (defun continuation-derived-type (cont)
77 (declare (type continuation cont))
78 (or (continuation-%derived-type cont)
79 (%continuation-derived-type cont)))
80 (defun %continuation-derived-type (cont)
81 (declare (type continuation cont))
82 (let ((proven (continuation-proven-type cont))
83 (asserted (continuation-asserted-type cont)))
84 (cond ((values-subtypep proven asserted)
85 (setf (continuation-%type-check cont) nil)
86 (setf (continuation-%derived-type cont) proven))
88 (unless (or (continuation-%type-check cont)
89 (not (continuation-dest cont))
90 (eq asserted *universal-type*))
91 (setf (continuation-%type-check cont) t))
93 (setf (continuation-%derived-type cont)
94 (values-type-intersection asserted proven))))))
96 ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to
97 ;;; date, then return it.
98 #!-sb-fluid (declaim (inline continuation-type-check))
99 (defun continuation-type-check (cont)
100 (declare (type continuation cont))
101 (continuation-derived-type cont)
102 (continuation-%type-check cont))
104 ;;; Return the derived type for CONT's first value. This is guaranteed
105 ;;; not to be a VALUES or FUNCTION type.
106 (declaim (ftype (function (continuation) ctype) continuation-type))
107 (defun continuation-type (cont)
108 (single-value-type (continuation-derived-type cont)))
110 ;;;; interface routines used by optimizers
112 ;;; This function is called by optimizers to indicate that something
113 ;;; interesting has happened to the value of Cont. Optimizers must
114 ;;; make sure that they don't call for reoptimization when nothing has
115 ;;; happened, since optimization will fail to terminate.
117 ;;; We clear any cached type for the continuation and set the
118 ;;; reoptimize flags on everything in sight, unless the continuation
119 ;;; is deleted (in which case we do nothing.)
121 ;;; Since this can get called during IR1 conversion, we have to be
122 ;;; careful not to fly into space when the Dest's Prev is missing.
123 (defun reoptimize-continuation (cont)
124 (declare (type continuation cont))
125 (unless (member (continuation-kind cont) '(:deleted :unused))
126 (setf (continuation-%derived-type cont) nil)
127 (let ((dest (continuation-dest cont)))
129 (setf (continuation-reoptimize cont) t)
130 (setf (node-reoptimize dest) t)
131 (let ((prev (node-prev dest)))
133 (let* ((block (continuation-block prev))
134 (component (block-component block)))
135 (when (typep dest 'cif)
136 (setf (block-test-modified block) t))
137 (setf (block-reoptimize block) t)
138 (setf (component-reoptimize component) t))))))
140 (setf (block-type-check (node-block node)) t)))
143 ;;; Annotate Node to indicate that its result has been proven to be
144 ;;; typep to RType. After IR1 conversion has happened, this is the
145 ;;; only correct way to supply information discovered about a node's
146 ;;; type. If you screw with the Node-Derived-Type directly, then
147 ;;; information may be lost and reoptimization may not happen.
149 ;;; What we do is intersect Rtype with Node's Derived-Type. If the
150 ;;; intersection is different from the old type, then we do a
151 ;;; Reoptimize-Continuation on the Node-Cont.
152 (defun derive-node-type (node rtype)
153 (declare (type node node) (type ctype rtype))
154 (let ((node-type (node-derived-type node)))
155 (unless (eq node-type rtype)
156 (let ((int (values-type-intersection node-type rtype)))
157 (when (type/= node-type int)
158 (when (and *check-consistency*
159 (eq int *empty-type*)
160 (not (eq rtype *empty-type*)))
161 (let ((*compiler-error-context* node))
163 "New inferred type ~S conflicts with old type:~
165 (type-specifier rtype) (type-specifier node-type))))
166 (setf (node-derived-type node) int)
167 (reoptimize-continuation (node-cont node))))))
170 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
171 ;;; error for CONT's value not to be TYPEP to TYPE. If we improve the
172 ;;; assertion, we set TYPE-CHECK and TYPE-ASSERTED to guarantee that
173 ;;; the new assertion will be checked.
174 (defun assert-continuation-type (cont type)
175 (declare (type continuation cont) (type ctype type))
176 (let ((cont-type (continuation-asserted-type cont)))
177 (unless (eq cont-type type)
178 (let ((int (values-type-intersection cont-type type)))
179 (when (type/= cont-type int)
180 (setf (continuation-asserted-type cont) int)
182 (setf (block-attributep (block-flags (node-block node))
183 type-check type-asserted)
185 (reoptimize-continuation cont)))))
188 ;;; Assert that CALL is to a function of the specified TYPE. It is
189 ;;; assumed that the call is legal and has only constants in the
190 ;;; keyword positions.
191 (defun assert-call-type (call type)
192 (declare (type combination call) (type fun-type type))
193 (derive-node-type call (fun-type-returns type))
194 (let ((args (combination-args call)))
195 (dolist (req (fun-type-required type))
196 (when (null args) (return-from assert-call-type))
197 (let ((arg (pop args)))
198 (assert-continuation-type arg req)))
199 (dolist (opt (fun-type-optional type))
200 (when (null args) (return-from assert-call-type))
201 (let ((arg (pop args)))
202 (assert-continuation-type arg opt)))
204 (let ((rest (fun-type-rest type)))
207 (assert-continuation-type arg rest))))
209 (dolist (key (fun-type-keywords type))
210 (let ((name (key-info-name key)))
211 (do ((arg args (cddr arg)))
213 (when (eq (continuation-value (first arg)) name)
214 (assert-continuation-type
215 (second arg) (key-info-type key)))))))
220 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
221 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
222 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
223 ;;; we are done, then another iteration would be beneficial.
225 ;;; We delete blocks when there is either no predecessor or the block
226 ;;; is in a lambda that has been deleted. These blocks would
227 ;;; eventually be deleted by DFO recomputation, but doing it here
228 ;;; immediately makes the effect available to IR1 optimization.
229 (defun ir1-optimize (component)
230 (declare (type component component))
231 (setf (component-reoptimize component) nil)
232 (do-blocks (block component)
234 ((or (block-delete-p block)
235 (null (block-pred block))
236 (eq (functional-kind (block-home-lambda block)) :deleted))
237 (delete-block block))
240 (let ((succ (block-succ block)))
241 (unless (and succ (null (rest succ)))
244 (let ((last (block-last block)))
247 (flush-dest (if-test last))
248 (when (unlink-node last)
251 (when (maybe-delete-exit last)
254 (unless (join-successor-if-possible block)
257 (when (and (block-reoptimize block) (block-component block))
258 (aver (not (block-delete-p block)))
259 (ir1-optimize-block block))
261 (when (and (block-flush-p block) (block-component block))
262 (aver (not (block-delete-p block)))
263 (flush-dead-code block)))))
267 ;;; Loop over the nodes in Block, looking for stuff that needs to be
268 ;;; optimized. We dispatch off of the type of each node with its
269 ;;; reoptimize flag set:
271 ;;; -- With a combination, we call Propagate-Function-Change whenever
272 ;;; the function changes, and call IR1-Optimize-Combination if any
273 ;;; argument changes.
274 ;;; -- With an Exit, we derive the node's type from the Value's type.
275 ;;; We don't propagate Cont's assertion to the Value, since if we
276 ;;; did, this would move the checking of Cont's assertion to the
277 ;;; exit. This wouldn't work with Catch and UWP, where the Exit
278 ;;; node is just a placeholder for the actual unknown exit.
280 ;;; Note that we clear the node & block reoptimize flags *before*
281 ;;; doing the optimization. This ensures that the node or block will
282 ;;; be reoptimized if necessary. We leave the NODE-OPTIMIZE flag set
283 ;;; going into IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
284 ;;; clear the flag itself.
285 (defun ir1-optimize-block (block)
286 (declare (type cblock block))
287 (setf (block-reoptimize block) nil)
288 (do-nodes (node cont block :restart-p t)
289 (when (node-reoptimize node)
290 (setf (node-reoptimize node) nil)
294 (ir1-optimize-combination node))
296 (ir1-optimize-if node))
298 (setf (node-reoptimize node) t)
299 (ir1-optimize-return node))
301 (ir1-optimize-mv-combination node))
303 (let ((value (exit-value node)))
305 (derive-node-type node (continuation-derived-type value)))))
307 (ir1-optimize-set node)))))
310 ;;; We cannot combine with a successor block if:
311 ;;; 1. The successor has more than one predecessor.
312 ;;; 2. The last node's CONT is also used somewhere else.
313 ;;; 3. The successor is the current block (infinite loop).
314 ;;; 4. The next block has a different cleanup, and thus we may want
315 ;;; to insert cleanup code between the two blocks at some point.
316 ;;; 5. The next block has a different home lambda, and thus the
317 ;;; control transfer is a non-local exit.
319 ;;; If we succeed, we return true, otherwise false.
321 ;;; Joining is easy when the successor's Start continuation is the
322 ;;; same from our Last's Cont. If they differ, then we can still join
323 ;;; when the last continuation has no next and the next continuation
324 ;;; has no uses. In this case, we replace the next continuation with
325 ;;; the last before joining the blocks.
326 (defun join-successor-if-possible (block)
327 (declare (type cblock block))
328 (let ((next (first (block-succ block))))
329 (when (block-start next)
330 (let* ((last (block-last block))
331 (last-cont (node-cont last))
332 (next-cont (block-start next)))
333 (cond ((or (rest (block-pred next))
334 (not (eq (continuation-use last-cont) last))
336 (not (eq (block-end-cleanup block)
337 (block-start-cleanup next)))
338 (not (eq (block-home-lambda block)
339 (block-home-lambda next))))
341 ((eq last-cont next-cont)
342 (join-blocks block next)
344 ((and (null (block-start-uses next))
345 (eq (continuation-kind last-cont) :inside-block))
346 (let ((next-node (continuation-next next-cont)))
347 ;; If next-cont does have a dest, it must be
348 ;; unreachable, since there are no uses.
349 ;; DELETE-CONTINUATION will mark the dest block as
350 ;; delete-p [and also this block, unless it is no
351 ;; longer backward reachable from the dest block.]
352 (delete-continuation next-cont)
353 (setf (node-prev next-node) last-cont)
354 (setf (continuation-next last-cont) next-node)
355 (setf (block-start next) last-cont)
356 (join-blocks block next))
361 ;;; Join together two blocks which have the same ending/starting
362 ;;; continuation. The code in Block2 is moved into Block1 and Block2
363 ;;; is deleted from the DFO. We combine the optimize flags for the two
364 ;;; blocks so that any indicated optimization gets done.
365 (defun join-blocks (block1 block2)
366 (declare (type cblock block1 block2))
367 (let* ((last (block-last block2))
368 (last-cont (node-cont last))
369 (succ (block-succ block2))
370 (start2 (block-start block2)))
371 (do ((cont start2 (node-cont (continuation-next cont))))
373 (when (eq (continuation-kind last-cont) :inside-block)
374 (setf (continuation-block last-cont) block1)))
375 (setf (continuation-block cont) block1))
377 (unlink-blocks block1 block2)
379 (unlink-blocks block2 block)
380 (link-blocks block1 block))
382 (setf (block-last block1) last)
383 (setf (continuation-kind start2) :inside-block))
385 (setf (block-flags block1)
386 (attributes-union (block-flags block1)
388 (block-attributes type-asserted test-modified)))
390 (let ((next (block-next block2))
391 (prev (block-prev block2)))
392 (setf (block-next prev) next)
393 (setf (block-prev next) prev))
397 ;;; Delete any nodes in BLOCK whose value is unused and have no
398 ;;; side-effects. We can delete sets of lexical variables when the set
399 ;;; variable has no references.
401 ;;; [### For now, don't delete potentially flushable calls when they
402 ;;; have the CALL attribute. Someday we should look at the funcitonal
403 ;;; args to determine if they have any side-effects.]
404 (defun flush-dead-code (block)
405 (declare (type cblock block))
406 (do-nodes-backwards (node cont block)
407 (unless (continuation-dest cont)
413 (let ((info (combination-kind node)))
414 (when (function-info-p info)
415 (let ((attr (function-info-attributes info)))
416 (when (and (ir1-attributep attr flushable)
417 (not (ir1-attributep attr call)))
418 (flush-dest (combination-fun node))
419 (dolist (arg (combination-args node))
421 (unlink-node node))))))
423 (when (eq (basic-combination-kind node) :local)
424 (let ((fun (combination-lambda node)))
425 (when (dolist (var (lambda-vars fun) t)
426 (when (or (leaf-refs var)
427 (lambda-var-sets var))
429 (flush-dest (first (basic-combination-args node)))
432 (let ((value (exit-value node)))
435 (setf (exit-value node) nil))))
437 (let ((var (set-var node)))
438 (when (and (lambda-var-p var)
439 (null (leaf-refs var)))
440 (flush-dest (set-value node))
441 (setf (basic-var-sets var)
442 (delete node (basic-var-sets var)))
443 (unlink-node node)))))))
445 (setf (block-flush-p block) nil)
448 ;;;; local call return type propagation
450 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
451 ;;; flag set. It iterates over the uses of the RESULT, looking for
452 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
453 ;;; call, then we union its type together with the types of other such
454 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
455 ;;; type with the RESULT's asserted type. We can make this
456 ;;; intersection now (potentially before type checking) because this
457 ;;; assertion on the result will eventually be checked (if
460 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
461 ;;; combination, which may change the succesor of the call to be the
462 ;;; called function, and if so, checks if the call can become an
463 ;;; assignment. If we convert to an assignment, we abort, since the
464 ;;; RETURN has been deleted.
465 (defun find-result-type (node)
466 (declare (type creturn node))
467 (let ((result (return-result node)))
468 (collect ((use-union *empty-type* values-type-union))
469 (do-uses (use result)
470 (cond ((and (basic-combination-p use)
471 (eq (basic-combination-kind use) :local))
472 (aver (eq (lambda-tail-set (node-home-lambda use))
473 (lambda-tail-set (combination-lambda use))))
474 (when (combination-p use)
475 (when (nth-value 1 (maybe-convert-tail-local-call use))
476 (return-from find-result-type (values)))))
478 (use-union (node-derived-type use)))))
479 (let ((int (values-type-intersection
480 (continuation-asserted-type result)
482 (setf (return-result-type node) int))))
485 ;;; Do stuff to realize that something has changed about the value
486 ;;; delivered to a return node. Since we consider the return values of
487 ;;; all functions in the tail set to be equivalent, this amounts to
488 ;;; bringing the entire tail set up to date. We iterate over the
489 ;;; returns for all the functions in the tail set, reanalyzing them
490 ;;; all (not treating Node specially.)
492 ;;; When we are done, we check whether the new type is different from
493 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
494 ;;; all the continuations for references to functions in the tail set.
495 ;;; This will cause IR1-OPTIMIZE-COMBINATION to derive the new type as
496 ;;; the results of the calls.
497 (defun ir1-optimize-return (node)
498 (declare (type creturn node))
499 (let* ((tails (lambda-tail-set (return-lambda node)))
500 (funs (tail-set-functions tails)))
501 (collect ((res *empty-type* values-type-union))
503 (let ((return (lambda-return fun)))
505 (when (node-reoptimize return)
506 (setf (node-reoptimize return) nil)
507 (find-result-type return))
508 (res (return-result-type return)))))
510 (when (type/= (res) (tail-set-type tails))
511 (setf (tail-set-type tails) (res))
512 (dolist (fun (tail-set-functions tails))
513 (dolist (ref (leaf-refs fun))
514 (reoptimize-continuation (node-cont ref)))))))
520 ;;; If the test has multiple uses, replicate the node when possible.
521 ;;; Also check whether the predicate is known to be true or false,
522 ;;; deleting the IF node in favor of the appropriate branch when this
524 (defun ir1-optimize-if (node)
525 (declare (type cif node))
526 (let ((test (if-test node))
527 (block (node-block node)))
529 (when (and (eq (block-start block) test)
530 (eq (continuation-next test) node)
531 (rest (block-start-uses block)))
533 (when (immediately-used-p test use)
534 (convert-if-if use node)
535 (when (continuation-use test) (return)))))
537 (let* ((type (continuation-type test))
539 (cond ((constant-continuation-p test)
540 (if (continuation-value test)
541 (if-alternative node)
542 (if-consequent node)))
543 ((not (types-equal-or-intersect type (specifier-type 'null)))
544 (if-alternative node))
545 ((type= type (specifier-type 'null))
546 (if-consequent node)))))
549 (when (rest (block-succ block))
550 (unlink-blocks block victim))
551 (setf (component-reanalyze (block-component (node-block node))) t)
552 (unlink-node node))))
555 ;;; Create a new copy of an IF Node that tests the value of the node
556 ;;; Use. The test must have >1 use, and must be immediately used by
557 ;;; Use. Node must be the only node in its block (implying that
558 ;;; block-start = if-test).
560 ;;; This optimization has an effect semantically similar to the
561 ;;; source-to-source transformation:
562 ;;; (IF (IF A B C) D E) ==>
563 ;;; (IF A (IF B D E) (IF C D E))
565 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
566 ;;; node so that dead code deletion notes will definitely not consider
567 ;;; either node to be part of the original source. One node might
568 ;;; become unreachable, resulting in a spurious note.
569 (defun convert-if-if (use node)
570 (declare (type node use) (type cif node))
571 (with-ir1-environment node
572 (let* ((block (node-block node))
573 (test (if-test node))
574 (cblock (if-consequent node))
575 (ablock (if-alternative node))
576 (use-block (node-block use))
577 (dummy-cont (make-continuation))
578 (new-cont (make-continuation))
579 (new-node (make-if :test new-cont
581 :alternative ablock))
582 (new-block (continuation-starts-block new-cont)))
583 (prev-link new-node new-cont)
584 (setf (continuation-dest new-cont) new-node)
585 (add-continuation-use new-node dummy-cont)
586 (setf (block-last new-block) new-node)
588 (unlink-blocks use-block block)
589 (delete-continuation-use use)
590 (add-continuation-use use new-cont)
591 (link-blocks use-block new-block)
593 (link-blocks new-block cblock)
594 (link-blocks new-block ablock)
596 (push "<IF Duplication>" (node-source-path node))
597 (push "<IF Duplication>" (node-source-path new-node))
599 (reoptimize-continuation test)
600 (reoptimize-continuation new-cont)
601 (setf (component-reanalyze *current-component*) t)))
604 ;;;; exit IR1 optimization
606 ;;; This function attempts to delete an exit node, returning true if
607 ;;; it deletes the block as a consequence:
608 ;;; -- If the exit is degenerate (has no Entry), then we don't do
609 ;;; anything, since there is nothing to be done.
610 ;;; -- If the exit node and its Entry have the same home lambda then
611 ;;; we know the exit is local, and can delete the exit. We change
612 ;;; uses of the Exit-Value to be uses of the original continuation,
613 ;;; then unlink the node. If the exit is to a TR context, then we
614 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
615 ;;; their value to this exit.
616 ;;; -- If there is no value (as in a GO), then we skip the value
619 ;;; This function is also called by environment analysis, since it
620 ;;; wants all exits to be optimized even if normal optimization was
622 (defun maybe-delete-exit (node)
623 (declare (type exit node))
624 (let ((value (exit-value node))
625 (entry (exit-entry node))
626 (cont (node-cont node)))
628 (eq (node-home-lambda node) (node-home-lambda entry)))
629 (setf (entry-exits entry) (delete node (entry-exits entry)))
634 (when (return-p (continuation-dest cont))
636 (when (and (basic-combination-p use)
637 (eq (basic-combination-kind use) :local))
639 (substitute-continuation-uses cont value)
640 (dolist (merge (merges))
641 (merge-tail-sets merge))))))))
643 ;;;; combination IR1 optimization
645 ;;; Report as we try each transform?
647 (defvar *show-transforms-p* nil)
649 ;;; Do IR1 optimizations on a COMBINATION node.
650 (declaim (ftype (function (combination) (values)) ir1-optimize-combination))
651 (defun ir1-optimize-combination (node)
652 (when (continuation-reoptimize (basic-combination-fun node))
653 (propagate-function-change node))
654 (let ((args (basic-combination-args node))
655 (kind (basic-combination-kind node)))
658 (let ((fun (combination-lambda node)))
659 (if (eq (functional-kind fun) :let)
660 (propagate-let-args node fun)
661 (propagate-local-call-args node fun))))
665 (setf (continuation-reoptimize arg) nil))))
669 (setf (continuation-reoptimize arg) nil)))
671 (let ((attr (function-info-attributes kind)))
672 (when (and (ir1-attributep attr foldable)
673 ;; KLUDGE: The next test could be made more sensitive,
674 ;; only suppressing constant-folding of functions with
675 ;; CALL attributes when they're actually passed
676 ;; function arguments. -- WHN 19990918
677 (not (ir1-attributep attr call))
678 (every #'constant-continuation-p args)
679 (continuation-dest (node-cont node))
680 ;; Even if the function is foldable in principle,
681 ;; it might be one of our low-level
682 ;; implementation-specific functions. Such
683 ;; functions don't necessarily exist at runtime on
684 ;; a plain vanilla ANSI Common Lisp
685 ;; cross-compilation host, in which case the
686 ;; cross-compiler can't fold it because the
687 ;; cross-compiler doesn't know how to evaluate it.
689 (let* ((ref (continuation-use (combination-fun node)))
690 (fun (leaf-name (ref-leaf ref))))
692 (constant-fold-call node)
693 (return-from ir1-optimize-combination)))
695 (let ((fun (function-info-derive-type kind)))
697 (let ((res (funcall fun node)))
699 (derive-node-type node res)
700 (maybe-terminate-block node nil)))))
702 (let ((fun (function-info-optimizer kind)))
703 (unless (and fun (funcall fun node))
704 (dolist (x (function-info-transforms kind))
706 (when *show-transforms-p*
707 (let* ((cont (basic-combination-fun node))
708 (fname (continuation-fun-name cont t)))
709 (/show "trying transform" x (transform-function x) "for" fname)))
710 (unless (ir1-transform node x)
712 (when *show-transforms-p*
713 (/show "quitting because IR1-TRANSFORM result was NIL"))
718 ;;; If Call is to a function that doesn't return (i.e. return type is
719 ;;; NIL), then terminate the block there, and link it to the component
720 ;;; tail. We also change the call's CONT to be a dummy continuation to
721 ;;; prevent the use from confusing things.
723 ;;; Except when called during IR1, we delete the continuation if it
724 ;;; has no other uses. (If it does have other uses, we reoptimize.)
726 ;;; Termination on the basis of a continuation type assertion is
728 ;;; -- The continuation is deleted (hence the assertion is spurious), or
729 ;;; -- We are in IR1 conversion (where THE assertions are subject to
731 (defun maybe-terminate-block (call ir1-p)
732 (declare (type basic-combination call))
733 (let* ((block (node-block call))
734 (cont (node-cont call))
735 (tail (component-tail (block-component block)))
736 (succ (first (block-succ block))))
737 (unless (or (and (eq call (block-last block)) (eq succ tail))
738 (block-delete-p block))
739 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
740 (not (or ir1-p (eq (continuation-kind cont) :deleted))))
741 (eq (node-derived-type call) *empty-type*))
743 (delete-continuation-use call)
746 (aver (and (eq (block-last block) call)
747 (eq (continuation-kind cont) :block-start))))
749 (setf (block-last block) call)
750 (link-blocks block (continuation-starts-block cont)))))
752 (node-ends-block call)
753 (delete-continuation-use call)
754 (if (eq (continuation-kind cont) :unused)
755 (delete-continuation cont)
756 (reoptimize-continuation cont))))
758 (unlink-blocks block (first (block-succ block)))
759 (setf (component-reanalyze (block-component block)) t)
760 (aver (not (block-succ block)))
761 (link-blocks block tail)
762 (add-continuation-use call (make-continuation))
765 ;;; This is called both by IR1 conversion and IR1 optimization when
766 ;;; they have verified the type signature for the call, and are
767 ;;; wondering if something should be done to special-case the call. If
768 ;;; CALL is a call to a global function, then see whether it defined
770 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
771 ;;; the expansion and change the call to call it. Expansion is
772 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
773 ;;; true, we never expand, since this function has already been
774 ;;; converted. Local call analysis will duplicate the definition if
775 ;;; necessary. We claim that the parent form is LABELS for context
776 ;;; declarations, since we don't want it to be considered a real
778 ;;; -- In addition to a direct check for the function name in the
779 ;;; table, we also must check for slot accessors. If the function
780 ;;; is a slot accessor, then we set the combination kind to the
781 ;;; function info of %Slot-Setter or %Slot-Accessor, as
783 ;;; -- If it is a known function, mark it as such by setting the KIND.
785 ;;; We return the leaf referenced (NIL if not a leaf) and the
786 ;;; FUNCTION-INFO assigned.
787 (defun recognize-known-call (call ir1-p)
788 (declare (type combination call))
789 (let* ((ref (continuation-use (basic-combination-fun call)))
790 (leaf (when (ref-p ref) (ref-leaf ref)))
791 (inlinep (if (defined-fun-p leaf)
792 (defined-fun-inlinep leaf)
795 ((eq inlinep :notinline) (values nil nil))
796 ((not (and (global-var-p leaf)
797 (eq (global-var-kind leaf) :global-function)))
802 ((nil :maybe-inline) (policy call (zerop space))))
803 (defined-fun-inline-expansion leaf)
804 (let ((fun (defined-fun-functional leaf)))
806 (and (eq inlinep :inline) (functional-kind fun))))
807 (inline-expansion-ok call))
809 (let ((res (ir1-convert-lambda-for-defun
810 (defined-fun-inline-expansion leaf)
812 #'ir1-convert-inline-lambda)))
813 (setf (defined-fun-functional leaf) res)
814 (change-ref-leaf ref res))))
817 (with-ir1-environment call
819 (local-call-analyze *current-component*))))
821 (values (ref-leaf (continuation-use (basic-combination-fun call)))
824 (let* ((name (leaf-name leaf))
825 (info (info :function :info
826 (if (slot-accessor-p leaf)
832 (values leaf (setf (basic-combination-kind call) info))
833 (values leaf nil)))))))
835 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
836 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
837 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
838 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
839 ;;; syntax check, arg/result type processing, but still call
840 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
841 ;;; and that checking is done by local call analysis.
842 (defun validate-call-type (call type ir1-p)
843 (declare (type combination call) (type ctype type))
844 (cond ((not (fun-type-p type))
845 (aver (multiple-value-bind (val win)
846 (csubtypep type (specifier-type 'function))
848 (recognize-known-call call ir1-p))
849 ((valid-function-use call type
850 :argument-test #'always-subtypep
851 :result-test #'always-subtypep
852 ;; KLUDGE: Common Lisp is such a dynamic
853 ;; language that all we can do here in
854 ;; general is issue a STYLE-WARNING. It
855 ;; would be nice to issue a full WARNING
856 ;; in the special case of of type
857 ;; mismatches within a compilation unit
858 ;; (as in section 3.2.2.3 of the spec)
859 ;; but at least as of sbcl-0.6.11, we
860 ;; don't keep track of whether the
861 ;; mismatched data came from the same
862 ;; compilation unit, so we can't do that.
865 ;; FIXME: Actually, I think we could
866 ;; issue a full WARNING if the call
867 ;; violates a DECLAIM FTYPE.
868 :error-function #'compiler-style-warning
869 :warning-function #'compiler-note)
870 (assert-call-type call type)
871 (maybe-terminate-block call ir1-p)
872 (recognize-known-call call ir1-p))
874 (setf (combination-kind call) :error)
877 ;;; This is called by IR1-OPTIMIZE when the function for a call has
878 ;;; changed. If the call is local, we try to let-convert it, and
879 ;;; derive the result type. If it is a :FULL call, we validate it
880 ;;; against the type, which recognizes known calls, does inline
881 ;;; expansion, etc. If a call to a predicate in a non-conditional
882 ;;; position or to a function with a source transform, then we
883 ;;; reconvert the form to give IR1 another chance.
884 (defun propagate-function-change (call)
885 (declare (type combination call))
886 (let ((*compiler-error-context* call)
887 (fun-cont (basic-combination-fun call)))
888 (setf (continuation-reoptimize fun-cont) nil)
889 (case (combination-kind call)
891 (let ((fun (combination-lambda call)))
892 (maybe-let-convert fun)
893 (unless (member (functional-kind fun) '(:let :assignment :deleted))
894 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
896 (multiple-value-bind (leaf info)
897 (validate-call-type call (continuation-type fun-cont) nil)
898 (cond ((functional-p leaf)
899 (convert-call-if-possible
900 (continuation-use (basic-combination-fun call))
903 ((or (info :function :source-transform (leaf-name leaf))
905 (ir1-attributep (function-info-attributes info)
907 (let ((dest (continuation-dest (node-cont call))))
908 (and dest (not (if-p dest))))))
909 (let ((name (leaf-name leaf)))
911 (let ((dums (make-gensym-list (length
912 (combination-args call)))))
915 (,name ,@dums))))))))))))
918 ;;;; known function optimization
920 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
921 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
922 ;;; replace it, otherwise add a new one.
923 (defun record-optimization-failure (node transform args)
924 (declare (type combination node) (type transform transform)
925 (type (or fun-type list) args))
926 (let* ((table (component-failed-optimizations *component-being-compiled*))
927 (found (assoc transform (gethash node table))))
929 (setf (cdr found) args)
930 (push (cons transform args) (gethash node table))))
933 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
934 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
935 ;;; doing the transform for some reason and FLAME is true, then we
936 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
937 ;;; finalize to pick up. We return true if the transform failed, and
938 ;;; thus further transformation should be attempted. We return false
939 ;;; if either the transform succeeded or was aborted.
940 (defun ir1-transform (node transform)
941 (declare (type combination node) (type transform transform))
942 (let* ((type (transform-type transform))
943 (fun (transform-function transform))
944 (constrained (fun-type-p type))
945 (table (component-failed-optimizations *component-being-compiled*))
946 (flame (if (transform-important transform)
947 (policy node (>= speed inhibit-warnings))
948 (policy node (> speed inhibit-warnings))))
949 (*compiler-error-context* node))
950 (cond ((not (member (transform-when transform)
952 ;; FIXME: Make sure that there's a transform for
953 ;; (MEMBER SYMBOL ..) into MEMQ.
954 ;; FIXME: Note that when/if I make SHARE operation to shared
955 ;; constant data between objects in the system, remember that a
956 ;; SHAREd list, or other SHAREd compound object, can be processed
957 ;; recursively, so that e.g. the two lists above can share their
958 ;; '(:BOTH) tail sublists.
959 (let ((when (transform-when transform)))
960 (not (or (eq when :both)
963 ((or (not constrained)
964 (valid-function-use node type :strict-result t))
965 (multiple-value-bind (severity args)
966 (catch 'give-up-ir1-transform
967 (transform-call node (funcall fun node))
974 (setf (combination-kind node) :error)
976 (apply #'compiler-warning args))
982 (record-optimization-failure node transform args))
983 (setf (gethash node table)
984 (remove transform (gethash node table) :key #'car)))
990 (valid-function-use node
992 :argument-test #'types-equal-or-intersect
994 #'values-types-equal-or-intersect))
995 (record-optimization-failure node transform type)
1000 ;;; When we don't like an IR1 transform, we throw the severity/reason
1003 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1004 ;;; aborting this attempt to transform the call, but admitting the
1005 ;;; possibility that this or some other transform will later succeed.
1006 ;;; If arguments are supplied, they are format arguments for an
1007 ;;; efficiency note.
1009 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1010 ;;; force a normal call to the function at run time. No further
1011 ;;; optimizations will be attempted.
1013 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1014 ;;; delay the transform on the node until later. REASONS specifies
1015 ;;; when the transform will be later retried. The :OPTIMIZE reason
1016 ;;; causes the transform to be delayed until after the current IR1
1017 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1018 ;;; be delayed until after constraint propagation.
1020 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1021 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1022 ;;; do CASE operations on the various REASON values, it might be a
1023 ;;; good idea to go OO, representing the reasons by objects, using
1024 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1025 ;;; SIGNAL instead of THROW.
1026 (declaim (ftype (function (&rest t) nil) give-up-ir1-transform))
1027 (defun give-up-ir1-transform (&rest args)
1028 (throw 'give-up-ir1-transform (values :failure args)))
1029 (defun abort-ir1-transform (&rest args)
1030 (throw 'give-up-ir1-transform (values :aborted args)))
1031 (defun delay-ir1-transform (node &rest reasons)
1032 (let ((assoc (assoc node *delayed-ir1-transforms*)))
1034 (setf *delayed-ir1-transforms*
1035 (acons node reasons *delayed-ir1-transforms*))
1036 (throw 'give-up-ir1-transform :delayed))
1038 (dolist (reason reasons)
1039 (pushnew reason (cdr assoc)))
1040 (throw 'give-up-ir1-transform :delayed)))))
1042 ;;; Clear any delayed transform with no reasons - these should have
1043 ;;; been tried in the last pass. Then remove the reason from the
1044 ;;; delayed transform reasons, and if any become empty then set
1045 ;;; reoptimize flags for the node. Return true if any transforms are
1047 (defun retry-delayed-ir1-transforms (reason)
1048 (setf *delayed-ir1-transforms*
1049 (remove-if-not #'cdr *delayed-ir1-transforms*))
1050 (let ((reoptimize nil))
1051 (dolist (assoc *delayed-ir1-transforms*)
1052 (let ((reasons (remove reason (cdr assoc))))
1053 (setf (cdr assoc) reasons)
1055 (let ((node (car assoc)))
1056 (unless (node-deleted node)
1058 (setf (node-reoptimize node) t)
1059 (let ((block (node-block node)))
1060 (setf (block-reoptimize block) t)
1061 (setf (component-reoptimize (block-component block)) t)))))))
1065 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1066 ;;; environment, and then install it as the function for the call
1067 ;;; NODE. We do local call analysis so that the new function is
1068 ;;; integrated into the control flow.
1069 (defun transform-call (node res)
1070 (declare (type combination node) (list res))
1071 (with-ir1-environment node
1072 (let ((new-fun (ir1-convert-inline-lambda res))
1073 (ref (continuation-use (combination-fun node))))
1074 (change-ref-leaf ref new-fun)
1075 (setf (combination-kind node) :full)
1076 (local-call-analyze *current-component*)))
1079 ;;; Replace a call to a foldable function of constant arguments with
1080 ;;; the result of evaluating the form. We insert the resulting
1081 ;;; constant node after the call, stealing the call's continuation. We
1082 ;;; give the call a continuation with no Dest, which should cause it
1083 ;;; and its arguments to go away. If there is an error during the
1084 ;;; evaluation, we give a warning and leave the call alone, making the
1085 ;;; call a :ERROR call.
1087 ;;; If there is more than one value, then we transform the call into a
1089 (defun constant-fold-call (call)
1090 (declare (type combination call))
1091 (let* ((args (mapcar #'continuation-value (combination-args call)))
1092 (ref (continuation-use (combination-fun call)))
1093 (fun (leaf-name (ref-leaf ref))))
1095 (multiple-value-bind (values win)
1096 (careful-call fun args call "constant folding")
1098 (setf (combination-kind call) :error)
1099 (let ((dummies (make-gensym-list (length args))))
1103 (declare (ignore ,@dummies))
1104 (values ,@(mapcar #'(lambda (x) `',x) values))))))))
1108 ;;;; local call optimization
1110 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1111 ;;; the leaf type is a function type, then just leave it alone, since
1112 ;;; TYPE is never going to be more specific than that (and
1113 ;;; TYPE-INTERSECTION would choke.)
1114 (defun propagate-to-refs (leaf type)
1115 (declare (type leaf leaf) (type ctype type))
1116 (let ((var-type (leaf-type leaf)))
1117 (unless (fun-type-p var-type)
1118 (let ((int (type-approx-intersection2 var-type type)))
1119 (when (type/= int var-type)
1120 (setf (leaf-type leaf) int)
1121 (dolist (ref (leaf-refs leaf))
1122 (derive-node-type ref int))))
1125 ;;; Figure out the type of a LET variable that has sets. We compute
1126 ;;; the union of the initial value Type and the types of all the set
1127 ;;; values and to a PROPAGATE-TO-REFS with this type.
1128 (defun propagate-from-sets (var type)
1129 (collect ((res type type-union))
1130 (dolist (set (basic-var-sets var))
1131 (res (continuation-type (set-value set)))
1132 (setf (node-reoptimize set) nil))
1133 (propagate-to-refs var (res)))
1136 ;;; If a LET variable, find the initial value's type and do
1137 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1139 (defun ir1-optimize-set (node)
1140 (declare (type cset node))
1141 (let ((var (set-var node)))
1142 (when (and (lambda-var-p var) (leaf-refs var))
1143 (let ((home (lambda-var-home var)))
1144 (when (eq (functional-kind home) :let)
1145 (let ((iv (let-var-initial-value var)))
1146 (setf (continuation-reoptimize iv) nil)
1147 (propagate-from-sets var (continuation-type iv)))))))
1149 (derive-node-type node (continuation-type (set-value node)))
1152 ;;; Return true if the value of Ref will always be the same (and is
1153 ;;; thus legal to substitute.)
1154 (defun constant-reference-p (ref)
1155 (declare (type ref ref))
1156 (let ((leaf (ref-leaf ref)))
1158 ((or constant functional) t)
1160 (null (lambda-var-sets leaf)))
1162 (not (eq (defined-fun-inlinep leaf) :notinline)))
1164 (case (global-var-kind leaf)
1165 (:global-function t)
1168 ;;; If we have a non-set LET var with a single use, then (if possible)
1169 ;;; replace the variable reference's CONT with the arg continuation.
1170 ;;; This is inhibited when:
1171 ;;; -- CONT has other uses, or
1172 ;;; -- CONT receives multiple values, or
1173 ;;; -- the reference is in a different environment from the variable, or
1174 ;;; -- either continuation has a funky TYPE-CHECK annotation.
1175 ;;; -- the continuations have incompatible assertions, so the new asserted type
1177 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1179 ;;; We change the REF to be a reference to NIL with unused value, and
1180 ;;; let it be flushed as dead code. A side-effect of this substitution
1181 ;;; is to delete the variable.
1182 (defun substitute-single-use-continuation (arg var)
1183 (declare (type continuation arg) (type lambda-var var))
1184 (let* ((ref (first (leaf-refs var)))
1185 (cont (node-cont ref))
1186 (cont-atype (continuation-asserted-type cont))
1187 (dest (continuation-dest cont)))
1188 (when (and (eq (continuation-use cont) ref)
1190 (not (typep dest '(or creturn exit mv-combination)))
1191 (eq (node-home-lambda ref)
1192 (lambda-home (lambda-var-home var)))
1193 (member (continuation-type-check arg) '(t nil))
1194 (member (continuation-type-check cont) '(t nil))
1195 (not (eq (values-type-intersection
1197 (continuation-asserted-type arg))
1199 (eq (lexenv-policy (node-lexenv dest))
1200 (lexenv-policy (node-lexenv (continuation-dest arg)))))
1201 (aver (member (continuation-kind arg)
1202 '(:block-start :deleted-block-start :inside-block)))
1203 (assert-continuation-type arg cont-atype)
1204 (setf (node-derived-type ref) *wild-type*)
1205 (change-ref-leaf ref (find-constant nil))
1206 (substitute-continuation arg cont)
1207 (reoptimize-continuation arg)
1210 ;;; Delete a LET, removing the call and bind nodes, and warning about
1211 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1212 ;;; along right away and delete the REF and then the lambda, since we
1213 ;;; flush the FUN continuation.
1214 (defun delete-let (fun)
1215 (declare (type clambda fun))
1216 (aver (member (functional-kind fun) '(:let :mv-let)))
1217 (note-unreferenced-vars fun)
1218 (let ((call (let-combination fun)))
1219 (flush-dest (basic-combination-fun call))
1221 (unlink-node (lambda-bind fun))
1222 (setf (lambda-bind fun) nil))
1225 ;;; This function is called when one of the arguments to a LET
1226 ;;; changes. We look at each changed argument. If the corresponding
1227 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1228 ;;; consider substituting for the variable, and also propagate
1229 ;;; derived-type information for the arg to all the Var's refs.
1231 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1232 ;;; subtype of the argument's asserted type. This prevents type
1233 ;;; checking from being defeated, and also ensures that the best
1234 ;;; representation for the variable can be used.
1236 ;;; Substitution of individual references is inhibited if the
1237 ;;; reference is in a different component from the home. This can only
1238 ;;; happen with closures over top-level lambda vars. In such cases,
1239 ;;; the references may have already been compiled, and thus can't be
1240 ;;; retroactively modified.
1242 ;;; If all of the variables are deleted (have no references) when we
1243 ;;; are done, then we delete the LET.
1245 ;;; Note that we are responsible for clearing the
1246 ;;; Continuation-Reoptimize flags.
1247 (defun propagate-let-args (call fun)
1248 (declare (type combination call) (type clambda fun))
1249 (loop for arg in (combination-args call)
1250 and var in (lambda-vars fun) do
1251 (when (and arg (continuation-reoptimize arg))
1252 (setf (continuation-reoptimize arg) nil)
1254 ((lambda-var-sets var)
1255 (propagate-from-sets var (continuation-type arg)))
1256 ((let ((use (continuation-use arg)))
1258 (let ((leaf (ref-leaf use)))
1259 (when (and (constant-reference-p use)
1260 (values-subtypep (leaf-type leaf)
1261 (continuation-asserted-type arg)))
1262 (propagate-to-refs var (continuation-type arg))
1263 (let ((this-comp (block-component (node-block use))))
1266 (cond ((eq (block-component (node-block ref))
1270 (aver (eq (functional-kind (lambda-home fun))
1275 ((and (null (rest (leaf-refs var)))
1276 (substitute-single-use-continuation arg var)))
1278 (propagate-to-refs var (continuation-type arg))))))
1280 (when (every #'null (combination-args call))
1285 ;;; This function is called when one of the args to a non-LET local
1286 ;;; call changes. For each changed argument corresponding to an unset
1287 ;;; variable, we compute the union of the types across all calls and
1288 ;;; propagate this type information to the var's refs.
1290 ;;; If the function has an XEP, then we don't do anything, since we
1291 ;;; won't discover anything.
1293 ;;; We can clear the Continuation-Reoptimize flags for arguments in
1294 ;;; all calls corresponding to changed arguments in Call, since the
1295 ;;; only use in IR1 optimization of the Reoptimize flag for local call
1296 ;;; args is right here.
1297 (defun propagate-local-call-args (call fun)
1298 (declare (type combination call) (type clambda fun))
1300 (unless (or (functional-entry-function fun)
1301 (lambda-optional-dispatch fun))
1302 (let* ((vars (lambda-vars fun))
1303 (union (mapcar #'(lambda (arg var)
1305 (continuation-reoptimize arg)
1306 (null (basic-var-sets var)))
1307 (continuation-type arg)))
1308 (basic-combination-args call)
1310 (this-ref (continuation-use (basic-combination-fun call))))
1312 (dolist (arg (basic-combination-args call))
1314 (setf (continuation-reoptimize arg) nil)))
1316 (dolist (ref (leaf-refs fun))
1317 (let ((dest (continuation-dest (node-cont ref))))
1318 (unless (or (eq ref this-ref) (not dest))
1320 (mapcar #'(lambda (this-arg old)
1322 (setf (continuation-reoptimize this-arg) nil)
1323 (type-union (continuation-type this-arg) old)))
1324 (basic-combination-args dest)
1327 (mapc #'(lambda (var type)
1329 (propagate-to-refs var type)))
1334 ;;;; multiple values optimization
1336 ;;; Do stuff to notice a change to a MV combination node. There are
1337 ;;; two main branches here:
1338 ;;; -- If the call is local, then it is already a MV let, or should
1339 ;;; become one. Note that although all :LOCAL MV calls must eventually
1340 ;;; be converted to :MV-LETs, there can be a window when the call
1341 ;;; is local, but has not been LET converted yet. This is because
1342 ;;; the entry-point lambdas may have stray references (in other
1343 ;;; entry points) that have not been deleted yet.
1344 ;;; -- The call is full. This case is somewhat similar to the non-MV
1345 ;;; combination optimization: we propagate return type information and
1346 ;;; notice non-returning calls. We also have an optimization
1347 ;;; which tries to convert MV-CALLs into MV-binds.
1348 (defun ir1-optimize-mv-combination (node)
1349 (ecase (basic-combination-kind node)
1351 (let ((fun-cont (basic-combination-fun node)))
1352 (when (continuation-reoptimize fun-cont)
1353 (setf (continuation-reoptimize fun-cont) nil)
1354 (maybe-let-convert (combination-lambda node))))
1355 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1356 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1357 (unless (convert-mv-bind-to-let node)
1358 (ir1-optimize-mv-bind node))))
1360 (let* ((fun (basic-combination-fun node))
1361 (fun-changed (continuation-reoptimize fun))
1362 (args (basic-combination-args node)))
1364 (setf (continuation-reoptimize fun) nil)
1365 (let ((type (continuation-type fun)))
1366 (when (fun-type-p type)
1367 (derive-node-type node (fun-type-returns type))))
1368 (maybe-terminate-block node nil)
1369 (let ((use (continuation-use fun)))
1370 (when (and (ref-p use) (functional-p (ref-leaf use)))
1371 (convert-call-if-possible use node)
1372 (when (eq (basic-combination-kind node) :local)
1373 (maybe-let-convert (ref-leaf use))))))
1374 (unless (or (eq (basic-combination-kind node) :local)
1375 (eq (continuation-fun-name fun) '%throw))
1376 (ir1-optimize-mv-call node))
1378 (setf (continuation-reoptimize arg) nil))))
1382 ;;; Propagate derived type info from the values continuation to the
1384 (defun ir1-optimize-mv-bind (node)
1385 (declare (type mv-combination node))
1386 (let ((arg (first (basic-combination-args node)))
1387 (vars (lambda-vars (combination-lambda node))))
1388 (multiple-value-bind (types nvals)
1389 (values-types (continuation-derived-type arg))
1390 (unless (eq nvals :unknown)
1391 (mapc #'(lambda (var type)
1392 (if (basic-var-sets var)
1393 (propagate-from-sets var type)
1394 (propagate-to-refs var type)))
1397 (make-list (max (- (length vars) nvals) 0)
1398 :initial-element (specifier-type 'null))))))
1399 (setf (continuation-reoptimize arg) nil))
1402 ;;; If possible, convert a general MV call to an MV-BIND. We can do
1404 ;;; -- The call has only one argument, and
1405 ;;; -- The function has a known fixed number of arguments, or
1406 ;;; -- The argument yields a known fixed number of values.
1408 ;;; What we do is change the function in the MV-CALL to be a lambda
1409 ;;; that "looks like an MV bind", which allows
1410 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1411 ;;; converted (the next time around.) This new lambda just calls the
1412 ;;; actual function with the MV-BIND variables as arguments. Note that
1413 ;;; this new MV bind is not let-converted immediately, as there are
1414 ;;; going to be stray references from the entry-point functions until
1415 ;;; they get deleted.
1417 ;;; In order to avoid loss of argument count checking, we only do the
1418 ;;; transformation according to a known number of expected argument if
1419 ;;; safety is unimportant. We can always convert if we know the number
1420 ;;; of actual values, since the normal call that we build will still
1421 ;;; do any appropriate argument count checking.
1423 ;;; We only attempt the transformation if the called function is a
1424 ;;; constant reference. This allows us to just splice the leaf into
1425 ;;; the new function, instead of trying to somehow bind the function
1426 ;;; expression. The leaf must be constant because we are evaluating it
1427 ;;; again in a different place. This also has the effect of squelching
1428 ;;; multiple warnings when there is an argument count error.
1429 (defun ir1-optimize-mv-call (node)
1430 (let ((fun (basic-combination-fun node))
1431 (*compiler-error-context* node)
1432 (ref (continuation-use (basic-combination-fun node)))
1433 (args (basic-combination-args node)))
1435 (unless (and (ref-p ref) (constant-reference-p ref)
1436 args (null (rest args)))
1437 (return-from ir1-optimize-mv-call))
1439 (multiple-value-bind (min max)
1440 (fun-type-nargs (continuation-type fun))
1442 (multiple-value-bind (types nvals)
1443 (values-types (continuation-derived-type (first args)))
1444 (declare (ignore types))
1445 (if (eq nvals :unknown) nil nvals))))
1448 (when (and min (< total-nvals min))
1450 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1453 (setf (basic-combination-kind node) :error)
1454 (return-from ir1-optimize-mv-call))
1455 (when (and max (> total-nvals max))
1457 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1460 (setf (basic-combination-kind node) :error)
1461 (return-from ir1-optimize-mv-call)))
1463 (let ((count (cond (total-nvals)
1464 ((and (policy node (zerop safety))
1469 (with-ir1-environment node
1470 (let* ((dums (make-gensym-list count))
1472 (fun (ir1-convert-lambda
1473 `(lambda (&optional ,@dums &rest ,ignore)
1474 (declare (ignore ,ignore))
1475 (funcall ,(ref-leaf ref) ,@dums)))))
1476 (change-ref-leaf ref fun)
1477 (aver (eq (basic-combination-kind node) :full))
1478 (local-call-analyze *current-component*)
1479 (aver (eq (basic-combination-kind node) :local)))))))))
1483 ;;; (multiple-value-bind
1492 ;;; What we actually do is convert the VALUES combination into a
1493 ;;; normal LET combination calling the original :MV-LET lambda. If
1494 ;;; there are extra args to VALUES, discard the corresponding
1495 ;;; continuations. If there are insufficient args, insert references
1497 (defun convert-mv-bind-to-let (call)
1498 (declare (type mv-combination call))
1499 (let* ((arg (first (basic-combination-args call)))
1500 (use (continuation-use arg)))
1501 (when (and (combination-p use)
1502 (eq (continuation-fun-name (combination-fun use))
1504 (let* ((fun (combination-lambda call))
1505 (vars (lambda-vars fun))
1506 (vals (combination-args use))
1507 (nvars (length vars))
1508 (nvals (length vals)))
1509 (cond ((> nvals nvars)
1510 (mapc #'flush-dest (subseq vals nvars))
1511 (setq vals (subseq vals 0 nvars)))
1513 (with-ir1-environment use
1514 (let ((node-prev (node-prev use)))
1515 (setf (node-prev use) nil)
1516 (setf (continuation-next node-prev) nil)
1517 (collect ((res vals))
1518 (loop as cont = (make-continuation use)
1519 and prev = node-prev then cont
1520 repeat (- nvars nvals)
1521 do (reference-constant prev cont nil)
1524 (prev-link use (car (last vals)))))))
1525 (setf (combination-args use) vals)
1526 (flush-dest (combination-fun use))
1527 (let ((fun-cont (basic-combination-fun call)))
1528 (setf (continuation-dest fun-cont) use)
1529 (setf (combination-fun use) fun-cont))
1530 (setf (combination-kind use) :local)
1531 (setf (functional-kind fun) :let)
1532 (flush-dest (first (basic-combination-args call)))
1535 (reoptimize-continuation (first vals)))
1536 (propagate-to-args use fun))
1540 ;;; (values-list (list x y z))
1545 ;;; In implementation, this is somewhat similar to
1546 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1547 ;;; args of the VALUES-LIST call, flushing the old argument
1548 ;;; continuation (allowing the LIST to be flushed.)
1549 (defoptimizer (values-list optimizer) ((list) node)
1550 (let ((use (continuation-use list)))
1551 (when (and (combination-p use)
1552 (eq (continuation-fun-name (combination-fun use))
1554 (change-ref-leaf (continuation-use (combination-fun node))
1555 (find-free-function 'values "in a strange place"))
1556 (setf (combination-kind node) :full)
1557 (let ((args (combination-args use)))
1559 (setf (continuation-dest arg) node))
1560 (setf (combination-args use) nil)
1562 (setf (combination-args node) args))
1565 ;;; If VALUES appears in a non-MV context, then effectively convert it
1566 ;;; to a PROG1. This allows the computation of the additional values
1567 ;;; to become dead code.
1568 (deftransform values ((&rest vals) * * :node node)
1569 (when (typep (continuation-dest (node-cont node))
1570 '(or creturn exit mv-combination))
1571 (give-up-ir1-transform))
1572 (setf (node-derived-type node) *wild-type*)
1574 (let ((dummies (make-gensym-list (length (cdr vals)))))
1575 `(lambda (val ,@dummies)
1576 (declare (ignore ,@dummies))