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))
87 ((and (values-subtypep proven (specifier-type 'function))
88 (values-subtypep asserted (specifier-type 'function)))
89 ;; It's physically impossible for a runtime type check to
90 ;; distinguish between the various subtypes of FUNCTION, so
91 ;; it'd be pointless to do more type checks here.
92 (setf (continuation-%type-check cont) nil)
93 (setf (continuation-%derived-type cont)
94 ;; FIXME: This should depend on optimization
95 ;; policy. This is for SPEED > SAFETY:
96 #+nil (values-type-intersection asserted proven)
97 ;; and this is for SAFETY >= SPEED:
100 (unless (or (continuation-%type-check cont)
101 (not (continuation-dest cont))
102 (eq asserted *universal-type*))
103 (setf (continuation-%type-check cont) t))
105 (setf (continuation-%derived-type cont)
106 (values-type-intersection asserted proven))))))
108 ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to
109 ;;; date, then return it.
110 #!-sb-fluid (declaim (inline continuation-type-check))
111 (defun continuation-type-check (cont)
112 (declare (type continuation cont))
113 (continuation-derived-type cont)
114 (continuation-%type-check cont))
116 ;;; Return the derived type for CONT's first value. This is guaranteed
117 ;;; not to be a VALUES or FUNCTION type.
118 (declaim (ftype (function (continuation) ctype) continuation-type))
119 (defun continuation-type (cont)
120 (single-value-type (continuation-derived-type cont)))
122 ;;;; interface routines used by optimizers
124 ;;; This function is called by optimizers to indicate that something
125 ;;; interesting has happened to the value of Cont. Optimizers must
126 ;;; make sure that they don't call for reoptimization when nothing has
127 ;;; happened, since optimization will fail to terminate.
129 ;;; We clear any cached type for the continuation and set the
130 ;;; reoptimize flags on everything in sight, unless the continuation
131 ;;; is deleted (in which case we do nothing.)
133 ;;; Since this can get called during IR1 conversion, we have to be
134 ;;; careful not to fly into space when the Dest's Prev is missing.
135 (defun reoptimize-continuation (cont)
136 (declare (type continuation cont))
137 (unless (member (continuation-kind cont) '(:deleted :unused))
138 (setf (continuation-%derived-type cont) nil)
139 (let ((dest (continuation-dest cont)))
141 (setf (continuation-reoptimize cont) t)
142 (setf (node-reoptimize dest) t)
143 (let ((prev (node-prev dest)))
145 (let* ((block (continuation-block prev))
146 (component (block-component block)))
147 (when (typep dest 'cif)
148 (setf (block-test-modified block) t))
149 (setf (block-reoptimize block) t)
150 (setf (component-reoptimize component) t))))))
152 (setf (block-type-check (node-block node)) t)))
155 ;;; Annotate Node to indicate that its result has been proven to be
156 ;;; typep to RType. After IR1 conversion has happened, this is the
157 ;;; only correct way to supply information discovered about a node's
158 ;;; type. If you screw with the Node-Derived-Type directly, then
159 ;;; information may be lost and reoptimization may not happen.
161 ;;; What we do is intersect Rtype with Node's Derived-Type. If the
162 ;;; intersection is different from the old type, then we do a
163 ;;; Reoptimize-Continuation on the Node-Cont.
164 (defun derive-node-type (node rtype)
165 (declare (type node node) (type ctype rtype))
166 (let ((node-type (node-derived-type node)))
167 (unless (eq node-type rtype)
168 (let ((int (values-type-intersection node-type rtype)))
169 (when (type/= node-type int)
170 (when (and *check-consistency*
171 (eq int *empty-type*)
172 (not (eq rtype *empty-type*)))
173 (let ((*compiler-error-context* node))
175 "New inferred type ~S conflicts with old type:~
176 ~% ~S~%*** possible internal error? Please report this."
177 (type-specifier rtype) (type-specifier node-type))))
178 (setf (node-derived-type node) int)
179 (reoptimize-continuation (node-cont node))))))
182 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
183 ;;; error for CONT's value not to be TYPEP to TYPE. If we improve the
184 ;;; assertion, we set TYPE-CHECK and TYPE-ASSERTED to guarantee that
185 ;;; the new assertion will be checked.
186 (defun assert-continuation-type (cont type)
187 (declare (type continuation cont) (type ctype type))
188 (let ((cont-type (continuation-asserted-type cont)))
189 (unless (eq cont-type type)
190 (let ((int (values-type-intersection cont-type type)))
191 (when (type/= cont-type int)
192 (setf (continuation-asserted-type cont) int)
194 (setf (block-attributep (block-flags (node-block node))
195 type-check type-asserted)
197 (reoptimize-continuation cont)))))
200 ;;; Assert that CALL is to a function of the specified TYPE. It is
201 ;;; assumed that the call is legal and has only constants in the
202 ;;; keyword positions.
203 (defun assert-call-type (call type)
204 (declare (type combination call) (type fun-type type))
205 (derive-node-type call (fun-type-returns type))
206 (let ((args (combination-args call)))
207 (dolist (req (fun-type-required type))
208 (when (null args) (return-from assert-call-type))
209 (let ((arg (pop args)))
210 (assert-continuation-type arg req)))
211 (dolist (opt (fun-type-optional type))
212 (when (null args) (return-from assert-call-type))
213 (let ((arg (pop args)))
214 (assert-continuation-type arg opt)))
216 (let ((rest (fun-type-rest type)))
219 (assert-continuation-type arg rest))))
221 (dolist (key (fun-type-keywords type))
222 (let ((name (key-info-name key)))
223 (do ((arg args (cddr arg)))
225 (when (eq (continuation-value (first arg)) name)
226 (assert-continuation-type
227 (second arg) (key-info-type key)))))))
232 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
233 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
234 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
235 ;;; we are done, then another iteration would be beneficial.
236 (defun ir1-optimize (component)
237 (declare (type component component))
238 (setf (component-reoptimize component) nil)
239 (do-blocks (block component)
241 ((or (block-delete-p block)
242 (null (block-pred block)))
243 (delete-block block))
244 ((eq (functional-kind (block-home-lambda block)) :deleted)
245 ;; Preserve the BLOCK-SUCC invariant that almost every block has
246 ;; one successor (and a block with DELETE-P set is an acceptable
248 (labels ((mark-blocks (block)
249 (dolist (pred (block-pred block))
250 (when (and (not (block-delete-p pred))
251 (eq (functional-kind (block-home-lambda pred))
253 (setf (block-delete-p pred) t)
254 (mark-blocks pred)))))
256 (delete-block block)))
259 (let ((succ (block-succ block)))
260 (unless (and succ (null (rest succ)))
263 (let ((last (block-last block)))
266 (flush-dest (if-test last))
267 (when (unlink-node last)
270 (when (maybe-delete-exit last)
273 (unless (join-successor-if-possible block)
276 (when (and (block-reoptimize block) (block-component block))
277 (aver (not (block-delete-p block)))
278 (ir1-optimize-block block))
280 ;; We delete blocks when there is either no predecessor or the
281 ;; block is in a lambda that has been deleted. These blocks
282 ;; would eventually be deleted by DFO recomputation, but doing
283 ;; it here immediately makes the effect available to IR1
285 (when (and (block-flush-p block) (block-component block))
286 (aver (not (block-delete-p block)))
287 (flush-dead-code block)))))
291 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
294 ;;; Note that although they are cleared here, REOPTIMIZE flags might
295 ;;; still be set upon return from this function, meaning that further
296 ;;; optimization is wanted (as a consequence of optimizations we did).
297 (defun ir1-optimize-block (block)
298 (declare (type cblock block))
299 ;; We clear the node and block REOPTIMIZE flags before doing the
300 ;; optimization, not after. This ensures that the node or block will
301 ;; be reoptimized if necessary.
302 (setf (block-reoptimize block) nil)
303 (do-nodes (node cont block :restart-p t)
304 (when (node-reoptimize node)
305 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
306 (setf (node-reoptimize node) nil)
310 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
311 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
312 ;; any argument changes.
313 (ir1-optimize-combination node))
315 (ir1-optimize-if node))
317 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
318 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
319 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
321 (setf (node-reoptimize node) t)
322 (ir1-optimize-return node))
324 (ir1-optimize-mv-combination node))
326 ;; With an EXIT, we derive the node's type from the VALUE's
327 ;; type. We don't propagate CONT's assertion to the VALUE,
328 ;; since if we did, this would move the checking of CONT's
329 ;; assertion to the exit. This wouldn't work with CATCH and
330 ;; UWP, where the EXIT node is just a placeholder for the
331 ;; actual unknown exit.
332 (let ((value (exit-value node)))
334 (derive-node-type node (continuation-derived-type value)))))
336 (ir1-optimize-set node)))))
339 ;;; Try to join with a successor block. If we succeed, we return true,
341 (defun join-successor-if-possible (block)
342 (declare (type cblock block))
343 (let ((next (first (block-succ block))))
344 (when (block-start next)
345 (let* ((last (block-last block))
346 (last-cont (node-cont last))
347 (next-cont (block-start next)))
348 (cond (;; We cannot combine with a successor block if:
350 ;; The successor has more than one predecessor.
351 (rest (block-pred next))
352 ;; The last node's CONT is also used somewhere else.
353 (not (eq (continuation-use last-cont) last))
354 ;; The successor is the current block (infinite loop).
356 ;; The next block has a different cleanup, and thus
357 ;; we may want to insert cleanup code between the
358 ;; two blocks at some point.
359 (not (eq (block-end-cleanup block)
360 (block-start-cleanup next)))
361 ;; The next block has a different home lambda, and
362 ;; thus the control transfer is a non-local exit.
363 (not (eq (block-home-lambda block)
364 (block-home-lambda next))))
366 ;; Joining is easy when the successor's START
367 ;; continuation is the same from our LAST's CONT.
368 ((eq last-cont next-cont)
369 (join-blocks block next)
371 ;; If they differ, then we can still join when the last
372 ;; continuation has no next and the next continuation
374 ((and (null (block-start-uses next))
375 (eq (continuation-kind last-cont) :inside-block))
376 ;; In this case, we replace the next
377 ;; continuation with the last before joining the blocks.
378 (let ((next-node (continuation-next next-cont)))
379 ;; If NEXT-CONT does have a dest, it must be
380 ;; unreachable, since there are no USES.
381 ;; DELETE-CONTINUATION will mark the dest block as
382 ;; DELETE-P [and also this block, unless it is no
383 ;; longer backward reachable from the dest block.]
384 (delete-continuation next-cont)
385 (setf (node-prev next-node) last-cont)
386 (setf (continuation-next last-cont) next-node)
387 (setf (block-start next) last-cont)
388 (join-blocks block next))
393 ;;; Join together two blocks which have the same ending/starting
394 ;;; continuation. The code in BLOCK2 is moved into BLOCK1 and BLOCK2
395 ;;; is deleted from the DFO. We combine the optimize flags for the two
396 ;;; blocks so that any indicated optimization gets done.
397 (defun join-blocks (block1 block2)
398 (declare (type cblock block1 block2))
399 (let* ((last (block-last block2))
400 (last-cont (node-cont last))
401 (succ (block-succ block2))
402 (start2 (block-start block2)))
403 (do ((cont start2 (node-cont (continuation-next cont))))
405 (when (eq (continuation-kind last-cont) :inside-block)
406 (setf (continuation-block last-cont) block1)))
407 (setf (continuation-block cont) block1))
409 (unlink-blocks block1 block2)
411 (unlink-blocks block2 block)
412 (link-blocks block1 block))
414 (setf (block-last block1) last)
415 (setf (continuation-kind start2) :inside-block))
417 (setf (block-flags block1)
418 (attributes-union (block-flags block1)
420 (block-attributes type-asserted test-modified)))
422 (let ((next (block-next block2))
423 (prev (block-prev block2)))
424 (setf (block-next prev) next)
425 (setf (block-prev next) prev))
429 ;;; Delete any nodes in BLOCK whose value is unused and which have no
430 ;;; side effects. We can delete sets of lexical variables when the set
431 ;;; variable has no references.
432 (defun flush-dead-code (block)
433 (declare (type cblock block))
434 (do-nodes-backwards (node cont block)
435 (unless (continuation-dest cont)
441 (let ((info (combination-kind node)))
442 (when (fun-info-p info)
443 (let ((attr (fun-info-attributes info)))
444 (when (and (not (ir1-attributep attr call))
445 ;; ### For now, don't delete potentially
446 ;; flushable calls when they have the CALL
447 ;; attribute. Someday we should look at the
448 ;; functional args to determine if they have
450 (if (policy node (= safety 3))
451 (and (ir1-attributep attr flushable)
453 (member (continuation-type-check arg)
455 (basic-combination-args node))
457 (info :function :type
458 (leaf-source-name (ref-leaf (continuation-use (basic-combination-fun node)))))
459 :result-test #'always-subtypep
462 (ir1-attributep attr unsafely-flushable)))
463 (flush-dest (combination-fun node))
464 (dolist (arg (combination-args node))
466 (unlink-node node))))))
468 (when (eq (basic-combination-kind node) :local)
469 (let ((fun (combination-lambda node)))
470 (when (dolist (var (lambda-vars fun) t)
471 (when (or (leaf-refs var)
472 (lambda-var-sets var))
474 (flush-dest (first (basic-combination-args node)))
477 (let ((value (exit-value node)))
480 (setf (exit-value node) nil))))
482 (let ((var (set-var node)))
483 (when (and (lambda-var-p var)
484 (null (leaf-refs var)))
485 (flush-dest (set-value node))
486 (setf (basic-var-sets var)
487 (delete node (basic-var-sets var)))
488 (unlink-node node)))))))
490 (setf (block-flush-p block) nil)
493 ;;;; local call return type propagation
495 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
496 ;;; flag set. It iterates over the uses of the RESULT, looking for
497 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
498 ;;; call, then we union its type together with the types of other such
499 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
500 ;;; type with the RESULT's asserted type. We can make this
501 ;;; intersection now (potentially before type checking) because this
502 ;;; assertion on the result will eventually be checked (if
505 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
506 ;;; combination, which may change the succesor of the call to be the
507 ;;; called function, and if so, checks if the call can become an
508 ;;; assignment. If we convert to an assignment, we abort, since the
509 ;;; RETURN has been deleted.
510 (defun find-result-type (node)
511 (declare (type creturn node))
512 (let ((result (return-result node)))
513 (collect ((use-union *empty-type* values-type-union))
514 (do-uses (use result)
515 (cond ((and (basic-combination-p use)
516 (eq (basic-combination-kind use) :local))
517 (aver (eq (lambda-tail-set (node-home-lambda use))
518 (lambda-tail-set (combination-lambda use))))
519 (when (combination-p use)
520 (when (nth-value 1 (maybe-convert-tail-local-call use))
521 (return-from find-result-type (values)))))
523 (use-union (node-derived-type use)))))
524 (let ((int (values-type-intersection
525 (continuation-asserted-type result)
527 (setf (return-result-type node) int))))
530 ;;; Do stuff to realize that something has changed about the value
531 ;;; delivered to a return node. Since we consider the return values of
532 ;;; all functions in the tail set to be equivalent, this amounts to
533 ;;; bringing the entire tail set up to date. We iterate over the
534 ;;; returns for all the functions in the tail set, reanalyzing them
535 ;;; all (not treating Node specially.)
537 ;;; When we are done, we check whether the new type is different from
538 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
539 ;;; all the continuations for references to functions in the tail set.
540 ;;; This will cause IR1-OPTIMIZE-COMBINATION to derive the new type as
541 ;;; the results of the calls.
542 (defun ir1-optimize-return (node)
543 (declare (type creturn node))
544 (let* ((tails (lambda-tail-set (return-lambda node)))
545 (funs (tail-set-funs tails)))
546 (collect ((res *empty-type* values-type-union))
548 (let ((return (lambda-return fun)))
550 (when (node-reoptimize return)
551 (setf (node-reoptimize return) nil)
552 (find-result-type return))
553 (res (return-result-type return)))))
555 (when (type/= (res) (tail-set-type tails))
556 (setf (tail-set-type tails) (res))
557 (dolist (fun (tail-set-funs tails))
558 (dolist (ref (leaf-refs fun))
559 (reoptimize-continuation (node-cont ref)))))))
565 ;;; If the test has multiple uses, replicate the node when possible.
566 ;;; Also check whether the predicate is known to be true or false,
567 ;;; deleting the IF node in favor of the appropriate branch when this
569 (defun ir1-optimize-if (node)
570 (declare (type cif node))
571 (let ((test (if-test node))
572 (block (node-block node)))
574 (when (and (eq (block-start block) test)
575 (eq (continuation-next test) node)
576 (rest (block-start-uses block)))
578 (when (immediately-used-p test use)
579 (convert-if-if use node)
580 (when (continuation-use test) (return)))))
582 (let* ((type (continuation-type test))
584 (cond ((constant-continuation-p test)
585 (if (continuation-value test)
586 (if-alternative node)
587 (if-consequent node)))
588 ((not (types-equal-or-intersect type (specifier-type 'null)))
589 (if-alternative node))
590 ((type= type (specifier-type 'null))
591 (if-consequent node)))))
594 (when (rest (block-succ block))
595 (unlink-blocks block victim))
596 (setf (component-reanalyze (node-component node)) t)
597 (unlink-node node))))
600 ;;; Create a new copy of an IF node that tests the value of the node
601 ;;; USE. The test must have >1 use, and must be immediately used by
602 ;;; USE. NODE must be the only node in its block (implying that
603 ;;; block-start = if-test).
605 ;;; This optimization has an effect semantically similar to the
606 ;;; source-to-source transformation:
607 ;;; (IF (IF A B C) D E) ==>
608 ;;; (IF A (IF B D E) (IF C D E))
610 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
611 ;;; node so that dead code deletion notes will definitely not consider
612 ;;; either node to be part of the original source. One node might
613 ;;; become unreachable, resulting in a spurious note.
614 (defun convert-if-if (use node)
615 (declare (type node use) (type cif node))
616 (with-ir1-environment-from-node node
617 (let* ((block (node-block node))
618 (test (if-test node))
619 (cblock (if-consequent node))
620 (ablock (if-alternative node))
621 (use-block (node-block use))
622 (dummy-cont (make-continuation))
623 (new-cont (make-continuation))
624 (new-node (make-if :test new-cont
626 :alternative ablock))
627 (new-block (continuation-starts-block new-cont)))
628 (link-node-to-previous-continuation new-node new-cont)
629 (setf (continuation-dest new-cont) new-node)
630 (add-continuation-use new-node dummy-cont)
631 (setf (block-last new-block) new-node)
633 (unlink-blocks use-block block)
634 (delete-continuation-use use)
635 (add-continuation-use use new-cont)
636 (link-blocks use-block new-block)
638 (link-blocks new-block cblock)
639 (link-blocks new-block ablock)
641 (push "<IF Duplication>" (node-source-path node))
642 (push "<IF Duplication>" (node-source-path new-node))
644 (reoptimize-continuation test)
645 (reoptimize-continuation new-cont)
646 (setf (component-reanalyze *current-component*) t)))
649 ;;;; exit IR1 optimization
651 ;;; This function attempts to delete an exit node, returning true if
652 ;;; it deletes the block as a consequence:
653 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
654 ;;; anything, since there is nothing to be done.
655 ;;; -- If the exit node and its ENTRY have the same home lambda then
656 ;;; we know the exit is local, and can delete the exit. We change
657 ;;; uses of the Exit-Value to be uses of the original continuation,
658 ;;; then unlink the node. If the exit is to a TR context, then we
659 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
660 ;;; their value to this exit.
661 ;;; -- If there is no value (as in a GO), then we skip the value
664 ;;; This function is also called by environment analysis, since it
665 ;;; wants all exits to be optimized even if normal optimization was
667 (defun maybe-delete-exit (node)
668 (declare (type exit node))
669 (let ((value (exit-value node))
670 (entry (exit-entry node))
671 (cont (node-cont node)))
673 (eq (node-home-lambda node) (node-home-lambda entry)))
674 (setf (entry-exits entry) (delete node (entry-exits entry)))
679 (when (return-p (continuation-dest cont))
681 (when (and (basic-combination-p use)
682 (eq (basic-combination-kind use) :local))
684 (substitute-continuation-uses cont value)
685 (dolist (merge (merges))
686 (merge-tail-sets merge))))))))
688 ;;;; combination IR1 optimization
690 ;;; Report as we try each transform?
692 (defvar *show-transforms-p* nil)
694 ;;; Do IR1 optimizations on a COMBINATION node.
695 (declaim (ftype (function (combination) (values)) ir1-optimize-combination))
696 (defun ir1-optimize-combination (node)
697 (when (continuation-reoptimize (basic-combination-fun node))
698 (propagate-fun-change node))
699 (let ((args (basic-combination-args node))
700 (kind (basic-combination-kind node)))
703 (let ((fun (combination-lambda node)))
704 (if (eq (functional-kind fun) :let)
705 (propagate-let-args node fun)
706 (propagate-local-call-args node fun))))
710 (setf (continuation-reoptimize arg) nil))))
714 (setf (continuation-reoptimize arg) nil)))
716 (let ((attr (fun-info-attributes kind)))
717 (when (and (ir1-attributep attr foldable)
718 ;; KLUDGE: The next test could be made more sensitive,
719 ;; only suppressing constant-folding of functions with
720 ;; CALL attributes when they're actually passed
721 ;; function arguments. -- WHN 19990918
722 (not (ir1-attributep attr call))
723 (every #'constant-continuation-p args)
724 (continuation-dest (node-cont node))
725 ;; Even if the function is foldable in principle,
726 ;; it might be one of our low-level
727 ;; implementation-specific functions. Such
728 ;; functions don't necessarily exist at runtime on
729 ;; a plain vanilla ANSI Common Lisp
730 ;; cross-compilation host, in which case the
731 ;; cross-compiler can't fold it because the
732 ;; cross-compiler doesn't know how to evaluate it.
734 (fboundp (combination-fun-source-name node)))
735 (constant-fold-call node)
736 (return-from ir1-optimize-combination)))
738 (let ((fun (fun-info-derive-type kind)))
740 (let ((res (funcall fun node)))
742 (derive-node-type node res)
743 (maybe-terminate-block node nil)))))
745 (let ((fun (fun-info-optimizer kind)))
746 (unless (and fun (funcall fun node))
747 (dolist (x (fun-info-transforms kind))
749 (when *show-transforms-p*
750 (let* ((cont (basic-combination-fun node))
751 (fname (continuation-fun-name cont t)))
752 (/show "trying transform" x (transform-function x) "for" fname)))
753 (unless (ir1-transform node x)
755 (when *show-transforms-p*
756 (/show "quitting because IR1-TRANSFORM result was NIL"))
761 ;;; If CALL is to a function that doesn't return (i.e. return type is
762 ;;; NIL), then terminate the block there, and link it to the component
763 ;;; tail. We also change the call's CONT to be a dummy continuation to
764 ;;; prevent the use from confusing things.
766 ;;; Except when called during IR1 [FIXME: What does this mean? Except
767 ;;; during IR1 conversion? What about IR1 optimization?], we delete
768 ;;; the continuation if it has no other uses. (If it does have other
769 ;;; uses, we reoptimize.)
771 ;;; Termination on the basis of a continuation type assertion is
773 ;;; -- The continuation is deleted (hence the assertion is spurious), or
774 ;;; -- We are in IR1 conversion (where THE assertions are subject to
776 (defun maybe-terminate-block (call ir1-converting-not-optimizing-p)
777 (declare (type basic-combination call))
778 (let* ((block (node-block call))
779 (cont (node-cont call))
780 (tail (component-tail (block-component block)))
781 (succ (first (block-succ block))))
782 (unless (or (and (eq call (block-last block)) (eq succ tail))
783 (block-delete-p block))
784 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
785 (not (or ir1-converting-not-optimizing-p
786 (eq (continuation-kind cont) :deleted))))
787 (eq (node-derived-type call) *empty-type*))
788 (cond (ir1-converting-not-optimizing-p
789 (delete-continuation-use call)
792 (aver (and (eq (block-last block) call)
793 (eq (continuation-kind cont) :block-start))))
795 (setf (block-last block) call)
796 (link-blocks block (continuation-starts-block cont)))))
798 (node-ends-block call)
799 (delete-continuation-use call)
800 (if (eq (continuation-kind cont) :unused)
801 (delete-continuation cont)
802 (reoptimize-continuation cont))))
804 (unlink-blocks block (first (block-succ block)))
805 (setf (component-reanalyze (block-component block)) t)
806 (aver (not (block-succ block)))
807 (link-blocks block tail)
808 (add-continuation-use call (make-continuation))
811 ;;; This is called both by IR1 conversion and IR1 optimization when
812 ;;; they have verified the type signature for the call, and are
813 ;;; wondering if something should be done to special-case the call. If
814 ;;; CALL is a call to a global function, then see whether it defined
816 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
817 ;;; the expansion and change the call to call it. Expansion is
818 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
819 ;;; true, we never expand, since this function has already been
820 ;;; converted. Local call analysis will duplicate the definition
821 ;;; if necessary. We claim that the parent form is LABELS for
822 ;;; context declarations, since we don't want it to be considered
823 ;;; a real global function.
824 ;;; -- If it is a known function, mark it as such by setting the KIND.
826 ;;; We return the leaf referenced (NIL if not a leaf) and the
827 ;;; FUN-INFO assigned.
829 ;;; FIXME: The IR1-CONVERTING-NOT-OPTIMIZING-P argument is what the
830 ;;; old CMU CL code called IR1-P, without explanation. My (WHN
831 ;;; 2002-01-09) tentative understanding of it is that we can call this
832 ;;; operation either in initial IR1 conversion or in later IR1
833 ;;; optimization, and it tells which is which. But it would be good
834 ;;; for someone who really understands it to check whether this is
836 (defun recognize-known-call (call ir1-converting-not-optimizing-p)
837 (declare (type combination call))
838 (let* ((ref (continuation-use (basic-combination-fun call)))
839 (leaf (when (ref-p ref) (ref-leaf ref)))
840 (inlinep (if (defined-fun-p leaf)
841 (defined-fun-inlinep leaf)
844 ((eq inlinep :notinline) (values nil nil))
845 ((not (and (global-var-p leaf)
846 (eq (global-var-kind leaf) :global-function)))
851 ((nil :maybe-inline) (policy call (zerop space))))
853 (defined-fun-inline-expansion leaf)
854 (let ((fun (defined-fun-functional leaf)))
856 (and (eq inlinep :inline) (functional-kind fun))))
857 (inline-expansion-ok call))
858 (flet (;; FIXME: Is this what the old CMU CL internal documentation
859 ;; called semi-inlining? A more descriptive name would
860 ;; be nice. -- WHN 2002-01-07
862 (let ((res (ir1-convert-lambda-for-defun
863 (defined-fun-inline-expansion leaf)
865 #'ir1-convert-inline-lambda)))
866 (setf (defined-fun-functional leaf) res)
867 (change-ref-leaf ref res))))
868 (if ir1-converting-not-optimizing-p
870 (with-ir1-environment-from-node call
872 (locall-analyze-component *current-component*))))
874 (values (ref-leaf (continuation-use (basic-combination-fun call)))
877 (let ((info (info :function :info (leaf-source-name leaf))))
879 (values leaf (setf (basic-combination-kind call) info))
880 (values leaf nil)))))))
882 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
883 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
884 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
885 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
886 ;;; syntax check, arg/result type processing, but still call
887 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
888 ;;; and that checking is done by local call analysis.
889 (defun validate-call-type (call type ir1-converting-not-optimizing-p)
890 (declare (type combination call) (type ctype type))
891 (cond ((not (fun-type-p type))
892 (aver (multiple-value-bind (val win)
893 (csubtypep type (specifier-type 'function))
895 (recognize-known-call call ir1-converting-not-optimizing-p))
896 ((valid-fun-use call type
897 :argument-test #'always-subtypep
898 :result-test #'always-subtypep
899 ;; KLUDGE: Common Lisp is such a dynamic
900 ;; language that all we can do here in
901 ;; general is issue a STYLE-WARNING. It
902 ;; would be nice to issue a full WARNING
903 ;; in the special case of of type
904 ;; mismatches within a compilation unit
905 ;; (as in section 3.2.2.3 of the spec)
906 ;; but at least as of sbcl-0.6.11, we
907 ;; don't keep track of whether the
908 ;; mismatched data came from the same
909 ;; compilation unit, so we can't do that.
912 ;; FIXME: Actually, I think we could
913 ;; issue a full WARNING if the call
914 ;; violates a DECLAIM FTYPE.
915 :lossage-fun #'compiler-style-warn
916 :unwinnage-fun #'compiler-note)
917 (assert-call-type call type)
918 (maybe-terminate-block call ir1-converting-not-optimizing-p)
919 (recognize-known-call call ir1-converting-not-optimizing-p))
921 (setf (combination-kind call) :error)
924 ;;; This is called by IR1-OPTIMIZE when the function for a call has
925 ;;; changed. If the call is local, we try to LET-convert it, and
926 ;;; derive the result type. If it is a :FULL call, we validate it
927 ;;; against the type, which recognizes known calls, does inline
928 ;;; expansion, etc. If a call to a predicate in a non-conditional
929 ;;; position or to a function with a source transform, then we
930 ;;; reconvert the form to give IR1 another chance.
931 (defun propagate-fun-change (call)
932 (declare (type combination call))
933 (let ((*compiler-error-context* call)
934 (fun-cont (basic-combination-fun call)))
935 (setf (continuation-reoptimize fun-cont) nil)
936 (case (combination-kind call)
938 (let ((fun (combination-lambda call)))
939 (maybe-let-convert fun)
940 (unless (member (functional-kind fun) '(:let :assignment :deleted))
941 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
943 (multiple-value-bind (leaf info)
944 (validate-call-type call (continuation-type fun-cont) nil)
945 (cond ((functional-p leaf)
946 (convert-call-if-possible
947 (continuation-use (basic-combination-fun call))
950 ((and (leaf-has-source-name-p leaf)
951 (or (info :function :source-transform (leaf-source-name leaf))
953 (ir1-attributep (fun-info-attributes info)
955 (let ((dest (continuation-dest (node-cont call))))
956 (and dest (not (if-p dest)))))))
957 ;; FIXME: This SYMBOLP is part of a literal
958 ;; translation of a test in the old CMU CL
959 ;; source, and it's not quite clear what
960 ;; the old source meant. Did it mean "has a
961 ;; valid name"? Or did it mean "is an
962 ;; ordinary function name, not a SETF
963 ;; function"? Either way, the old CMU CL
964 ;; code probably didn't deal with SETF
965 ;; functions correctly, and neither does
966 ;; this new SBCL code, and that should be fixed.
967 (when (symbolp (leaf-source-name leaf))
968 (let ((dummies (make-gensym-list
969 (length (combination-args call)))))
972 (,(leaf-source-name leaf)
974 (leaf-source-name leaf))))))))))
977 ;;;; known function optimization
979 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
980 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
981 ;;; replace it, otherwise add a new one.
982 (defun record-optimization-failure (node transform args)
983 (declare (type combination node) (type transform transform)
984 (type (or fun-type list) args))
985 (let* ((table (component-failed-optimizations *component-being-compiled*))
986 (found (assoc transform (gethash node table))))
988 (setf (cdr found) args)
989 (push (cons transform args) (gethash node table))))
992 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
993 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
994 ;;; doing the transform for some reason and FLAME is true, then we
995 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
996 ;;; finalize to pick up. We return true if the transform failed, and
997 ;;; thus further transformation should be attempted. We return false
998 ;;; if either the transform succeeded or was aborted.
999 (defun ir1-transform (node transform)
1000 (declare (type combination node) (type transform transform))
1001 (let* ((type (transform-type transform))
1002 (fun (transform-function transform))
1003 (constrained (fun-type-p type))
1004 (table (component-failed-optimizations *component-being-compiled*))
1005 (flame (if (transform-important transform)
1006 (policy node (>= speed inhibit-warnings))
1007 (policy node (> speed inhibit-warnings))))
1008 (*compiler-error-context* node))
1009 (cond ((or (not constrained)
1010 (valid-fun-use node type :strict-result t))
1011 (multiple-value-bind (severity args)
1012 (catch 'give-up-ir1-transform
1013 (transform-call node
1015 (combination-fun-source-name node))
1019 (remhash node table)
1022 (setf (combination-kind node) :error)
1024 (apply #'compiler-warn args))
1025 (remhash node table)
1030 (record-optimization-failure node transform args))
1031 (setf (gethash node table)
1032 (remove transform (gethash node table) :key #'car)))
1035 (remhash node table)
1040 :argument-test #'types-equal-or-intersect
1041 :result-test #'values-types-equal-or-intersect))
1042 (record-optimization-failure node transform type)
1047 ;;; When we don't like an IR1 transform, we throw the severity/reason
1050 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1051 ;;; aborting this attempt to transform the call, but admitting the
1052 ;;; possibility that this or some other transform will later succeed.
1053 ;;; If arguments are supplied, they are format arguments for an
1054 ;;; efficiency note.
1056 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1057 ;;; force a normal call to the function at run time. No further
1058 ;;; optimizations will be attempted.
1060 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1061 ;;; delay the transform on the node until later. REASONS specifies
1062 ;;; when the transform will be later retried. The :OPTIMIZE reason
1063 ;;; causes the transform to be delayed until after the current IR1
1064 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1065 ;;; be delayed until after constraint propagation.
1067 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1068 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1069 ;;; do CASE operations on the various REASON values, it might be a
1070 ;;; good idea to go OO, representing the reasons by objects, using
1071 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1072 ;;; SIGNAL instead of THROW.
1073 (declaim (ftype (function (&rest t) nil) give-up-ir1-transform))
1074 (defun give-up-ir1-transform (&rest args)
1075 (throw 'give-up-ir1-transform (values :failure args)))
1076 (defun abort-ir1-transform (&rest args)
1077 (throw 'give-up-ir1-transform (values :aborted args)))
1078 (defun delay-ir1-transform (node &rest reasons)
1079 (let ((assoc (assoc node *delayed-ir1-transforms*)))
1081 (setf *delayed-ir1-transforms*
1082 (acons node reasons *delayed-ir1-transforms*))
1083 (throw 'give-up-ir1-transform :delayed))
1085 (dolist (reason reasons)
1086 (pushnew reason (cdr assoc)))
1087 (throw 'give-up-ir1-transform :delayed)))))
1089 ;;; Clear any delayed transform with no reasons - these should have
1090 ;;; been tried in the last pass. Then remove the reason from the
1091 ;;; delayed transform reasons, and if any become empty then set
1092 ;;; reoptimize flags for the node. Return true if any transforms are
1094 (defun retry-delayed-ir1-transforms (reason)
1095 (setf *delayed-ir1-transforms*
1096 (remove-if-not #'cdr *delayed-ir1-transforms*))
1097 (let ((reoptimize nil))
1098 (dolist (assoc *delayed-ir1-transforms*)
1099 (let ((reasons (remove reason (cdr assoc))))
1100 (setf (cdr assoc) reasons)
1102 (let ((node (car assoc)))
1103 (unless (node-deleted node)
1105 (setf (node-reoptimize node) t)
1106 (let ((block (node-block node)))
1107 (setf (block-reoptimize block) t)
1108 (setf (component-reoptimize (block-component block)) t)))))))
1111 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1112 ;;; environment, and then install it as the function for the call
1113 ;;; NODE. We do local call analysis so that the new function is
1114 ;;; integrated into the control flow.
1116 ;;; We require the original function source name in order to generate
1117 ;;; a meaningful debug name for the lambda we set up. (It'd be
1118 ;;; possible to do this starting from debug names as well as source
1119 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1120 ;;; generality, since source names are always known to our callers.)
1121 (defun transform-call (node res source-name)
1122 (declare (type combination node) (list res))
1123 (aver (and (legal-fun-name-p source-name)
1124 (not (eql source-name '.anonymous.))))
1125 (with-ir1-environment-from-node node
1126 (let ((new-fun (ir1-convert-inline-lambda
1128 :debug-name (debug-namify "LAMBDA-inlined ~A"
1131 "<unknown function>"))))
1132 (ref (continuation-use (combination-fun node))))
1133 (change-ref-leaf ref new-fun)
1134 (setf (combination-kind node) :full)
1135 (locall-analyze-component *current-component*)))
1138 ;;; Replace a call to a foldable function of constant arguments with
1139 ;;; the result of evaluating the form. We insert the resulting
1140 ;;; constant node after the call, stealing the call's continuation. We
1141 ;;; give the call a continuation with no DEST, which should cause it
1142 ;;; and its arguments to go away. If there is an error during the
1143 ;;; evaluation, we give a warning and leave the call alone, making the
1144 ;;; call a :ERROR call.
1146 ;;; If there is more than one value, then we transform the call into a
1148 (defun constant-fold-call (call)
1149 (let ((args (mapcar #'continuation-value (combination-args call)))
1150 (fun-name (combination-fun-source-name call)))
1151 (multiple-value-bind (values win)
1152 (careful-call fun-name
1155 ;; Note: CMU CL had COMPILER-WARN here, and that
1156 ;; seems more natural, but it's probably not.
1158 ;; It's especially not while bug 173 exists:
1161 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1163 ;; can cause constant-folding TYPE-ERRORs (in
1164 ;; #'<=) when END can be proved to be NIL, even
1165 ;; though the code is perfectly legal and safe
1166 ;; because a NIL value of END means that the
1167 ;; #'<= will never be executed.
1169 ;; Moreover, even without bug 173,
1170 ;; quite-possibly-valid code like
1171 ;; (COND ((NONINLINED-PREDICATE END)
1172 ;; (UNLESS (<= END SIZE))
1174 ;; (where NONINLINED-PREDICATE is something the
1175 ;; compiler can't do at compile time, but which
1176 ;; turns out to make the #'<= expression
1177 ;; unreachable when END=NIL) could cause errors
1178 ;; when the compiler tries to constant-fold (<=
1181 ;; So, with or without bug 173, it'd be
1182 ;; unnecessarily evil to do a full
1183 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1184 ;; from COMPILE-FILE) for legal code, so we we
1185 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1186 #'compiler-style-warn
1189 (setf (combination-kind call) :error)
1190 (let ((dummies (make-gensym-list (length args))))
1194 (declare (ignore ,@dummies))
1195 (values ,@(mapcar (lambda (x) `',x) values)))
1199 ;;;; local call optimization
1201 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1202 ;;; the leaf type is a function type, then just leave it alone, since
1203 ;;; TYPE is never going to be more specific than that (and
1204 ;;; TYPE-INTERSECTION would choke.)
1205 (defun propagate-to-refs (leaf type)
1206 (declare (type leaf leaf) (type ctype type))
1207 (let ((var-type (leaf-type leaf)))
1208 (unless (fun-type-p var-type)
1209 (let ((int (type-approx-intersection2 var-type type)))
1210 (when (type/= int var-type)
1211 (setf (leaf-type leaf) int)
1212 (dolist (ref (leaf-refs leaf))
1213 (derive-node-type ref int))))
1216 ;;; Figure out the type of a LET variable that has sets. We compute
1217 ;;; the union of the initial value Type and the types of all the set
1218 ;;; values and to a PROPAGATE-TO-REFS with this type.
1219 (defun propagate-from-sets (var type)
1220 (collect ((res type type-union))
1221 (dolist (set (basic-var-sets var))
1222 (res (continuation-type (set-value set)))
1223 (setf (node-reoptimize set) nil))
1224 (propagate-to-refs var (res)))
1227 ;;; If a LET variable, find the initial value's type and do
1228 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1230 (defun ir1-optimize-set (node)
1231 (declare (type cset node))
1232 (let ((var (set-var node)))
1233 (when (and (lambda-var-p var) (leaf-refs var))
1234 (let ((home (lambda-var-home var)))
1235 (when (eq (functional-kind home) :let)
1236 (let ((iv (let-var-initial-value var)))
1237 (setf (continuation-reoptimize iv) nil)
1238 (propagate-from-sets var (continuation-type iv)))))))
1240 (derive-node-type node (continuation-type (set-value node)))
1243 ;;; Return true if the value of REF will always be the same (and is
1244 ;;; thus legal to substitute.)
1245 (defun constant-reference-p (ref)
1246 (declare (type ref ref))
1247 (let ((leaf (ref-leaf ref)))
1249 ((or constant functional) t)
1251 (null (lambda-var-sets leaf)))
1253 (not (eq (defined-fun-inlinep leaf) :notinline)))
1255 (case (global-var-kind leaf)
1256 (:global-function t))))))
1258 ;;; If we have a non-set LET var with a single use, then (if possible)
1259 ;;; replace the variable reference's CONT with the arg continuation.
1260 ;;; This is inhibited when:
1261 ;;; -- CONT has other uses, or
1262 ;;; -- CONT receives multiple values, or
1263 ;;; -- the reference is in a different environment from the variable, or
1264 ;;; -- either continuation has a funky TYPE-CHECK annotation.
1265 ;;; -- the continuations have incompatible assertions, so the new asserted type
1267 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1269 ;;; We change the REF to be a reference to NIL with unused value, and
1270 ;;; let it be flushed as dead code. A side effect of this substitution
1271 ;;; is to delete the variable.
1272 (defun substitute-single-use-continuation (arg var)
1273 (declare (type continuation arg) (type lambda-var var))
1274 (let* ((ref (first (leaf-refs var)))
1275 (cont (node-cont ref))
1276 (cont-atype (continuation-asserted-type cont))
1277 (dest (continuation-dest cont)))
1278 (when (and (eq (continuation-use cont) ref)
1280 (not (typep dest '(or creturn exit mv-combination)))
1281 (eq (node-home-lambda ref)
1282 (lambda-home (lambda-var-home var)))
1283 (member (continuation-type-check arg) '(t nil))
1284 (member (continuation-type-check cont) '(t nil))
1285 (not (eq (values-type-intersection
1287 (continuation-asserted-type arg))
1289 (eq (lexenv-policy (node-lexenv dest))
1290 (lexenv-policy (node-lexenv (continuation-dest arg)))))
1291 (aver (member (continuation-kind arg)
1292 '(:block-start :deleted-block-start :inside-block)))
1293 (assert-continuation-type arg cont-atype)
1294 (setf (node-derived-type ref) *wild-type*)
1295 (change-ref-leaf ref (find-constant nil))
1296 (substitute-continuation arg cont)
1297 (reoptimize-continuation arg)
1300 ;;; Delete a LET, removing the call and bind nodes, and warning about
1301 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1302 ;;; along right away and delete the REF and then the lambda, since we
1303 ;;; flush the FUN continuation.
1304 (defun delete-let (clambda)
1305 (declare (type clambda clambda))
1306 (aver (functional-letlike-p clambda))
1307 (note-unreferenced-vars clambda)
1308 (let ((call (let-combination clambda)))
1309 (flush-dest (basic-combination-fun call))
1311 (unlink-node (lambda-bind clambda))
1312 (setf (lambda-bind clambda) nil))
1315 ;;; This function is called when one of the arguments to a LET
1316 ;;; changes. We look at each changed argument. If the corresponding
1317 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1318 ;;; consider substituting for the variable, and also propagate
1319 ;;; derived-type information for the arg to all the VAR's refs.
1321 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1322 ;;; subtype of the argument's asserted type. This prevents type
1323 ;;; checking from being defeated, and also ensures that the best
1324 ;;; representation for the variable can be used.
1326 ;;; Substitution of individual references is inhibited if the
1327 ;;; reference is in a different component from the home. This can only
1328 ;;; happen with closures over top level lambda vars. In such cases,
1329 ;;; the references may have already been compiled, and thus can't be
1330 ;;; retroactively modified.
1332 ;;; If all of the variables are deleted (have no references) when we
1333 ;;; are done, then we delete the LET.
1335 ;;; Note that we are responsible for clearing the
1336 ;;; CONTINUATION-REOPTIMIZE flags.
1337 (defun propagate-let-args (call fun)
1338 (declare (type combination call) (type clambda fun))
1339 (loop for arg in (combination-args call)
1340 and var in (lambda-vars fun) do
1341 (when (and arg (continuation-reoptimize arg))
1342 (setf (continuation-reoptimize arg) nil)
1344 ((lambda-var-sets var)
1345 (propagate-from-sets var (continuation-type arg)))
1346 ((let ((use (continuation-use arg)))
1348 (let ((leaf (ref-leaf use)))
1349 (when (and (constant-reference-p use)
1350 (values-subtypep (leaf-type leaf)
1351 (continuation-asserted-type arg)))
1352 (propagate-to-refs var (continuation-type arg))
1353 (let ((use-component (node-component use)))
1356 (cond ((eq (node-component ref) use-component)
1359 (aver (lambda-toplevelish-p (lambda-home fun)))
1363 ((and (null (rest (leaf-refs var)))
1364 (substitute-single-use-continuation arg var)))
1366 (propagate-to-refs var (continuation-type arg))))))
1368 (when (every #'null (combination-args call))
1373 ;;; This function is called when one of the args to a non-LET local
1374 ;;; call changes. For each changed argument corresponding to an unset
1375 ;;; variable, we compute the union of the types across all calls and
1376 ;;; propagate this type information to the var's refs.
1378 ;;; If the function has an XEP, then we don't do anything, since we
1379 ;;; won't discover anything.
1381 ;;; We can clear the Continuation-Reoptimize flags for arguments in
1382 ;;; all calls corresponding to changed arguments in Call, since the
1383 ;;; only use in IR1 optimization of the Reoptimize flag for local call
1384 ;;; args is right here.
1385 (defun propagate-local-call-args (call fun)
1386 (declare (type combination call) (type clambda fun))
1388 (unless (or (functional-entry-fun fun)
1389 (lambda-optional-dispatch fun))
1390 (let* ((vars (lambda-vars fun))
1391 (union (mapcar (lambda (arg var)
1393 (continuation-reoptimize arg)
1394 (null (basic-var-sets var)))
1395 (continuation-type arg)))
1396 (basic-combination-args call)
1398 (this-ref (continuation-use (basic-combination-fun call))))
1400 (dolist (arg (basic-combination-args call))
1402 (setf (continuation-reoptimize arg) nil)))
1404 (dolist (ref (leaf-refs fun))
1405 (let ((dest (continuation-dest (node-cont ref))))
1406 (unless (or (eq ref this-ref) (not dest))
1408 (mapcar (lambda (this-arg old)
1410 (setf (continuation-reoptimize this-arg) nil)
1411 (type-union (continuation-type this-arg) old)))
1412 (basic-combination-args dest)
1415 (mapc (lambda (var type)
1417 (propagate-to-refs var type)))
1422 ;;;; multiple values optimization
1424 ;;; Do stuff to notice a change to a MV combination node. There are
1425 ;;; two main branches here:
1426 ;;; -- If the call is local, then it is already a MV let, or should
1427 ;;; become one. Note that although all :LOCAL MV calls must eventually
1428 ;;; be converted to :MV-LETs, there can be a window when the call
1429 ;;; is local, but has not been LET converted yet. This is because
1430 ;;; the entry-point lambdas may have stray references (in other
1431 ;;; entry points) that have not been deleted yet.
1432 ;;; -- The call is full. This case is somewhat similar to the non-MV
1433 ;;; combination optimization: we propagate return type information and
1434 ;;; notice non-returning calls. We also have an optimization
1435 ;;; which tries to convert MV-CALLs into MV-binds.
1436 (defun ir1-optimize-mv-combination (node)
1437 (ecase (basic-combination-kind node)
1439 (let ((fun-cont (basic-combination-fun node)))
1440 (when (continuation-reoptimize fun-cont)
1441 (setf (continuation-reoptimize fun-cont) nil)
1442 (maybe-let-convert (combination-lambda node))))
1443 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1444 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1445 (unless (convert-mv-bind-to-let node)
1446 (ir1-optimize-mv-bind node))))
1448 (let* ((fun (basic-combination-fun node))
1449 (fun-changed (continuation-reoptimize fun))
1450 (args (basic-combination-args node)))
1452 (setf (continuation-reoptimize fun) nil)
1453 (let ((type (continuation-type fun)))
1454 (when (fun-type-p type)
1455 (derive-node-type node (fun-type-returns type))))
1456 (maybe-terminate-block node nil)
1457 (let ((use (continuation-use fun)))
1458 (when (and (ref-p use) (functional-p (ref-leaf use)))
1459 (convert-call-if-possible use node)
1460 (when (eq (basic-combination-kind node) :local)
1461 (maybe-let-convert (ref-leaf use))))))
1462 (unless (or (eq (basic-combination-kind node) :local)
1463 (eq (continuation-fun-name fun) '%throw))
1464 (ir1-optimize-mv-call node))
1466 (setf (continuation-reoptimize arg) nil))))
1470 ;;; Propagate derived type info from the values continuation to the
1472 (defun ir1-optimize-mv-bind (node)
1473 (declare (type mv-combination node))
1474 (let ((arg (first (basic-combination-args node)))
1475 (vars (lambda-vars (combination-lambda node))))
1476 (multiple-value-bind (types nvals)
1477 (values-types (continuation-derived-type arg))
1478 (unless (eq nvals :unknown)
1479 (mapc (lambda (var type)
1480 (if (basic-var-sets var)
1481 (propagate-from-sets var type)
1482 (propagate-to-refs var type)))
1485 (make-list (max (- (length vars) nvals) 0)
1486 :initial-element (specifier-type 'null))))))
1487 (setf (continuation-reoptimize arg) nil))
1490 ;;; If possible, convert a general MV call to an MV-BIND. We can do
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.
1496 ;;; What we do is change the function in the MV-CALL to be a lambda
1497 ;;; that "looks like an MV bind", which allows
1498 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1499 ;;; converted (the next time around.) This new lambda just calls the
1500 ;;; actual function with the MV-BIND variables as arguments. Note that
1501 ;;; this new MV bind is not let-converted immediately, as there are
1502 ;;; going to be stray references from the entry-point functions until
1503 ;;; they get deleted.
1505 ;;; In order to avoid loss of argument count checking, we only do the
1506 ;;; transformation according to a known number of expected argument if
1507 ;;; safety is unimportant. We can always convert if we know the number
1508 ;;; of actual values, since the normal call that we build will still
1509 ;;; do any appropriate argument count checking.
1511 ;;; We only attempt the transformation if the called function is a
1512 ;;; constant reference. This allows us to just splice the leaf into
1513 ;;; the new function, instead of trying to somehow bind the function
1514 ;;; expression. The leaf must be constant because we are evaluating it
1515 ;;; again in a different place. This also has the effect of squelching
1516 ;;; multiple warnings when there is an argument count error.
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)))
1523 (unless (and (ref-p ref) (constant-reference-p ref)
1524 args (null (rest args)))
1525 (return-from ir1-optimize-mv-call))
1527 (multiple-value-bind (min max)
1528 (fun-type-nargs (continuation-type fun))
1530 (multiple-value-bind (types nvals)
1531 (values-types (continuation-derived-type (first args)))
1532 (declare (ignore types))
1533 (if (eq nvals :unknown) nil nvals))))
1536 (when (and min (< total-nvals min))
1538 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1541 (setf (basic-combination-kind node) :error)
1542 (return-from ir1-optimize-mv-call))
1543 (when (and max (> total-nvals max))
1545 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1548 (setf (basic-combination-kind node) :error)
1549 (return-from ir1-optimize-mv-call)))
1551 (let ((count (cond (total-nvals)
1552 ((and (policy node (zerop safety))
1557 (with-ir1-environment-from-node node
1558 (let* ((dums (make-gensym-list count))
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 (aver (eq (basic-combination-kind node) :full))
1566 (locall-analyze-component *current-component*)
1567 (aver (eq (basic-combination-kind node) :local)))))))))
1571 ;;; (multiple-value-bind
1580 ;;; What we actually do is convert the VALUES combination into a
1581 ;;; normal LET combination calling the original :MV-LET lambda. If
1582 ;;; there are extra args to VALUES, discard the corresponding
1583 ;;; continuations. If there are insufficient args, insert references
1585 (defun convert-mv-bind-to-let (call)
1586 (declare (type mv-combination call))
1587 (let* ((arg (first (basic-combination-args call)))
1588 (use (continuation-use arg)))
1589 (when (and (combination-p use)
1590 (eq (continuation-fun-name (combination-fun use))
1592 (let* ((fun (combination-lambda call))
1593 (vars (lambda-vars fun))
1594 (vals (combination-args use))
1595 (nvars (length vars))
1596 (nvals (length vals)))
1597 (cond ((> nvals nvars)
1598 (mapc #'flush-dest (subseq vals nvars))
1599 (setq vals (subseq vals 0 nvars)))
1601 (with-ir1-environment-from-node use
1602 (let ((node-prev (node-prev use)))
1603 (setf (node-prev use) nil)
1604 (setf (continuation-next node-prev) nil)
1605 (collect ((res vals))
1606 (loop as cont = (make-continuation use)
1607 and prev = node-prev then cont
1608 repeat (- nvars nvals)
1609 do (reference-constant prev cont nil)
1612 (link-node-to-previous-continuation use
1613 (car (last vals)))))))
1614 (setf (combination-args use) vals)
1615 (flush-dest (combination-fun use))
1616 (let ((fun-cont (basic-combination-fun call)))
1617 (setf (continuation-dest fun-cont) use)
1618 (setf (combination-fun use) fun-cont))
1619 (setf (combination-kind use) :local)
1620 (setf (functional-kind fun) :let)
1621 (flush-dest (first (basic-combination-args call)))
1624 (reoptimize-continuation (first vals)))
1625 (propagate-to-args use fun))
1629 ;;; (values-list (list x y z))
1634 ;;; In implementation, this is somewhat similar to
1635 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1636 ;;; args of the VALUES-LIST call, flushing the old argument
1637 ;;; continuation (allowing the LIST to be flushed.)
1638 (defoptimizer (values-list optimizer) ((list) node)
1639 (let ((use (continuation-use list)))
1640 (when (and (combination-p use)
1641 (eq (continuation-fun-name (combination-fun use))
1643 (change-ref-leaf (continuation-use (combination-fun node))
1644 (find-free-fun 'values "in a strange place"))
1645 (setf (combination-kind node) :full)
1646 (let ((args (combination-args use)))
1648 (setf (continuation-dest arg) node))
1649 (setf (combination-args use) nil)
1651 (setf (combination-args node) args))
1654 ;;; If VALUES appears in a non-MV context, then effectively convert it
1655 ;;; to a PROG1. This allows the computation of the additional values
1656 ;;; to become dead code.
1657 (deftransform values ((&rest vals) * * :node node)
1658 (when (typep (continuation-dest (node-cont node))
1659 '(or creturn exit mv-combination))
1660 (give-up-ir1-transform))
1661 (setf (node-derived-type node) *wild-type*)
1663 (let ((dummies (make-gensym-list (length (cdr vals)))))
1664 `(lambda (val ,@dummies)
1665 (declare (ignore ,@dummies))