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 (principal-continuation-use thing)))
26 (and (ref-p use) (constant-p (ref-leaf use))))))
28 ;;; Return the constant value for a continuation whose only use is a
30 (declaim (ftype (function (continuation) t) continuation-value))
31 (defun continuation-value (cont)
32 (let ((use (principal-continuation-use cont)))
33 (constant-value (ref-leaf use))))
35 ;;;; interface for obtaining results of type inference
37 ;;; Our best guess for the type of this continuation's value. Note
38 ;;; that this may be VALUES or FUNCTION type, which cannot be passed
39 ;;; as an argument to the normal type operations. See
40 ;;; CONTINUATION-TYPE. This may be called on deleted continuations,
41 ;;; always returning *.
43 ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the
44 ;;; result is a subtype of the assertion. If so, return the proven
45 ;;; type and set TYPE-CHECK to NIL. Otherwise, return the intersection
46 ;;; of the asserted and proven types, and set TYPE-CHECK T. If
47 ;;; TYPE-CHECK already has a non-null value, then preserve it. Only in
48 ;;; the somewhat unusual circumstance of a newly discovered assertion
49 ;;; will we change TYPE-CHECK from NIL to T.
51 ;;; The result value is cached in the CONTINUATION-%DERIVED-TYPE slot.
52 ;;; If the slot is true, just return that value, otherwise recompute
53 ;;; and stash the value there.
54 #!-sb-fluid (declaim (inline continuation-derived-type))
55 (defun continuation-derived-type (cont)
56 (declare (type continuation cont))
57 (or (continuation-%derived-type cont)
58 (setf (continuation-%derived-type cont)
59 (%continuation-derived-type cont))))
60 (defun %continuation-derived-type (cont)
61 (declare (type continuation cont))
62 (ecase (continuation-kind cont)
63 ((:block-start :deleted-block-start)
64 (let ((uses (block-start-uses (continuation-block cont))))
66 (do ((res (node-derived-type (first uses))
67 (values-type-union (node-derived-type (first current))
69 (current (rest uses) (rest current)))
73 (node-derived-type (continuation-use cont)))))
75 ;;; Return the derived type for CONT's first value. This is guaranteed
76 ;;; not to be a VALUES or FUNCTION type.
77 (declaim (ftype (sfunction (continuation) ctype) continuation-type))
78 (defun continuation-type (cont)
79 (single-value-type (continuation-derived-type cont)))
81 ;;; If CONT is an argument of a function, return a type which the
82 ;;; function checks CONT for.
83 #!-sb-fluid (declaim (inline continuation-externally-checkable-type))
84 (defun continuation-externally-checkable-type (cont)
85 (or (continuation-%externally-checkable-type cont)
86 (%continuation-%externally-checkable-type cont)))
87 (defun %continuation-%externally-checkable-type (cont)
88 (declare (type continuation cont))
89 (let ((dest (continuation-dest cont)))
91 (combination-p dest)))
92 ;; TODO: MV-COMBINATION
93 (setf (continuation-%externally-checkable-type cont) *wild-type*)
94 (let* ((fun (combination-fun dest))
95 (args (combination-args dest))
96 (fun-type (continuation-type fun)))
97 (setf (continuation-%externally-checkable-type fun) *wild-type*)
98 (if (or (not (call-full-like-p dest))
99 (not (fun-type-p fun-type))
100 ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)).
101 (fun-type-wild-args fun-type))
104 (setf (continuation-%externally-checkable-type arg)
106 (map-combination-args-and-types
108 (setf (continuation-%externally-checkable-type arg)
109 (acond ((continuation-%externally-checkable-type arg)
110 (values-type-intersection
111 it (coerce-to-values type)))
112 (t (coerce-to-values type)))))
114 (continuation-%externally-checkable-type cont))
115 (declaim (inline flush-continuation-externally-checkable-type))
116 (defun flush-continuation-externally-checkable-type (cont)
117 (declare (type continuation cont))
118 (setf (continuation-%externally-checkable-type cont) nil))
120 ;;;; interface routines used by optimizers
122 ;;; This function is called by optimizers to indicate that something
123 ;;; interesting has happened to the value of CONT. Optimizers must
124 ;;; make sure that they don't call for reoptimization when nothing has
125 ;;; happened, since optimization will fail to terminate.
127 ;;; We clear any cached type for the continuation and set the
128 ;;; reoptimize flags on everything in sight, unless the continuation
129 ;;; is deleted (in which case we do nothing.)
131 ;;; Since this can get called during IR1 conversion, we have to be
132 ;;; careful not to fly into space when the DEST's PREV is missing.
133 (defun reoptimize-continuation (cont)
134 (declare (type continuation cont))
135 (setf (continuation-%derived-type cont) nil)
136 (unless (member (continuation-kind cont) '(:deleted :unused))
137 (let ((dest (continuation-dest cont)))
139 (setf (continuation-reoptimize cont) t)
140 (setf (node-reoptimize dest) t)
141 (let ((prev (node-prev dest)))
143 (let* ((block (continuation-block prev))
144 (component (block-component block)))
145 (when (typep dest 'cif)
146 (setf (block-test-modified block) t))
147 (setf (block-reoptimize block) t)
148 (setf (component-reoptimize component) t))))))
150 (setf (block-type-check (node-block node)) t)))
153 (defun reoptimize-continuation-uses (cont)
154 (declare (type continuation cont))
155 (dolist (use (find-uses cont))
156 (setf (node-reoptimize use) t)
157 (setf (block-reoptimize (node-block use)) t)
158 (setf (component-reoptimize (node-component use)) t)))
160 ;;; Annotate NODE to indicate that its result has been proven to be
161 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
162 ;;; only correct way to supply information discovered about a node's
163 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
164 ;;; information may be lost and reoptimization may not happen.
166 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
167 ;;; intersection is different from the old type, then we do a
168 ;;; REOPTIMIZE-CONTINUATION on the NODE-CONT.
169 (defun derive-node-type (node rtype)
170 (declare (type node node) (type ctype rtype))
171 (let ((node-type (node-derived-type node)))
172 (unless (eq node-type rtype)
173 (let ((int (values-type-intersection node-type rtype))
174 (cont (node-cont node)))
175 (when (type/= node-type int)
176 (when (and *check-consistency*
177 (eq int *empty-type*)
178 (not (eq rtype *empty-type*)))
179 (let ((*compiler-error-context* node))
181 "New inferred type ~S conflicts with old type:~
182 ~% ~S~%*** possible internal error? Please report this."
183 (type-specifier rtype) (type-specifier node-type))))
184 (setf (node-derived-type node) int)
185 (when (and (ref-p node)
186 (lambda-var-p (ref-leaf node)))
187 (let ((type (single-value-type int)))
188 (when (and (member-type-p type)
189 (null (rest (member-type-members type))))
190 (change-ref-leaf node (find-constant
191 (first (member-type-members type)))))))
192 (reoptimize-continuation cont)))))
195 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
196 ;;; error for CONT's value not to be TYPEP to TYPE. We implement it
197 ;;; splitting off DEST a new CAST node. If we improve the assertion,
198 ;;; we set TYPE-CHECK and TYPE-ASSERTED to guarantee that the new
199 ;;; assertion will be checked. We return the new "argument"
200 ;;; continuation of DEST.
201 (defun assert-continuation-type (cont type policy)
202 (declare (type continuation cont) (type ctype type))
203 (if (values-subtypep (continuation-derived-type cont) type)
205 (let* ((dest (continuation-dest cont))
206 (prev-cont (node-prev dest)))
208 (with-ir1-environment-from-node dest
209 (let* ((cast (make-cast cont type policy))
210 (checked-value (make-continuation)))
211 (setf (continuation-next prev-cont) cast
212 (node-prev cast) prev-cont)
213 (use-continuation cast checked-value)
214 (link-node-to-previous-continuation dest checked-value)
215 (substitute-continuation checked-value cont)
216 (setf (continuation-dest cont) cast)
217 (reoptimize-continuation cont)
223 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
224 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
225 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
226 ;;; we are done, then another iteration would be beneficial.
227 (defun ir1-optimize (component)
228 (declare (type component component))
229 (setf (component-reoptimize component) nil)
230 (do-blocks (block component)
232 ;; We delete blocks when there is either no predecessor or the
233 ;; block is in a lambda that has been deleted. These blocks
234 ;; would eventually be deleted by DFO recomputation, but doing
235 ;; it here immediately makes the effect available to IR1
237 ((or (block-delete-p block)
238 (null (block-pred block)))
239 (delete-block block))
240 ((eq (functional-kind (block-home-lambda block)) :deleted)
241 ;; Preserve the BLOCK-SUCC invariant that almost every block has
242 ;; one successor (and a block with DELETE-P set is an acceptable
244 (mark-for-deletion block)
245 (delete-block block))
248 (let ((succ (block-succ block)))
249 (unless (singleton-p succ)
252 (let ((last (block-last block)))
255 (flush-dest (if-test last))
256 (when (unlink-node last)
259 (when (maybe-delete-exit last)
262 (unless (join-successor-if-possible block)
265 (when (and (block-reoptimize block) (block-component block))
266 (aver (not (block-delete-p block)))
267 (ir1-optimize-block block))
269 (cond ((and (block-delete-p block) (block-component block))
270 (delete-block block))
271 ((and (block-flush-p block) (block-component block))
272 (flush-dead-code block))))))
276 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
279 ;;; Note that although they are cleared here, REOPTIMIZE flags might
280 ;;; still be set upon return from this function, meaning that further
281 ;;; optimization is wanted (as a consequence of optimizations we did).
282 (defun ir1-optimize-block (block)
283 (declare (type cblock block))
284 ;; We clear the node and block REOPTIMIZE flags before doing the
285 ;; optimization, not after. This ensures that the node or block will
286 ;; be reoptimized if necessary.
287 (setf (block-reoptimize block) nil)
288 (do-nodes (node cont block :restart-p t)
289 (when (node-reoptimize node)
290 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
291 (setf (node-reoptimize node) nil)
295 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
296 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
297 ;; any argument changes.
298 (ir1-optimize-combination node))
300 (ir1-optimize-if node))
302 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
303 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
304 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
306 (setf (node-reoptimize node) t)
307 (ir1-optimize-return node))
309 (ir1-optimize-mv-combination node))
311 ;; With an EXIT, we derive the node's type from the VALUE's
312 ;; type. We don't propagate CONT's assertion to the VALUE,
313 ;; since if we did, this would move the checking of CONT's
314 ;; assertion to the exit. This wouldn't work with CATCH and
315 ;; UWP, where the EXIT node is just a placeholder for the
316 ;; actual unknown exit.
317 (let ((value (exit-value node)))
319 (derive-node-type node (continuation-derived-type value)))))
321 (ir1-optimize-set node))
323 (ir1-optimize-cast node)))))
327 ;;; Try to join with a successor block. If we succeed, we return true,
329 (defun join-successor-if-possible (block)
330 (declare (type cblock block))
331 (let ((next (first (block-succ block))))
332 (when (block-start next) ; NEXT is not an END-OF-COMPONENT marker
333 (let* ((last (block-last block))
334 (last-cont (node-cont last))
335 (next-cont (block-start next)))
336 (cond (;; We cannot combine with a successor block if:
338 ;; The successor has more than one predecessor.
339 (rest (block-pred next))
340 ;; The last node's CONT is also used somewhere else.
341 ;; (as in (IF <cond> (M-V-PROG1 ...) (M-V-PROG1 ...)))
342 (not (eq (continuation-use last-cont) last))
343 ;; The successor is the current block (infinite loop).
345 ;; The next block has a different cleanup, and thus
346 ;; we may want to insert cleanup code between the
347 ;; two blocks at some point.
348 (not (eq (block-end-cleanup block)
349 (block-start-cleanup next)))
350 ;; The next block has a different home lambda, and
351 ;; thus the control transfer is a non-local exit.
352 (not (eq (block-home-lambda block)
353 (block-home-lambda next))))
355 ;; Joining is easy when the successor's START
356 ;; continuation is the same from our LAST's CONT.
357 ((eq last-cont next-cont)
358 (join-blocks block next)
360 ;; If they differ, then we can still join when the last
361 ;; continuation has no next and the next continuation
363 ((and (null (block-start-uses next))
364 (eq (continuation-kind last-cont) :inside-block))
365 ;; In this case, we replace the next
366 ;; continuation with the last before joining the blocks.
367 (let ((next-node (continuation-next next-cont)))
368 ;; If NEXT-CONT does have a dest, it must be
369 ;; unreachable, since there are no USES.
370 ;; DELETE-CONTINUATION will mark the dest block as
371 ;; DELETE-P [and also this block, unless it is no
372 ;; longer backward reachable from the dest block.]
373 (delete-continuation next-cont)
374 (setf (node-prev next-node) last-cont)
375 (setf (continuation-next last-cont) next-node)
376 (setf (block-start next) last-cont)
377 (join-blocks block next))
379 ((and (null (block-start-uses next))
380 (not (typep (continuation-dest last-cont)
382 (null (continuation-lexenv-uses last-cont)))
383 (assert (null (find-uses next-cont)))
384 (when (continuation-dest last-cont)
385 (substitute-continuation next-cont last-cont))
386 (delete-continuation-use last)
387 (add-continuation-use last next-cont)
388 (setf (continuation-%derived-type next-cont) nil)
389 (join-blocks block next)
394 ;;; Join together two blocks which have the same ending/starting
395 ;;; continuation. The code in BLOCK2 is moved into BLOCK1 and BLOCK2
396 ;;; is deleted from the DFO. We combine the optimize flags for the two
397 ;;; blocks so that any indicated optimization gets done.
398 (defun join-blocks (block1 block2)
399 (declare (type cblock block1 block2))
400 (let* ((last (block-last block2))
401 (last-cont (node-cont last))
402 (succ (block-succ block2))
403 (start2 (block-start block2)))
404 (do ((cont start2 (node-cont (continuation-next cont))))
406 (when (eq (continuation-kind last-cont) :inside-block)
407 (setf (continuation-block last-cont) block1)))
408 (setf (continuation-block cont) block1))
410 (unlink-blocks block1 block2)
412 (unlink-blocks block2 block)
413 (link-blocks block1 block))
415 (setf (block-last block1) last)
416 (setf (continuation-kind start2) :inside-block))
418 (setf (block-flags block1)
419 (attributes-union (block-flags block1)
421 (block-attributes type-asserted test-modified)))
423 (let ((next (block-next block2))
424 (prev (block-prev block2)))
425 (setf (block-next prev) next)
426 (setf (block-prev next) prev))
430 ;;; Delete any nodes in BLOCK whose value is unused and which have no
431 ;;; side effects. We can delete sets of lexical variables when the set
432 ;;; variable has no references.
433 (defun flush-dead-code (block)
434 (declare (type cblock block))
435 (do-nodes-backwards (node cont block)
436 (unless (continuation-dest cont)
442 (let ((info (combination-kind node)))
443 (when (fun-info-p info)
444 (let ((attr (fun-info-attributes info)))
445 (when (and (not (ir1-attributep attr call))
446 ;; ### For now, don't delete potentially
447 ;; flushable calls when they have the CALL
448 ;; attribute. Someday we should look at the
449 ;; functional args to determine if they have
451 (if (policy node (= safety 3))
452 (ir1-attributep attr flushable)
453 (ir1-attributep attr unsafely-flushable)))
454 (flush-combination node))))))
456 (when (eq (basic-combination-kind node) :local)
457 (let ((fun (combination-lambda node)))
458 (when (dolist (var (lambda-vars fun) t)
459 (when (or (leaf-refs var)
460 (lambda-var-sets var))
462 (flush-dest (first (basic-combination-args node)))
465 (let ((value (exit-value node)))
468 (setf (exit-value node) nil))))
470 (let ((var (set-var node)))
471 (when (and (lambda-var-p var)
472 (null (leaf-refs var)))
473 (flush-dest (set-value node))
474 (setf (basic-var-sets var)
475 (delete node (basic-var-sets var)))
476 (unlink-node node))))
478 (unless (cast-type-check node)
479 (flush-dest (cast-value node))
480 (unlink-node node))))))
482 (setf (block-flush-p block) nil)
485 ;;;; local call return type propagation
487 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
488 ;;; flag set. It iterates over the uses of the RESULT, looking for
489 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
490 ;;; call, then we union its type together with the types of other such
491 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
492 ;;; type with the RESULT's asserted type. We can make this
493 ;;; intersection now (potentially before type checking) because this
494 ;;; assertion on the result will eventually be checked (if
497 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
498 ;;; combination, which may change the succesor of the call to be the
499 ;;; called function, and if so, checks if the call can become an
500 ;;; assignment. If we convert to an assignment, we abort, since the
501 ;;; RETURN has been deleted.
502 (defun find-result-type (node)
503 (declare (type creturn node))
504 (let ((result (return-result node)))
505 (collect ((use-union *empty-type* values-type-union))
506 (do-uses (use result)
507 (cond ((and (basic-combination-p use)
508 (eq (basic-combination-kind use) :local))
509 (aver (eq (lambda-tail-set (node-home-lambda use))
510 (lambda-tail-set (combination-lambda use))))
511 (when (combination-p use)
512 (when (nth-value 1 (maybe-convert-tail-local-call use))
513 (return-from find-result-type (values)))))
515 (use-union (node-derived-type use)))))
517 ;; (values-type-intersection
518 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
522 (setf (return-result-type node) int))))
525 ;;; Do stuff to realize that something has changed about the value
526 ;;; delivered to a return node. Since we consider the return values of
527 ;;; all functions in the tail set to be equivalent, this amounts to
528 ;;; bringing the entire tail set up to date. We iterate over the
529 ;;; returns for all the functions in the tail set, reanalyzing them
530 ;;; all (not treating NODE specially.)
532 ;;; When we are done, we check whether the new type is different from
533 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
534 ;;; all the continuations for references to functions in the tail set.
535 ;;; This will cause IR1-OPTIMIZE-COMBINATION to derive the new type as
536 ;;; the results of the calls.
537 (defun ir1-optimize-return (node)
538 (declare (type creturn node))
539 (let* ((tails (lambda-tail-set (return-lambda node)))
540 (funs (tail-set-funs tails)))
541 (collect ((res *empty-type* values-type-union))
543 (let ((return (lambda-return fun)))
545 (when (node-reoptimize return)
546 (setf (node-reoptimize return) nil)
547 (find-result-type return))
548 (res (return-result-type return)))))
550 (when (type/= (res) (tail-set-type tails))
551 (setf (tail-set-type tails) (res))
552 (dolist (fun (tail-set-funs tails))
553 (dolist (ref (leaf-refs fun))
554 (reoptimize-continuation (node-cont ref)))))))
560 ;;; If the test has multiple uses, replicate the node when possible.
561 ;;; Also check whether the predicate is known to be true or false,
562 ;;; deleting the IF node in favor of the appropriate branch when this
564 (defun ir1-optimize-if (node)
565 (declare (type cif node))
566 (let ((test (if-test node))
567 (block (node-block node)))
569 (when (and (eq (block-start block) test)
570 (eq (continuation-next test) node)
571 (rest (block-start-uses block)))
573 (when (immediately-used-p test use)
574 (convert-if-if use node)
575 (when (continuation-use test) (return)))))
577 (let* ((type (continuation-type test))
579 (cond ((constant-continuation-p test)
580 (if (continuation-value test)
581 (if-alternative node)
582 (if-consequent node)))
583 ((not (types-equal-or-intersect type (specifier-type 'null)))
584 (if-alternative node))
585 ((type= type (specifier-type 'null))
586 (if-consequent node)))))
589 (when (rest (block-succ block))
590 (unlink-blocks block victim))
591 (setf (component-reanalyze (node-component node)) t)
592 (unlink-node node))))
595 ;;; Create a new copy of an IF node that tests the value of the node
596 ;;; USE. The test must have >1 use, and must be immediately used by
597 ;;; USE. NODE must be the only node in its block (implying that
598 ;;; block-start = if-test).
600 ;;; This optimization has an effect semantically similar to the
601 ;;; source-to-source transformation:
602 ;;; (IF (IF A B C) D E) ==>
603 ;;; (IF A (IF B D E) (IF C D E))
605 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
606 ;;; node so that dead code deletion notes will definitely not consider
607 ;;; either node to be part of the original source. One node might
608 ;;; become unreachable, resulting in a spurious note.
609 (defun convert-if-if (use node)
610 (declare (type node use) (type cif node))
611 (with-ir1-environment-from-node node
612 (let* ((block (node-block node))
613 (test (if-test node))
614 (cblock (if-consequent node))
615 (ablock (if-alternative node))
616 (use-block (node-block use))
617 (dummy-cont (make-continuation))
618 (new-cont (make-continuation))
619 (new-node (make-if :test new-cont
621 :alternative ablock))
622 (new-block (continuation-starts-block new-cont)))
623 (link-node-to-previous-continuation new-node new-cont)
624 (setf (continuation-dest new-cont) new-node)
625 (flush-continuation-externally-checkable-type new-cont)
626 (add-continuation-use new-node dummy-cont)
627 (setf (block-last new-block) new-node)
629 (unlink-blocks use-block block)
630 (delete-continuation-use use)
631 (add-continuation-use use new-cont)
632 (link-blocks use-block new-block)
634 (link-blocks new-block cblock)
635 (link-blocks new-block ablock)
637 (push "<IF Duplication>" (node-source-path node))
638 (push "<IF Duplication>" (node-source-path new-node))
640 (reoptimize-continuation test)
641 (reoptimize-continuation new-cont)
642 (setf (component-reanalyze *current-component*) t)))
645 ;;;; exit IR1 optimization
647 ;;; This function attempts to delete an exit node, returning true if
648 ;;; it deletes the block as a consequence:
649 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
650 ;;; anything, since there is nothing to be done.
651 ;;; -- If the exit node and its ENTRY have the same home lambda then
652 ;;; we know the exit is local, and can delete the exit. We change
653 ;;; uses of the Exit-Value to be uses of the original continuation,
654 ;;; then unlink the node. If the exit is to a TR context, then we
655 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
656 ;;; their value to this exit.
657 ;;; -- If there is no value (as in a GO), then we skip the value
660 ;;; This function is also called by environment analysis, since it
661 ;;; wants all exits to be optimized even if normal optimization was
663 (defun maybe-delete-exit (node)
664 (declare (type exit node))
665 (let ((value (exit-value node))
666 (entry (exit-entry node))
667 (cont (node-cont node)))
669 (eq (node-home-lambda node) (node-home-lambda entry)))
670 (setf (entry-exits entry) (delete node (entry-exits entry)))
672 (delete-filter node cont value)
673 (unlink-node node)))))
676 ;;;; combination IR1 optimization
678 ;;; Report as we try each transform?
680 (defvar *show-transforms-p* nil)
682 ;;; Do IR1 optimizations on a COMBINATION node.
683 (declaim (ftype (function (combination) (values)) ir1-optimize-combination))
684 (defun ir1-optimize-combination (node)
685 (when (continuation-reoptimize (basic-combination-fun node))
686 (propagate-fun-change node))
687 (let ((args (basic-combination-args node))
688 (kind (basic-combination-kind node)))
691 (let ((fun (combination-lambda node)))
692 (if (eq (functional-kind fun) :let)
693 (propagate-let-args node fun)
694 (propagate-local-call-args node fun))))
698 (setf (continuation-reoptimize arg) nil))))
702 (setf (continuation-reoptimize arg) nil)))
704 (let ((attr (fun-info-attributes kind)))
705 (when (and (ir1-attributep attr foldable)
706 ;; KLUDGE: The next test could be made more sensitive,
707 ;; only suppressing constant-folding of functions with
708 ;; CALL attributes when they're actually passed
709 ;; function arguments. -- WHN 19990918
710 (not (ir1-attributep attr call))
711 (every #'constant-continuation-p args)
712 (continuation-dest (node-cont node))
713 ;; Even if the function is foldable in principle,
714 ;; it might be one of our low-level
715 ;; implementation-specific functions. Such
716 ;; functions don't necessarily exist at runtime on
717 ;; a plain vanilla ANSI Common Lisp
718 ;; cross-compilation host, in which case the
719 ;; cross-compiler can't fold it because the
720 ;; cross-compiler doesn't know how to evaluate it.
722 (or (fboundp (combination-fun-source-name node))
723 (progn (format t ";;; !!! Unbound fun: (~S~{ ~S~})~%"
724 (combination-fun-source-name node)
725 (mapcar #'continuation-value args))
727 (constant-fold-call node)
728 (return-from ir1-optimize-combination)))
730 (let ((fun (fun-info-derive-type kind)))
732 (let ((res (funcall fun node)))
734 (derive-node-type node (coerce-to-values res))
735 (maybe-terminate-block node nil)))))
737 (let ((fun (fun-info-optimizer kind)))
738 (unless (and fun (funcall fun node))
739 (dolist (x (fun-info-transforms kind))
741 (when *show-transforms-p*
742 (let* ((cont (basic-combination-fun node))
743 (fname (continuation-fun-name cont t)))
744 (/show "trying transform" x (transform-function x) "for" fname)))
745 (unless (ir1-transform node x)
747 (when *show-transforms-p*
748 (/show "quitting because IR1-TRANSFORM result was NIL"))
753 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
754 ;;; the block there, and link it to the component tail. We also change
755 ;;; the NODE's CONT to be a dummy continuation to prevent the use from
756 ;;; confusing things.
758 ;;; Except when called during IR1 convertion, we delete the
759 ;;; continuation if it has no other uses. (If it does have other uses,
762 ;;; Termination on the basis of a continuation type is
764 ;;; -- The continuation is deleted (hence the assertion is spurious), or
765 ;;; -- We are in IR1 conversion (where THE assertions are subject to
766 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
767 ;;; uses can(?) be added later. -- APD, 2003-07-17
768 (defun maybe-terminate-block (node ir1-converting-not-optimizing-p)
769 (declare (type (or basic-combination cast) node))
770 (let* ((block (node-block node))
771 (cont (node-cont node))
772 (tail (component-tail (block-component block)))
773 (succ (first (block-succ block))))
774 (unless (or (and (eq node (block-last block)) (eq succ tail))
775 (block-delete-p block))
776 (when (or (and (not (or ir1-converting-not-optimizing-p
777 (eq (continuation-kind cont) :deleted)))
778 (eq (continuation-derived-type cont) *empty-type*))
779 (eq (node-derived-type node) *empty-type*))
780 (cond (ir1-converting-not-optimizing-p
781 (delete-continuation-use node)
784 (aver (and (eq (block-last block) node)
785 (eq (continuation-kind cont) :block-start))))
787 (setf (block-last block) node)
788 (link-blocks block (continuation-starts-block cont)))))
790 (node-ends-block node)
791 (delete-continuation-use node)
792 (if (eq (continuation-kind cont) :unused)
793 (delete-continuation cont)
794 (reoptimize-continuation cont))))
796 (unlink-blocks block (first (block-succ block)))
797 (setf (component-reanalyze (block-component block)) t)
798 (aver (not (block-succ block)))
799 (link-blocks block tail)
800 (add-continuation-use node (make-continuation))
803 ;;; This is called both by IR1 conversion and IR1 optimization when
804 ;;; they have verified the type signature for the call, and are
805 ;;; wondering if something should be done to special-case the call. If
806 ;;; CALL is a call to a global function, then see whether it defined
808 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
809 ;;; the expansion and change the call to call it. Expansion is
810 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
811 ;;; true, we never expand, since this function has already been
812 ;;; converted. Local call analysis will duplicate the definition
813 ;;; if necessary. We claim that the parent form is LABELS for
814 ;;; context declarations, since we don't want it to be considered
815 ;;; a real global function.
816 ;;; -- If it is a known function, mark it as such by setting the KIND.
818 ;;; We return the leaf referenced (NIL if not a leaf) and the
819 ;;; FUN-INFO assigned.
820 (defun recognize-known-call (call ir1-converting-not-optimizing-p)
821 (declare (type combination call))
822 (let* ((ref (continuation-use (basic-combination-fun call)))
823 (leaf (when (ref-p ref) (ref-leaf ref)))
824 (inlinep (if (defined-fun-p leaf)
825 (defined-fun-inlinep leaf)
828 ((eq inlinep :notinline) (values nil nil))
829 ((not (and (global-var-p leaf)
830 (eq (global-var-kind leaf) :global-function)))
835 ((nil :maybe-inline) (policy call (zerop space))))
837 (defined-fun-inline-expansion leaf)
838 (let ((fun (defined-fun-functional leaf)))
840 (and (eq inlinep :inline) (functional-kind fun))))
841 (inline-expansion-ok call))
842 (flet (;; FIXME: Is this what the old CMU CL internal documentation
843 ;; called semi-inlining? A more descriptive name would
844 ;; be nice. -- WHN 2002-01-07
846 (let ((res (ir1-convert-lambda-for-defun
847 (defined-fun-inline-expansion leaf)
849 #'ir1-convert-inline-lambda)))
850 (setf (defined-fun-functional leaf) res)
851 (change-ref-leaf ref res))))
852 (if ir1-converting-not-optimizing-p
854 (with-ir1-environment-from-node call
856 (locall-analyze-component *current-component*))))
858 (values (ref-leaf (continuation-use (basic-combination-fun call)))
861 (let ((info (info :function :info (leaf-source-name leaf))))
863 (values leaf (setf (basic-combination-kind call) info))
864 (values leaf nil)))))))
866 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
867 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
868 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
869 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
870 ;;; syntax check, arg/result type processing, but still call
871 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
872 ;;; and that checking is done by local call analysis.
873 (defun validate-call-type (call type ir1-converting-not-optimizing-p)
874 (declare (type combination call) (type ctype type))
875 (cond ((not (fun-type-p type))
876 (aver (multiple-value-bind (val win)
877 (csubtypep type (specifier-type 'function))
879 (recognize-known-call call ir1-converting-not-optimizing-p))
880 ((valid-fun-use call type
881 :argument-test #'always-subtypep
882 :result-test #'always-subtypep
883 ;; KLUDGE: Common Lisp is such a dynamic
884 ;; language that all we can do here in
885 ;; general is issue a STYLE-WARNING. It
886 ;; would be nice to issue a full WARNING
887 ;; in the special case of of type
888 ;; mismatches within a compilation unit
889 ;; (as in section 3.2.2.3 of the spec)
890 ;; but at least as of sbcl-0.6.11, we
891 ;; don't keep track of whether the
892 ;; mismatched data came from the same
893 ;; compilation unit, so we can't do that.
896 ;; FIXME: Actually, I think we could
897 ;; issue a full WARNING if the call
898 ;; violates a DECLAIM FTYPE.
899 :lossage-fun #'compiler-style-warn
900 :unwinnage-fun #'compiler-notify)
901 (assert-call-type call type)
902 (maybe-terminate-block call ir1-converting-not-optimizing-p)
903 (recognize-known-call call ir1-converting-not-optimizing-p))
905 (setf (combination-kind call) :error)
908 ;;; This is called by IR1-OPTIMIZE when the function for a call has
909 ;;; changed. If the call is local, we try to LET-convert it, and
910 ;;; derive the result type. If it is a :FULL call, we validate it
911 ;;; against the type, which recognizes known calls, does inline
912 ;;; expansion, etc. If a call to a predicate in a non-conditional
913 ;;; position or to a function with a source transform, then we
914 ;;; reconvert the form to give IR1 another chance.
915 (defun propagate-fun-change (call)
916 (declare (type combination call))
917 (let ((*compiler-error-context* call)
918 (fun-cont (basic-combination-fun call)))
919 (setf (continuation-reoptimize fun-cont) nil)
920 (case (combination-kind call)
922 (let ((fun (combination-lambda call)))
923 (maybe-let-convert fun)
924 (unless (member (functional-kind fun) '(:let :assignment :deleted))
925 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
927 (multiple-value-bind (leaf info)
928 (validate-call-type call (continuation-type fun-cont) nil)
929 (cond ((functional-p leaf)
930 (convert-call-if-possible
931 (continuation-use (basic-combination-fun call))
934 ((and (leaf-has-source-name-p leaf)
935 (or (info :function :source-transform (leaf-source-name leaf))
937 (ir1-attributep (fun-info-attributes info)
939 (let ((dest (continuation-dest (node-cont call))))
940 (and dest (not (if-p dest)))))))
941 (let ((name (leaf-source-name leaf))
942 (dummies (make-gensym-list
943 (length (combination-args call)))))
946 (,@(if (symbolp name)
950 (leaf-source-name leaf)))))))))
953 ;;;; known function optimization
955 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
956 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
957 ;;; replace it, otherwise add a new one.
958 (defun record-optimization-failure (node transform args)
959 (declare (type combination node) (type transform transform)
960 (type (or fun-type list) args))
961 (let* ((table (component-failed-optimizations *component-being-compiled*))
962 (found (assoc transform (gethash node table))))
964 (setf (cdr found) args)
965 (push (cons transform args) (gethash node table))))
968 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
969 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
970 ;;; doing the transform for some reason and FLAME is true, then we
971 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
972 ;;; finalize to pick up. We return true if the transform failed, and
973 ;;; thus further transformation should be attempted. We return false
974 ;;; if either the transform succeeded or was aborted.
975 (defun ir1-transform (node transform)
976 (declare (type combination node) (type transform transform))
977 (let* ((type (transform-type transform))
978 (fun (transform-function transform))
979 (constrained (fun-type-p type))
980 (table (component-failed-optimizations *component-being-compiled*))
981 (flame (if (transform-important transform)
982 (policy node (>= speed inhibit-warnings))
983 (policy node (> speed inhibit-warnings))))
984 (*compiler-error-context* node))
985 (cond ((or (not constrained)
986 (valid-fun-use node type))
987 (multiple-value-bind (severity args)
988 (catch 'give-up-ir1-transform
991 (combination-fun-source-name node))
998 (setf (combination-kind node) :error)
1000 (apply #'compiler-warn args))
1001 (remhash node table)
1006 (record-optimization-failure node transform args))
1007 (setf (gethash node table)
1008 (remove transform (gethash node table) :key #'car)))
1011 (remhash node table)
1016 :argument-test #'types-equal-or-intersect
1017 :result-test #'values-types-equal-or-intersect))
1018 (record-optimization-failure node transform type)
1023 ;;; When we don't like an IR1 transform, we throw the severity/reason
1026 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1027 ;;; aborting this attempt to transform the call, but admitting the
1028 ;;; possibility that this or some other transform will later succeed.
1029 ;;; If arguments are supplied, they are format arguments for an
1030 ;;; efficiency note.
1032 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1033 ;;; force a normal call to the function at run time. No further
1034 ;;; optimizations will be attempted.
1036 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1037 ;;; delay the transform on the node until later. REASONS specifies
1038 ;;; when the transform will be later retried. The :OPTIMIZE reason
1039 ;;; causes the transform to be delayed until after the current IR1
1040 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1041 ;;; be delayed until after constraint propagation.
1043 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1044 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1045 ;;; do CASE operations on the various REASON values, it might be a
1046 ;;; good idea to go OO, representing the reasons by objects, using
1047 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1048 ;;; SIGNAL instead of THROW.
1049 (declaim (ftype (function (&rest t) nil) give-up-ir1-transform))
1050 (defun give-up-ir1-transform (&rest args)
1051 (throw 'give-up-ir1-transform (values :failure args)))
1052 (defun abort-ir1-transform (&rest args)
1053 (throw 'give-up-ir1-transform (values :aborted args)))
1054 (defun delay-ir1-transform (node &rest reasons)
1055 (let ((assoc (assoc node *delayed-ir1-transforms*)))
1057 (setf *delayed-ir1-transforms*
1058 (acons node reasons *delayed-ir1-transforms*))
1059 (throw 'give-up-ir1-transform :delayed))
1061 (dolist (reason reasons)
1062 (pushnew reason (cdr assoc)))
1063 (throw 'give-up-ir1-transform :delayed)))))
1065 ;;; Clear any delayed transform with no reasons - these should have
1066 ;;; been tried in the last pass. Then remove the reason from the
1067 ;;; delayed transform reasons, and if any become empty then set
1068 ;;; reoptimize flags for the node. Return true if any transforms are
1070 (defun retry-delayed-ir1-transforms (reason)
1071 (setf *delayed-ir1-transforms*
1072 (remove-if-not #'cdr *delayed-ir1-transforms*))
1073 (let ((reoptimize nil))
1074 (dolist (assoc *delayed-ir1-transforms*)
1075 (let ((reasons (remove reason (cdr assoc))))
1076 (setf (cdr assoc) reasons)
1078 (let ((node (car assoc)))
1079 (unless (node-deleted node)
1081 (setf (node-reoptimize node) t)
1082 (let ((block (node-block node)))
1083 (setf (block-reoptimize block) t)
1084 (setf (component-reoptimize (block-component block)) t)))))))
1087 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1088 ;;; environment, and then install it as the function for the call
1089 ;;; NODE. We do local call analysis so that the new function is
1090 ;;; integrated into the control flow.
1092 ;;; We require the original function source name in order to generate
1093 ;;; a meaningful debug name for the lambda we set up. (It'd be
1094 ;;; possible to do this starting from debug names as well as source
1095 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1096 ;;; generality, since source names are always known to our callers.)
1097 (defun transform-call (call res source-name)
1098 (declare (type combination call) (list res))
1099 (aver (and (legal-fun-name-p source-name)
1100 (not (eql source-name '.anonymous.))))
1101 (node-ends-block call)
1102 (with-ir1-environment-from-node call
1103 (with-component-last-block (*current-component*
1104 (block-next (node-block call)))
1105 (let ((new-fun (ir1-convert-inline-lambda
1107 :debug-name (debug-namify "LAMBDA-inlined ~A"
1110 "<unknown function>"))))
1111 (ref (continuation-use (combination-fun call))))
1112 (change-ref-leaf ref new-fun)
1113 (setf (combination-kind call) :full)
1114 (locall-analyze-component *current-component*))))
1117 ;;; Replace a call to a foldable function of constant arguments with
1118 ;;; the result of evaluating the form. If there is an error during the
1119 ;;; evaluation, we give a warning and leave the call alone, making the
1120 ;;; call a :ERROR call.
1122 ;;; If there is more than one value, then we transform the call into a
1125 ;;; An old commentary also said:
1127 ;;; We insert the resulting constant node after the call, stealing
1128 ;;; the call's continuation. We give the call a continuation with no
1129 ;;; DEST, which should cause it and its arguments to go away.
1131 ;;; This seems to be more efficient, than the current code. Maybe we
1132 ;;; should really implement it? -- APD, 2002-12-23
1133 (defun constant-fold-call (call)
1134 (let ((args (mapcar #'continuation-value (combination-args call)))
1135 (fun-name (combination-fun-source-name call)))
1136 (multiple-value-bind (values win)
1137 (careful-call fun-name
1140 ;; Note: CMU CL had COMPILER-WARN here, and that
1141 ;; seems more natural, but it's probably not.
1143 ;; It's especially not while bug 173 exists:
1146 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1148 ;; can cause constant-folding TYPE-ERRORs (in
1149 ;; #'<=) when END can be proved to be NIL, even
1150 ;; though the code is perfectly legal and safe
1151 ;; because a NIL value of END means that the
1152 ;; #'<= will never be executed.
1154 ;; Moreover, even without bug 173,
1155 ;; quite-possibly-valid code like
1156 ;; (COND ((NONINLINED-PREDICATE END)
1157 ;; (UNLESS (<= END SIZE))
1159 ;; (where NONINLINED-PREDICATE is something the
1160 ;; compiler can't do at compile time, but which
1161 ;; turns out to make the #'<= expression
1162 ;; unreachable when END=NIL) could cause errors
1163 ;; when the compiler tries to constant-fold (<=
1166 ;; So, with or without bug 173, it'd be
1167 ;; unnecessarily evil to do a full
1168 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1169 ;; from COMPILE-FILE) for legal code, so we we
1170 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1171 #'compiler-style-warn
1174 (setf (combination-kind call) :error))
1175 ((and (proper-list-of-length-p values 1)
1176 (eq (continuation-kind (node-cont call)) :inside-block))
1177 (with-ir1-environment-from-node call
1178 (let* ((cont (node-cont call))
1179 (next (continuation-next cont))
1180 (prev (make-continuation)))
1181 (delete-continuation-use call)
1182 (add-continuation-use call prev)
1183 (reference-constant prev cont (first values))
1184 (setf (continuation-next cont) next)
1185 ;; FIXME: type checking?
1186 (reoptimize-continuation cont)
1187 (reoptimize-continuation prev)
1188 (flush-combination call))))
1189 (t (let ((dummies (make-gensym-list (length args))))
1193 (declare (ignore ,@dummies))
1194 (values ,@(mapcar (lambda (x) `',x) values)))
1198 ;;;; local call optimization
1200 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1201 ;;; the leaf type is a function type, then just leave it alone, since
1202 ;;; TYPE is never going to be more specific than that (and
1203 ;;; TYPE-INTERSECTION would choke.)
1204 (defun propagate-to-refs (leaf type)
1205 (declare (type leaf leaf) (type ctype type))
1206 (let ((var-type (leaf-type leaf)))
1207 (unless (fun-type-p var-type)
1208 (let ((int (type-approx-intersection2 var-type type)))
1209 (when (type/= int var-type)
1210 (setf (leaf-type leaf) int)
1211 (dolist (ref (leaf-refs leaf))
1212 (derive-node-type ref (make-single-value-type int))
1213 (let* ((cont (node-cont ref))
1214 (dest (continuation-dest cont)))
1215 ;; KLUDGE: LET var substitution
1216 (when (combination-p dest)
1217 (reoptimize-continuation cont))))))
1220 ;;; Iteration variable: exactly one SETQ of the form:
1222 ;;; (let ((var initial))
1224 ;;; (setq var (+ var step))
1226 (defun maybe-infer-iteration-var-type (var initial-type)
1227 (binding* ((sets (lambda-var-sets var) :exit-if-null)
1229 (() (null (rest sets)) :exit-if-null)
1230 (set-use (principal-continuation-use (set-value set)))
1231 (() (and (combination-p set-use)
1232 (fun-info-p (combination-kind set-use))
1233 (eq (combination-fun-source-name set-use) '+))
1235 (+-args (basic-combination-args set-use))
1236 (() (and (proper-list-of-length-p +-args 2 2)
1237 (let ((first (principal-continuation-use
1240 (eq (ref-leaf first) var))))
1242 (step-type (continuation-type (second +-args)))
1243 (set-type (continuation-type (set-value set))))
1244 (when (and (numeric-type-p initial-type)
1245 (numeric-type-p step-type)
1246 (numeric-type-equal initial-type step-type))
1247 (multiple-value-bind (low high)
1248 (cond ((csubtypep step-type (specifier-type '(real 0 *)))
1249 (values (numeric-type-low initial-type)
1250 (when (and (numeric-type-p set-type)
1251 (numeric-type-equal set-type initial-type))
1252 (numeric-type-high set-type))))
1253 ((csubtypep step-type (specifier-type '(real * 0)))
1254 (values (when (and (numeric-type-p set-type)
1255 (numeric-type-equal set-type initial-type))
1256 (numeric-type-low set-type))
1257 (numeric-type-high initial-type)))
1260 (modified-numeric-type initial-type
1263 :enumerable nil)))))
1264 (deftransform + ((x y) * * :result result)
1265 "check for iteration variable reoptimization"
1266 (let ((dest (principal-continuation-end result))
1267 (use (principal-continuation-use x)))
1268 (when (and (ref-p use)
1272 (reoptimize-continuation (set-value dest))))
1273 (give-up-ir1-transform))
1275 ;;; Figure out the type of a LET variable that has sets. We compute
1276 ;;; the union of the INITIAL-TYPE and the types of all the set
1277 ;;; values and to a PROPAGATE-TO-REFS with this type.
1278 (defun propagate-from-sets (var initial-type)
1279 (collect ((res initial-type type-union))
1280 (dolist (set (basic-var-sets var))
1281 (let ((type (continuation-type (set-value set))))
1283 (when (node-reoptimize set)
1284 (derive-node-type set (make-single-value-type type))
1285 (setf (node-reoptimize set) nil))))
1287 (awhen (maybe-infer-iteration-var-type var initial-type)
1289 (propagate-to-refs var res)))
1292 ;;; If a LET variable, find the initial value's type and do
1293 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1295 (defun ir1-optimize-set (node)
1296 (declare (type cset node))
1297 (let ((var (set-var node)))
1298 (when (and (lambda-var-p var) (leaf-refs var))
1299 (let ((home (lambda-var-home var)))
1300 (when (eq (functional-kind home) :let)
1301 (let* ((initial-value (let-var-initial-value var))
1302 (initial-type (continuation-type initial-value)))
1303 (setf (continuation-reoptimize initial-value) nil)
1304 (propagate-from-sets var initial-type))))))
1306 (derive-node-type node (make-single-value-type
1307 (continuation-type (set-value node))))
1310 ;;; Return true if the value of REF will always be the same (and is
1311 ;;; thus legal to substitute.)
1312 (defun constant-reference-p (ref)
1313 (declare (type ref ref))
1314 (let ((leaf (ref-leaf ref)))
1316 ((or constant functional) t)
1318 (null (lambda-var-sets leaf)))
1320 (not (eq (defined-fun-inlinep leaf) :notinline)))
1322 (case (global-var-kind leaf)
1324 (let ((name (leaf-source-name leaf)))
1326 (eq (symbol-package (fun-name-block-name name))
1328 (info :function :info name)))))))))
1330 ;;; If we have a non-set LET var with a single use, then (if possible)
1331 ;;; replace the variable reference's CONT with the arg continuation.
1332 ;;; This is inhibited when:
1333 ;;; -- CONT has other uses, or
1334 ;;; -- the reference is in a different environment from the variable, or
1335 ;;; -- CONT carries unknown number of values, or
1336 ;;; -- DEST is return or exit, or
1337 ;;; -- DEST is sensitive to the number of values and ARG return non-one value.
1339 ;;; We change the REF to be a reference to NIL with unused value, and
1340 ;;; let it be flushed as dead code. A side effect of this substitution
1341 ;;; is to delete the variable.
1342 (defun substitute-single-use-continuation (arg var)
1343 (declare (type continuation arg) (type lambda-var var))
1344 (let* ((ref (first (leaf-refs var)))
1345 (cont (node-cont ref))
1346 (dest (continuation-dest cont)))
1347 (when (and (eq (continuation-use cont) ref)
1351 (and (type-single-value-p (continuation-derived-type arg))
1352 (multiple-value-bind (pdest pprev)
1353 (principal-continuation-end cont)
1354 (declare (ignore pdest))
1355 (continuation-single-value-p pprev))))
1357 (or (eq (basic-combination-fun dest) cont)
1358 (and (eq (basic-combination-kind dest) :local)
1359 (type-single-value-p (continuation-derived-type arg)))))
1363 ;; (AVER (CONTINUATION-SINGLE-VALUE-P CONT))
1365 (eq (node-home-lambda ref)
1366 (lambda-home (lambda-var-home var))))
1367 (aver (member (continuation-kind arg)
1368 '(:block-start :deleted-block-start :inside-block)))
1369 (setf (node-derived-type ref) *wild-type*)
1370 (change-ref-leaf ref (find-constant nil))
1371 (substitute-continuation arg cont)
1372 (reoptimize-continuation arg)
1375 ;;; Delete a LET, removing the call and bind nodes, and warning about
1376 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1377 ;;; along right away and delete the REF and then the lambda, since we
1378 ;;; flush the FUN continuation.
1379 (defun delete-let (clambda)
1380 (declare (type clambda clambda))
1381 (aver (functional-letlike-p clambda))
1382 (note-unreferenced-vars clambda)
1383 (let ((call (let-combination clambda)))
1384 (flush-dest (basic-combination-fun call))
1386 (unlink-node (lambda-bind clambda))
1387 (setf (lambda-bind clambda) nil))
1390 ;;; This function is called when one of the arguments to a LET
1391 ;;; changes. We look at each changed argument. If the corresponding
1392 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1393 ;;; consider substituting for the variable, and also propagate
1394 ;;; derived-type information for the arg to all the VAR's refs.
1396 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1397 ;;; subtype of the argument's leaf type. This prevents type checking
1398 ;;; from being defeated, and also ensures that the best representation
1399 ;;; for the variable can be used.
1401 ;;; Substitution of individual references is inhibited if the
1402 ;;; reference is in a different component from the home. This can only
1403 ;;; happen with closures over top level lambda vars. In such cases,
1404 ;;; the references may have already been compiled, and thus can't be
1405 ;;; retroactively modified.
1407 ;;; If all of the variables are deleted (have no references) when we
1408 ;;; are done, then we delete the LET.
1410 ;;; Note that we are responsible for clearing the
1411 ;;; CONTINUATION-REOPTIMIZE flags.
1412 (defun propagate-let-args (call fun)
1413 (declare (type combination call) (type clambda fun))
1414 (loop for arg in (combination-args call)
1415 and var in (lambda-vars fun) do
1416 (when (and arg (continuation-reoptimize arg))
1417 (setf (continuation-reoptimize arg) nil)
1419 ((lambda-var-sets var)
1420 (propagate-from-sets var (continuation-type arg)))
1421 ((let ((use (continuation-use arg)))
1423 (let ((leaf (ref-leaf use)))
1424 (when (and (constant-reference-p use)
1425 (csubtypep (leaf-type leaf)
1426 ;; (NODE-DERIVED-TYPE USE) would
1427 ;; be better -- APD, 2003-05-15
1429 (propagate-to-refs var (continuation-type arg))
1430 (let ((use-component (node-component use)))
1433 (cond ((eq (node-component ref) use-component)
1436 (aver (lambda-toplevelish-p (lambda-home fun)))
1440 ((and (null (rest (leaf-refs var)))
1441 (substitute-single-use-continuation arg var)))
1443 (propagate-to-refs var (continuation-type arg))))))
1445 (when (every #'not (combination-args call))
1450 ;;; This function is called when one of the args to a non-LET local
1451 ;;; call changes. For each changed argument corresponding to an unset
1452 ;;; variable, we compute the union of the types across all calls and
1453 ;;; propagate this type information to the var's refs.
1455 ;;; If the function has an XEP, then we don't do anything, since we
1456 ;;; won't discover anything.
1458 ;;; We can clear the CONTINUATION-REOPTIMIZE flags for arguments in
1459 ;;; all calls corresponding to changed arguments in CALL, since the
1460 ;;; only use in IR1 optimization of the REOPTIMIZE flag for local call
1461 ;;; args is right here.
1462 (defun propagate-local-call-args (call fun)
1463 (declare (type combination call) (type clambda fun))
1465 (unless (or (functional-entry-fun fun)
1466 (lambda-optional-dispatch fun))
1467 (let* ((vars (lambda-vars fun))
1468 (union (mapcar (lambda (arg var)
1470 (continuation-reoptimize arg)
1471 (null (basic-var-sets var)))
1472 (continuation-type arg)))
1473 (basic-combination-args call)
1475 (this-ref (continuation-use (basic-combination-fun call))))
1477 (dolist (arg (basic-combination-args call))
1479 (setf (continuation-reoptimize arg) nil)))
1481 (dolist (ref (leaf-refs fun))
1482 (let ((dest (continuation-dest (node-cont ref))))
1483 (unless (or (eq ref this-ref) (not dest))
1485 (mapcar (lambda (this-arg old)
1487 (setf (continuation-reoptimize this-arg) nil)
1488 (type-union (continuation-type this-arg) old)))
1489 (basic-combination-args dest)
1492 (mapc (lambda (var type)
1494 (propagate-to-refs var type)))
1499 ;;;; multiple values optimization
1501 ;;; Do stuff to notice a change to a MV combination node. There are
1502 ;;; two main branches here:
1503 ;;; -- If the call is local, then it is already a MV let, or should
1504 ;;; become one. Note that although all :LOCAL MV calls must eventually
1505 ;;; be converted to :MV-LETs, there can be a window when the call
1506 ;;; is local, but has not been LET converted yet. This is because
1507 ;;; the entry-point lambdas may have stray references (in other
1508 ;;; entry points) that have not been deleted yet.
1509 ;;; -- The call is full. This case is somewhat similar to the non-MV
1510 ;;; combination optimization: we propagate return type information and
1511 ;;; notice non-returning calls. We also have an optimization
1512 ;;; which tries to convert MV-CALLs into MV-binds.
1513 (defun ir1-optimize-mv-combination (node)
1514 (ecase (basic-combination-kind node)
1516 (let ((fun-cont (basic-combination-fun node)))
1517 (when (continuation-reoptimize fun-cont)
1518 (setf (continuation-reoptimize fun-cont) nil)
1519 (maybe-let-convert (combination-lambda node))))
1520 (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1521 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1522 (unless (convert-mv-bind-to-let node)
1523 (ir1-optimize-mv-bind node))))
1525 (let* ((fun (basic-combination-fun node))
1526 (fun-changed (continuation-reoptimize fun))
1527 (args (basic-combination-args node)))
1529 (setf (continuation-reoptimize fun) nil)
1530 (let ((type (continuation-type fun)))
1531 (when (fun-type-p type)
1532 (derive-node-type node (fun-type-returns type))))
1533 (maybe-terminate-block node nil)
1534 (let ((use (continuation-use fun)))
1535 (when (and (ref-p use) (functional-p (ref-leaf use)))
1536 (convert-call-if-possible use node)
1537 (when (eq (basic-combination-kind node) :local)
1538 (maybe-let-convert (ref-leaf use))))))
1539 (unless (or (eq (basic-combination-kind node) :local)
1540 (eq (continuation-fun-name fun) '%throw))
1541 (ir1-optimize-mv-call node))
1543 (setf (continuation-reoptimize arg) nil))))
1547 ;;; Propagate derived type info from the values continuation to the
1549 (defun ir1-optimize-mv-bind (node)
1550 (declare (type mv-combination node))
1551 (let* ((arg (first (basic-combination-args node)))
1552 (vars (lambda-vars (combination-lambda node)))
1553 (n-vars (length vars))
1554 (types (values-type-in (continuation-derived-type arg)
1556 (loop for var in vars
1558 do (if (basic-var-sets var)
1559 (propagate-from-sets var type)
1560 (propagate-to-refs var type)))
1561 (setf (continuation-reoptimize arg) nil))
1564 ;;; If possible, convert a general MV call to an MV-BIND. We can do
1566 ;;; -- The call has only one argument, and
1567 ;;; -- The function has a known fixed number of arguments, or
1568 ;;; -- The argument yields a known fixed number of values.
1570 ;;; What we do is change the function in the MV-CALL to be a lambda
1571 ;;; that "looks like an MV bind", which allows
1572 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1573 ;;; converted (the next time around.) This new lambda just calls the
1574 ;;; actual function with the MV-BIND variables as arguments. Note that
1575 ;;; this new MV bind is not let-converted immediately, as there are
1576 ;;; going to be stray references from the entry-point functions until
1577 ;;; they get deleted.
1579 ;;; In order to avoid loss of argument count checking, we only do the
1580 ;;; transformation according to a known number of expected argument if
1581 ;;; safety is unimportant. We can always convert if we know the number
1582 ;;; of actual values, since the normal call that we build will still
1583 ;;; do any appropriate argument count checking.
1585 ;;; We only attempt the transformation if the called function is a
1586 ;;; constant reference. This allows us to just splice the leaf into
1587 ;;; the new function, instead of trying to somehow bind the function
1588 ;;; expression. The leaf must be constant because we are evaluating it
1589 ;;; again in a different place. This also has the effect of squelching
1590 ;;; multiple warnings when there is an argument count error.
1591 (defun ir1-optimize-mv-call (node)
1592 (let ((fun (basic-combination-fun node))
1593 (*compiler-error-context* node)
1594 (ref (continuation-use (basic-combination-fun node)))
1595 (args (basic-combination-args node)))
1597 (unless (and (ref-p ref) (constant-reference-p ref)
1599 (return-from ir1-optimize-mv-call))
1601 (multiple-value-bind (min max)
1602 (fun-type-nargs (continuation-type fun))
1604 (multiple-value-bind (types nvals)
1605 (values-types (continuation-derived-type (first args)))
1606 (declare (ignore types))
1607 (if (eq nvals :unknown) nil nvals))))
1610 (when (and min (< total-nvals min))
1612 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1615 (setf (basic-combination-kind node) :error)
1616 (return-from ir1-optimize-mv-call))
1617 (when (and max (> total-nvals max))
1619 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1622 (setf (basic-combination-kind node) :error)
1623 (return-from ir1-optimize-mv-call)))
1625 (let ((count (cond (total-nvals)
1626 ((and (policy node (zerop verify-arg-count))
1631 (with-ir1-environment-from-node node
1632 (let* ((dums (make-gensym-list count))
1634 (fun (ir1-convert-lambda
1635 `(lambda (&optional ,@dums &rest ,ignore)
1636 (declare (ignore ,ignore))
1637 (funcall ,(ref-leaf ref) ,@dums)))))
1638 (change-ref-leaf ref fun)
1639 (aver (eq (basic-combination-kind node) :full))
1640 (locall-analyze-component *current-component*)
1641 (aver (eq (basic-combination-kind node) :local)))))))))
1645 ;;; (multiple-value-bind
1654 ;;; What we actually do is convert the VALUES combination into a
1655 ;;; normal LET combination calling the original :MV-LET lambda. If
1656 ;;; there are extra args to VALUES, discard the corresponding
1657 ;;; continuations. If there are insufficient args, insert references
1659 (defun convert-mv-bind-to-let (call)
1660 (declare (type mv-combination call))
1661 (let* ((arg (first (basic-combination-args call)))
1662 (use (continuation-use arg)))
1663 (when (and (combination-p use)
1664 (eq (continuation-fun-name (combination-fun use))
1666 (let* ((fun (combination-lambda call))
1667 (vars (lambda-vars fun))
1668 (vals (combination-args use))
1669 (nvars (length vars))
1670 (nvals (length vals)))
1671 (cond ((> nvals nvars)
1672 (mapc #'flush-dest (subseq vals nvars))
1673 (setq vals (subseq vals 0 nvars)))
1675 (with-ir1-environment-from-node use
1676 (let ((node-prev (node-prev use)))
1677 (setf (node-prev use) nil)
1678 (setf (continuation-next node-prev) nil)
1679 (collect ((res vals))
1680 (loop for cont = (make-continuation use)
1681 and prev = node-prev then cont
1682 repeat (- nvars nvals)
1683 do (reference-constant prev cont nil)
1686 (link-node-to-previous-continuation use
1687 (car (last vals)))))))
1688 (setf (combination-args use) vals)
1689 (flush-dest (combination-fun use))
1690 (let ((fun-cont (basic-combination-fun call)))
1691 (setf (continuation-dest fun-cont) use)
1692 (setf (combination-fun use) fun-cont)
1693 (flush-continuation-externally-checkable-type fun-cont))
1694 (setf (combination-kind use) :local)
1695 (setf (functional-kind fun) :let)
1696 (flush-dest (first (basic-combination-args call)))
1699 (reoptimize-continuation (first vals)))
1700 (propagate-to-args use fun)
1701 (reoptimize-call use))
1705 ;;; (values-list (list x y z))
1710 ;;; In implementation, this is somewhat similar to
1711 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1712 ;;; args of the VALUES-LIST call, flushing the old argument
1713 ;;; continuation (allowing the LIST to be flushed.)
1715 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
1716 (defoptimizer (values-list optimizer) ((list) node)
1717 (let ((use (continuation-use list)))
1718 (when (and (combination-p use)
1719 (eq (continuation-fun-name (combination-fun use))
1722 ;; FIXME: VALUES might not satisfy an assertion on NODE-CONT.
1723 (change-ref-leaf (continuation-use (combination-fun node))
1724 (find-free-fun 'values "in a strange place"))
1725 (setf (combination-kind node) :full)
1726 (let ((args (combination-args use)))
1728 (setf (continuation-dest arg) node)
1729 (flush-continuation-externally-checkable-type arg))
1730 (setf (combination-args use) nil)
1732 (setf (combination-args node) args))
1735 ;;; If VALUES appears in a non-MV context, then effectively convert it
1736 ;;; to a PROG1. This allows the computation of the additional values
1737 ;;; to become dead code.
1738 (deftransform values ((&rest vals) * * :node node)
1739 (unless (continuation-single-value-p (node-cont node))
1740 (give-up-ir1-transform))
1741 (setf (node-derived-type node) *wild-type*)
1742 (principal-continuation-single-valuify (node-cont node))
1744 (let ((dummies (make-gensym-list (length (cdr vals)))))
1745 `(lambda (val ,@dummies)
1746 (declare (ignore ,@dummies))
1752 (defun ir1-optimize-cast (cast &optional do-not-optimize)
1753 (declare (type cast cast))
1754 (let* ((value (cast-value cast))
1755 (value-type (continuation-derived-type value))
1756 (cont (node-cont cast))
1757 (dest (continuation-dest cont))
1758 (atype (cast-asserted-type cast))
1759 (int (values-type-intersection value-type atype)))
1760 (derive-node-type cast int)
1761 (when (eq int *empty-type*)
1762 (unless (eq value-type *empty-type*)
1764 ;; FIXME: Do it in one step.
1765 (filter-continuation
1767 `(multiple-value-call #'list 'dummy))
1768 (filter-continuation
1770 ;; FIXME: Derived type.
1771 `(%compile-time-type-error 'dummy
1772 ',(type-specifier atype)
1773 ',(type-specifier value-type)))
1774 ;; KLUDGE: FILTER-CONTINUATION does not work for
1775 ;; non-returning functions, so we declare the return type of
1776 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
1778 (derive-node-type (continuation-use value) *empty-type*)
1779 (maybe-terminate-block (continuation-use value) nil)
1780 ;; FIXME: Is it necessary?
1781 (aver (null (block-pred (node-block cast))))
1782 (setf (block-delete-p (node-block cast)) t)
1783 (return-from ir1-optimize-cast)))
1784 (when (eq (node-derived-type cast) *empty-type*)
1785 (maybe-terminate-block cast nil))
1787 (when (and (not do-not-optimize)
1788 (values-subtypep value-type
1789 (cast-asserted-type cast)))
1790 (delete-filter cast cont value)
1791 (reoptimize-continuation cont)
1792 (when (continuation-single-value-p cont)
1793 (note-single-valuified-continuation cont))
1795 (reoptimize-continuation-uses cont))
1796 (return-from ir1-optimize-cast t))
1798 (when (and (not do-not-optimize)
1799 (not (continuation-use value))
1802 (do-uses (use value)
1803 (when (and (values-subtypep (node-derived-type use) atype)
1804 (immediately-used-p value use))
1805 (ensure-block-start cont)
1806 (delete-continuation-use use)
1807 (add-continuation-use use cont)
1808 (unlink-blocks (node-block use) (node-block cast))
1809 (link-blocks (node-block use) (continuation-block cont))
1810 (when (and (return-p dest)
1811 (basic-combination-p use)
1812 (eq (basic-combination-kind use) :local))
1814 (dolist (use (merges))
1815 (merge-tail-sets use))))
1817 (when (and (cast-%type-check cast)
1818 (values-subtypep value-type
1819 (cast-type-to-check cast)))
1820 (setf (cast-%type-check cast) nil)))
1822 (unless do-not-optimize
1823 (setf (node-reoptimize cast) nil)))