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 an LVAR whose sole use is a reference to a
23 (defun constant-lvar-p (thing)
25 (let ((use (principal-lvar-use thing)))
26 (and (ref-p use) (constant-p (ref-leaf use))))))
28 ;;; Return the constant value for an LVAR whose only use is a constant
30 (declaim (ftype (function (lvar) t) lvar-value))
31 (defun lvar-value (lvar)
32 (let ((use (principal-lvar-use lvar)))
33 (constant-value (ref-leaf use))))
35 ;;;; interface for obtaining results of type inference
37 ;;; Our best guess for the type of this lvar's value. Note that this
38 ;;; may be VALUES or FUNCTION type, which cannot be passed as an
39 ;;; argument to the normal type operations. See LVAR-TYPE.
41 ;;; The result value is cached in the LVAR-%DERIVED-TYPE slot. If the
42 ;;; slot is true, just return that value, otherwise recompute and
43 ;;; stash the value there.
44 #!-sb-fluid (declaim (inline lvar-derived-type))
45 (defun lvar-derived-type (lvar)
46 (declare (type lvar lvar))
47 (or (lvar-%derived-type lvar)
48 (setf (lvar-%derived-type lvar)
49 (%lvar-derived-type lvar))))
50 (defun %lvar-derived-type (lvar)
51 (declare (type lvar lvar))
52 (let ((uses (lvar-uses lvar)))
53 (cond ((null uses) *empty-type*)
55 (do ((res (node-derived-type (first uses))
56 (values-type-union (node-derived-type (first current))
58 (current (rest uses) (rest current)))
59 ((null current) res)))
61 (node-derived-type (lvar-uses lvar))))))
63 ;;; Return the derived type for LVAR's first value. This is guaranteed
64 ;;; not to be a VALUES or FUNCTION type.
65 (declaim (ftype (sfunction (lvar) ctype) lvar-type))
66 (defun lvar-type (lvar)
67 (single-value-type (lvar-derived-type lvar)))
69 ;;; If LVAR is an argument of a function, return a type which the
70 ;;; function checks LVAR for.
71 #!-sb-fluid (declaim (inline lvar-externally-checkable-type))
72 (defun lvar-externally-checkable-type (lvar)
73 (or (lvar-%externally-checkable-type lvar)
74 (%lvar-%externally-checkable-type lvar)))
75 (defun %lvar-%externally-checkable-type (lvar)
76 (declare (type lvar lvar))
77 (let ((dest (lvar-dest lvar)))
78 (if (not (and dest (combination-p dest)))
79 ;; TODO: MV-COMBINATION
80 (setf (lvar-%externally-checkable-type lvar) *wild-type*)
81 (let* ((fun (combination-fun dest))
82 (args (combination-args dest))
83 (fun-type (lvar-type fun)))
84 (setf (lvar-%externally-checkable-type fun) *wild-type*)
85 (if (or (not (call-full-like-p dest))
86 (not (fun-type-p fun-type))
87 ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)).
88 (fun-type-wild-args fun-type))
91 (setf (lvar-%externally-checkable-type arg)
93 (map-combination-args-and-types
95 (setf (lvar-%externally-checkable-type arg)
96 (acond ((lvar-%externally-checkable-type arg)
97 (values-type-intersection
98 it (coerce-to-values type)))
99 (t (coerce-to-values type)))))
101 (lvar-%externally-checkable-type lvar))
102 #!-sb-fluid(declaim (inline flush-lvar-externally-checkable-type))
103 (defun flush-lvar-externally-checkable-type (lvar)
104 (declare (type lvar lvar))
105 (setf (lvar-%externally-checkable-type lvar) nil))
107 ;;;; interface routines used by optimizers
109 ;;; This function is called by optimizers to indicate that something
110 ;;; interesting has happened to the value of LVAR. Optimizers must
111 ;;; make sure that they don't call for reoptimization when nothing has
112 ;;; happened, since optimization will fail to terminate.
114 ;;; We clear any cached type for the lvar and set the reoptimize flags
115 ;;; on everything in sight.
116 (defun reoptimize-lvar (lvar)
117 (declare (type (or lvar null) lvar))
119 (setf (lvar-%derived-type lvar) nil)
120 (let ((dest (lvar-dest lvar)))
122 (setf (lvar-reoptimize lvar) t)
123 (setf (node-reoptimize dest) t)
124 (binding* (;; Since this may be called during IR1 conversion,
125 ;; PREV may be missing.
126 (prev (node-prev dest) :exit-if-null)
127 (block (ctran-block prev))
128 (component (block-component block)))
129 (when (typep dest 'cif)
130 (setf (block-test-modified block) t))
131 (setf (block-reoptimize block) t)
132 (setf (component-reoptimize component) t))))
134 (setf (block-type-check (node-block node)) t)))
137 (defun reoptimize-lvar-uses (lvar)
138 (declare (type lvar lvar))
140 (setf (node-reoptimize use) t)
141 (setf (block-reoptimize (node-block use)) t)
142 (setf (component-reoptimize (node-component use)) t)))
144 ;;; Annotate NODE to indicate that its result has been proven to be
145 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
146 ;;; only correct way to supply information discovered about a node's
147 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
148 ;;; information may be lost and reoptimization may not happen.
150 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
151 ;;; intersection is different from the old type, then we do a
152 ;;; REOPTIMIZE-LVAR on the NODE-LVAR.
153 (defun derive-node-type (node rtype)
154 (declare (type valued-node node) (type ctype rtype))
155 (let ((node-type (node-derived-type node)))
156 (unless (eq node-type rtype)
157 (let ((int (values-type-intersection node-type rtype))
158 (lvar (node-lvar node)))
159 (when (type/= node-type int)
160 (when (and *check-consistency*
161 (eq int *empty-type*)
162 (not (eq rtype *empty-type*)))
163 (let ((*compiler-error-context* node))
165 "New inferred type ~S conflicts with old type:~
166 ~% ~S~%*** possible internal error? Please report this."
167 (type-specifier rtype) (type-specifier node-type))))
168 (setf (node-derived-type node) int)
169 ;; If the new type consists of only one object, replace the
170 ;; node with a constant reference.
171 (when (and (ref-p node)
172 (lambda-var-p (ref-leaf node)))
173 (let ((type (single-value-type int)))
174 (when (and (member-type-p type)
175 (null (rest (member-type-members type))))
176 (change-ref-leaf node (find-constant
177 (first (member-type-members type)))))))
178 (reoptimize-lvar lvar)))))
181 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
182 ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it
183 ;;; splitting off DEST a new CAST node; old LVAR will deliver values
184 ;;; to CAST. If we improve the assertion, we set TYPE-CHECK and
185 ;;; TYPE-ASSERTED to guarantee that the new assertion will be checked.
186 (defun assert-lvar-type (lvar type policy)
187 (declare (type lvar lvar) (type ctype type))
188 (unless (values-subtypep (lvar-derived-type lvar) type)
189 (let* ((dest (lvar-dest lvar))
190 (ctran (node-prev dest)))
191 (with-ir1-environment-from-node dest
192 (let* ((cast (make-cast lvar type policy))
193 (internal-lvar (make-lvar))
194 (internal-ctran (make-ctran)))
195 (setf (ctran-next ctran) cast
196 (node-prev cast) ctran)
197 (use-continuation cast internal-ctran internal-lvar)
198 (link-node-to-previous-ctran dest internal-ctran)
199 (substitute-lvar internal-lvar lvar)
200 (setf (lvar-dest lvar) cast)
201 (reoptimize-lvar lvar)
202 (when (return-p dest)
203 (node-ends-block cast))
204 (setf (block-attributep (block-flags (node-block cast))
205 type-check type-asserted)
211 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
212 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
213 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
214 ;;; we are done, then another iteration would be beneficial.
215 (defun ir1-optimize (component)
216 (declare (type component component))
217 (setf (component-reoptimize component) nil)
218 (do-blocks (block component)
220 ;; We delete blocks when there is either no predecessor or the
221 ;; block is in a lambda that has been deleted. These blocks
222 ;; would eventually be deleted by DFO recomputation, but doing
223 ;; it here immediately makes the effect available to IR1
225 ((or (block-delete-p block)
226 (null (block-pred block)))
227 (delete-block block))
228 ((eq (functional-kind (block-home-lambda block)) :deleted)
229 ;; Preserve the BLOCK-SUCC invariant that almost every block has
230 ;; one successor (and a block with DELETE-P set is an acceptable
232 (mark-for-deletion block)
233 (delete-block block))
236 (let ((succ (block-succ block)))
237 (unless (singleton-p succ)
240 (let ((last (block-last block)))
243 (flush-dest (if-test last))
244 (when (unlink-node last)
247 (when (maybe-delete-exit last)
250 (unless (join-successor-if-possible block)
253 (when (and (block-reoptimize block) (block-component block))
254 (aver (not (block-delete-p block)))
255 (ir1-optimize-block block))
257 (cond ((and (block-delete-p block) (block-component block))
258 (delete-block block))
259 ((and (block-flush-p block) (block-component block))
260 (flush-dead-code block))))))
264 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
267 ;;; Note that although they are cleared here, REOPTIMIZE flags might
268 ;;; still be set upon return from this function, meaning that further
269 ;;; optimization is wanted (as a consequence of optimizations we did).
270 (defun ir1-optimize-block (block)
271 (declare (type cblock block))
272 ;; We clear the node and block REOPTIMIZE flags before doing the
273 ;; optimization, not after. This ensures that the node or block will
274 ;; be reoptimized if necessary.
275 (setf (block-reoptimize block) nil)
276 (do-nodes (node nil block :restart-p t)
277 (when (node-reoptimize node)
278 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
279 (setf (node-reoptimize node) nil)
283 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
284 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
285 ;; any argument changes.
286 (ir1-optimize-combination node))
288 (ir1-optimize-if node))
290 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
291 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
292 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
294 (setf (node-reoptimize node) t)
295 (ir1-optimize-return node))
297 (ir1-optimize-mv-combination node))
299 ;; With an EXIT, we derive the node's type from the VALUE's
301 (let ((value (exit-value node)))
303 (derive-node-type node (lvar-derived-type value)))))
305 (ir1-optimize-set node))
307 (ir1-optimize-cast node)))))
311 ;;; Try to join with a successor block. If we succeed, we return true,
313 (defun join-successor-if-possible (block)
314 (declare (type cblock block))
315 (let ((next (first (block-succ block))))
316 (when (block-start next) ; NEXT is not an END-OF-COMPONENT marker
317 (cond ( ;; We cannot combine with a successor block if:
319 ;; The successor has more than one predecessor.
320 (rest (block-pred next))
321 ;; The successor is the current block (infinite loop).
323 ;; The next block has a different cleanup, and thus
324 ;; we may want to insert cleanup code between the
325 ;; two blocks at some point.
326 (not (eq (block-end-cleanup block)
327 (block-start-cleanup next)))
328 ;; The next block has a different home lambda, and
329 ;; thus the control transfer is a non-local exit.
330 (not (eq (block-home-lambda block)
331 (block-home-lambda next))))
334 (join-blocks block next)
337 ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1
338 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags
339 ;;; for the two blocks so that any indicated optimization gets done.
340 (defun join-blocks (block1 block2)
341 (declare (type cblock block1 block2))
342 (let* ((last1 (block-last block1))
343 (last2 (block-last block2))
344 (succ (block-succ block2))
345 (start2 (block-start block2)))
346 (do ((ctran start2 (node-next (ctran-next ctran))))
348 (setf (ctran-block ctran) block1))
350 (unlink-blocks block1 block2)
352 (unlink-blocks block2 block)
353 (link-blocks block1 block))
355 (setf (ctran-kind start2) :inside-block)
356 (setf (node-next last1) start2)
357 (setf (ctran-use start2) last1)
358 (setf (block-last block1) last2))
360 (setf (block-flags block1)
361 (attributes-union (block-flags block1)
363 (block-attributes type-asserted test-modified)))
365 (let ((next (block-next block2))
366 (prev (block-prev block2)))
367 (setf (block-next prev) next)
368 (setf (block-prev next) prev))
372 ;;; Delete any nodes in BLOCK whose value is unused and which have no
373 ;;; side effects. We can delete sets of lexical variables when the set
374 ;;; variable has no references.
375 (defun flush-dead-code (block)
376 (declare (type cblock block))
377 (setf (block-flush-p block) nil)
378 (do-nodes-backwards (node lvar block)
385 (let ((info (combination-kind node)))
386 (when (fun-info-p info)
387 (let ((attr (fun-info-attributes info)))
388 (when (and (not (ir1-attributep attr call))
389 ;; ### For now, don't delete potentially
390 ;; flushable calls when they have the CALL
391 ;; attribute. Someday we should look at the
392 ;; functional args to determine if they have
394 (if (policy node (= safety 3))
395 (ir1-attributep attr flushable)
396 (ir1-attributep attr unsafely-flushable)))
397 (flush-combination node))))))
399 (when (eq (basic-combination-kind node) :local)
400 (let ((fun (combination-lambda node)))
401 (when (dolist (var (lambda-vars fun) t)
402 (when (or (leaf-refs var)
403 (lambda-var-sets var))
405 (flush-dest (first (basic-combination-args node)))
408 (let ((value (exit-value node)))
411 (setf (exit-value node) nil))))
413 (let ((var (set-var node)))
414 (when (and (lambda-var-p var)
415 (null (leaf-refs var)))
416 (flush-dest (set-value node))
417 (setf (basic-var-sets var)
418 (delq node (basic-var-sets var)))
419 (unlink-node node))))
421 (unless (cast-type-check node)
422 (flush-dest (cast-value node))
423 (unlink-node node))))))
427 ;;;; local call return type propagation
429 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
430 ;;; flag set. It iterates over the uses of the RESULT, looking for
431 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
432 ;;; call, then we union its type together with the types of other such
433 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
434 ;;; type with the RESULT's asserted type. We can make this
435 ;;; intersection now (potentially before type checking) because this
436 ;;; assertion on the result will eventually be checked (if
439 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
440 ;;; combination, which may change the succesor of the call to be the
441 ;;; called function, and if so, checks if the call can become an
442 ;;; assignment. If we convert to an assignment, we abort, since the
443 ;;; RETURN has been deleted.
444 (defun find-result-type (node)
445 (declare (type creturn node))
446 (let ((result (return-result node)))
447 (collect ((use-union *empty-type* values-type-union))
448 (do-uses (use result)
449 (let ((use-home (node-home-lambda use)))
450 (cond ((or (eq (functional-kind use-home) :deleted)
451 (block-delete-p (node-block use))))
452 ((and (basic-combination-p use)
453 (eq (basic-combination-kind use) :local))
454 (aver (eq (lambda-tail-set use-home)
455 (lambda-tail-set (combination-lambda use))))
456 (when (combination-p use)
457 (when (nth-value 1 (maybe-convert-tail-local-call use))
458 (return-from find-result-type (values)))))
460 (use-union (node-derived-type use))))))
462 ;; (values-type-intersection
463 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
467 (setf (return-result-type node) int))))
470 ;;; Do stuff to realize that something has changed about the value
471 ;;; delivered to a return node. Since we consider the return values of
472 ;;; all functions in the tail set to be equivalent, this amounts to
473 ;;; bringing the entire tail set up to date. We iterate over the
474 ;;; returns for all the functions in the tail set, reanalyzing them
475 ;;; all (not treating NODE specially.)
477 ;;; When we are done, we check whether the new type is different from
478 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
479 ;;; all the lvars for references to functions in the tail set. This
480 ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the
481 ;;; results of the calls.
482 (defun ir1-optimize-return (node)
483 (declare (type creturn node))
484 (let* ((tails (lambda-tail-set (return-lambda node)))
485 (funs (tail-set-funs tails)))
486 (collect ((res *empty-type* values-type-union))
488 (let ((return (lambda-return fun)))
490 (when (node-reoptimize return)
491 (setf (node-reoptimize return) nil)
492 (find-result-type return))
493 (res (return-result-type return)))))
495 (when (type/= (res) (tail-set-type tails))
496 (setf (tail-set-type tails) (res))
497 (dolist (fun (tail-set-funs tails))
498 (dolist (ref (leaf-refs fun))
499 (reoptimize-lvar (node-lvar ref)))))))
505 ;;; If the test has multiple uses, replicate the node when possible.
506 ;;; Also check whether the predicate is known to be true or false,
507 ;;; deleting the IF node in favor of the appropriate branch when this
509 (defun ir1-optimize-if (node)
510 (declare (type cif node))
511 (let ((test (if-test node))
512 (block (node-block node)))
514 (when (and (eq (block-start-node block) node)
515 (listp (lvar-uses test)))
517 (when (immediately-used-p test use)
518 (convert-if-if use node)
519 (when (not (listp (lvar-uses test))) (return)))))
521 (let* ((type (lvar-type test))
523 (cond ((constant-lvar-p test)
524 (if (lvar-value test)
525 (if-alternative node)
526 (if-consequent node)))
527 ((not (types-equal-or-intersect type (specifier-type 'null)))
528 (if-alternative node))
529 ((type= type (specifier-type 'null))
530 (if-consequent node)))))
533 (when (rest (block-succ block))
534 (unlink-blocks block victim))
535 (setf (component-reanalyze (node-component node)) t)
536 (unlink-node node))))
539 ;;; Create a new copy of an IF node that tests the value of the node
540 ;;; USE. The test must have >1 use, and must be immediately used by
541 ;;; USE. NODE must be the only node in its block (implying that
542 ;;; block-start = if-test).
544 ;;; This optimization has an effect semantically similar to the
545 ;;; source-to-source transformation:
546 ;;; (IF (IF A B C) D E) ==>
547 ;;; (IF A (IF B D E) (IF C D E))
549 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
550 ;;; node so that dead code deletion notes will definitely not consider
551 ;;; either node to be part of the original source. One node might
552 ;;; become unreachable, resulting in a spurious note.
553 (defun convert-if-if (use node)
554 (declare (type node use) (type cif node))
555 (with-ir1-environment-from-node node
556 (let* ((block (node-block node))
557 (test (if-test node))
558 (cblock (if-consequent node))
559 (ablock (if-alternative node))
560 (use-block (node-block use))
561 (new-ctran (make-ctran))
562 (new-lvar (make-lvar))
563 (new-node (make-if :test new-lvar
565 :alternative ablock))
566 (new-block (ctran-starts-block new-ctran)))
567 (link-node-to-previous-ctran new-node new-ctran)
568 (setf (lvar-dest new-lvar) new-node)
569 (setf (block-last new-block) new-node)
571 (unlink-blocks use-block block)
572 (%delete-lvar-use use)
573 (add-lvar-use use new-lvar)
574 (link-blocks use-block new-block)
576 (link-blocks new-block cblock)
577 (link-blocks new-block ablock)
579 (push "<IF Duplication>" (node-source-path node))
580 (push "<IF Duplication>" (node-source-path new-node))
582 (reoptimize-lvar test)
583 (reoptimize-lvar new-lvar)
584 (setf (component-reanalyze *current-component*) t)))
587 ;;;; exit IR1 optimization
589 ;;; This function attempts to delete an exit node, returning true if
590 ;;; it deletes the block as a consequence:
591 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
592 ;;; anything, since there is nothing to be done.
593 ;;; -- If the exit node and its ENTRY have the same home lambda then
594 ;;; we know the exit is local, and can delete the exit. We change
595 ;;; uses of the Exit-Value to be uses of the original lvar,
596 ;;; then unlink the node. If the exit is to a TR context, then we
597 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
598 ;;; their value to this exit.
599 ;;; -- If there is no value (as in a GO), then we skip the value
602 ;;; This function is also called by environment analysis, since it
603 ;;; wants all exits to be optimized even if normal optimization was
605 (defun maybe-delete-exit (node)
606 (declare (type exit node))
607 (let ((value (exit-value node))
608 (entry (exit-entry node)))
610 (eq (node-home-lambda node) (node-home-lambda entry)))
611 (setf (entry-exits entry) (delq node (entry-exits entry)))
613 (delete-filter node (node-lvar node) value)
614 (unlink-node node)))))
617 ;;;; combination IR1 optimization
619 ;;; Report as we try each transform?
621 (defvar *show-transforms-p* nil)
623 ;;; Do IR1 optimizations on a COMBINATION node.
624 (declaim (ftype (function (combination) (values)) ir1-optimize-combination))
625 (defun ir1-optimize-combination (node)
626 (when (lvar-reoptimize (basic-combination-fun node))
627 (propagate-fun-change node))
628 (let ((args (basic-combination-args node))
629 (kind (basic-combination-kind node)))
632 (let ((fun (combination-lambda node)))
633 (if (eq (functional-kind fun) :let)
634 (propagate-let-args node fun)
635 (propagate-local-call-args node fun))))
639 (setf (lvar-reoptimize arg) nil))))
643 (setf (lvar-reoptimize arg) nil)))
645 (let ((attr (fun-info-attributes kind)))
646 (when (and (ir1-attributep attr foldable)
647 ;; KLUDGE: The next test could be made more sensitive,
648 ;; only suppressing constant-folding of functions with
649 ;; CALL attributes when they're actually passed
650 ;; function arguments. -- WHN 19990918
651 (not (ir1-attributep attr call))
652 (every #'constant-lvar-p args)
654 ;; Even if the function is foldable in principle,
655 ;; it might be one of our low-level
656 ;; implementation-specific functions. Such
657 ;; functions don't necessarily exist at runtime on
658 ;; a plain vanilla ANSI Common Lisp
659 ;; cross-compilation host, in which case the
660 ;; cross-compiler can't fold it because the
661 ;; cross-compiler doesn't know how to evaluate it.
663 (or (fboundp (combination-fun-source-name node))
664 (progn (format t ";;; !!! Unbound fun: (~S~{ ~S~})~%"
665 (combination-fun-source-name node)
666 (mapcar #'lvar-value args))
668 (constant-fold-call node)
669 (return-from ir1-optimize-combination)))
671 (let ((fun (fun-info-derive-type kind)))
673 (let ((res (funcall fun node)))
675 (derive-node-type node (coerce-to-values res))
676 (maybe-terminate-block node nil)))))
678 (let ((fun (fun-info-optimizer kind)))
679 (unless (and fun (funcall fun node))
680 (dolist (x (fun-info-transforms kind))
682 (when *show-transforms-p*
683 (let* ((lvar (basic-combination-fun node))
684 (fname (lvar-fun-name lvar t)))
685 (/show "trying transform" x (transform-function x) "for" fname)))
686 (unless (ir1-transform node x)
688 (when *show-transforms-p*
689 (/show "quitting because IR1-TRANSFORM result was NIL"))
694 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
695 ;;; the block there, and link it to the component tail.
697 ;;; Except when called during IR1 convertion, we delete the
698 ;;; continuation if it has no other uses. (If it does have other uses,
701 ;;; Termination on the basis of a continuation type is
703 ;;; -- The continuation is deleted (hence the assertion is spurious), or
704 ;;; -- We are in IR1 conversion (where THE assertions are subject to
705 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
706 ;;; uses can(?) be added later. -- APD, 2003-07-17
708 ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30
709 (defun maybe-terminate-block (node ir1-converting-not-optimizing-p)
710 (declare (type (or basic-combination cast) node))
711 (let* ((block (node-block node))
712 (lvar (node-lvar node))
713 (ctran (node-next node))
714 (tail (component-tail (block-component block)))
715 (succ (first (block-succ block))))
716 (unless (or (and (eq node (block-last block)) (eq succ tail))
717 (block-delete-p block))
718 (when (eq (node-derived-type node) *empty-type*)
719 (cond (ir1-converting-not-optimizing-p
722 (aver (eq (block-last block) node)))
724 (setf (block-last block) node)
725 (setf (ctran-use ctran) nil)
726 (setf (ctran-kind ctran) :unused)
727 (setf (ctran-block ctran) nil)
728 (setf (node-next node) nil)
729 (link-blocks block (ctran-starts-block ctran)))))
731 (node-ends-block node)))
733 (unlink-blocks block (first (block-succ block)))
734 (setf (component-reanalyze (block-component block)) t)
735 (aver (not (block-succ block)))
736 (link-blocks block tail)
737 (if ir1-converting-not-optimizing-p
738 (%delete-lvar-use node)
739 (delete-lvar-use node))
742 ;;; This is called both by IR1 conversion and IR1 optimization when
743 ;;; they have verified the type signature for the call, and are
744 ;;; wondering if something should be done to special-case the call. If
745 ;;; CALL is a call to a global function, then see whether it defined
747 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
748 ;;; the expansion and change the call to call it. Expansion is
749 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
750 ;;; true, we never expand, since this function has already been
751 ;;; converted. Local call analysis will duplicate the definition
752 ;;; if necessary. We claim that the parent form is LABELS for
753 ;;; context declarations, since we don't want it to be considered
754 ;;; a real global function.
755 ;;; -- If it is a known function, mark it as such by setting the KIND.
757 ;;; We return the leaf referenced (NIL if not a leaf) and the
758 ;;; FUN-INFO assigned.
759 (defun recognize-known-call (call ir1-converting-not-optimizing-p)
760 (declare (type combination call))
761 (let* ((ref (lvar-uses (basic-combination-fun call)))
762 (leaf (when (ref-p ref) (ref-leaf ref)))
763 (inlinep (if (defined-fun-p leaf)
764 (defined-fun-inlinep leaf)
767 ((eq inlinep :notinline) (values nil nil))
768 ((not (and (global-var-p leaf)
769 (eq (global-var-kind leaf) :global-function)))
774 ((nil :maybe-inline) (policy call (zerop space))))
776 (defined-fun-inline-expansion leaf)
777 (let ((fun (defined-fun-functional leaf)))
779 (and (eq inlinep :inline) (functional-kind fun))))
780 (inline-expansion-ok call))
781 (flet (;; FIXME: Is this what the old CMU CL internal documentation
782 ;; called semi-inlining? A more descriptive name would
783 ;; be nice. -- WHN 2002-01-07
785 (let ((res (ir1-convert-lambda-for-defun
786 (defined-fun-inline-expansion leaf)
788 #'ir1-convert-inline-lambda)))
789 (setf (defined-fun-functional leaf) res)
790 (change-ref-leaf ref res))))
791 (if ir1-converting-not-optimizing-p
793 (with-ir1-environment-from-node call
795 (locall-analyze-component *current-component*))))
797 (values (ref-leaf (lvar-uses (basic-combination-fun call)))
800 (let ((info (info :function :info (leaf-source-name leaf))))
802 (values leaf (setf (basic-combination-kind call) info))
803 (values leaf nil)))))))
805 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
806 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
807 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
808 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
809 ;;; syntax check, arg/result type processing, but still call
810 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
811 ;;; and that checking is done by local call analysis.
812 (defun validate-call-type (call type ir1-converting-not-optimizing-p)
813 (declare (type combination call) (type ctype type))
814 (cond ((not (fun-type-p type))
815 (aver (multiple-value-bind (val win)
816 (csubtypep type (specifier-type 'function))
818 (recognize-known-call call ir1-converting-not-optimizing-p))
819 ((valid-fun-use call type
820 :argument-test #'always-subtypep
821 :result-test #'always-subtypep
822 ;; KLUDGE: Common Lisp is such a dynamic
823 ;; language that all we can do here in
824 ;; general is issue a STYLE-WARNING. It
825 ;; would be nice to issue a full WARNING
826 ;; in the special case of of type
827 ;; mismatches within a compilation unit
828 ;; (as in section 3.2.2.3 of the spec)
829 ;; but at least as of sbcl-0.6.11, we
830 ;; don't keep track of whether the
831 ;; mismatched data came from the same
832 ;; compilation unit, so we can't do that.
835 ;; FIXME: Actually, I think we could
836 ;; issue a full WARNING if the call
837 ;; violates a DECLAIM FTYPE.
838 :lossage-fun #'compiler-style-warn
839 :unwinnage-fun #'compiler-notify)
840 (assert-call-type call type)
841 (maybe-terminate-block call ir1-converting-not-optimizing-p)
842 (recognize-known-call call ir1-converting-not-optimizing-p))
844 (setf (combination-kind call) :error)
847 ;;; This is called by IR1-OPTIMIZE when the function for a call has
848 ;;; changed. If the call is local, we try to LET-convert it, and
849 ;;; derive the result type. If it is a :FULL call, we validate it
850 ;;; against the type, which recognizes known calls, does inline
851 ;;; expansion, etc. If a call to a predicate in a non-conditional
852 ;;; position or to a function with a source transform, then we
853 ;;; reconvert the form to give IR1 another chance.
854 (defun propagate-fun-change (call)
855 (declare (type combination call))
856 (let ((*compiler-error-context* call)
857 (fun-lvar (basic-combination-fun call)))
858 (setf (lvar-reoptimize fun-lvar) nil)
859 (case (combination-kind call)
861 (let ((fun (combination-lambda call)))
862 (maybe-let-convert fun)
863 (unless (member (functional-kind fun) '(:let :assignment :deleted))
864 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
866 (multiple-value-bind (leaf info)
867 (validate-call-type call (lvar-type fun-lvar) nil)
868 (cond ((functional-p leaf)
869 (convert-call-if-possible
870 (lvar-uses (basic-combination-fun call))
873 ((and (leaf-has-source-name-p leaf)
874 (or (info :function :source-transform (leaf-source-name leaf))
876 (ir1-attributep (fun-info-attributes info)
878 (let ((lvar (node-lvar call)))
879 (and lvar (not (if-p (lvar-dest lvar))))))))
880 (let ((name (leaf-source-name leaf))
881 (dummies (make-gensym-list
882 (length (combination-args call)))))
885 (,@(if (symbolp name)
889 (leaf-source-name leaf)))))))))
892 ;;;; known function optimization
894 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
895 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
896 ;;; replace it, otherwise add a new one.
897 (defun record-optimization-failure (node transform args)
898 (declare (type combination node) (type transform transform)
899 (type (or fun-type list) args))
900 (let* ((table (component-failed-optimizations *component-being-compiled*))
901 (found (assoc transform (gethash node table))))
903 (setf (cdr found) args)
904 (push (cons transform args) (gethash node table))))
907 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
908 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
909 ;;; doing the transform for some reason and FLAME is true, then we
910 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
911 ;;; finalize to pick up. We return true if the transform failed, and
912 ;;; thus further transformation should be attempted. We return false
913 ;;; if either the transform succeeded or was aborted.
914 (defun ir1-transform (node transform)
915 (declare (type combination node) (type transform transform))
916 (let* ((type (transform-type transform))
917 (fun (transform-function transform))
918 (constrained (fun-type-p type))
919 (table (component-failed-optimizations *component-being-compiled*))
920 (flame (if (transform-important transform)
921 (policy node (>= speed inhibit-warnings))
922 (policy node (> speed inhibit-warnings))))
923 (*compiler-error-context* node))
924 (cond ((or (not constrained)
925 (valid-fun-use node type))
926 (multiple-value-bind (severity args)
927 (catch 'give-up-ir1-transform
930 (combination-fun-source-name node))
937 (setf (combination-kind node) :error)
939 (apply #'compiler-warn args))
945 (record-optimization-failure node transform args))
946 (setf (gethash node table)
947 (remove transform (gethash node table) :key #'car)))
955 :argument-test #'types-equal-or-intersect
956 :result-test #'values-types-equal-or-intersect))
957 (record-optimization-failure node transform type)
962 ;;; When we don't like an IR1 transform, we throw the severity/reason
965 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
966 ;;; aborting this attempt to transform the call, but admitting the
967 ;;; possibility that this or some other transform will later succeed.
968 ;;; If arguments are supplied, they are format arguments for an
971 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
972 ;;; force a normal call to the function at run time. No further
973 ;;; optimizations will be attempted.
975 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
976 ;;; delay the transform on the node until later. REASONS specifies
977 ;;; when the transform will be later retried. The :OPTIMIZE reason
978 ;;; causes the transform to be delayed until after the current IR1
979 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
980 ;;; be delayed until after constraint propagation.
982 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
983 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
984 ;;; do CASE operations on the various REASON values, it might be a
985 ;;; good idea to go OO, representing the reasons by objects, using
986 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
987 ;;; SIGNAL instead of THROW.
988 (declaim (ftype (function (&rest t) nil) give-up-ir1-transform))
989 (defun give-up-ir1-transform (&rest args)
990 (throw 'give-up-ir1-transform (values :failure args)))
991 (defun abort-ir1-transform (&rest args)
992 (throw 'give-up-ir1-transform (values :aborted args)))
993 (defun delay-ir1-transform (node &rest reasons)
994 (let ((assoc (assoc node *delayed-ir1-transforms*)))
996 (setf *delayed-ir1-transforms*
997 (acons node reasons *delayed-ir1-transforms*))
998 (throw 'give-up-ir1-transform :delayed))
1000 (dolist (reason reasons)
1001 (pushnew reason (cdr assoc)))
1002 (throw 'give-up-ir1-transform :delayed)))))
1004 ;;; Clear any delayed transform with no reasons - these should have
1005 ;;; been tried in the last pass. Then remove the reason from the
1006 ;;; delayed transform reasons, and if any become empty then set
1007 ;;; reoptimize flags for the node. Return true if any transforms are
1009 (defun retry-delayed-ir1-transforms (reason)
1010 (setf *delayed-ir1-transforms*
1011 (remove-if-not #'cdr *delayed-ir1-transforms*))
1012 (let ((reoptimize nil))
1013 (dolist (assoc *delayed-ir1-transforms*)
1014 (let ((reasons (remove reason (cdr assoc))))
1015 (setf (cdr assoc) reasons)
1017 (let ((node (car assoc)))
1018 (unless (node-deleted node)
1020 (setf (node-reoptimize node) t)
1021 (let ((block (node-block node)))
1022 (setf (block-reoptimize block) t)
1023 (setf (component-reoptimize (block-component block)) t)))))))
1026 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1027 ;;; environment, and then install it as the function for the call
1028 ;;; NODE. We do local call analysis so that the new function is
1029 ;;; integrated into the control flow.
1031 ;;; We require the original function source name in order to generate
1032 ;;; a meaningful debug name for the lambda we set up. (It'd be
1033 ;;; possible to do this starting from debug names as well as source
1034 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1035 ;;; generality, since source names are always known to our callers.)
1036 (defun transform-call (call res source-name)
1037 (declare (type combination call) (list res))
1038 (aver (and (legal-fun-name-p source-name)
1039 (not (eql source-name '.anonymous.))))
1040 (node-ends-block call)
1041 (with-ir1-environment-from-node call
1042 (with-component-last-block (*current-component*
1043 (block-next (node-block call)))
1044 (let ((new-fun (ir1-convert-inline-lambda
1046 :debug-name (debug-namify "LAMBDA-inlined ~A"
1049 "<unknown function>"))))
1050 (ref (lvar-use (combination-fun call))))
1051 (change-ref-leaf ref new-fun)
1052 (setf (combination-kind call) :full)
1053 (locall-analyze-component *current-component*))))
1056 ;;; Replace a call to a foldable function of constant arguments with
1057 ;;; the result of evaluating the form. If there is an error during the
1058 ;;; evaluation, we give a warning and leave the call alone, making the
1059 ;;; call a :ERROR call.
1061 ;;; If there is more than one value, then we transform the call into a
1063 (defun constant-fold-call (call)
1064 (let ((args (mapcar #'lvar-value (combination-args call)))
1065 (fun-name (combination-fun-source-name call)))
1066 (multiple-value-bind (values win)
1067 (careful-call fun-name
1070 ;; Note: CMU CL had COMPILER-WARN here, and that
1071 ;; seems more natural, but it's probably not.
1073 ;; It's especially not while bug 173 exists:
1076 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1078 ;; can cause constant-folding TYPE-ERRORs (in
1079 ;; #'<=) when END can be proved to be NIL, even
1080 ;; though the code is perfectly legal and safe
1081 ;; because a NIL value of END means that the
1082 ;; #'<= will never be executed.
1084 ;; Moreover, even without bug 173,
1085 ;; quite-possibly-valid code like
1086 ;; (COND ((NONINLINED-PREDICATE END)
1087 ;; (UNLESS (<= END SIZE))
1089 ;; (where NONINLINED-PREDICATE is something the
1090 ;; compiler can't do at compile time, but which
1091 ;; turns out to make the #'<= expression
1092 ;; unreachable when END=NIL) could cause errors
1093 ;; when the compiler tries to constant-fold (<=
1096 ;; So, with or without bug 173, it'd be
1097 ;; unnecessarily evil to do a full
1098 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1099 ;; from COMPILE-FILE) for legal code, so we we
1100 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1101 #'compiler-style-warn
1104 (setf (combination-kind call) :error))
1105 ((and (proper-list-of-length-p values 1))
1106 (with-ir1-environment-from-node call
1107 (let* ((lvar (node-lvar call))
1108 (prev (node-prev call))
1109 (intermediate-ctran (make-ctran)))
1110 (%delete-lvar-use call)
1111 (setf (ctran-next prev) nil)
1112 (setf (node-prev call) nil)
1113 (reference-constant prev intermediate-ctran lvar
1115 (link-node-to-previous-ctran call intermediate-ctran)
1116 (reoptimize-lvar lvar)
1117 (flush-combination call))))
1118 (t (let ((dummies (make-gensym-list (length args))))
1122 (declare (ignore ,@dummies))
1123 (values ,@(mapcar (lambda (x) `',x) values)))
1127 ;;;; local call optimization
1129 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1130 ;;; the leaf type is a function type, then just leave it alone, since
1131 ;;; TYPE is never going to be more specific than that (and
1132 ;;; TYPE-INTERSECTION would choke.)
1133 (defun propagate-to-refs (leaf type)
1134 (declare (type leaf leaf) (type ctype type))
1135 (let ((var-type (leaf-type leaf)))
1136 (unless (fun-type-p var-type)
1137 (let ((int (type-approx-intersection2 var-type type)))
1138 (when (type/= int var-type)
1139 (setf (leaf-type leaf) int)
1140 (dolist (ref (leaf-refs leaf))
1141 (derive-node-type ref (make-single-value-type int))
1142 ;; KLUDGE: LET var substitution
1143 (let* ((lvar (node-lvar ref)))
1144 (when (and lvar (combination-p (lvar-dest lvar)))
1145 (reoptimize-lvar lvar))))))
1148 ;;; Iteration variable: exactly one SETQ of the form:
1150 ;;; (let ((var initial))
1152 ;;; (setq var (+ var step))
1154 (defun maybe-infer-iteration-var-type (var initial-type)
1155 (binding* ((sets (lambda-var-sets var) :exit-if-null)
1157 (() (null (rest sets)) :exit-if-null)
1158 (set-use (principal-lvar-use (set-value set)))
1159 (() (and (combination-p set-use)
1160 (fun-info-p (combination-kind set-use))
1161 (eq (combination-fun-source-name set-use) '+))
1163 (+-args (basic-combination-args set-use))
1164 (() (and (proper-list-of-length-p +-args 2 2)
1165 (let ((first (principal-lvar-use
1168 (eq (ref-leaf first) var))))
1170 (step-type (lvar-type (second +-args)))
1171 (set-type (lvar-type (set-value set))))
1172 (when (and (numeric-type-p initial-type)
1173 (numeric-type-p step-type)
1174 (numeric-type-equal initial-type step-type))
1175 (multiple-value-bind (low high)
1176 (cond ((csubtypep step-type (specifier-type '(real 0 *)))
1177 (values (numeric-type-low initial-type)
1178 (when (and (numeric-type-p set-type)
1179 (numeric-type-equal set-type initial-type))
1180 (numeric-type-high set-type))))
1181 ((csubtypep step-type (specifier-type '(real * 0)))
1182 (values (when (and (numeric-type-p set-type)
1183 (numeric-type-equal set-type initial-type))
1184 (numeric-type-low set-type))
1185 (numeric-type-high initial-type)))
1188 (modified-numeric-type initial-type
1191 :enumerable nil)))))
1192 (deftransform + ((x y) * * :result result)
1193 "check for iteration variable reoptimization"
1194 (let ((dest (principal-lvar-end result))
1195 (use (principal-lvar-use x)))
1196 (when (and (ref-p use)
1200 (reoptimize-lvar (set-value dest))))
1201 (give-up-ir1-transform))
1203 ;;; Figure out the type of a LET variable that has sets. We compute
1204 ;;; the union of the INITIAL-TYPE and the types of all the set
1205 ;;; values and to a PROPAGATE-TO-REFS with this type.
1206 (defun propagate-from-sets (var initial-type)
1207 (collect ((res initial-type type-union))
1208 (dolist (set (basic-var-sets var))
1209 (let ((type (lvar-type (set-value set))))
1211 (when (node-reoptimize set)
1212 (derive-node-type set (make-single-value-type type))
1213 (setf (node-reoptimize set) nil))))
1215 (awhen (maybe-infer-iteration-var-type var initial-type)
1217 (propagate-to-refs var res)))
1220 ;;; If a LET variable, find the initial value's type and do
1221 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1223 (defun ir1-optimize-set (node)
1224 (declare (type cset node))
1225 (let ((var (set-var node)))
1226 (when (and (lambda-var-p var) (leaf-refs var))
1227 (let ((home (lambda-var-home var)))
1228 (when (eq (functional-kind home) :let)
1229 (let* ((initial-value (let-var-initial-value var))
1230 (initial-type (lvar-type initial-value)))
1231 (setf (lvar-reoptimize initial-value) nil)
1232 (propagate-from-sets var initial-type))))))
1234 (derive-node-type node (make-single-value-type
1235 (lvar-type (set-value node))))
1238 ;;; Return true if the value of REF will always be the same (and is
1239 ;;; thus legal to substitute.)
1240 (defun constant-reference-p (ref)
1241 (declare (type ref ref))
1242 (let ((leaf (ref-leaf ref)))
1244 ((or constant functional) t)
1246 (null (lambda-var-sets leaf)))
1248 (not (eq (defined-fun-inlinep leaf) :notinline)))
1250 (case (global-var-kind leaf)
1252 (let ((name (leaf-source-name leaf)))
1254 (eq (symbol-package (fun-name-block-name name))
1256 (info :function :info name)))))))))
1258 ;;; If we have a non-set LET var with a single use, then (if possible)
1259 ;;; replace the variable reference's LVAR with the arg lvar.
1261 ;;; We change the REF to be a reference to NIL with unused value, and
1262 ;;; let it be flushed as dead code. A side effect of this substitution
1263 ;;; is to delete the variable.
1264 (defun substitute-single-use-lvar (arg var)
1265 (declare (type lvar arg) (type lambda-var var))
1266 (binding* ((ref (first (leaf-refs var)))
1267 (lvar (node-lvar ref) :exit-if-null)
1268 (dest (lvar-dest lvar)))
1270 ;; Think about (LET ((A ...)) (IF ... A ...)): two
1271 ;; LVAR-USEs should not be met on one path.
1272 (eq (lvar-uses lvar) ref)
1274 ;; we should not change lifetime of unknown values lvars
1276 (and (type-single-value-p (lvar-derived-type arg))
1277 (multiple-value-bind (pdest pprev)
1278 (principal-lvar-end lvar)
1279 (declare (ignore pdest))
1280 (lvar-single-value-p pprev))))
1282 (or (eq (basic-combination-fun dest) lvar)
1283 (and (eq (basic-combination-kind dest) :local)
1284 (type-single-value-p (lvar-derived-type arg)))))
1286 ;; While CRETURN and EXIT nodes may be known-values,
1287 ;; they have their own complications, such as
1288 ;; substitution into CRETURN may create new tail calls.
1291 (aver (lvar-single-value-p lvar))
1293 (eq (node-home-lambda ref)
1294 (lambda-home (lambda-var-home var))))
1295 (setf (node-derived-type ref) *wild-type*)
1296 (substitute-lvar-uses lvar arg)
1297 (delete-lvar-use ref)
1298 (change-ref-leaf ref (find-constant nil))
1301 (reoptimize-lvar lvar)
1304 ;;; Delete a LET, removing the call and bind nodes, and warning about
1305 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1306 ;;; along right away and delete the REF and then the lambda, since we
1307 ;;; flush the FUN lvar.
1308 (defun delete-let (clambda)
1309 (declare (type clambda clambda))
1310 (aver (functional-letlike-p clambda))
1311 (note-unreferenced-vars clambda)
1312 (let ((call (let-combination clambda)))
1313 (flush-dest (basic-combination-fun call))
1315 (unlink-node (lambda-bind clambda))
1316 (setf (lambda-bind clambda) nil))
1319 ;;; This function is called when one of the arguments to a LET
1320 ;;; changes. We look at each changed argument. If the corresponding
1321 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1322 ;;; consider substituting for the variable, and also propagate
1323 ;;; derived-type information for the arg to all the VAR's refs.
1325 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1326 ;;; subtype of the argument's leaf type. This prevents type checking
1327 ;;; from being defeated, and also ensures that the best representation
1328 ;;; for the variable can be used.
1330 ;;; Substitution of individual references is inhibited if the
1331 ;;; reference is in a different component from the home. This can only
1332 ;;; happen with closures over top level lambda vars. In such cases,
1333 ;;; the references may have already been compiled, and thus can't be
1334 ;;; retroactively modified.
1336 ;;; If all of the variables are deleted (have no references) when we
1337 ;;; are done, then we delete the LET.
1339 ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE
1341 (defun propagate-let-args (call fun)
1342 (declare (type combination call) (type clambda fun))
1343 (loop for arg in (combination-args call)
1344 and var in (lambda-vars fun) do
1345 (when (and arg (lvar-reoptimize arg))
1346 (setf (lvar-reoptimize arg) nil)
1348 ((lambda-var-sets var)
1349 (propagate-from-sets var (lvar-type arg)))
1350 ((let ((use (lvar-uses arg)))
1352 (let ((leaf (ref-leaf use)))
1353 (when (and (constant-reference-p use)
1354 (csubtypep (leaf-type leaf)
1355 ;; (NODE-DERIVED-TYPE USE) would
1356 ;; be better -- APD, 2003-05-15
1358 (propagate-to-refs var (lvar-type arg))
1359 (let ((use-component (node-component use)))
1360 (prog1 (substitute-leaf-if
1362 (cond ((eq (node-component ref) use-component)
1365 (aver (lambda-toplevelish-p (lambda-home fun)))
1369 ((and (null (rest (leaf-refs var)))
1370 (substitute-single-use-lvar arg var)))
1372 (propagate-to-refs var (lvar-type arg))))))
1374 (when (every #'not (combination-args call))
1379 ;;; This function is called when one of the args to a non-LET local
1380 ;;; call changes. For each changed argument corresponding to an unset
1381 ;;; variable, we compute the union of the types across all calls and
1382 ;;; propagate this type information to the var's refs.
1384 ;;; If the function has an XEP, then we don't do anything, since we
1385 ;;; won't discover anything.
1387 ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls
1388 ;;; corresponding to changed arguments in CALL, since the only use in
1389 ;;; IR1 optimization of the REOPTIMIZE flag for local call args is
1391 (defun propagate-local-call-args (call fun)
1392 (declare (type combination call) (type clambda fun))
1394 (unless (or (functional-entry-fun fun)
1395 (lambda-optional-dispatch fun))
1396 (let* ((vars (lambda-vars fun))
1397 (union (mapcar (lambda (arg var)
1399 (lvar-reoptimize arg)
1400 (null (basic-var-sets var)))
1402 (basic-combination-args call)
1404 (this-ref (lvar-use (basic-combination-fun call))))
1406 (dolist (arg (basic-combination-args call))
1408 (setf (lvar-reoptimize arg) nil)))
1410 (dolist (ref (leaf-refs fun))
1411 (let ((dest (node-dest ref)))
1412 (unless (or (eq ref this-ref) (not dest))
1414 (mapcar (lambda (this-arg old)
1416 (setf (lvar-reoptimize this-arg) nil)
1417 (type-union (lvar-type this-arg) old)))
1418 (basic-combination-args dest)
1421 (loop for var in vars
1423 when type do (propagate-to-refs var type))))
1427 ;;;; multiple values optimization
1429 ;;; Do stuff to notice a change to a MV combination node. There are
1430 ;;; two main branches here:
1431 ;;; -- If the call is local, then it is already a MV let, or should
1432 ;;; become one. Note that although all :LOCAL MV calls must eventually
1433 ;;; be converted to :MV-LETs, there can be a window when the call
1434 ;;; is local, but has not been LET converted yet. This is because
1435 ;;; the entry-point lambdas may have stray references (in other
1436 ;;; entry points) that have not been deleted yet.
1437 ;;; -- The call is full. This case is somewhat similar to the non-MV
1438 ;;; combination optimization: we propagate return type information and
1439 ;;; notice non-returning calls. We also have an optimization
1440 ;;; which tries to convert MV-CALLs into MV-binds.
1441 (defun ir1-optimize-mv-combination (node)
1442 (ecase (basic-combination-kind node)
1444 (let ((fun-lvar (basic-combination-fun node)))
1445 (when (lvar-reoptimize fun-lvar)
1446 (setf (lvar-reoptimize fun-lvar) nil)
1447 (maybe-let-convert (combination-lambda node))))
1448 (setf (lvar-reoptimize (first (basic-combination-args node))) nil)
1449 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1450 (unless (convert-mv-bind-to-let node)
1451 (ir1-optimize-mv-bind node))))
1453 (let* ((fun (basic-combination-fun node))
1454 (fun-changed (lvar-reoptimize fun))
1455 (args (basic-combination-args node)))
1457 (setf (lvar-reoptimize fun) nil)
1458 (let ((type (lvar-type fun)))
1459 (when (fun-type-p type)
1460 (derive-node-type node (fun-type-returns type))))
1461 (maybe-terminate-block node nil)
1462 (let ((use (lvar-uses fun)))
1463 (when (and (ref-p use) (functional-p (ref-leaf use)))
1464 (convert-call-if-possible use node)
1465 (when (eq (basic-combination-kind node) :local)
1466 (maybe-let-convert (ref-leaf use))))))
1467 (unless (or (eq (basic-combination-kind node) :local)
1468 (eq (lvar-fun-name fun) '%throw))
1469 (ir1-optimize-mv-call node))
1471 (setf (lvar-reoptimize arg) nil))))
1475 ;;; Propagate derived type info from the values lvar to the vars.
1476 (defun ir1-optimize-mv-bind (node)
1477 (declare (type mv-combination node))
1478 (let* ((arg (first (basic-combination-args node)))
1479 (vars (lambda-vars (combination-lambda node)))
1480 (n-vars (length vars))
1481 (types (values-type-in (lvar-derived-type arg)
1483 (loop for var in vars
1485 do (if (basic-var-sets var)
1486 (propagate-from-sets var type)
1487 (propagate-to-refs var type)))
1488 (setf (lvar-reoptimize arg) nil))
1491 ;;; If possible, convert a general MV call to an MV-BIND. We can do
1493 ;;; -- The call has only one argument, and
1494 ;;; -- The function has a known fixed number of arguments, or
1495 ;;; -- The argument yields a known fixed number of values.
1497 ;;; What we do is change the function in the MV-CALL to be a lambda
1498 ;;; that "looks like an MV bind", which allows
1499 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1500 ;;; converted (the next time around.) This new lambda just calls the
1501 ;;; actual function with the MV-BIND variables as arguments. Note that
1502 ;;; this new MV bind is not let-converted immediately, as there are
1503 ;;; going to be stray references from the entry-point functions until
1504 ;;; they get deleted.
1506 ;;; In order to avoid loss of argument count checking, we only do the
1507 ;;; transformation according to a known number of expected argument if
1508 ;;; safety is unimportant. We can always convert if we know the number
1509 ;;; of actual values, since the normal call that we build will still
1510 ;;; do any appropriate argument count checking.
1512 ;;; We only attempt the transformation if the called function is a
1513 ;;; constant reference. This allows us to just splice the leaf into
1514 ;;; the new function, instead of trying to somehow bind the function
1515 ;;; expression. The leaf must be constant because we are evaluating it
1516 ;;; again in a different place. This also has the effect of squelching
1517 ;;; multiple warnings when there is an argument count error.
1518 (defun ir1-optimize-mv-call (node)
1519 (let ((fun (basic-combination-fun node))
1520 (*compiler-error-context* node)
1521 (ref (lvar-uses (basic-combination-fun node)))
1522 (args (basic-combination-args node)))
1524 (unless (and (ref-p ref) (constant-reference-p ref)
1526 (return-from ir1-optimize-mv-call))
1528 (multiple-value-bind (min max)
1529 (fun-type-nargs (lvar-type fun))
1531 (multiple-value-bind (types nvals)
1532 (values-types (lvar-derived-type (first args)))
1533 (declare (ignore types))
1534 (if (eq nvals :unknown) nil nvals))))
1537 (when (and min (< total-nvals min))
1539 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1542 (setf (basic-combination-kind node) :error)
1543 (return-from ir1-optimize-mv-call))
1544 (when (and max (> total-nvals max))
1546 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1549 (setf (basic-combination-kind node) :error)
1550 (return-from ir1-optimize-mv-call)))
1552 (let ((count (cond (total-nvals)
1553 ((and (policy node (zerop verify-arg-count))
1558 (with-ir1-environment-from-node node
1559 (let* ((dums (make-gensym-list count))
1561 (fun (ir1-convert-lambda
1562 `(lambda (&optional ,@dums &rest ,ignore)
1563 (declare (ignore ,ignore))
1564 (funcall ,(ref-leaf ref) ,@dums)))))
1565 (change-ref-leaf ref fun)
1566 (aver (eq (basic-combination-kind node) :full))
1567 (locall-analyze-component *current-component*)
1568 (aver (eq (basic-combination-kind node) :local)))))))))
1572 ;;; (multiple-value-bind
1581 ;;; What we actually do is convert the VALUES combination into a
1582 ;;; normal LET combination calling the original :MV-LET lambda. If
1583 ;;; there are extra args to VALUES, discard the corresponding
1584 ;;; lvars. If there are insufficient args, insert references to NIL.
1585 (defun convert-mv-bind-to-let (call)
1586 (declare (type mv-combination call))
1587 (let* ((arg (first (basic-combination-args call)))
1588 (use (lvar-uses arg)))
1589 (when (and (combination-p use)
1590 (eq (lvar-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 (ctran-next node-prev) nil)
1605 (collect ((res vals))
1606 (loop for count below (- nvars nvals)
1607 for prev = node-prev then ctran
1608 for ctran = (make-ctran)
1609 and lvar = (make-lvar use)
1610 do (reference-constant prev ctran lvar nil)
1612 finally (link-node-to-previous-ctran
1614 (setq vals (res)))))))
1615 (setf (combination-args use) vals)
1616 (flush-dest (combination-fun use))
1617 (let ((fun-lvar (basic-combination-fun call)))
1618 (setf (lvar-dest fun-lvar) use)
1619 (setf (combination-fun use) fun-lvar)
1620 (flush-lvar-externally-checkable-type fun-lvar))
1621 (setf (combination-kind use) :local)
1622 (setf (functional-kind fun) :let)
1623 (flush-dest (first (basic-combination-args call)))
1626 (reoptimize-lvar (first vals)))
1627 (propagate-to-args use fun)
1628 (reoptimize-call use))
1632 ;;; (values-list (list x y z))
1637 ;;; In implementation, this is somewhat similar to
1638 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1639 ;;; args of the VALUES-LIST call, flushing the old argument lvar
1640 ;;; (allowing the LIST to be flushed.)
1642 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
1643 (defoptimizer (values-list optimizer) ((list) node)
1644 (let ((use (lvar-uses list)))
1645 (when (and (combination-p use)
1646 (eq (lvar-fun-name (combination-fun use))
1649 ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR.
1650 (change-ref-leaf (lvar-uses (combination-fun node))
1651 (find-free-fun 'values "in a strange place"))
1652 (setf (combination-kind node) :full)
1653 (let ((args (combination-args use)))
1655 (setf (lvar-dest arg) node)
1656 (flush-lvar-externally-checkable-type arg))
1657 (setf (combination-args use) nil)
1659 (setf (combination-args node) args))
1662 ;;; If VALUES appears in a non-MV context, then effectively convert it
1663 ;;; to a PROG1. This allows the computation of the additional values
1664 ;;; to become dead code.
1665 (deftransform values ((&rest vals) * * :node node)
1666 (unless (lvar-single-value-p (node-lvar node))
1667 (give-up-ir1-transform))
1668 (setf (node-derived-type node) *wild-type*)
1669 (principal-lvar-single-valuify (node-lvar node))
1671 (let ((dummies (make-gensym-list (length (cdr vals)))))
1672 `(lambda (val ,@dummies)
1673 (declare (ignore ,@dummies))
1679 (defun ir1-optimize-cast (cast &optional do-not-optimize)
1680 (declare (type cast cast))
1681 (let* ((value (cast-value cast))
1682 (value-type (lvar-derived-type value))
1683 (atype (cast-asserted-type cast))
1684 (int (values-type-intersection value-type atype)))
1685 (derive-node-type cast int)
1686 (when (eq int *empty-type*)
1687 (unless (eq value-type *empty-type*)
1689 ;; FIXME: Do it in one step.
1692 `(multiple-value-call #'list 'dummy))
1695 ;; FIXME: Derived type.
1696 `(%compile-time-type-error 'dummy
1697 ',(type-specifier atype)
1698 ',(type-specifier value-type)))
1699 ;; KLUDGE: FILTER-LVAR does not work for non-returning
1700 ;; functions, so we declare the return type of
1701 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
1703 (setq value (cast-value cast))
1704 (derive-node-type (lvar-uses value) *empty-type*)
1705 (maybe-terminate-block (lvar-uses value) nil)
1706 ;; FIXME: Is it necessary?
1707 (aver (null (block-pred (node-block cast))))
1708 (setf (block-delete-p (node-block cast)) t)
1709 (return-from ir1-optimize-cast)))
1710 (when (eq (node-derived-type cast) *empty-type*)
1711 (maybe-terminate-block cast nil))
1713 (when (not do-not-optimize)
1714 (let ((lvar (node-lvar cast)))
1715 (when (values-subtypep value-type (cast-asserted-type cast))
1716 (delete-filter cast lvar value)
1718 (reoptimize-lvar lvar)
1719 (when (lvar-single-value-p lvar)
1720 (note-single-valuified-lvar lvar)))
1721 (return-from ir1-optimize-cast t))
1723 (when (and (listp (lvar-uses value))
1725 ;; Pathwise removing of CAST
1726 (let ((ctran (node-next cast))
1727 (dest (lvar-dest lvar))
1730 (do-uses (use value)
1731 (when (and (values-subtypep (node-derived-type use) atype)
1732 (immediately-used-p value use))
1734 (when ctran (ensure-block-start ctran))
1735 (setq next-block (first (block-succ (node-block cast)))))
1736 (%delete-lvar-use use)
1737 (add-lvar-use use lvar)
1738 (unlink-blocks (node-block use) (node-block cast))
1739 (link-blocks (node-block use) next-block)
1740 (when (and (return-p dest)
1741 (basic-combination-p use)
1742 (eq (basic-combination-kind use) :local))
1744 (dolist (use (merges))
1745 (merge-tail-sets use)))))))
1747 (when (and (cast-%type-check cast)
1748 (values-subtypep value-type
1749 (cast-type-to-check cast)))
1750 (setf (cast-%type-check cast) nil)))
1752 (unless do-not-optimize
1753 (setf (node-reoptimize cast) nil)))