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)
24 (declare (type (or lvar null) thing))
26 (let ((use (principal-lvar-use thing)))
27 (and (ref-p use) (constant-p (ref-leaf use))))))
29 ;;; Return the constant value for an LVAR whose only use is a constant
31 (declaim (ftype (function (lvar) t) lvar-value))
32 (defun lvar-value (lvar)
33 (let ((use (principal-lvar-use lvar)))
34 (constant-value (ref-leaf use))))
36 ;;;; interface for obtaining results of type inference
38 ;;; Our best guess for the type of this lvar's value. Note that this
39 ;;; may be VALUES or FUNCTION type, which cannot be passed as an
40 ;;; argument to the normal type operations. See LVAR-TYPE.
42 ;;; The result value is cached in the LVAR-%DERIVED-TYPE slot. If the
43 ;;; slot is true, just return that value, otherwise recompute and
44 ;;; stash the value there.
45 #!-sb-fluid (declaim (inline lvar-derived-type))
46 (defun lvar-derived-type (lvar)
47 (declare (type lvar lvar))
48 (or (lvar-%derived-type lvar)
49 (setf (lvar-%derived-type lvar)
50 (%lvar-derived-type lvar))))
51 (defun %lvar-derived-type (lvar)
52 (declare (type lvar lvar))
53 (let ((uses (lvar-uses lvar)))
54 (cond ((null uses) *empty-type*)
56 (do ((res (node-derived-type (first uses))
57 (values-type-union (node-derived-type (first current))
59 (current (rest uses) (rest current)))
60 ((null current) res)))
62 (node-derived-type (lvar-uses lvar))))))
64 ;;; Return the derived type for LVAR's first value. This is guaranteed
65 ;;; not to be a VALUES or FUNCTION type.
66 (declaim (ftype (sfunction (lvar) ctype) lvar-type))
67 (defun lvar-type (lvar)
68 (single-value-type (lvar-derived-type lvar)))
70 ;;; If LVAR is an argument of a function, return a type which the
71 ;;; function checks LVAR for.
72 #!-sb-fluid (declaim (inline lvar-externally-checkable-type))
73 (defun lvar-externally-checkable-type (lvar)
74 (or (lvar-%externally-checkable-type lvar)
75 (%lvar-%externally-checkable-type lvar)))
76 (defun %lvar-%externally-checkable-type (lvar)
77 (declare (type lvar lvar))
78 (let ((dest (lvar-dest lvar)))
79 (if (not (and dest (combination-p dest)))
80 ;; TODO: MV-COMBINATION
81 (setf (lvar-%externally-checkable-type lvar) *wild-type*)
82 (let* ((fun (combination-fun dest))
83 (args (combination-args dest))
84 (fun-type (lvar-type fun)))
85 (setf (lvar-%externally-checkable-type fun) *wild-type*)
86 (if (or (not (call-full-like-p dest))
87 (not (fun-type-p fun-type))
88 ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)).
89 (fun-type-wild-args fun-type))
92 (setf (lvar-%externally-checkable-type arg)
94 (map-combination-args-and-types
96 (setf (lvar-%externally-checkable-type arg)
97 (acond ((lvar-%externally-checkable-type arg)
98 (values-type-intersection
99 it (coerce-to-values type)))
100 (t (coerce-to-values type)))))
102 (lvar-%externally-checkable-type lvar))
103 #!-sb-fluid(declaim (inline flush-lvar-externally-checkable-type))
104 (defun flush-lvar-externally-checkable-type (lvar)
105 (declare (type lvar lvar))
106 (setf (lvar-%externally-checkable-type lvar) nil))
108 ;;;; interface routines used by optimizers
110 ;;; This function is called by optimizers to indicate that something
111 ;;; interesting has happened to the value of LVAR. Optimizers must
112 ;;; make sure that they don't call for reoptimization when nothing has
113 ;;; happened, since optimization will fail to terminate.
115 ;;; We clear any cached type for the lvar and set the reoptimize flags
116 ;;; on everything in sight.
117 (defun reoptimize-lvar (lvar)
118 (declare (type (or lvar null) lvar))
120 (setf (lvar-%derived-type lvar) nil)
121 (let ((dest (lvar-dest lvar)))
123 (setf (lvar-reoptimize lvar) t)
124 (setf (node-reoptimize dest) t)
125 (binding* (;; Since this may be called during IR1 conversion,
126 ;; PREV may be missing.
127 (prev (node-prev dest) :exit-if-null)
128 (block (ctran-block prev))
129 (component (block-component block)))
130 (when (typep dest 'cif)
131 (setf (block-test-modified block) t))
132 (setf (block-reoptimize block) t)
133 (setf (component-reoptimize component) t))))
135 (setf (block-type-check (node-block node)) t)))
138 (defun reoptimize-lvar-uses (lvar)
139 (declare (type lvar lvar))
141 (setf (node-reoptimize use) t)
142 (setf (block-reoptimize (node-block use)) t)
143 (setf (component-reoptimize (node-component use)) t)))
145 ;;; Annotate NODE to indicate that its result has been proven to be
146 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
147 ;;; only correct way to supply information discovered about a node's
148 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
149 ;;; information may be lost and reoptimization may not happen.
151 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
152 ;;; intersection is different from the old type, then we do a
153 ;;; REOPTIMIZE-LVAR on the NODE-LVAR.
154 (defun derive-node-type (node rtype)
155 (declare (type valued-node node) (type ctype rtype))
156 (let ((node-type (node-derived-type node)))
157 (unless (eq node-type rtype)
158 (let ((int (values-type-intersection node-type rtype))
159 (lvar (node-lvar node)))
160 (when (type/= node-type int)
161 (when (and *check-consistency*
162 (eq int *empty-type*)
163 (not (eq rtype *empty-type*)))
164 (let ((*compiler-error-context* node))
166 "New inferred type ~S conflicts with old type:~
167 ~% ~S~%*** possible internal error? Please report this."
168 (type-specifier rtype) (type-specifier node-type))))
169 (setf (node-derived-type node) int)
170 ;; If the new type consists of only one object, replace the
171 ;; node with a constant reference.
172 (when (and (ref-p node)
173 (lambda-var-p (ref-leaf node)))
174 (let ((type (single-value-type int)))
175 (when (and (member-type-p type)
176 (null (rest (member-type-members type))))
177 (change-ref-leaf node (find-constant
178 (first (member-type-members type)))))))
179 (reoptimize-lvar lvar)))))
182 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
183 ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it
184 ;;; splitting off DEST a new CAST node; old LVAR will deliver values
185 ;;; to CAST. If we improve the assertion, we set TYPE-CHECK and
186 ;;; TYPE-ASSERTED to guarantee that the new assertion will be checked.
187 (defun assert-lvar-type (lvar type policy)
188 (declare (type lvar lvar) (type ctype type))
189 (unless (values-subtypep (lvar-derived-type lvar) type)
190 (let* ((dest (lvar-dest lvar))
191 (ctran (node-prev dest)))
192 (with-ir1-environment-from-node dest
193 (let* ((cast (make-cast lvar type policy))
194 (internal-lvar (make-lvar))
195 (internal-ctran (make-ctran)))
196 (setf (ctran-next ctran) cast
197 (node-prev cast) ctran)
198 (use-continuation cast internal-ctran internal-lvar)
199 (link-node-to-previous-ctran dest internal-ctran)
200 (substitute-lvar internal-lvar lvar)
201 (setf (lvar-dest lvar) cast)
202 (reoptimize-lvar lvar)
203 (when (return-p dest)
204 (node-ends-block cast))
205 (setf (block-attributep (block-flags (node-block cast))
206 type-check type-asserted)
212 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
213 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
214 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
215 ;;; we are done, then another iteration would be beneficial.
216 (defun ir1-optimize (component)
217 (declare (type component component))
218 (setf (component-reoptimize component) nil)
219 (do-blocks (block component)
221 ;; We delete blocks when there is either no predecessor or the
222 ;; block is in a lambda that has been deleted. These blocks
223 ;; would eventually be deleted by DFO recomputation, but doing
224 ;; it here immediately makes the effect available to IR1
226 ((or (block-delete-p block)
227 (null (block-pred block)))
228 (delete-block block))
229 ((eq (functional-kind (block-home-lambda block)) :deleted)
230 ;; Preserve the BLOCK-SUCC invariant that almost every block has
231 ;; one successor (and a block with DELETE-P set is an acceptable
233 (mark-for-deletion block)
234 (delete-block block))
237 (let ((succ (block-succ block)))
238 (unless (singleton-p succ)
241 (let ((last (block-last block)))
244 (flush-dest (if-test last))
245 (when (unlink-node last)
248 (when (maybe-delete-exit last)
251 (unless (join-successor-if-possible block)
254 (when (and (block-reoptimize block) (block-component block))
255 (aver (not (block-delete-p block)))
256 (ir1-optimize-block block))
258 (cond ((and (block-delete-p block) (block-component block))
259 (delete-block block))
260 ((and (block-flush-p block) (block-component block))
261 (flush-dead-code block))))))
265 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
268 ;;; Note that although they are cleared here, REOPTIMIZE flags might
269 ;;; still be set upon return from this function, meaning that further
270 ;;; optimization is wanted (as a consequence of optimizations we did).
271 (defun ir1-optimize-block (block)
272 (declare (type cblock block))
273 ;; We clear the node and block REOPTIMIZE flags before doing the
274 ;; optimization, not after. This ensures that the node or block will
275 ;; be reoptimized if necessary.
276 (setf (block-reoptimize block) nil)
277 (do-nodes (node nil block :restart-p t)
278 (when (node-reoptimize node)
279 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
280 (setf (node-reoptimize node) nil)
284 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
285 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
286 ;; any argument changes.
287 (ir1-optimize-combination node))
289 (ir1-optimize-if node))
291 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
292 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
293 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
295 (setf (node-reoptimize node) t)
296 (ir1-optimize-return node))
298 (ir1-optimize-mv-combination node))
300 ;; With an EXIT, we derive the node's type from the VALUE's
302 (let ((value (exit-value node)))
304 (derive-node-type node (lvar-derived-type value)))))
306 (ir1-optimize-set node))
308 (ir1-optimize-cast node)))))
312 ;;; Try to join with a successor block. If we succeed, we return true,
314 (defun join-successor-if-possible (block)
315 (declare (type cblock block))
316 (let ((next (first (block-succ block))))
317 (when (block-start next) ; NEXT is not an END-OF-COMPONENT marker
318 (cond ( ;; We cannot combine with a successor block if:
320 ;; The successor has more than one predecessor.
321 (rest (block-pred next))
322 ;; The successor is the current block (infinite loop).
324 ;; The next block has a different cleanup, and thus
325 ;; we may want to insert cleanup code between the
326 ;; two blocks at some point.
327 (not (eq (block-end-cleanup block)
328 (block-start-cleanup next)))
329 ;; The next block has a different home lambda, and
330 ;; thus the control transfer is a non-local exit.
331 (not (eq (block-home-lambda block)
332 (block-home-lambda next))))
335 (join-blocks block next)
338 ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1
339 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags
340 ;;; for the two blocks so that any indicated optimization gets done.
341 (defun join-blocks (block1 block2)
342 (declare (type cblock block1 block2))
343 (let* ((last1 (block-last block1))
344 (last2 (block-last block2))
345 (succ (block-succ block2))
346 (start2 (block-start block2)))
347 (do ((ctran start2 (node-next (ctran-next ctran))))
349 (setf (ctran-block ctran) block1))
351 (unlink-blocks block1 block2)
353 (unlink-blocks block2 block)
354 (link-blocks block1 block))
356 (setf (ctran-kind start2) :inside-block)
357 (setf (node-next last1) start2)
358 (setf (ctran-use start2) last1)
359 (setf (block-last block1) last2))
361 (setf (block-flags block1)
362 (attributes-union (block-flags block1)
364 (block-attributes type-asserted test-modified)))
366 (let ((next (block-next block2))
367 (prev (block-prev block2)))
368 (setf (block-next prev) next)
369 (setf (block-prev next) prev))
373 ;;; Delete any nodes in BLOCK whose value is unused and which have no
374 ;;; side effects. We can delete sets of lexical variables when the set
375 ;;; variable has no references.
376 (defun flush-dead-code (block)
377 (declare (type cblock block))
378 (setf (block-flush-p block) nil)
379 (do-nodes-backwards (node lvar block :restart-p t)
386 (let ((info (combination-kind node)))
387 (when (fun-info-p info)
388 (let ((attr (fun-info-attributes info)))
389 (when (and (not (ir1-attributep attr call))
390 ;; ### For now, don't delete potentially
391 ;; flushable calls when they have the CALL
392 ;; attribute. Someday we should look at the
393 ;; functional args to determine if they have
395 (if (policy node (= safety 3))
396 (ir1-attributep attr flushable)
397 (ir1-attributep attr unsafely-flushable)))
398 (flush-combination node))))))
400 (when (eq (basic-combination-kind node) :local)
401 (let ((fun (combination-lambda node)))
402 (when (dolist (var (lambda-vars fun) t)
403 (when (or (leaf-refs var)
404 (lambda-var-sets var))
406 (flush-dest (first (basic-combination-args node)))
409 (let ((value (exit-value node)))
412 (setf (exit-value node) nil))))
414 (let ((var (set-var node)))
415 (when (and (lambda-var-p var)
416 (null (leaf-refs var)))
417 (flush-dest (set-value node))
418 (setf (basic-var-sets var)
419 (delq node (basic-var-sets var)))
420 (unlink-node node))))
422 (unless (cast-type-check node)
423 (flush-dest (cast-value node))
424 (unlink-node node))))))
428 ;;;; local call return type propagation
430 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
431 ;;; flag set. It iterates over the uses of the RESULT, looking for
432 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
433 ;;; call, then we union its type together with the types of other such
434 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
435 ;;; type with the RESULT's asserted type. We can make this
436 ;;; intersection now (potentially before type checking) because this
437 ;;; assertion on the result will eventually be checked (if
440 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
441 ;;; combination, which may change the succesor of the call to be the
442 ;;; called function, and if so, checks if the call can become an
443 ;;; assignment. If we convert to an assignment, we abort, since the
444 ;;; RETURN has been deleted.
445 (defun find-result-type (node)
446 (declare (type creturn node))
447 (let ((result (return-result node)))
448 (collect ((use-union *empty-type* values-type-union))
449 (do-uses (use result)
450 (let ((use-home (node-home-lambda use)))
451 (cond ((or (eq (functional-kind use-home) :deleted)
452 (block-delete-p (node-block use))))
453 ((and (basic-combination-p use)
454 (eq (basic-combination-kind use) :local))
455 (aver (eq (lambda-tail-set use-home)
456 (lambda-tail-set (combination-lambda use))))
457 (when (combination-p use)
458 (when (nth-value 1 (maybe-convert-tail-local-call use))
459 (return-from find-result-type (values)))))
461 (use-union (node-derived-type use))))))
463 ;; (values-type-intersection
464 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
468 (setf (return-result-type node) int))))
471 ;;; Do stuff to realize that something has changed about the value
472 ;;; delivered to a return node. Since we consider the return values of
473 ;;; all functions in the tail set to be equivalent, this amounts to
474 ;;; bringing the entire tail set up to date. We iterate over the
475 ;;; returns for all the functions in the tail set, reanalyzing them
476 ;;; all (not treating NODE specially.)
478 ;;; When we are done, we check whether the new type is different from
479 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
480 ;;; all the lvars for references to functions in the tail set. This
481 ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the
482 ;;; results of the calls.
483 (defun ir1-optimize-return (node)
484 (declare (type creturn node))
485 (let* ((tails (lambda-tail-set (return-lambda node)))
486 (funs (tail-set-funs tails)))
487 (collect ((res *empty-type* values-type-union))
489 (let ((return (lambda-return fun)))
491 (when (node-reoptimize return)
492 (setf (node-reoptimize return) nil)
493 (find-result-type return))
494 (res (return-result-type return)))))
496 (when (type/= (res) (tail-set-type tails))
497 (setf (tail-set-type tails) (res))
498 (dolist (fun (tail-set-funs tails))
499 (dolist (ref (leaf-refs fun))
500 (reoptimize-lvar (node-lvar ref)))))))
506 ;;; If the test has multiple uses, replicate the node when possible.
507 ;;; Also check whether the predicate is known to be true or false,
508 ;;; deleting the IF node in favor of the appropriate branch when this
510 (defun ir1-optimize-if (node)
511 (declare (type cif node))
512 (let ((test (if-test node))
513 (block (node-block node)))
515 (when (and (eq (block-start-node block) node)
516 (listp (lvar-uses test)))
518 (when (immediately-used-p test use)
519 (convert-if-if use node)
520 (when (not (listp (lvar-uses test))) (return)))))
522 (let* ((type (lvar-type test))
524 (cond ((constant-lvar-p test)
525 (if (lvar-value test)
526 (if-alternative node)
527 (if-consequent node)))
528 ((not (types-equal-or-intersect type (specifier-type 'null)))
529 (if-alternative node))
530 ((type= type (specifier-type 'null))
531 (if-consequent node)))))
534 (when (rest (block-succ block))
535 (unlink-blocks block victim))
536 (setf (component-reanalyze (node-component node)) t)
537 (unlink-node node))))
540 ;;; Create a new copy of an IF node that tests the value of the node
541 ;;; USE. The test must have >1 use, and must be immediately used by
542 ;;; USE. NODE must be the only node in its block (implying that
543 ;;; block-start = if-test).
545 ;;; This optimization has an effect semantically similar to the
546 ;;; source-to-source transformation:
547 ;;; (IF (IF A B C) D E) ==>
548 ;;; (IF A (IF B D E) (IF C D E))
550 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
551 ;;; node so that dead code deletion notes will definitely not consider
552 ;;; either node to be part of the original source. One node might
553 ;;; become unreachable, resulting in a spurious note.
554 (defun convert-if-if (use node)
555 (declare (type node use) (type cif node))
556 (with-ir1-environment-from-node node
557 (let* ((block (node-block node))
558 (test (if-test node))
559 (cblock (if-consequent node))
560 (ablock (if-alternative node))
561 (use-block (node-block use))
562 (new-ctran (make-ctran))
563 (new-lvar (make-lvar))
564 (new-node (make-if :test new-lvar
566 :alternative ablock))
567 (new-block (ctran-starts-block new-ctran)))
568 (link-node-to-previous-ctran new-node new-ctran)
569 (setf (lvar-dest new-lvar) new-node)
570 (setf (block-last new-block) new-node)
572 (unlink-blocks use-block block)
573 (%delete-lvar-use use)
574 (add-lvar-use use new-lvar)
575 (link-blocks use-block new-block)
577 (link-blocks new-block cblock)
578 (link-blocks new-block ablock)
580 (push "<IF Duplication>" (node-source-path node))
581 (push "<IF Duplication>" (node-source-path new-node))
583 (reoptimize-lvar test)
584 (reoptimize-lvar new-lvar)
585 (setf (component-reanalyze *current-component*) t)))
588 ;;;; exit IR1 optimization
590 ;;; This function attempts to delete an exit node, returning true if
591 ;;; it deletes the block as a consequence:
592 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
593 ;;; anything, since there is nothing to be done.
594 ;;; -- If the exit node and its ENTRY have the same home lambda then
595 ;;; we know the exit is local, and can delete the exit. We change
596 ;;; uses of the Exit-Value to be uses of the original lvar,
597 ;;; then unlink the node. If the exit is to a TR context, then we
598 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
599 ;;; their value to this exit.
600 ;;; -- If there is no value (as in a GO), then we skip the value
603 ;;; This function is also called by environment analysis, since it
604 ;;; wants all exits to be optimized even if normal optimization was
606 (defun maybe-delete-exit (node)
607 (declare (type exit node))
608 (let ((value (exit-value node))
609 (entry (exit-entry node)))
611 (eq (node-home-lambda node) (node-home-lambda entry)))
612 (setf (entry-exits entry) (delq node (entry-exits entry)))
614 (delete-filter node (node-lvar node) value)
615 (unlink-node node)))))
618 ;;;; combination IR1 optimization
620 ;;; Report as we try each transform?
622 (defvar *show-transforms-p* nil)
624 ;;; Do IR1 optimizations on a COMBINATION node.
625 (declaim (ftype (function (combination) (values)) ir1-optimize-combination))
626 (defun ir1-optimize-combination (node)
627 (when (lvar-reoptimize (basic-combination-fun node))
628 (propagate-fun-change node)
629 (maybe-terminate-block node nil))
630 (let ((args (basic-combination-args node))
631 (kind (basic-combination-kind node)))
634 (let ((fun (combination-lambda node)))
635 (if (eq (functional-kind fun) :let)
636 (propagate-let-args node fun)
637 (propagate-local-call-args node fun))))
641 (setf (lvar-reoptimize arg) nil))))
645 (setf (lvar-reoptimize arg) nil)))
647 (let ((attr (fun-info-attributes kind)))
648 (when (and (ir1-attributep attr foldable)
649 ;; KLUDGE: The next test could be made more sensitive,
650 ;; only suppressing constant-folding of functions with
651 ;; CALL attributes when they're actually passed
652 ;; function arguments. -- WHN 19990918
653 (not (ir1-attributep attr call))
654 (every #'constant-lvar-p args)
656 ;; Even if the function is foldable in principle,
657 ;; it might be one of our low-level
658 ;; implementation-specific functions. Such
659 ;; functions don't necessarily exist at runtime on
660 ;; a plain vanilla ANSI Common Lisp
661 ;; cross-compilation host, in which case the
662 ;; cross-compiler can't fold it because the
663 ;; cross-compiler doesn't know how to evaluate it.
665 (or (fboundp (combination-fun-source-name node))
666 (progn (format t ";;; !!! Unbound fun: (~S~{ ~S~})~%"
667 (combination-fun-source-name node)
668 (mapcar #'lvar-value args))
670 (constant-fold-call node)
671 (return-from ir1-optimize-combination)))
673 (let ((fun (fun-info-derive-type kind)))
675 (let ((res (funcall fun node)))
677 (derive-node-type node (coerce-to-values res))
678 (maybe-terminate-block node nil)))))
680 (let ((fun (fun-info-optimizer kind)))
681 (unless (and fun (funcall fun node))
682 (dolist (x (fun-info-transforms kind))
684 (when *show-transforms-p*
685 (let* ((lvar (basic-combination-fun node))
686 (fname (lvar-fun-name lvar t)))
687 (/show "trying transform" x (transform-function x) "for" fname)))
688 (unless (ir1-transform node x)
690 (when *show-transforms-p*
691 (/show "quitting because IR1-TRANSFORM result was NIL"))
696 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
697 ;;; the block there, and link it to the component tail.
699 ;;; Except when called during IR1 convertion, we delete the
700 ;;; continuation if it has no other uses. (If it does have other uses,
703 ;;; Termination on the basis of a continuation type is
705 ;;; -- The continuation is deleted (hence the assertion is spurious), or
706 ;;; -- We are in IR1 conversion (where THE assertions are subject to
707 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
708 ;;; uses can(?) be added later. -- APD, 2003-07-17
710 ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30
711 (defun maybe-terminate-block (node ir1-converting-not-optimizing-p)
712 (declare (type (or basic-combination cast) node))
713 (let* ((block (node-block node))
714 (lvar (node-lvar node))
715 (ctran (node-next node))
716 (tail (component-tail (block-component block)))
717 (succ (first (block-succ block))))
718 (unless (or (and (eq node (block-last block)) (eq succ tail))
719 (block-delete-p block))
720 (when (eq (node-derived-type node) *empty-type*)
721 (cond (ir1-converting-not-optimizing-p
724 (aver (eq (block-last block) node)))
726 (setf (block-last block) node)
727 (setf (ctran-use ctran) nil)
728 (setf (ctran-kind ctran) :unused)
729 (setf (ctran-block ctran) nil)
730 (setf (node-next node) nil)
731 (link-blocks block (ctran-starts-block ctran)))))
733 (node-ends-block node)))
735 (unlink-blocks block (first (block-succ block)))
736 (setf (component-reanalyze (block-component block)) t)
737 (aver (not (block-succ block)))
738 (link-blocks block tail)
739 (if ir1-converting-not-optimizing-p
740 (%delete-lvar-use node)
741 (delete-lvar-use node))
744 ;;; This is called both by IR1 conversion and IR1 optimization when
745 ;;; they have verified the type signature for the call, and are
746 ;;; wondering if something should be done to special-case the call. If
747 ;;; CALL is a call to a global function, then see whether it defined
749 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
750 ;;; the expansion and change the call to call it. Expansion is
751 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
752 ;;; true, we never expand, since this function has already been
753 ;;; converted. Local call analysis will duplicate the definition
754 ;;; if necessary. We claim that the parent form is LABELS for
755 ;;; context declarations, since we don't want it to be considered
756 ;;; a real global function.
757 ;;; -- If it is a known function, mark it as such by setting the KIND.
759 ;;; We return the leaf referenced (NIL if not a leaf) and the
760 ;;; FUN-INFO assigned.
761 (defun recognize-known-call (call ir1-converting-not-optimizing-p)
762 (declare (type combination call))
763 (let* ((ref (lvar-uses (basic-combination-fun call)))
764 (leaf (when (ref-p ref) (ref-leaf ref)))
765 (inlinep (if (defined-fun-p leaf)
766 (defined-fun-inlinep leaf)
769 ((eq inlinep :notinline) (values nil nil))
770 ((not (and (global-var-p leaf)
771 (eq (global-var-kind leaf) :global-function)))
776 ((nil :maybe-inline) (policy call (zerop space))))
778 (defined-fun-inline-expansion leaf)
779 (let ((fun (defined-fun-functional leaf)))
781 (and (eq inlinep :inline) (functional-kind fun))))
782 (inline-expansion-ok call))
783 (flet (;; FIXME: Is this what the old CMU CL internal documentation
784 ;; called semi-inlining? A more descriptive name would
785 ;; be nice. -- WHN 2002-01-07
787 (let ((res (ir1-convert-lambda-for-defun
788 (defined-fun-inline-expansion leaf)
790 #'ir1-convert-inline-lambda)))
791 (setf (defined-fun-functional leaf) res)
792 (change-ref-leaf ref res))))
793 (if ir1-converting-not-optimizing-p
795 (with-ir1-environment-from-node call
797 (locall-analyze-component *current-component*))))
799 (values (ref-leaf (lvar-uses (basic-combination-fun call)))
802 (let ((info (info :function :info (leaf-source-name leaf))))
804 (values leaf (setf (basic-combination-kind call) info))
805 (values leaf nil)))))))
807 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
808 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
809 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
810 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
811 ;;; syntax check, arg/result type processing, but still call
812 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
813 ;;; and that checking is done by local call analysis.
814 (defun validate-call-type (call type ir1-converting-not-optimizing-p)
815 (declare (type combination call) (type ctype type))
816 (cond ((not (fun-type-p type))
817 (aver (multiple-value-bind (val win)
818 (csubtypep type (specifier-type 'function))
820 (recognize-known-call call ir1-converting-not-optimizing-p))
821 ((valid-fun-use call type
822 :argument-test #'always-subtypep
823 :result-test #'always-subtypep
824 ;; KLUDGE: Common Lisp is such a dynamic
825 ;; language that all we can do here in
826 ;; general is issue a STYLE-WARNING. It
827 ;; would be nice to issue a full WARNING
828 ;; in the special case of of type
829 ;; mismatches within a compilation unit
830 ;; (as in section 3.2.2.3 of the spec)
831 ;; but at least as of sbcl-0.6.11, we
832 ;; don't keep track of whether the
833 ;; mismatched data came from the same
834 ;; compilation unit, so we can't do that.
837 ;; FIXME: Actually, I think we could
838 ;; issue a full WARNING if the call
839 ;; violates a DECLAIM FTYPE.
840 :lossage-fun #'compiler-style-warn
841 :unwinnage-fun #'compiler-notify)
842 (assert-call-type call type)
843 (maybe-terminate-block call ir1-converting-not-optimizing-p)
844 (recognize-known-call call ir1-converting-not-optimizing-p))
846 (setf (combination-kind call) :error)
849 ;;; This is called by IR1-OPTIMIZE when the function for a call has
850 ;;; changed. If the call is local, we try to LET-convert it, and
851 ;;; derive the result type. If it is a :FULL call, we validate it
852 ;;; against the type, which recognizes known calls, does inline
853 ;;; expansion, etc. If a call to a predicate in a non-conditional
854 ;;; position or to a function with a source transform, then we
855 ;;; reconvert the form to give IR1 another chance.
856 (defun propagate-fun-change (call)
857 (declare (type combination call))
858 (let ((*compiler-error-context* call)
859 (fun-lvar (basic-combination-fun call)))
860 (setf (lvar-reoptimize fun-lvar) nil)
861 (case (combination-kind call)
863 (let ((fun (combination-lambda call)))
864 (maybe-let-convert fun)
865 (unless (member (functional-kind fun) '(:let :assignment :deleted))
866 (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
868 (multiple-value-bind (leaf info)
869 (validate-call-type call (lvar-type fun-lvar) nil)
870 (cond ((functional-p leaf)
871 (convert-call-if-possible
872 (lvar-uses (basic-combination-fun call))
875 ((and (leaf-has-source-name-p leaf)
876 (or (info :function :source-transform (leaf-source-name leaf))
878 (ir1-attributep (fun-info-attributes info)
880 (let ((lvar (node-lvar call)))
881 (and lvar (not (if-p (lvar-dest lvar))))))))
882 (let ((name (leaf-source-name leaf))
883 (dummies (make-gensym-list
884 (length (combination-args call)))))
887 (,@(if (symbolp name)
891 (leaf-source-name leaf)))))))))
894 ;;;; known function optimization
896 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
897 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
898 ;;; replace it, otherwise add a new one.
899 (defun record-optimization-failure (node transform args)
900 (declare (type combination node) (type transform transform)
901 (type (or fun-type list) args))
902 (let* ((table (component-failed-optimizations *component-being-compiled*))
903 (found (assoc transform (gethash node table))))
905 (setf (cdr found) args)
906 (push (cons transform args) (gethash node table))))
909 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
910 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
911 ;;; doing the transform for some reason and FLAME is true, then we
912 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
913 ;;; finalize to pick up. We return true if the transform failed, and
914 ;;; thus further transformation should be attempted. We return false
915 ;;; if either the transform succeeded or was aborted.
916 (defun ir1-transform (node transform)
917 (declare (type combination node) (type transform transform))
918 (let* ((type (transform-type transform))
919 (fun (transform-function transform))
920 (constrained (fun-type-p type))
921 (table (component-failed-optimizations *component-being-compiled*))
922 (flame (if (transform-important transform)
923 (policy node (>= speed inhibit-warnings))
924 (policy node (> speed inhibit-warnings))))
925 (*compiler-error-context* node))
926 (cond ((or (not constrained)
927 (valid-fun-use node type))
928 (multiple-value-bind (severity args)
929 (catch 'give-up-ir1-transform
932 (combination-fun-source-name node))
939 (setf (combination-kind node) :error)
941 (apply #'compiler-warn args))
947 (record-optimization-failure node transform args))
948 (setf (gethash node table)
949 (remove transform (gethash node table) :key #'car)))
957 :argument-test #'types-equal-or-intersect
958 :result-test #'values-types-equal-or-intersect))
959 (record-optimization-failure node transform type)
964 ;;; When we don't like an IR1 transform, we throw the severity/reason
967 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
968 ;;; aborting this attempt to transform the call, but admitting the
969 ;;; possibility that this or some other transform will later succeed.
970 ;;; If arguments are supplied, they are format arguments for an
973 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
974 ;;; force a normal call to the function at run time. No further
975 ;;; optimizations will be attempted.
977 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
978 ;;; delay the transform on the node until later. REASONS specifies
979 ;;; when the transform will be later retried. The :OPTIMIZE reason
980 ;;; causes the transform to be delayed until after the current IR1
981 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
982 ;;; be delayed until after constraint propagation.
984 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
985 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
986 ;;; do CASE operations on the various REASON values, it might be a
987 ;;; good idea to go OO, representing the reasons by objects, using
988 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
989 ;;; SIGNAL instead of THROW.
990 (declaim (ftype (function (&rest t) nil) give-up-ir1-transform))
991 (defun give-up-ir1-transform (&rest args)
992 (throw 'give-up-ir1-transform (values :failure args)))
993 (defun abort-ir1-transform (&rest args)
994 (throw 'give-up-ir1-transform (values :aborted args)))
995 (defun delay-ir1-transform (node &rest reasons)
996 (let ((assoc (assoc node *delayed-ir1-transforms*)))
998 (setf *delayed-ir1-transforms*
999 (acons node reasons *delayed-ir1-transforms*))
1000 (throw 'give-up-ir1-transform :delayed))
1002 (dolist (reason reasons)
1003 (pushnew reason (cdr assoc)))
1004 (throw 'give-up-ir1-transform :delayed)))))
1006 ;;; Clear any delayed transform with no reasons - these should have
1007 ;;; been tried in the last pass. Then remove the reason from the
1008 ;;; delayed transform reasons, and if any become empty then set
1009 ;;; reoptimize flags for the node. Return true if any transforms are
1011 (defun retry-delayed-ir1-transforms (reason)
1012 (setf *delayed-ir1-transforms*
1013 (remove-if-not #'cdr *delayed-ir1-transforms*))
1014 (let ((reoptimize nil))
1015 (dolist (assoc *delayed-ir1-transforms*)
1016 (let ((reasons (remove reason (cdr assoc))))
1017 (setf (cdr assoc) reasons)
1019 (let ((node (car assoc)))
1020 (unless (node-deleted node)
1022 (setf (node-reoptimize node) t)
1023 (let ((block (node-block node)))
1024 (setf (block-reoptimize block) t)
1025 (setf (component-reoptimize (block-component block)) t)))))))
1028 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1029 ;;; environment, and then install it as the function for the call
1030 ;;; NODE. We do local call analysis so that the new function is
1031 ;;; integrated into the control flow.
1033 ;;; We require the original function source name in order to generate
1034 ;;; a meaningful debug name for the lambda we set up. (It'd be
1035 ;;; possible to do this starting from debug names as well as source
1036 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1037 ;;; generality, since source names are always known to our callers.)
1038 (defun transform-call (call res source-name)
1039 (declare (type combination call) (list res))
1040 (aver (and (legal-fun-name-p source-name)
1041 (not (eql source-name '.anonymous.))))
1042 (node-ends-block call)
1043 (with-ir1-environment-from-node call
1044 (with-component-last-block (*current-component*
1045 (block-next (node-block call)))
1046 (let ((new-fun (ir1-convert-inline-lambda
1048 :debug-name (debug-namify "LAMBDA-inlined ~A"
1051 "<unknown function>"))))
1052 (ref (lvar-use (combination-fun call))))
1053 (change-ref-leaf ref new-fun)
1054 (setf (combination-kind call) :full)
1055 (locall-analyze-component *current-component*))))
1058 ;;; Replace a call to a foldable function of constant arguments with
1059 ;;; the result of evaluating the form. If there is an error during the
1060 ;;; evaluation, we give a warning and leave the call alone, making the
1061 ;;; call a :ERROR call.
1063 ;;; If there is more than one value, then we transform the call into a
1065 (defun constant-fold-call (call)
1066 (let ((args (mapcar #'lvar-value (combination-args call)))
1067 (fun-name (combination-fun-source-name call)))
1068 (multiple-value-bind (values win)
1069 (careful-call fun-name
1072 ;; Note: CMU CL had COMPILER-WARN here, and that
1073 ;; seems more natural, but it's probably not.
1075 ;; It's especially not while bug 173 exists:
1078 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1080 ;; can cause constant-folding TYPE-ERRORs (in
1081 ;; #'<=) when END can be proved to be NIL, even
1082 ;; though the code is perfectly legal and safe
1083 ;; because a NIL value of END means that the
1084 ;; #'<= will never be executed.
1086 ;; Moreover, even without bug 173,
1087 ;; quite-possibly-valid code like
1088 ;; (COND ((NONINLINED-PREDICATE END)
1089 ;; (UNLESS (<= END SIZE))
1091 ;; (where NONINLINED-PREDICATE is something the
1092 ;; compiler can't do at compile time, but which
1093 ;; turns out to make the #'<= expression
1094 ;; unreachable when END=NIL) could cause errors
1095 ;; when the compiler tries to constant-fold (<=
1098 ;; So, with or without bug 173, it'd be
1099 ;; unnecessarily evil to do a full
1100 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1101 ;; from COMPILE-FILE) for legal code, so we we
1102 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1103 #'compiler-style-warn
1106 (setf (combination-kind call) :error))
1107 ((and (proper-list-of-length-p values 1))
1108 (with-ir1-environment-from-node call
1109 (let* ((lvar (node-lvar call))
1110 (prev (node-prev call))
1111 (intermediate-ctran (make-ctran)))
1112 (%delete-lvar-use call)
1113 (setf (ctran-next prev) nil)
1114 (setf (node-prev call) nil)
1115 (reference-constant prev intermediate-ctran lvar
1117 (link-node-to-previous-ctran call intermediate-ctran)
1118 (reoptimize-lvar lvar)
1119 (flush-combination call))))
1120 (t (let ((dummies (make-gensym-list (length args))))
1124 (declare (ignore ,@dummies))
1125 (values ,@(mapcar (lambda (x) `',x) values)))
1129 ;;;; local call optimization
1131 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1132 ;;; the leaf type is a function type, then just leave it alone, since
1133 ;;; TYPE is never going to be more specific than that (and
1134 ;;; TYPE-INTERSECTION would choke.)
1135 (defun propagate-to-refs (leaf type)
1136 (declare (type leaf leaf) (type ctype type))
1137 (let ((var-type (leaf-type leaf)))
1138 (unless (fun-type-p var-type)
1139 (let ((int (type-approx-intersection2 var-type type)))
1140 (when (type/= int var-type)
1141 (setf (leaf-type leaf) int)
1142 (dolist (ref (leaf-refs leaf))
1143 (derive-node-type ref (make-single-value-type int))
1144 ;; KLUDGE: LET var substitution
1145 (let* ((lvar (node-lvar ref)))
1146 (when (and lvar (combination-p (lvar-dest lvar)))
1147 (reoptimize-lvar lvar))))))
1150 ;;; Iteration variable: exactly one SETQ of the form:
1152 ;;; (let ((var initial))
1154 ;;; (setq var (+ var step))
1156 (defun maybe-infer-iteration-var-type (var initial-type)
1157 (binding* ((sets (lambda-var-sets var) :exit-if-null)
1159 (() (null (rest sets)) :exit-if-null)
1160 (set-use (principal-lvar-use (set-value set)))
1161 (() (and (combination-p set-use)
1162 (fun-info-p (combination-kind set-use))
1163 (eq (combination-fun-source-name set-use) '+))
1165 (+-args (basic-combination-args set-use))
1166 (() (and (proper-list-of-length-p +-args 2 2)
1167 (let ((first (principal-lvar-use
1170 (eq (ref-leaf first) var))))
1172 (step-type (lvar-type (second +-args)))
1173 (set-type (lvar-type (set-value set))))
1174 (when (and (numeric-type-p initial-type)
1175 (numeric-type-p step-type)
1176 (numeric-type-equal initial-type step-type))
1177 (multiple-value-bind (low high)
1178 (cond ((csubtypep step-type (specifier-type '(real 0 *)))
1179 (values (numeric-type-low initial-type)
1180 (when (and (numeric-type-p set-type)
1181 (numeric-type-equal set-type initial-type))
1182 (numeric-type-high set-type))))
1183 ((csubtypep step-type (specifier-type '(real * 0)))
1184 (values (when (and (numeric-type-p set-type)
1185 (numeric-type-equal set-type initial-type))
1186 (numeric-type-low set-type))
1187 (numeric-type-high initial-type)))
1190 (modified-numeric-type initial-type
1193 :enumerable nil)))))
1194 (deftransform + ((x y) * * :result result)
1195 "check for iteration variable reoptimization"
1196 (let ((dest (principal-lvar-end result))
1197 (use (principal-lvar-use x)))
1198 (when (and (ref-p use)
1202 (reoptimize-lvar (set-value dest))))
1203 (give-up-ir1-transform))
1205 ;;; Figure out the type of a LET variable that has sets. We compute
1206 ;;; the union of the INITIAL-TYPE and the types of all the set
1207 ;;; values and to a PROPAGATE-TO-REFS with this type.
1208 (defun propagate-from-sets (var initial-type)
1209 (collect ((res initial-type type-union))
1210 (dolist (set (basic-var-sets var))
1211 (let ((type (lvar-type (set-value set))))
1213 (when (node-reoptimize set)
1214 (derive-node-type set (make-single-value-type type))
1215 (setf (node-reoptimize set) nil))))
1217 (awhen (maybe-infer-iteration-var-type var initial-type)
1219 (propagate-to-refs var res)))
1222 ;;; If a LET variable, find the initial value's type and do
1223 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1225 (defun ir1-optimize-set (node)
1226 (declare (type cset node))
1227 (let ((var (set-var node)))
1228 (when (and (lambda-var-p var) (leaf-refs var))
1229 (let ((home (lambda-var-home var)))
1230 (when (eq (functional-kind home) :let)
1231 (let* ((initial-value (let-var-initial-value var))
1232 (initial-type (lvar-type initial-value)))
1233 (setf (lvar-reoptimize initial-value) nil)
1234 (propagate-from-sets var initial-type))))))
1236 (derive-node-type node (make-single-value-type
1237 (lvar-type (set-value node))))
1240 ;;; Return true if the value of REF will always be the same (and is
1241 ;;; thus legal to substitute.)
1242 (defun constant-reference-p (ref)
1243 (declare (type ref ref))
1244 (let ((leaf (ref-leaf ref)))
1246 ((or constant functional) t)
1248 (null (lambda-var-sets leaf)))
1250 (not (eq (defined-fun-inlinep leaf) :notinline)))
1252 (case (global-var-kind leaf)
1254 (let ((name (leaf-source-name leaf)))
1256 (eq (symbol-package (fun-name-block-name name))
1258 (info :function :info name)))))))))
1260 ;;; If we have a non-set LET var with a single use, then (if possible)
1261 ;;; replace the variable reference's LVAR with the arg lvar.
1263 ;;; We change the REF to be a reference to NIL with unused value, and
1264 ;;; let it be flushed as dead code. A side effect of this substitution
1265 ;;; is to delete the variable.
1266 (defun substitute-single-use-lvar (arg var)
1267 (declare (type lvar arg) (type lambda-var var))
1268 (binding* ((ref (first (leaf-refs var)))
1269 (lvar (node-lvar ref) :exit-if-null)
1270 (dest (lvar-dest lvar)))
1272 ;; Think about (LET ((A ...)) (IF ... A ...)): two
1273 ;; LVAR-USEs should not be met on one path.
1274 (eq (lvar-uses lvar) ref)
1276 ;; we should not change lifetime of unknown values lvars
1278 (and (type-single-value-p (lvar-derived-type arg))
1279 (multiple-value-bind (pdest pprev)
1280 (principal-lvar-end lvar)
1281 (declare (ignore pdest))
1282 (lvar-single-value-p pprev))))
1284 (or (eq (basic-combination-fun dest) lvar)
1285 (and (eq (basic-combination-kind dest) :local)
1286 (type-single-value-p (lvar-derived-type arg)))))
1288 ;; While CRETURN and EXIT nodes may be known-values,
1289 ;; they have their own complications, such as
1290 ;; substitution into CRETURN may create new tail calls.
1293 (aver (lvar-single-value-p lvar))
1295 (eq (node-home-lambda ref)
1296 (lambda-home (lambda-var-home var))))
1297 (setf (node-derived-type ref) *wild-type*)
1298 (substitute-lvar-uses lvar arg)
1299 (delete-lvar-use ref)
1300 (change-ref-leaf ref (find-constant nil))
1303 (reoptimize-lvar lvar)
1306 ;;; Delete a LET, removing the call and bind nodes, and warning about
1307 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1308 ;;; along right away and delete the REF and then the lambda, since we
1309 ;;; flush the FUN lvar.
1310 (defun delete-let (clambda)
1311 (declare (type clambda clambda))
1312 (aver (functional-letlike-p clambda))
1313 (note-unreferenced-vars clambda)
1314 (let ((call (let-combination clambda)))
1315 (flush-dest (basic-combination-fun call))
1317 (unlink-node (lambda-bind clambda))
1318 (setf (lambda-bind clambda) nil))
1321 ;;; This function is called when one of the arguments to a LET
1322 ;;; changes. We look at each changed argument. If the corresponding
1323 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1324 ;;; consider substituting for the variable, and also propagate
1325 ;;; derived-type information for the arg to all the VAR's refs.
1327 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1328 ;;; subtype of the argument's leaf type. This prevents type checking
1329 ;;; from being defeated, and also ensures that the best representation
1330 ;;; for the variable can be used.
1332 ;;; Substitution of individual references is inhibited if the
1333 ;;; reference is in a different component from the home. This can only
1334 ;;; happen with closures over top level lambda vars. In such cases,
1335 ;;; the references may have already been compiled, and thus can't be
1336 ;;; retroactively modified.
1338 ;;; If all of the variables are deleted (have no references) when we
1339 ;;; are done, then we delete the LET.
1341 ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE
1343 (defun propagate-let-args (call fun)
1344 (declare (type combination call) (type clambda fun))
1345 (loop for arg in (combination-args call)
1346 and var in (lambda-vars fun) do
1347 (when (and arg (lvar-reoptimize arg))
1348 (setf (lvar-reoptimize arg) nil)
1350 ((lambda-var-sets var)
1351 (propagate-from-sets var (lvar-type arg)))
1352 ((let ((use (lvar-uses arg)))
1354 (let ((leaf (ref-leaf use)))
1355 (when (and (constant-reference-p use)
1356 (csubtypep (leaf-type leaf)
1357 ;; (NODE-DERIVED-TYPE USE) would
1358 ;; be better -- APD, 2003-05-15
1360 (propagate-to-refs var (lvar-type arg))
1361 (let ((use-component (node-component use)))
1362 (prog1 (substitute-leaf-if
1364 (cond ((eq (node-component ref) use-component)
1367 (aver (lambda-toplevelish-p (lambda-home fun)))
1371 ((and (null (rest (leaf-refs var)))
1372 (substitute-single-use-lvar arg var)))
1374 (propagate-to-refs var (lvar-type arg))))))
1376 (when (every #'not (combination-args call))
1381 ;;; This function is called when one of the args to a non-LET local
1382 ;;; call changes. For each changed argument corresponding to an unset
1383 ;;; variable, we compute the union of the types across all calls and
1384 ;;; propagate this type information to the var's refs.
1386 ;;; If the function has an XEP, then we don't do anything, since we
1387 ;;; won't discover anything.
1389 ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls
1390 ;;; corresponding to changed arguments in CALL, since the only use in
1391 ;;; IR1 optimization of the REOPTIMIZE flag for local call args is
1393 (defun propagate-local-call-args (call fun)
1394 (declare (type combination call) (type clambda fun))
1396 (unless (or (functional-entry-fun fun)
1397 (lambda-optional-dispatch fun))
1398 (let* ((vars (lambda-vars fun))
1399 (union (mapcar (lambda (arg var)
1401 (lvar-reoptimize arg)
1402 (null (basic-var-sets var)))
1404 (basic-combination-args call)
1406 (this-ref (lvar-use (basic-combination-fun call))))
1408 (dolist (arg (basic-combination-args call))
1410 (setf (lvar-reoptimize arg) nil)))
1412 (dolist (ref (leaf-refs fun))
1413 (let ((dest (node-dest ref)))
1414 (unless (or (eq ref this-ref) (not dest))
1416 (mapcar (lambda (this-arg old)
1418 (setf (lvar-reoptimize this-arg) nil)
1419 (type-union (lvar-type this-arg) old)))
1420 (basic-combination-args dest)
1423 (loop for var in vars
1425 when type do (propagate-to-refs var type))))
1429 ;;;; multiple values optimization
1431 ;;; Do stuff to notice a change to a MV combination node. There are
1432 ;;; two main branches here:
1433 ;;; -- If the call is local, then it is already a MV let, or should
1434 ;;; become one. Note that although all :LOCAL MV calls must eventually
1435 ;;; be converted to :MV-LETs, there can be a window when the call
1436 ;;; is local, but has not been LET converted yet. This is because
1437 ;;; the entry-point lambdas may have stray references (in other
1438 ;;; entry points) that have not been deleted yet.
1439 ;;; -- The call is full. This case is somewhat similar to the non-MV
1440 ;;; combination optimization: we propagate return type information and
1441 ;;; notice non-returning calls. We also have an optimization
1442 ;;; which tries to convert MV-CALLs into MV-binds.
1443 (defun ir1-optimize-mv-combination (node)
1444 (ecase (basic-combination-kind node)
1446 (let ((fun-lvar (basic-combination-fun node)))
1447 (when (lvar-reoptimize fun-lvar)
1448 (setf (lvar-reoptimize fun-lvar) nil)
1449 (maybe-let-convert (combination-lambda node))))
1450 (setf (lvar-reoptimize (first (basic-combination-args node))) nil)
1451 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1452 (unless (convert-mv-bind-to-let node)
1453 (ir1-optimize-mv-bind node))))
1455 (let* ((fun (basic-combination-fun node))
1456 (fun-changed (lvar-reoptimize fun))
1457 (args (basic-combination-args node)))
1459 (setf (lvar-reoptimize fun) nil)
1460 (let ((type (lvar-type fun)))
1461 (when (fun-type-p type)
1462 (derive-node-type node (fun-type-returns type))))
1463 (maybe-terminate-block node nil)
1464 (let ((use (lvar-uses fun)))
1465 (when (and (ref-p use) (functional-p (ref-leaf use)))
1466 (convert-call-if-possible use node)
1467 (when (eq (basic-combination-kind node) :local)
1468 (maybe-let-convert (ref-leaf use))))))
1469 (unless (or (eq (basic-combination-kind node) :local)
1470 (eq (lvar-fun-name fun) '%throw))
1471 (ir1-optimize-mv-call node))
1473 (setf (lvar-reoptimize arg) nil))))
1477 ;;; Propagate derived type info from the values lvar to the vars.
1478 (defun ir1-optimize-mv-bind (node)
1479 (declare (type mv-combination node))
1480 (let* ((arg (first (basic-combination-args node)))
1481 (vars (lambda-vars (combination-lambda node)))
1482 (n-vars (length vars))
1483 (types (values-type-in (lvar-derived-type arg)
1485 (loop for var in vars
1487 do (if (basic-var-sets var)
1488 (propagate-from-sets var type)
1489 (propagate-to-refs var type)))
1490 (setf (lvar-reoptimize arg) nil))
1493 ;;; If possible, convert a general MV call to an MV-BIND. We can do
1495 ;;; -- The call has only one argument, and
1496 ;;; -- The function has a known fixed number of arguments, or
1497 ;;; -- The argument yields a known fixed number of values.
1499 ;;; What we do is change the function in the MV-CALL to be a lambda
1500 ;;; that "looks like an MV bind", which allows
1501 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1502 ;;; converted (the next time around.) This new lambda just calls the
1503 ;;; actual function with the MV-BIND variables as arguments. Note that
1504 ;;; this new MV bind is not let-converted immediately, as there are
1505 ;;; going to be stray references from the entry-point functions until
1506 ;;; they get deleted.
1508 ;;; In order to avoid loss of argument count checking, we only do the
1509 ;;; transformation according to a known number of expected argument if
1510 ;;; safety is unimportant. We can always convert if we know the number
1511 ;;; of actual values, since the normal call that we build will still
1512 ;;; do any appropriate argument count checking.
1514 ;;; We only attempt the transformation if the called function is a
1515 ;;; constant reference. This allows us to just splice the leaf into
1516 ;;; the new function, instead of trying to somehow bind the function
1517 ;;; expression. The leaf must be constant because we are evaluating it
1518 ;;; again in a different place. This also has the effect of squelching
1519 ;;; multiple warnings when there is an argument count error.
1520 (defun ir1-optimize-mv-call (node)
1521 (let ((fun (basic-combination-fun node))
1522 (*compiler-error-context* node)
1523 (ref (lvar-uses (basic-combination-fun node)))
1524 (args (basic-combination-args node)))
1526 (unless (and (ref-p ref) (constant-reference-p ref)
1528 (return-from ir1-optimize-mv-call))
1530 (multiple-value-bind (min max)
1531 (fun-type-nargs (lvar-type fun))
1533 (multiple-value-bind (types nvals)
1534 (values-types (lvar-derived-type (first args)))
1535 (declare (ignore types))
1536 (if (eq nvals :unknown) nil nvals))))
1539 (when (and min (< total-nvals min))
1541 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1544 (setf (basic-combination-kind node) :error)
1545 (return-from ir1-optimize-mv-call))
1546 (when (and max (> total-nvals max))
1548 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1551 (setf (basic-combination-kind node) :error)
1552 (return-from ir1-optimize-mv-call)))
1554 (let ((count (cond (total-nvals)
1555 ((and (policy node (zerop verify-arg-count))
1560 (with-ir1-environment-from-node node
1561 (let* ((dums (make-gensym-list count))
1563 (fun (ir1-convert-lambda
1564 `(lambda (&optional ,@dums &rest ,ignore)
1565 (declare (ignore ,ignore))
1566 (funcall ,(ref-leaf ref) ,@dums)))))
1567 (change-ref-leaf ref fun)
1568 (aver (eq (basic-combination-kind node) :full))
1569 (locall-analyze-component *current-component*)
1570 (aver (eq (basic-combination-kind node) :local)))))))))
1574 ;;; (multiple-value-bind
1583 ;;; What we actually do is convert the VALUES combination into a
1584 ;;; normal LET combination calling the original :MV-LET lambda. If
1585 ;;; there are extra args to VALUES, discard the corresponding
1586 ;;; lvars. If there are insufficient args, insert references to NIL.
1587 (defun convert-mv-bind-to-let (call)
1588 (declare (type mv-combination call))
1589 (let* ((arg (first (basic-combination-args call)))
1590 (use (lvar-uses arg)))
1591 (when (and (combination-p use)
1592 (eq (lvar-fun-name (combination-fun use))
1594 (let* ((fun (combination-lambda call))
1595 (vars (lambda-vars fun))
1596 (vals (combination-args use))
1597 (nvars (length vars))
1598 (nvals (length vals)))
1599 (cond ((> nvals nvars)
1600 (mapc #'flush-dest (subseq vals nvars))
1601 (setq vals (subseq vals 0 nvars)))
1603 (with-ir1-environment-from-node use
1604 (let ((node-prev (node-prev use)))
1605 (setf (node-prev use) nil)
1606 (setf (ctran-next node-prev) nil)
1607 (collect ((res vals))
1608 (loop for count below (- nvars nvals)
1609 for prev = node-prev then ctran
1610 for ctran = (make-ctran)
1611 and lvar = (make-lvar use)
1612 do (reference-constant prev ctran lvar nil)
1614 finally (link-node-to-previous-ctran
1616 (setq vals (res)))))))
1617 (setf (combination-args use) vals)
1618 (flush-dest (combination-fun use))
1619 (let ((fun-lvar (basic-combination-fun call)))
1620 (setf (lvar-dest fun-lvar) use)
1621 (setf (combination-fun use) fun-lvar)
1622 (flush-lvar-externally-checkable-type fun-lvar))
1623 (setf (combination-kind use) :local)
1624 (setf (functional-kind fun) :let)
1625 (flush-dest (first (basic-combination-args call)))
1628 (reoptimize-lvar (first vals)))
1629 (propagate-to-args use fun)
1630 (reoptimize-call use))
1634 ;;; (values-list (list x y z))
1639 ;;; In implementation, this is somewhat similar to
1640 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1641 ;;; args of the VALUES-LIST call, flushing the old argument lvar
1642 ;;; (allowing the LIST to be flushed.)
1644 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
1645 (defoptimizer (values-list optimizer) ((list) node)
1646 (let ((use (lvar-uses list)))
1647 (when (and (combination-p use)
1648 (eq (lvar-fun-name (combination-fun use))
1651 ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR.
1652 (change-ref-leaf (lvar-uses (combination-fun node))
1653 (find-free-fun 'values "in a strange place"))
1654 (setf (combination-kind node) :full)
1655 (let ((args (combination-args use)))
1657 (setf (lvar-dest arg) node)
1658 (flush-lvar-externally-checkable-type arg))
1659 (setf (combination-args use) nil)
1661 (setf (combination-args node) args))
1664 ;;; If VALUES appears in a non-MV context, then effectively convert it
1665 ;;; to a PROG1. This allows the computation of the additional values
1666 ;;; to become dead code.
1667 (deftransform values ((&rest vals) * * :node node)
1668 (unless (lvar-single-value-p (node-lvar node))
1669 (give-up-ir1-transform))
1670 (setf (node-derived-type node) *wild-type*)
1671 (principal-lvar-single-valuify (node-lvar node))
1673 (let ((dummies (make-gensym-list (length (cdr vals)))))
1674 `(lambda (val ,@dummies)
1675 (declare (ignore ,@dummies))
1681 (defun ir1-optimize-cast (cast &optional do-not-optimize)
1682 (declare (type cast cast))
1683 (let ((value (cast-value cast))
1684 (atype (cast-asserted-type cast)))
1685 (when (not do-not-optimize)
1686 (let ((lvar (node-lvar cast)))
1687 (when (values-subtypep (lvar-derived-type value)
1688 (cast-asserted-type cast))
1689 (delete-filter cast lvar value)
1691 (reoptimize-lvar lvar)
1692 (when (lvar-single-value-p lvar)
1693 (note-single-valuified-lvar lvar)))
1694 (return-from ir1-optimize-cast t))
1696 (when (and (listp (lvar-uses value))
1698 ;; Pathwise removing of CAST
1699 (let ((ctran (node-next cast))
1700 (dest (lvar-dest lvar))
1703 (do-uses (use value)
1704 (when (and (values-subtypep (node-derived-type use) atype)
1705 (immediately-used-p value use))
1707 (when ctran (ensure-block-start ctran))
1708 (setq next-block (first (block-succ (node-block cast)))))
1709 (%delete-lvar-use use)
1710 (add-lvar-use use lvar)
1711 (unlink-blocks (node-block use) (node-block cast))
1712 (link-blocks (node-block use) next-block)
1713 (when (and (return-p dest)
1714 (basic-combination-p use)
1715 (eq (basic-combination-kind use) :local))
1717 (dolist (use (merges))
1718 (merge-tail-sets use)))))))
1720 (let* ((value-type (lvar-derived-type value))
1721 (int (values-type-intersection value-type atype)))
1722 (derive-node-type cast int)
1723 (when (eq int *empty-type*)
1724 (unless (eq value-type *empty-type*)
1726 ;; FIXME: Do it in one step.
1729 `(multiple-value-call #'list 'dummy))
1732 ;; FIXME: Derived type.
1733 `(%compile-time-type-error 'dummy
1734 ',(type-specifier atype)
1735 ',(type-specifier value-type)))
1736 ;; KLUDGE: FILTER-LVAR does not work for non-returning
1737 ;; functions, so we declare the return type of
1738 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
1740 (setq value (cast-value cast))
1741 (derive-node-type (lvar-uses value) *empty-type*)
1742 (maybe-terminate-block (lvar-uses value) nil)
1743 ;; FIXME: Is it necessary?
1744 (aver (null (block-pred (node-block cast))))
1745 (setf (block-delete-p (node-block cast)) t)
1746 (return-from ir1-optimize-cast)))
1747 (when (eq (node-derived-type cast) *empty-type*)
1748 (maybe-terminate-block cast nil))
1750 (when (and (cast-%type-check cast)
1751 (values-subtypep value-type
1752 (cast-type-to-check cast)))
1753 (setf (cast-%type-check cast) nil))))
1755 (unless do-not-optimize
1756 (setf (node-reoptimize cast) nil)))