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Revision 1.66 - (hide annotations)
Tue Feb 24 09:58:18 1998 UTC (16 years, 1 month ago) by dtc
Branch: MAIN
Changes since 1.65: +4 -1 lines
When constant-folding succeeds alway transform the call so that even
non-flushable functions are flushed.  For single value calls it had
been just unlinking the result and inserting the constant but this
failed to flush the call if it didn't have a flushable attribute, for
example numeric constant coercions were not being flush when
successful leading to rather inefficient code.
1 wlott 1.1 ;;; -*- Package: C; Log: C.Log -*-
2     ;;;
3     ;;; **********************************************************************
4 ram 1.24 ;;; This code was written as part of the CMU Common Lisp project at
5     ;;; Carnegie Mellon University, and has been placed in the public domain.
6     ;;;
7     (ext:file-comment
8 dtc 1.66 "$Header: /tiger/var/lib/cvsroots/cmucl/src/compiler/ir1opt.lisp,v 1.66 1998/02/24 09:58:18 dtc Exp $")
9 ram 1.24 ;;;
10 wlott 1.1 ;;; **********************************************************************
11     ;;;
12     ;;; This file implements the IR1 optimization phase of the compiler. IR1
13     ;;; optimization is a grab-bag of optimizations that don't make major changes
14     ;;; to the block-level control flow and don't use flow analysis. These
15     ;;; optimizations can mostly be classified as "meta-evaluation", but there is a
16     ;;; sizable top-down component as well.
17     ;;;
18     ;;; Written by Rob MacLachlan
19     ;;;
20 ram 1.46 (in-package :c)
21 wlott 1.1
22    
23     ;;;; Interface for obtaining results of constant folding:
24    
25     ;;; Constant-Continuation-P -- Interface
26     ;;;
27     ;;; Return true if the sole use of Cont is a reference to a constant leaf.
28     ;;;
29     (proclaim '(function constant-continuation-p (continuation) boolean))
30     (defun constant-continuation-p (cont)
31     (let ((use (continuation-use cont)))
32     (and (ref-p use)
33     (constant-p (ref-leaf use)))))
34    
35    
36     ;;; Continuation-Value -- Interface
37     ;;;
38     ;;; Return the constant value for a continuation whose only use is a
39     ;;; constant node.
40     ;;;
41     (proclaim '(function continuation-value (continuation) t))
42     (defun continuation-value (cont)
43 ram 1.10 (assert (constant-continuation-p cont))
44 wlott 1.1 (constant-value (ref-leaf (continuation-use cont))))
45    
46    
47     ;;;; Interface for obtaining results of type inference:
48    
49     ;;; CONTINUATION-PROVEN-TYPE -- Interface
50     ;;;
51     ;;; Return a (possibly values) type that describes what we have proven about
52     ;;; the type of Cont without taking any type assertions into consideration.
53     ;;; This is just the union of the NODE-DERIVED-TYPE of all the uses. Most
54     ;;; often people use CONTINUATION-DERIVED-TYPE or CONTINUATION-TYPE instead of
55     ;;; using this function directly.
56     ;;;
57     (defun continuation-proven-type (cont)
58     (declare (type continuation cont))
59     (ecase (continuation-kind cont)
60     ((:block-start :deleted-block-start)
61     (let ((uses (block-start-uses (continuation-block cont))))
62     (if uses
63     (do ((res (node-derived-type (first uses))
64     (values-type-union (node-derived-type (first current))
65     res))
66     (current (rest uses) (rest current)))
67     ((null current) res))
68     *empty-type*)))
69     (:inside-block
70     (node-derived-type (continuation-use cont)))))
71    
72    
73     ;;; Continuation-Derived-Type -- Interface
74     ;;;
75     ;;; Our best guess for the type of this continuation's value. Note that
76     ;;; this may be Values or Function type, which cannot be passed as an argument
77     ;;; to the normal type operations. See Continuation-Type. This may be called
78     ;;; on deleted continuations, always returning *.
79     ;;;
80     ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the result
81     ;;; is a subtype of the assertion. If so, return the proven type and set
82     ;;; TYPE-CHECK to nil. Otherwise, return the intersection of the asserted and
83     ;;; proven types, and set TYPE-CHECK T. If TYPE-CHECK already has a non-null
84     ;;; value, then preserve it. Only in the somewhat unusual circumstance of
85     ;;; a newly discovered assertion will we change TYPE-CHECK from NIL to T.
86     ;;;
87     ;;; The result value is cached in the Continuation-%Derived-Type. If the
88     ;;; slot is true, just return that value, otherwise recompute and stash the
89     ;;; value there.
90     ;;;
91     (proclaim '(inline continuation-derived-type))
92     (defun continuation-derived-type (cont)
93     (declare (type continuation cont))
94     (or (continuation-%derived-type cont)
95     (%continuation-derived-type cont)))
96     ;;;
97     (defun %continuation-derived-type (cont)
98     (declare (type continuation cont))
99     (let ((proven (continuation-proven-type cont))
100     (asserted (continuation-asserted-type cont)))
101     (cond ((values-subtypep proven asserted)
102     (setf (continuation-%type-check cont) nil)
103     (setf (continuation-%derived-type cont) proven))
104     (t
105     (unless (or (continuation-%type-check cont)
106     (not (continuation-dest cont))
107     (eq asserted *universal-type*))
108     (setf (continuation-%type-check cont) t))
109    
110     (setf (continuation-%derived-type cont)
111     (values-type-intersection asserted proven))))))
112    
113    
114     ;;; CONTINUATION-TYPE-CHECK -- Interface
115     ;;;
116     ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to date, then
117     ;;; return it.
118     ;;;
119     (proclaim '(inline continuation-type-check))
120     (defun continuation-type-check (cont)
121     (declare (type continuation cont))
122     (continuation-derived-type cont)
123     (continuation-%type-check cont))
124    
125    
126     ;;; Continuation-Type -- Interface
127     ;;;
128     ;;; Return the derived type for Cont's first value. This is guaranteed not
129     ;;; to be a Values or Function type.
130     ;;;
131 wlott 1.14 (proclaim '(function continuation-type (continuation) ctype))
132 wlott 1.1 (defun continuation-type (cont)
133     (single-value-type (continuation-derived-type cont)))
134    
135    
136     ;;;; Interface routines used by optimizers:
137    
138     ;;; Reoptimize-Continuation -- Interface
139     ;;;
140     ;;; This function is called by optimizers to indicate that something
141     ;;; interesting has happened to the value of Cont. Optimizers must make sure
142     ;;; that they don't call for reoptimization when nothing has happened, since
143     ;;; optimization will fail to terminate.
144     ;;;
145     ;;; We clear any cached type for the continuation and set the reoptimize
146     ;;; flags on everything in sight, unless the continuation is deleted (in which
147     ;;; case we do nothing.)
148     ;;;
149     ;;; Since this can get called curing IR1 conversion, we have to be careful
150     ;;; not to fly into space when the Dest's Prev is missing.
151     ;;;
152     (defun reoptimize-continuation (cont)
153     (declare (type continuation cont))
154 ram 1.29 (unless (member (continuation-kind cont) '(:deleted :unused))
155 wlott 1.1 (setf (continuation-%derived-type cont) nil)
156     (let ((dest (continuation-dest cont)))
157     (when dest
158     (setf (continuation-reoptimize cont) t)
159     (setf (node-reoptimize dest) t)
160     (let ((prev (node-prev dest)))
161     (when prev
162     (let* ((block (continuation-block prev))
163     (component (block-component block)))
164 ram 1.18 (when (typep dest 'cif)
165     (setf (block-test-modified block) t))
166 wlott 1.1 (setf (block-reoptimize block) t)
167     (setf (component-reoptimize component) t))))))
168     (do-uses (node cont)
169     (setf (block-type-check (node-block node)) t)))
170     (undefined-value))
171    
172    
173     ;;; Derive-Node-Type -- Interface
174     ;;;
175     ;;; Annotate Node to indicate that its result has been proven to be typep to
176     ;;; RType. After IR1 conversion has happened, this is the only correct way to
177     ;;; supply information discovered about a node's type. If you fuck with the
178     ;;; Node-Derived-Type directly, then information may be lost and reoptimization
179     ;;; may not happen.
180     ;;;
181     ;;; What we do is intersect Rtype with Node's Derived-Type. If the
182     ;;; intersection is different from the old type, then we do a
183     ;;; Reoptimize-Continuation on the Node-Cont.
184     ;;;
185     (defun derive-node-type (node rtype)
186     (declare (type node node) (type ctype rtype))
187     (let ((node-type (node-derived-type node)))
188     (unless (eq node-type rtype)
189     (let ((int (values-type-intersection node-type rtype)))
190     (when (type/= node-type int)
191 ram 1.38 (when (and *check-consistency*
192     (eq int *empty-type*)
193 ram 1.34 (not (eq rtype *empty-type*)))
194     (let ((*compiler-error-context* node))
195     (compiler-warning
196     "New inferred type ~S conflicts with old type:~
197     ~% ~S~%*** Bug?"
198     (type-specifier rtype) (type-specifier node-type))))
199 wlott 1.1 (setf (node-derived-type node) int)
200     (reoptimize-continuation (node-cont node))))))
201     (undefined-value))
202    
203 ram 1.50 (declaim (start-block assert-continuation-type assert-call-type))
204 wlott 1.1
205     ;;; Assert-Continuation-Type -- Interface
206     ;;;
207     ;;; Similar to Derive-Node-Type, but asserts that it is an error for Cont's
208     ;;; value not to be typep to Type. If we improve the assertion, we set
209 ram 1.11 ;;; TYPE-CHECK and TYPE-ASSERTED to guarantee that the new assertion will be
210     ;;; checked.
211 wlott 1.1 ;;;
212     (defun assert-continuation-type (cont type)
213     (declare (type continuation cont) (type ctype type))
214     (let ((cont-type (continuation-asserted-type cont)))
215     (unless (eq cont-type type)
216     (let ((int (values-type-intersection cont-type type)))
217     (when (type/= cont-type int)
218     (setf (continuation-asserted-type cont) int)
219     (do-uses (node cont)
220 ram 1.11 (setf (block-attributep (block-flags (node-block node))
221     type-check type-asserted)
222     t))
223 wlott 1.1 (reoptimize-continuation cont)))))
224     (undefined-value))
225    
226    
227     ;;; Assert-Call-Type -- Interface
228     ;;;
229     ;;; Assert that Call is to a function of the specified Type. It is assumed
230     ;;; that the call is legal and has only constants in the keyword positions.
231     ;;;
232     (defun assert-call-type (call type)
233     (declare (type combination call) (type function-type type))
234     (derive-node-type call (function-type-returns type))
235     (let ((args (combination-args call)))
236     (dolist (req (function-type-required type))
237     (when (null args) (return-from assert-call-type))
238     (let ((arg (pop args)))
239     (assert-continuation-type arg req)))
240     (dolist (opt (function-type-optional type))
241     (when (null args) (return-from assert-call-type))
242     (let ((arg (pop args)))
243     (assert-continuation-type arg opt)))
244    
245     (let ((rest (function-type-rest type)))
246     (when rest
247     (dolist (arg args)
248     (assert-continuation-type arg rest))))
249    
250     (dolist (key (function-type-keywords type))
251     (let ((name (key-info-name key)))
252     (do ((arg args (cddr arg)))
253     ((null arg))
254     (when (eq (continuation-value (first arg)) name)
255     (assert-continuation-type
256     (second arg) (key-info-type key)))))))
257     (undefined-value))
258    
259    
260 ram 1.50 ;;;; IR1-OPTIMIZE:
261    
262     (declaim (start-block ir1-optimize))
263    
264 wlott 1.1 ;;; IR1-Optimize -- Interface
265     ;;;
266     ;;; Do one forward pass over Component, deleting unreachable blocks and
267 ram 1.11 ;;; doing IR1 optimizations. We can ignore all blocks that don't have the
268     ;;; Reoptimize flag set. If Component-Reoptimize is true when we are done,
269 wlott 1.1 ;;; then another iteration would be beneficial.
270     ;;;
271     ;;; We delete blocks when there is either no predecessor or the block is in
272     ;;; a lambda that has been deleted. These blocks would eventually be deleted
273     ;;; by DFO recomputation, but doing it here immediately makes the effect
274     ;;; avaliable to IR1 optimization.
275     ;;;
276     (defun ir1-optimize (component)
277     (declare (type component component))
278     (setf (component-reoptimize component) nil)
279     (do-blocks (block component)
280     (cond
281     ((or (block-delete-p block)
282     (null (block-pred block))
283 ram 1.11 (eq (functional-kind (block-home-lambda block)) :deleted))
284 wlott 1.1 (delete-block block))
285     (t
286     (loop
287     (let ((succ (block-succ block)))
288     (unless (and succ (null (rest succ)))
289     (return)))
290    
291     (let ((last (block-last block)))
292     (typecase last
293     (cif
294     (flush-dest (if-test last))
295     (when (unlink-node last) (return)))
296     (exit
297     (when (maybe-delete-exit last) (return)))))
298    
299     (unless (join-successor-if-possible block)
300     (return)))
301    
302 ram 1.11 (when (and (block-reoptimize block) (block-component block))
303 wlott 1.1 (assert (not (block-delete-p block)))
304     (ir1-optimize-block block))
305    
306 ram 1.11 (when (and (block-flush-p block) (block-component block))
307 wlott 1.1 (assert (not (block-delete-p block)))
308     (flush-dead-code block)))))
309    
310     (undefined-value))
311    
312    
313     ;;; IR1-Optimize-Block -- Internal
314     ;;;
315     ;;; Loop over the nodes in Block, looking for stuff that needs to be
316     ;;; optimized. We dispatch off of the type of each node with its reoptimize
317     ;;; flag set:
318     ;;; -- With a combination, we call Propagate-Function-Change whenever the
319     ;;; function changes, and call IR1-Optimize-Combination if any argument
320     ;;; changes.
321     ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
322     ;;; propagate Cont's assertion to the Value, since if we did, this would
323     ;;; move the checking of Cont's assertion to the exit. This wouldn't work
324     ;;; with Catch and UWP, where the Exit node is just a placeholder for the
325     ;;; actual unknown exit.
326     ;;;
327     ;;; Note that we clear the node & block reoptimize flags *before* doing the
328     ;;; optimization. This ensures that the node or block will be reoptimized if
329 ram 1.19 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
330 wlott 1.1 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
331     ;;;
332     (defun ir1-optimize-block (block)
333     (declare (type cblock block))
334     (setf (block-reoptimize block) nil)
335 ram 1.19 (do-nodes (node cont block :restart-p t)
336 wlott 1.1 (when (node-reoptimize node)
337     (setf (node-reoptimize node) nil)
338     (typecase node
339     (ref)
340     (combination
341 ram 1.50 (ir1-optimize-combination node))
342 wlott 1.1 (cif
343     (ir1-optimize-if node))
344     (creturn
345     (setf (node-reoptimize node) t)
346     (ir1-optimize-return node))
347 ram 1.6 (mv-combination
348 ram 1.21 (ir1-optimize-mv-combination node))
349 wlott 1.1 (exit
350     (let ((value (exit-value node)))
351     (when value
352     (derive-node-type node (continuation-derived-type value)))))
353     (cset
354     (ir1-optimize-set node)))))
355     (undefined-value))
356    
357 ram 1.50
358 wlott 1.1 ;;; Join-Successor-If-Possible -- Internal
359     ;;;
360     ;;; We cannot combine with a successor block if:
361     ;;; 1] The successor has more than one predecessor.
362     ;;; 2] The last node's Cont is also used somewhere else.
363     ;;; 3] The successor is the current block (infinite loop).
364     ;;; 4] The next block has a different cleanup, and thus we may want to insert
365     ;;; cleanup code between the two blocks at some point.
366     ;;; 5] The next block has a different home lambda, and thus the control
367     ;;; transfer is a non-local exit.
368     ;;;
369     ;;; If we succeed, we return true, otherwise false.
370     ;;;
371     ;;; Joining is easy when the successor's Start continuation is the same from
372     ;;; our Last's Cont. If they differ, then we can still join when the last
373     ;;; continuation has no next and the next continuation has no uses. In this
374 ram 1.5 ;;; case, we replace the next continuation with the last before joining the
375 wlott 1.1 ;;; blocks.
376     ;;;
377     (defun join-successor-if-possible (block)
378     (declare (type cblock block))
379     (let ((next (first (block-succ block))))
380 ram 1.11 (when (block-start next)
381 wlott 1.1 (let* ((last (block-last block))
382     (last-cont (node-cont last))
383 ram 1.11 (next-cont (block-start next)))
384 wlott 1.1 (cond ((or (rest (block-pred next))
385 ram 1.5 (not (eq (continuation-use last-cont) last))
386 wlott 1.1 (eq next block)
387 ram 1.11 (not (eq (block-end-cleanup block)
388     (block-start-cleanup next)))
389     (not (eq (block-home-lambda block)
390     (block-home-lambda next))))
391 wlott 1.1 nil)
392 ram 1.5 ((eq last-cont next-cont)
393 wlott 1.1 (join-blocks block next)
394     t)
395 ram 1.5 ((and (null (block-start-uses next))
396     (eq (continuation-kind last-cont) :inside-block))
397     (let ((next-node (continuation-next next-cont)))
398 ram 1.30 ;;
399     ;; If next-cont does have a dest, it must be unreachable,
400     ;; since there are no uses. DELETE-CONTINUATION will mark the
401     ;; dest block as delete-p [and also this block, unless it is
402     ;; no longer backward reachable from the dest block.]
403 ram 1.5 (delete-continuation next-cont)
404     (setf (node-prev next-node) last-cont)
405     (setf (continuation-next last-cont) next-node)
406     (setf (block-start next) last-cont)
407     (join-blocks block next))
408 wlott 1.1 t)
409     (t
410     nil))))))
411    
412    
413     ;;; Join-Blocks -- Internal
414     ;;;
415     ;;; Join together two blocks which have the same ending/starting
416     ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
417 ram 1.11 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
418     ;;; that any indicated optimization gets done.
419 wlott 1.1 ;;;
420     (defun join-blocks (block1 block2)
421     (declare (type cblock block1 block2))
422     (let* ((last (block-last block2))
423     (last-cont (node-cont last))
424     (succ (block-succ block2))
425     (start2 (block-start block2)))
426     (do ((cont start2 (node-cont (continuation-next cont))))
427     ((eq cont last-cont)
428     (when (eq (continuation-kind last-cont) :inside-block)
429     (setf (continuation-block last-cont) block1)))
430     (setf (continuation-block cont) block1))
431    
432     (unlink-blocks block1 block2)
433     (dolist (block succ)
434     (unlink-blocks block2 block)
435     (link-blocks block1 block))
436    
437     (setf (block-last block1) last)
438     (setf (continuation-kind start2) :inside-block))
439    
440 ram 1.11 (setf (block-flags block1)
441     (attributes-union (block-flags block1)
442     (block-flags block2)
443     (block-attributes type-asserted test-modified)))
444 wlott 1.1
445     (let ((next (block-next block2))
446     (prev (block-prev block2)))
447     (setf (block-next prev) next)
448     (setf (block-prev next) prev))
449    
450     (undefined-value))
451    
452 ram 1.50 ;;; Flush-Dead-Code -- Internal
453     ;;;
454     ;;; Delete any nodes in Block whose value is unused and have no
455     ;;; side-effects. We can delete sets of lexical variables when the set
456     ;;; variable has no references.
457     ;;;
458     ;;; [### For now, don't delete potentially flushable calls when they have the
459     ;;; Call attribute. Someday we should look at the funcitonal args to determine
460     ;;; if they have any side-effects.]
461     ;;;
462     (defun flush-dead-code (block)
463     (declare (type cblock block))
464     (do-nodes-backwards (node cont block)
465     (unless (continuation-dest cont)
466     (typecase node
467     (ref
468     (delete-ref node)
469     (unlink-node node))
470     (combination
471     (let ((info (combination-kind node)))
472     (when (function-info-p info)
473     (let ((attr (function-info-attributes info)))
474     (when (and (ir1-attributep attr flushable)
475     (not (ir1-attributep attr call)))
476     (flush-dest (combination-fun node))
477     (dolist (arg (combination-args node))
478     (flush-dest arg))
479     (unlink-node node))))))
480     (mv-combination
481     (when (eq (basic-combination-kind node) :local)
482     (let ((fun (combination-lambda node)))
483     (when (dolist (var (lambda-vars fun) t)
484     (when (or (leaf-refs var)
485     (lambda-var-sets var))
486     (return nil)))
487     (flush-dest (first (basic-combination-args node)))
488     (delete-let fun)))))
489     (exit
490     (let ((value (exit-value node)))
491     (when value
492     (flush-dest value)
493     (setf (exit-value node) nil))))
494     (cset
495     (let ((var (set-var node)))
496     (when (and (lambda-var-p var)
497     (null (leaf-refs var)))
498     (flush-dest (set-value node))
499     (setf (basic-var-sets var)
500     (delete node (basic-var-sets var)))
501     (unlink-node node)))))))
502    
503     (setf (block-flush-p block) nil)
504     (undefined-value))
505    
506     (declaim (end-block))
507    
508 wlott 1.1
509     ;;;; Local call return type propagation:
510    
511     ;;; Find-Result-Type -- Internal
512     ;;;
513     ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
514     ;;; set. It iterates over the uses of the RESULT, looking for interesting
515 ram 1.46 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
516     ;;; its type together with the types of other such uses. We assign to the
517     ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
518     ;;; type. We can make this intersection now (potentially before type checking)
519     ;;; because this assertion on the result will eventually be checked (if
520     ;;; appropriate.)
521 wlott 1.1 ;;;
522 ram 1.46 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
523     ;;; which may change the succesor of the call to be the called function, and if
524 ram 1.56 ;;; so, checks if the call can become an assignment. If we convert to an
525     ;;; assignment, we abort, since the RETURN has been deleted.
526 ram 1.46 ;;;
527     (defun find-result-type (node)
528 wlott 1.1 (declare (type creturn node))
529 ram 1.46 (let ((result (return-result node)))
530 wlott 1.1 (collect ((use-union *empty-type* values-type-union))
531     (do-uses (use result)
532 ram 1.34 (cond ((and (basic-combination-p use)
533 ram 1.46 (eq (basic-combination-kind use) :local))
534     (assert (eq (lambda-tail-set (node-home-lambda use))
535     (lambda-tail-set (combination-lambda use))))
536 ram 1.39 (when (combination-p use)
537 ram 1.56 (when (nth-value 1 (maybe-convert-tail-local-call use))
538     (return-from find-result-type (undefined-value)))))
539 ram 1.34 (t
540     (use-union (node-derived-type use)))))
541 wlott 1.1 (let ((int (values-type-intersection
542     (continuation-asserted-type result)
543     (use-union))))
544 ram 1.46 (setf (return-result-type node) int))))
545     (undefined-value))
546 wlott 1.1
547    
548     ;;; IR1-Optimize-Return -- Internal
549     ;;;
550     ;;; Do stuff to realize that something has changed about the value delivered
551     ;;; to a return node. Since we consider the return values of all functions in
552     ;;; the tail set to be equivalent, this amounts to bringing the entire tail set
553     ;;; up to date. We iterate over the returns for all the functions in the tail
554     ;;; set, reanalyzing them all (not treating Node specially.)
555     ;;;
556     ;;; When we are done, we check if the new type is different from the old
557     ;;; TAIL-SET-TYPE. If so, we set the type and also reoptimize all the
558     ;;; continuations for references to functions in the tail set. This will
559     ;;; cause IR1-OPTIMIZE-COMBINATION to derive the new type as the results of the
560     ;;; calls.
561     ;;;
562     (defun ir1-optimize-return (node)
563     (declare (type creturn node))
564 ram 1.46 (let* ((tails (lambda-tail-set (return-lambda node)))
565     (funs (tail-set-functions tails)))
566 wlott 1.1 (collect ((res *empty-type* values-type-union))
567 ram 1.46 (dolist (fun funs)
568     (let ((return (lambda-return fun)))
569     (when return
570     (when (node-reoptimize return)
571 ram 1.58 (setf (node-reoptimize return) nil)
572 ram 1.46 (find-result-type return))
573     (res (return-result-type return)))))
574 wlott 1.1
575     (when (type/= (res) (tail-set-type tails))
576     (setf (tail-set-type tails) (res))
577     (dolist (fun (tail-set-functions tails))
578     (dolist (ref (leaf-refs fun))
579     (reoptimize-continuation (node-cont ref)))))))
580    
581     (undefined-value))
582    
583    
584 ram 1.50 ;;; IF optimization:
585    
586     (declaim (start-block ir1-optimize-if))
587    
588 wlott 1.1 ;;; IR1-Optimize-If -- Internal
589     ;;;
590     ;;; If the test has multiple uses, replicate the node when possible. Also
591     ;;; check if the predicate is known to be true or false, deleting the IF node
592     ;;; in favor of the appropriate branch when this is the case.
593     ;;;
594     (defun ir1-optimize-if (node)
595     (declare (type cif node))
596     (let ((test (if-test node))
597     (block (node-block node)))
598    
599     (when (and (eq (block-start block) test)
600     (eq (continuation-next test) node)
601     (rest (block-start-uses block)))
602     (do-uses (use test)
603     (when (immediately-used-p test use)
604     (convert-if-if use node)
605     (when (continuation-use test) (return)))))
606    
607     (let* ((type (continuation-type test))
608     (victim
609     (cond ((constant-continuation-p test)
610     (if (continuation-value test)
611     (if-alternative node)
612     (if-consequent node)))
613     ((not (types-intersect type *null-type*))
614     (if-alternative node))
615     ((type= type *null-type*)
616     (if-consequent node)))))
617     (when victim
618     (flush-dest test)
619     (when (rest (block-succ block))
620     (unlink-blocks block victim))
621     (setf (component-reanalyze (block-component (node-block node))) t)
622     (unlink-node node))))
623     (undefined-value))
624    
625    
626     ;;; Convert-If-If -- Internal
627     ;;;
628     ;;; Create a new copy of an IF Node that tests the value of the node Use.
629     ;;; The test must have >1 use, and must be immediately used by Use. Node must
630     ;;; be the only node in its block (implying that block-start = if-test).
631     ;;;
632     ;;; This optimization has an effect semantically similar to the
633     ;;; source-to-source transformation:
634     ;;; (IF (IF A B C) D E) ==>
635     ;;; (IF A (IF B D E) (IF C D E))
636     ;;;
637 ram 1.55 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new node so
638     ;;; that dead code deletion notes will definitely not consider either node to
639     ;;; be part of the original source. One node might become unreachable,
640     ;;; resulting in a spurious note.
641     ;;;
642 wlott 1.1 (defun convert-if-if (use node)
643     (declare (type node use) (type cif node))
644     (with-ir1-environment node
645     (let* ((block (node-block node))
646     (test (if-test node))
647     (cblock (if-consequent node))
648     (ablock (if-alternative node))
649     (use-block (node-block use))
650     (dummy-cont (make-continuation))
651     (new-cont (make-continuation))
652 ram 1.11 (new-node (make-if :test new-cont
653 wlott 1.1 :consequent cblock :alternative ablock))
654     (new-block (continuation-starts-block new-cont)))
655     (prev-link new-node new-cont)
656     (setf (continuation-dest new-cont) new-node)
657     (add-continuation-use new-node dummy-cont)
658     (setf (block-last new-block) new-node)
659    
660     (unlink-blocks use-block block)
661     (delete-continuation-use use)
662     (add-continuation-use use new-cont)
663     (link-blocks use-block new-block)
664    
665     (link-blocks new-block cblock)
666     (link-blocks new-block ablock)
667 ram 1.55
668     (push "<IF Duplication>" (node-source-path node))
669     (push "<IF Duplication>" (node-source-path new-node))
670 wlott 1.1
671     (reoptimize-continuation test)
672     (reoptimize-continuation new-cont)
673     (setf (component-reanalyze *current-component*) t)))
674     (undefined-value))
675    
676 ram 1.50 (declaim (end-block))
677    
678 wlott 1.1
679     ;;;; Exit IR1 optimization:
680    
681     ;;; Maybe-Delete-Exit -- Interface
682     ;;;
683     ;;; This function attempts to delete an exit node, returning true if it
684     ;;; deletes the block as a consequence:
685     ;;; -- If the exit is degenerate (has no Entry), then we don't do anything,
686     ;;; since there is nothing to be done.
687     ;;; -- If the exit node and its Entry have the same home lambda then we know
688     ;;; the exit is local, and can delete the exit. We change uses of the
689     ;;; Exit-Value to be uses of the original continuation, then unlink the
690 ram 1.46 ;;; node. If the exit is to a TR context, then we must do MERGE-TAIL-SETS
691     ;;; on any local calls which delivered their value to this exit.
692 wlott 1.1 ;;; -- If there is no value (as in a GO), then we skip the value semantics.
693     ;;;
694     ;;; This function is also called by environment analysis, since it wants all
695     ;;; exits to be optimized even if normal optimization was omitted.
696     ;;;
697     (defun maybe-delete-exit (node)
698     (declare (type exit node))
699     (let ((value (exit-value node))
700     (entry (exit-entry node))
701     (cont (node-cont node)))
702     (when (and entry
703 ram 1.11 (eq (node-home-lambda node) (node-home-lambda entry)))
704     (setf (entry-exits entry) (delete node (entry-exits entry)))
705 wlott 1.1 (prog1
706     (unlink-node node)
707     (when value
708 ram 1.46 (collect ((merges))
709     (when (return-p (continuation-dest cont))
710     (do-uses (use value)
711     (when (and (basic-combination-p use)
712     (eq (basic-combination-kind use) :local))
713     (merges use))))
714     (substitute-continuation-uses cont value)
715     (dolist (merge (merges))
716     (merge-tail-sets merge))))))))
717 wlott 1.1
718    
719     ;;;; Combination IR1 optimization:
720    
721 ram 1.50 (declaim (start-block ir1-optimize-combination maybe-terminate-block
722     validate-call-type))
723    
724 wlott 1.1 ;;; Ir1-Optimize-Combination -- Internal
725     ;;;
726     ;;; Do IR1 optimizations on a Combination node.
727     ;;;
728     (proclaim '(function ir1-optimize-combination (combination) void))
729     (defun ir1-optimize-combination (node)
730 ram 1.50 (when (continuation-reoptimize (basic-combination-fun node))
731     (propagate-function-change node))
732 wlott 1.1 (let ((args (basic-combination-args node))
733     (kind (basic-combination-kind node)))
734     (case kind
735     (:local
736     (let ((fun (combination-lambda node)))
737     (if (eq (functional-kind fun) :let)
738     (propagate-let-args node fun)
739     (propagate-local-call-args node fun))))
740 ram 1.50 ((:full :error)
741 wlott 1.1 (dolist (arg args)
742     (when arg
743     (setf (continuation-reoptimize arg) nil))))
744     (t
745     (dolist (arg args)
746     (when arg
747     (setf (continuation-reoptimize arg) nil)))
748    
749     (let ((attr (function-info-attributes kind)))
750     (when (and (ir1-attributep attr foldable)
751     (not (ir1-attributep attr call))
752     (every #'constant-continuation-p args)
753     (continuation-dest (node-cont node)))
754     (constant-fold-call node)
755     (return-from ir1-optimize-combination)))
756 ram 1.18
757 wlott 1.1 (let ((fun (function-info-derive-type kind)))
758     (when fun
759     (let ((res (funcall fun node)))
760     (when res
761 ram 1.50 (derive-node-type node res)
762     (maybe-terminate-block node nil)))))
763 ram 1.18
764 wlott 1.1 (let ((fun (function-info-optimizer kind)))
765     (unless (and fun (funcall fun node))
766     (dolist (x (function-info-transforms kind))
767 ram 1.28 (unless (ir1-transform node x)
768 wlott 1.2 (return))))))))
769 wlott 1.1
770     (undefined-value))
771    
772    
773 ram 1.29 ;;; MAYBE-TERMINATE-BLOCK -- Interface
774     ;;;
775     ;;; If Call is to a function that doesn't return (type NIL), then terminate
776 ram 1.31 ;;; the block there, and link it to the component tail. We also change the
777     ;;; call's CONT to be a dummy continuation to prevent the use from confusing
778     ;;; things.
779 ram 1.29 ;;;
780 ram 1.30 ;;; Except when called during IR1, we delete the continuation if it has no
781     ;;; other uses. (If it does have other uses, we reoptimize.)
782     ;;;
783 ram 1.31 ;;; Termination on the basis of a continuation type assertion is inhibited
784     ;;; when:
785     ;;; -- The continuation is deleted (hence the assertion is spurious), or
786     ;;; -- We are in IR1 conversion (where THE assertions are subject to
787     ;;; weakening.)
788     ;;;
789 ram 1.30 (defun maybe-terminate-block (call ir1-p)
790 ram 1.29 (declare (type basic-combination call))
791 ram 1.32 (let* ((block (node-block call))
792     (cont (node-cont call))
793     (tail (component-tail (block-component block)))
794     (succ (first (block-succ block))))
795     (unless (or (and (eq call (block-last block)) (eq succ tail))
796 ram 1.50 (block-delete-p block)
797     *converting-for-interpreter*)
798 ram 1.32 (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
799     (not (or ir1-p (eq (continuation-kind cont) :deleted))))
800     (eq (node-derived-type call) *empty-type*))
801     (cond (ir1-p
802     (delete-continuation-use call)
803     (cond
804     ((block-last block)
805     (assert (and (eq (block-last block) call)
806     (eq (continuation-kind cont) :block-start))))
807     (t
808     (setf (block-last block) call)
809     (link-blocks block (continuation-starts-block cont)))))
810 ram 1.30 (t
811 ram 1.32 (node-ends-block call)
812     (delete-continuation-use call)
813     (if (eq (continuation-kind cont) :unused)
814     (delete-continuation cont)
815     (reoptimize-continuation cont))))
816    
817     (unlink-blocks block (first (block-succ block)))
818 ram 1.45 (setf (component-reanalyze (block-component block)) t)
819 ram 1.32 (assert (not (block-succ block)))
820     (link-blocks block tail)
821     (add-continuation-use call (make-continuation))
822     t))))
823 ram 1.30
824 ram 1.29
825 wlott 1.1 ;;; Recognize-Known-Call -- Interface
826     ;;;
827 ram 1.50 ;;; Called both by IR1 conversion and IR1 optimization when they have
828     ;;; verified the type signature for the call, and are wondering if something
829     ;;; should be done to special-case the call. If Call is a call to a global
830     ;;; function, then see if it defined or known:
831     ;;; -- If a DEFINED-FUNCTION should be inline expanded, then convert the
832     ;;; expansion and change the call to call it. Expansion is enabled if
833     ;;; :INLINE or if space=0. If the FUNCTIONAL slot is true, we never expand,
834     ;;; since this function has already been converted. Local call analysis
835     ;;; will duplicate the definition if necessary. We claim that the parent
836     ;;; form is LABELS for context declarations, since we don't want it to be
837     ;;; considered a real global function.
838     ;;; -- In addition to a direct check for the function name in the table, we
839     ;;; also must check for slot accessors. If the function is a slot accessor,
840     ;;; then we set the combination kind to the function info of %Slot-Setter or
841     ;;; %Slot-Accessor, as appropriate.
842     ;;; -- If it is a known function, mark it as such by setting the Kind.
843 wlott 1.1 ;;;
844 ram 1.50 ;;; We return the leaf referenced (NIL if not a leaf) and the function-info
845     ;;; assigned.
846 ram 1.19 ;;;
847 ram 1.50 (defun recognize-known-call (call ir1-p)
848 wlott 1.1 (declare (type combination call))
849 ram 1.50 (let* ((ref (continuation-use (basic-combination-fun call)))
850     (leaf (when (ref-p ref) (ref-leaf ref)))
851 ram 1.60 (inlinep (if (and (defined-function-p leaf)
852 ram 1.61 (not (byte-compiling)))
853 ram 1.50 (defined-function-inlinep leaf)
854     :no-chance)))
855     (cond
856     ((eq inlinep :notinline) (values nil nil))
857     ((not (and (global-var-p leaf)
858     (eq (global-var-kind leaf) :global-function)))
859     (values leaf nil))
860     ((and (ecase inlinep
861     (:inline t)
862     (:no-chance nil)
863     ((nil :maybe-inline) (policy call (zerop space))))
864     (defined-function-inline-expansion leaf)
865     (let ((fun (defined-function-functional leaf)))
866     (or (not fun)
867     (and (eq inlinep :inline) (functional-kind fun))))
868     (inline-expansion-ok call))
869     (flet ((frob ()
870     (let ((res (ir1-convert-lambda-for-defun
871     (defined-function-inline-expansion leaf)
872 ram 1.53 leaf t
873 ram 1.50 #'ir1-convert-inline-lambda
874     'labels)))
875     (setf (defined-function-functional leaf) res)
876     (change-ref-leaf ref res))))
877     (if ir1-p
878     (frob)
879     (with-ir1-environment call
880     (frob)
881     (local-call-analyze *current-component*))))
882 ram 1.53
883 ram 1.50 (values (ref-leaf (continuation-use (basic-combination-fun call)))
884     nil))
885     (t
886     (let* ((name (leaf-name leaf))
887 wlott 1.62 (info (if (dylan-function-var-p leaf)
888     (dylan-function-var-function-info leaf)
889     (info function info
890     (if (slot-accessor-p leaf)
891     (if (consp name)
892     '%slot-setter
893     '%slot-accessor)
894     name)))))
895 ram 1.50 (if info
896     (values leaf (setf (basic-combination-kind call) info))
897     (values leaf nil)))))))
898 wlott 1.1
899    
900 ram 1.50 ;;; VALIDATE-CALL-TYPE -- Internal
901     ;;;
902     ;;; Check if Call satisfies Type. If so, apply the type to the call, and do
903     ;;; MAYBE-TERMINATE-BLOCK and return the values of RECOGNIZE-KNOWN-CALL. If an
904 ram 1.57 ;;; error, set the combination kind and return NIL, NIL. If the type is just
905     ;;; FUNCTION, then skip the syntax check, arg/result type processing, but still
906     ;;; call RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda, and
907     ;;; that checking is done by local call analysis.
908 ram 1.50 ;;;
909     (defun validate-call-type (call type ir1-p)
910     (declare (type combination call) (type ctype type))
911 ram 1.57 (cond ((not (function-type-p type))
912     (assert (multiple-value-bind
913     (val win)
914     (csubtypep type (specifier-type 'function))
915     (or val (not win))))
916     (recognize-known-call call ir1-p))
917 ram 1.50 ((valid-function-use call type
918     :argument-test #'always-subtypep
919     :result-test #'always-subtypep
920     :error-function #'compiler-warning
921     :warning-function #'compiler-note)
922     (assert-call-type call type)
923     (maybe-terminate-block call ir1-p)
924     (recognize-known-call call ir1-p))
925     (t
926     (setf (combination-kind call) :error)
927     (values nil nil))))
928    
929    
930 wlott 1.1 ;;; Propagate-Function-Change -- Internal
931     ;;;
932     ;;; Called by Ir1-Optimize when the function for a call has changed.
933 ram 1.50 ;;; If the call is local, we try to let-convert it, and derive the result type.
934     ;;; If it is a :FULL call, we validate it against the type, which recognizes
935     ;;; known calls, does inline expansion, etc. If a call to a predicate in a
936     ;;; non-conditional position or to a function with a source transform, then we
937     ;;; reconvert the form to give IR1 another chance.
938 wlott 1.1 ;;;
939     (defun propagate-function-change (call)
940     (declare (type combination call))
941 ram 1.50 (let ((*compiler-error-context* call)
942     (fun-cont (basic-combination-fun call)))
943     (setf (continuation-reoptimize fun-cont) nil)
944     (case (combination-kind call)
945     (:local
946     (let ((fun (combination-lambda call)))
947     (maybe-let-convert fun)
948     (unless (member (functional-kind fun) '(:let :assignment :deleted))
949     (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
950     (:full
951     (multiple-value-bind
952     (leaf info)
953 ram 1.59 (validate-call-type call (continuation-type fun-cont) nil)
954 ram 1.50 (cond ((functional-p leaf)
955     (convert-call-if-possible
956     (continuation-use (basic-combination-fun call))
957     call))
958     ((not leaf))
959     ((or (info function source-transform (leaf-name leaf))
960     (and info
961     (ir1-attributep (function-info-attributes info)
962     predicate)
963     (let ((dest (continuation-dest (node-cont call))))
964     (and dest (not (if-p dest))))))
965     (let ((name (leaf-name leaf)))
966     (when (symbolp name)
967     (let ((dums (loop repeat (length (combination-args call))
968     collect (gensym))))
969     (transform-call call
970     `(lambda ,dums
971     (,name ,@dums))))))))))))
972 wlott 1.1 (undefined-value))
973    
974    
975     ;;;; Known function optimization:
976    
977 ram 1.15
978     ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
979     ;;;
980 ram 1.50 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for Node, Fun
981 ram 1.28 ;;; and Args. If there is already a note for Node and Transform, replace it,
982 ram 1.15 ;;; otherwise add a new one.
983     ;;;
984 ram 1.28 (defun record-optimization-failure (node transform args)
985     (declare (type combination node) (type transform transform)
986 ram 1.15 (type (or function-type list) args))
987 ram 1.50 (let* ((table (component-failed-optimizations *compile-component*))
988     (found (assoc transform (gethash node table))))
989 ram 1.15 (if found
990     (setf (cdr found) args)
991 ram 1.50 (push (cons transform args) (gethash node table))))
992 ram 1.15 (undefined-value))
993    
994    
995 wlott 1.1 ;;; IR1-Transform -- Internal
996     ;;;
997     ;;; Attempt to transform Node using Function, subject to the call type
998     ;;; constraint Type. If we are inhibited from doing the transform for some
999     ;;; reason and Flame is true, then we make a note of the message in
1000 ram 1.50 ;;; FAILED-OPTIMIZATIONS for IR1 finalize to pick up. We return true if
1001 wlott 1.2 ;;; the transform failed, and thus further transformation should be
1002     ;;; attempted. We return false if either the transform suceeded or was
1003     ;;; aborted.
1004 wlott 1.1 ;;;
1005 ram 1.28 (defun ir1-transform (node transform)
1006     (declare (type combination node) (type transform transform))
1007     (let* ((type (transform-type transform))
1008     (fun (transform-function transform))
1009     (constrained (function-type-p type))
1010 ram 1.50 (table (component-failed-optimizations *compile-component*))
1011 wlott 1.41 (flame
1012     (if (transform-important transform)
1013     (policy node (>= speed brevity))
1014     (policy node (> speed brevity))))
1015 ram 1.28 (*compiler-error-context* node))
1016 ram 1.60 (cond ((let ((when (transform-when transform)))
1017     (not (or (eq when :both)
1018     (eq when (if *byte-compiling* :byte :native)))))
1019     t)
1020     ((or (not constrained)
1021 ram 1.19 (valid-function-use node type :strict-result t))
1022 wlott 1.1 (multiple-value-bind
1023     (severity args)
1024     (catch 'give-up
1025     (transform-call node (funcall fun node))
1026     (values :none nil))
1027     (ecase severity
1028 ram 1.15 (:none
1029 ram 1.50 (remhash node table)
1030 ram 1.15 nil)
1031 wlott 1.1 (:aborted
1032 ram 1.50 (setf (combination-kind node) :error)
1033 wlott 1.1 (when args
1034 wlott 1.2 (apply #'compiler-warning args))
1035 ram 1.50 (remhash node table)
1036 wlott 1.2 nil)
1037 wlott 1.1 (:failure
1038 ram 1.15 (if args
1039     (when flame
1040 ram 1.28 (record-optimization-failure node transform args))
1041 ram 1.50 (setf (gethash node table)
1042     (remove transform (gethash node table) :key #'car)))
1043 wlott 1.2 t))))
1044 wlott 1.1 ((and flame
1045     (valid-function-use node type
1046     :argument-test #'types-intersect
1047     :result-test #'values-types-intersect))
1048 ram 1.28 (record-optimization-failure node transform type)
1049 wlott 1.13 t)
1050     (t
1051 wlott 1.2 t))))
1052 wlott 1.1
1053 ram 1.50 (declaim (end-block))
1054 wlott 1.1
1055     ;;; GIVE-UP, ABORT-TRANSFORM -- Interface
1056     ;;;
1057     ;;; Just throw the severity and args...
1058     ;;;
1059     (proclaim '(function give-up (&rest t) nil))
1060     (defun give-up (&rest args)
1061     "This function is used to throw out of an IR1 transform, aborting this
1062     attempt to transform the call, but admitting the possibility that this or
1063     some other transform will later suceed. If arguments are supplied, they are
1064     format arguments for an efficiency note."
1065     (throw 'give-up (values :failure args)))
1066     ;;;
1067     (defun abort-transform (&rest args)
1068     "This function is used to throw out of an IR1 transform and force a normal
1069     call to the function at run time. No further optimizations will be
1070     attempted."
1071     (throw 'give-up (values :aborted args)))
1072    
1073    
1074     ;;; Transform-Call -- Internal
1075     ;;;
1076     ;;; Take the lambda-expression Res, IR1 convert it in the proper
1077     ;;; environment, and then install it as the function for the call Node. We do
1078     ;;; local call analysis so that the new function is integrated into the control
1079 ram 1.50 ;;; flow.
1080 wlott 1.1 ;;;
1081     (defun transform-call (node res)
1082     (declare (type combination node) (list res))
1083     (with-ir1-environment node
1084 ram 1.50 (let ((new-fun (ir1-convert-inline-lambda res))
1085 wlott 1.1 (ref (continuation-use (combination-fun node))))
1086     (change-ref-leaf ref new-fun)
1087     (setf (combination-kind node) :full)
1088     (local-call-analyze *current-component*)))
1089     (undefined-value))
1090    
1091    
1092     ;;; Constant-Fold-Call -- Internal
1093     ;;;
1094     ;;; Replace a call to a foldable function of constant arguments with the
1095     ;;; result of evaluating the form. We insert the resulting constant node after
1096     ;;; the call, stealing the call's continuation. We give the call a
1097     ;;; continuation with no Dest, which should cause it and its arguments to go
1098     ;;; away. If there is an error during the evaluation, we give a warning and
1099 ram 1.50 ;;; leave the call alone, making the call a :ERROR call.
1100 wlott 1.1 ;;;
1101 ram 1.50 ;;; If there is more than one value, then we transform the call into a
1102     ;;; values form.
1103 wlott 1.1 ;;;
1104     (defun constant-fold-call (call)
1105     (declare (type combination call))
1106     (let* ((args (mapcar #'continuation-value (combination-args call)))
1107     (ref (continuation-use (combination-fun call)))
1108     (fun (leaf-name (ref-leaf ref))))
1109    
1110     (multiple-value-bind (values win)
1111     (careful-call fun args call "constant folding")
1112     (cond
1113     ((not win)
1114 ram 1.50 (setf (combination-kind call) :error))
1115 dtc 1.66 ;; X Always transform the call below so that non-flushable
1116     ;; functions get flushed if the constant folding works.
1117     #+nil
1118 wlott 1.1 ((= (length values) 1)
1119     (with-ir1-environment call
1120 wlott 1.37 (when (producing-fasl-file)
1121     (maybe-emit-make-load-forms (first values)))
1122 wlott 1.1 (let* ((leaf (find-constant (first values)))
1123 ram 1.50 (node (make-ref (leaf-type leaf) leaf))
1124 wlott 1.1 (dummy (make-continuation))
1125     (cont (node-cont call))
1126     (block (node-block call))
1127     (next (continuation-next cont)))
1128     (push node (leaf-refs leaf))
1129     (setf (leaf-ever-used leaf) t)
1130    
1131     (delete-continuation-use call)
1132     (add-continuation-use call dummy)
1133     (prev-link node dummy)
1134     (add-continuation-use node cont)
1135     (setf (continuation-next cont) next)
1136     (when (eq call (block-last block))
1137     (setf (block-last block) node))
1138 ram 1.19 (reoptimize-continuation cont))))
1139     (t
1140     (let ((dummies (loop repeat (length args)
1141     collect (gensym))))
1142     (transform-call
1143     call
1144     `(lambda ,dummies
1145     (declare (ignore ,@dummies))
1146     (values ,@(mapcar #'(lambda (x) `',x) values)))))))))
1147 wlott 1.1
1148     (undefined-value))
1149    
1150    
1151     ;;;; Local call optimization:
1152    
1153 ram 1.50 (declaim (start-block ir1-optimize-set constant-reference-p delete-let
1154     propagate-let-args propagate-local-call-args
1155 ram 1.52 propagate-to-refs propagate-from-sets
1156     ir1-optimize-mv-combination))
1157 ram 1.50
1158 wlott 1.1 ;;; Propagate-To-Refs -- Internal
1159     ;;;
1160     ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1161     ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1162     ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1163     ;;;
1164     (defun propagate-to-refs (leaf type)
1165     (declare (type leaf leaf) (type ctype type))
1166     (let ((var-type (leaf-type leaf)))
1167     (unless (function-type-p var-type)
1168     (let ((int (type-intersection var-type type)))
1169     (when (type/= int var-type)
1170     (setf (leaf-type leaf) int)
1171     (dolist (ref (leaf-refs leaf))
1172     (derive-node-type ref int))))
1173     (undefined-value))))
1174    
1175    
1176     ;;; PROPAGATE-FROM-SETS -- Internal
1177     ;;;
1178     ;;; Figure out the type of a LET variable that has sets. We compute the
1179     ;;; union of the initial value Type and the types of all the set values and to
1180     ;;; a PROPAGATE-TO-REFS with this type.
1181     ;;;
1182     (defun propagate-from-sets (var type)
1183 ram 1.6 (collect ((res type type-union))
1184 wlott 1.1 (dolist (set (basic-var-sets var))
1185     (res (continuation-type (set-value set)))
1186     (setf (node-reoptimize set) nil))
1187     (propagate-to-refs var (res)))
1188     (undefined-value))
1189    
1190    
1191     ;;; IR1-OPTIMIZE-SET -- Internal
1192     ;;;
1193     ;;; If a let variable, find the initial value's type and do
1194     ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1195     ;;;
1196     (defun ir1-optimize-set (node)
1197     (declare (type cset node))
1198     (let ((var (set-var node)))
1199     (when (and (lambda-var-p var) (leaf-refs var))
1200     (let ((home (lambda-var-home var)))
1201     (when (eq (functional-kind home) :let)
1202     (let ((iv (let-var-initial-value var)))
1203     (setf (continuation-reoptimize iv) nil)
1204     (propagate-from-sets var (continuation-type iv)))))))
1205    
1206     (derive-node-type node (continuation-type (set-value node)))
1207     (undefined-value))
1208    
1209    
1210 ram 1.17 ;;; CONSTANT-REFERENCE-P -- Interface
1211 ram 1.7 ;;;
1212     ;;; Return true if the value of Ref will always be the same (and is thus
1213 ram 1.50 ;;; legal to substitute.)
1214 ram 1.7 ;;;
1215     (defun constant-reference-p (ref)
1216     (declare (type ref ref))
1217     (let ((leaf (ref-leaf ref)))
1218     (typecase leaf
1219 ram 1.50 ((or constant functional) t)
1220 ram 1.7 (lambda-var
1221     (null (lambda-var-sets leaf)))
1222 ram 1.50 (defined-function
1223     (not (eq (defined-function-inlinep leaf) :notinline)))
1224 ram 1.7 (global-var
1225     (case (global-var-kind leaf)
1226 ram 1.50 (:global-function t)
1227 ram 1.7 (:constant t))))))
1228    
1229    
1230     ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1231     ;;;
1232     ;;; If we have a non-set let var with a single use, then (if possible)
1233     ;;; replace the variable reference's CONT with the arg continuation. This is
1234     ;;; inhibited when:
1235     ;;; -- CONT has other uses, or
1236     ;;; -- CONT receives multiple values, or
1237 ram 1.9 ;;; -- the reference is in a different environment from the variable, or
1238     ;;; -- either continuation has a funky TYPE-CHECK annotation.
1239 ram 1.43 ;;; -- the continuations have incompatible assertions, so the new asserted type
1240     ;;; would be NIL.
1241 ram 1.27 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1242 ram 1.7 ;;;
1243     ;;; We change the Ref to be a reference to NIL with unused value, and let it
1244     ;;; be flushed as dead code. A side-effect of this substitution is to delete
1245     ;;; the variable.
1246     ;;;
1247     (defun substitute-single-use-continuation (arg var)
1248     (declare (type continuation arg) (type lambda-var var))
1249     (let* ((ref (first (leaf-refs var)))
1250     (cont (node-cont ref))
1251 ram 1.43 (cont-atype (continuation-asserted-type cont))
1252 ram 1.7 (dest (continuation-dest cont)))
1253     (when (and (eq (continuation-use cont) ref)
1254     dest
1255     (not (typep dest '(or creturn exit mv-combination)))
1256 ram 1.11 (eq (node-home-lambda ref)
1257 ram 1.9 (lambda-home (lambda-var-home var)))
1258     (member (continuation-type-check arg) '(t nil))
1259 ram 1.27 (member (continuation-type-check cont) '(t nil))
1260 ram 1.43 (not (eq (values-type-intersection
1261     cont-atype
1262     (continuation-asserted-type arg))
1263     *empty-type*))
1264 ram 1.27 (eq (lexenv-cookie (node-lexenv dest))
1265     (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1266 ram 1.25 (assert (member (continuation-kind arg)
1267     '(:block-start :deleted-block-start :inside-block)))
1268 ram 1.43 (assert-continuation-type arg cont-atype)
1269 ram 1.34 (setf (node-derived-type ref) *wild-type*)
1270 ram 1.7 (change-ref-leaf ref (find-constant nil))
1271     (substitute-continuation arg cont)
1272     (reoptimize-continuation arg)
1273     t)))
1274    
1275    
1276 ram 1.19 ;;; DELETE-LET -- Interface
1277     ;;;
1278     ;;; Delete a Let, removing the call and bind nodes, and warning about any
1279     ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1280     ;;; away and delete the REF and then the lambda, since we flush the FUN
1281     ;;; continuation.
1282     ;;;
1283     (defun delete-let (fun)
1284     (declare (type clambda fun))
1285 ram 1.42 (assert (member (functional-kind fun) '(:let :mv-let)))
1286 ram 1.19 (note-unreferenced-vars fun)
1287     (let ((call (let-combination fun)))
1288 ram 1.42 (flush-dest (basic-combination-fun call))
1289 ram 1.19 (unlink-node call)
1290     (unlink-node (lambda-bind fun))
1291     (setf (lambda-bind fun) nil))
1292     (undefined-value))
1293    
1294    
1295 wlott 1.1 ;;; Propagate-Let-Args -- Internal
1296     ;;;
1297     ;;; This function is called when one of the arguments to a LET changes. We
1298     ;;; look at each changed argument. If the corresponding variable is set, then
1299     ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1300     ;;; variable, and also propagate derived-type information for the arg to all
1301     ;;; the Var's refs.
1302     ;;;
1303 ram 1.16 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1304     ;;; subtype of the argument's asserted type. This prevents type checking from
1305     ;;; being defeated, and also ensures that the best representation for the
1306     ;;; variable can be used.
1307 wlott 1.1 ;;;
1308 ram 1.26 ;;; Substitution of individual references is inhibited if the reference is
1309     ;;; in a different component from the home. This can only happen with closures
1310     ;;; over top-level lambda vars. In such cases, the references may have already
1311     ;;; been compiled, and thus can't be retroactively modified.
1312     ;;;
1313 ram 1.19 ;;; If all of the variables are deleted (have no references) when we are
1314     ;;; done, then we delete the let.
1315     ;;;
1316 wlott 1.1 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1317     ;;; flags.
1318     ;;;
1319     (defun propagate-let-args (call fun)
1320     (declare (type combination call) (type clambda fun))
1321 ram 1.19 (loop for arg in (combination-args call)
1322     and var in (lambda-vars fun) do
1323     (when (and arg (continuation-reoptimize arg))
1324     (setf (continuation-reoptimize arg) nil)
1325     (cond
1326     ((lambda-var-sets var)
1327     (propagate-from-sets var (continuation-type arg)))
1328     ((let ((use (continuation-use arg)))
1329     (when (ref-p use)
1330     (let ((leaf (ref-leaf use)))
1331     (when (and (constant-reference-p use)
1332     (values-subtypep (leaf-type leaf)
1333     (continuation-asserted-type arg)))
1334     (propagate-to-refs var (continuation-type arg))
1335 ram 1.26 (let ((this-comp (block-component (node-block use))))
1336     (substitute-leaf-if
1337     #'(lambda (ref)
1338     (cond ((eq (block-component (node-block ref))
1339     this-comp)
1340     t)
1341     (t
1342     (assert (eq (functional-kind (lambda-home fun))
1343     :top-level))
1344     nil)))
1345     leaf var))
1346 ram 1.19 t)))))
1347     ((and (null (rest (leaf-refs var)))
1348 wlott 1.47 (not *byte-compiling*)
1349 ram 1.19 (substitute-single-use-continuation arg var)))
1350     (t
1351     (propagate-to-refs var (continuation-type arg))))))
1352    
1353     (when (every #'null (combination-args call))
1354     (delete-let fun))
1355    
1356 wlott 1.1 (undefined-value))
1357    
1358    
1359     ;;; Propagate-Local-Call-Args -- Internal
1360     ;;;
1361     ;;; This function is called when one of the args to a non-let local call
1362     ;;; changes. For each changed argument corresponding to an unset variable, we
1363     ;;; compute the union of the types across all calls and propagate this type
1364     ;;; information to the var's refs.
1365     ;;;
1366     ;;; If the function has an XEP, then we don't do anything, since we won't
1367     ;;; discover anything.
1368     ;;;
1369     ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1370     ;;; corresponding to changed arguments in Call, since the only use in IR1
1371     ;;; optimization of the Reoptimize flag for local call args is right here.
1372     ;;;
1373     (defun propagate-local-call-args (call fun)
1374     (declare (type combination call) (type clambda fun))
1375    
1376 ram 1.64 (unless (or (functional-entry-function fun)
1377     (lambda-optional-dispatch fun))
1378 wlott 1.1 (let* ((vars (lambda-vars fun))
1379     (union (mapcar #'(lambda (arg var)
1380     (when (and arg
1381     (continuation-reoptimize arg)
1382     (null (basic-var-sets var)))
1383     (continuation-type arg)))
1384     (basic-combination-args call)
1385     vars))
1386     (this-ref (continuation-use (basic-combination-fun call))))
1387    
1388     (dolist (arg (basic-combination-args call))
1389     (when arg
1390     (setf (continuation-reoptimize arg) nil)))
1391    
1392     (dolist (ref (leaf-refs fun))
1393 ram 1.63 (let ((dest (continuation-dest (node-cont ref))))
1394     (unless (or (eq ref this-ref) (not dest))
1395     (setq union
1396     (mapcar #'(lambda (this-arg old)
1397     (when old
1398     (setf (continuation-reoptimize this-arg) nil)
1399     (type-union (continuation-type this-arg) old)))
1400     (basic-combination-args dest)
1401     union)))))
1402 wlott 1.1
1403     (mapc #'(lambda (var type)
1404     (when type
1405     (propagate-to-refs var type)))
1406     vars union)))
1407    
1408 ram 1.6 (undefined-value))
1409    
1410 ram 1.50 (declaim (end-block))
1411    
1412 ram 1.6
1413 ram 1.19 ;;;; Multiple values optimization:
1414    
1415 ram 1.21 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1416     ;;;
1417 ram 1.32 ;;; Do stuff to notice a change to a MV combination node. There are two
1418     ;;; main branches here:
1419     ;;; -- If the call is local, then it is already a MV let, or should become one.
1420     ;;; Note that although all :LOCAL MV calls must eventually be converted to
1421     ;;; :MV-LETs, there can be a window when the call is local, but has not
1422     ;;; been let converted yet. This is because the entry-point lambdas may
1423     ;;; have stray references (in other entry points) that have not been
1424     ;;; deleted yet.
1425     ;;; -- The call is full. This case is somewhat similar to the non-MV
1426     ;;; combination optimization: we propagate return type information and
1427     ;;; notice non-returning calls. We also have an optimization
1428     ;;; which tries to convert MV-CALLs into MV-binds.
1429 ram 1.21 ;;;
1430     (defun ir1-optimize-mv-combination (node)
1431 ram 1.50 (ecase (basic-combination-kind node)
1432     (:local
1433 ram 1.54 (let ((fun-cont (basic-combination-fun node)))
1434     (when (continuation-reoptimize fun-cont)
1435     (setf (continuation-reoptimize fun-cont) nil)
1436 ram 1.50 (maybe-let-convert (combination-lambda node))))
1437     (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1438     (when (eq (functional-kind (combination-lambda node)) :mv-let)
1439     (unless (convert-mv-bind-to-let node)
1440     (ir1-optimize-mv-bind node))))
1441     (:full
1442     (let* ((fun (basic-combination-fun node))
1443     (fun-changed (continuation-reoptimize fun))
1444     (args (basic-combination-args node)))
1445     (when fun-changed
1446     (setf (continuation-reoptimize fun) nil)
1447     (let ((type (continuation-type fun)))
1448     (when (function-type-p type)
1449     (derive-node-type node (function-type-returns type))))
1450     (maybe-terminate-block node nil)
1451     (let ((use (continuation-use fun)))
1452     (when (and (ref-p use) (functional-p (ref-leaf use)))
1453     (convert-call-if-possible use node)
1454 ram 1.54 (when (eq (basic-combination-kind node) :local)
1455     (maybe-let-convert (ref-leaf use))))))
1456 ram 1.50 (unless (or (eq (basic-combination-kind node) :local)
1457     (eq (continuation-function-name fun) '%throw))
1458     (ir1-optimize-mv-call node))
1459     (dolist (arg args)
1460     (setf (continuation-reoptimize arg) nil))))
1461     (:error))
1462 ram 1.21 (undefined-value))
1463    
1464    
1465 ram 1.6 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1466     ;;;
1467     ;;; Propagate derived type info from the values continuation to the vars.
1468     ;;;
1469     (defun ir1-optimize-mv-bind (node)
1470     (declare (type mv-combination node))
1471     (let ((arg (first (basic-combination-args node)))
1472     (vars (lambda-vars (combination-lambda node))))
1473     (multiple-value-bind (types nvals)
1474     (values-types (continuation-derived-type arg))
1475     (unless (eq nvals :unknown)
1476     (mapc #'(lambda (var type)
1477     (if (basic-var-sets var)
1478     (propagate-from-sets var type)
1479     (propagate-to-refs var type)))
1480     vars
1481     (append types
1482     (make-list (max (- (length vars) nvals) 0)
1483     :initial-element *null-type*)))))
1484    
1485     (setf (continuation-reoptimize arg) nil))
1486 wlott 1.1 (undefined-value))
1487 ram 1.19
1488    
1489 ram 1.21 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1490 ram 1.19 ;;;
1491 ram 1.21 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1492     ;;; if:
1493 ram 1.22 ;;; -- The call has only one argument, and
1494 ram 1.21 ;;; -- The function has a known fixed number of arguments, or
1495 ram 1.22 ;;; -- The argument yields a known fixed number of values.
1496 ram 1.21 ;;;
1497     ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1498     ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1499     ;;; this call can be converted (the next time around.) This new lambda just
1500 ram 1.31 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1501     ;;; that this new MV bind is not let-converted immediately, as there are going
1502     ;;; to be stray references from the entry-point functions until they get
1503     ;;; deleted.
1504 ram 1.21 ;;;
1505     ;;; In order to avoid loss of argument count checking, we only do the
1506     ;;; transformation according to a known number of expected argument if safety
1507     ;;; is unimportant. We can always convert if we know the number of actual
1508     ;;; values, since the normal call that we build will still do any appropriate
1509     ;;; argument count checking.
1510     ;;;
1511     ;;; We only attempt the transformation if the called function is a constant
1512     ;;; reference. This allows us to just splice the leaf into the new function,
1513     ;;; instead of trying to somehow bind the function expression. The leaf must
1514     ;;; be constant because we are evaluating it again in a different place. This
1515     ;;; also has the effect of squelching multiple warnings when there is an
1516     ;;; argument count error.
1517     ;;;
1518     (defun ir1-optimize-mv-call (node)
1519     (let ((fun (basic-combination-fun node))
1520     (*compiler-error-context* node)
1521 ram 1.22 (ref (continuation-use (basic-combination-fun node)))
1522     (args (basic-combination-args node)))
1523 ram 1.21
1524 ram 1.22 (unless (and (ref-p ref) (constant-reference-p ref)
1525     args (null (rest args)))
1526 ram 1.21 (return-from ir1-optimize-mv-call))
1527    
1528     (multiple-value-bind (min max)
1529     (function-type-nargs (continuation-type fun))
1530 ram 1.22 (let ((total-nvals
1531     (multiple-value-bind
1532     (types nvals)
1533     (values-types (continuation-derived-type (first args)))
1534     (declare (ignore types))
1535     (if (eq nvals :unknown) nil nvals))))
1536 ram 1.21
1537 ram 1.22 (when total-nvals
1538     (when (and min (< total-nvals min))
1539     (compiler-warning
1540     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1541     at least ~R."
1542     total-nvals min)
1543 ram 1.50 (setf (basic-combination-kind node) :error)
1544 ram 1.22 (return-from ir1-optimize-mv-call))
1545     (when (and max (> total-nvals max))
1546     (compiler-warning
1547     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1548     at most ~R."
1549     total-nvals max)
1550 ram 1.50 (setf (basic-combination-kind node) :error)
1551 ram 1.22 (return-from ir1-optimize-mv-call)))
1552 ram 1.21
1553 ram 1.22 (let ((count (cond (total-nvals)
1554     ((and (policy node (zerop safety)) (eql min max))
1555     min)
1556     (t nil))))
1557     (when count
1558     (with-ir1-environment node
1559     (let* ((dums (loop repeat count collect (gensym)))
1560     (ignore (gensym))
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     (assert (eq (basic-combination-kind node) :full))
1567     (local-call-analyze *current-component*)
1568 ram 1.23 (assert (eq (basic-combination-kind node) :local)))))))))
1569 ram 1.21 (undefined-value))
1570    
1571    
1572     ;;; CONVERT-MV-BIND-TO-LET -- Internal
1573     ;;;
1574 ram 1.19 ;;; If we see:
1575     ;;; (multiple-value-bind (x y)
1576     ;;; (values xx yy)
1577     ;;; ...)
1578     ;;; Convert to:
1579     ;;; (let ((x xx)
1580     ;;; (y yy))
1581     ;;; ...)
1582     ;;;
1583     ;;; What we actually do is convert the VALUES combination into a normal let
1584 ram 1.31 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1585 ram 1.19 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1586     ;;; args, insert references to NIL.
1587     ;;;
1588 ram 1.21 (defun convert-mv-bind-to-let (call)
1589     (declare (type mv-combination call))
1590     (let* ((arg (first (basic-combination-args call)))
1591     (use (continuation-use arg)))
1592     (when (and (combination-p use)
1593     (eq (continuation-function-name (combination-fun use))
1594     'values))
1595     (let* ((fun (combination-lambda call))
1596 ram 1.19 (vars (lambda-vars fun))
1597 ram 1.21 (vals (combination-args use))
1598 ram 1.19 (nvars (length vars))
1599     (nvals (length vals)))
1600     (cond ((> nvals nvars)
1601     (mapc #'flush-dest (subseq vals nvars))
1602     (setq vals (subseq vals 0 nvars)))
1603     ((< nvals nvars)
1604 ram 1.21 (with-ir1-environment use
1605     (let ((node-prev (node-prev use)))
1606     (setf (node-prev use) nil)
1607 ram 1.19 (setf (continuation-next node-prev) nil)
1608     (collect ((res vals))
1609 ram 1.21 (loop as cont = (make-continuation use)
1610 ram 1.19 and prev = node-prev then cont
1611     repeat (- nvars nvals)
1612     do (reference-constant prev cont nil)
1613     (res cont))
1614     (setq vals (res)))
1615 ram 1.21 (prev-link use (car (last vals)))))))
1616     (setf (combination-args use) vals)
1617     (flush-dest (combination-fun use))
1618     (let ((fun-cont (basic-combination-fun call)))
1619     (setf (continuation-dest fun-cont) use)
1620     (setf (combination-fun use) fun-cont))
1621     (setf (combination-kind use) :local)
1622 ram 1.19 (setf (functional-kind fun) :let)
1623 ram 1.21 (flush-dest (first (basic-combination-args call)))
1624     (unlink-node call)
1625 ram 1.19 (when vals
1626 ram 1.20 (reoptimize-continuation (first vals)))
1627 ram 1.21 (propagate-to-args use fun))
1628     t)))
1629    
1630    
1631     ;;; VALUES-LIST IR1 optimizer -- Internal
1632     ;;;
1633     ;;; If we see:
1634     ;;; (values-list (list x y z))
1635     ;;;
1636     ;;; Convert to:
1637     ;;; (values x y z)
1638     ;;;
1639     ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1640     ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1641     ;;; the old argument continuation (allowing the LIST to be flushed.)
1642     ;;;
1643     (defoptimizer (values-list optimizer) ((list) node)
1644     (let ((use (continuation-use list)))
1645     (when (and (combination-p use)
1646     (eq (continuation-function-name (combination-fun use))
1647     'list))
1648     (change-ref-leaf (continuation-use (combination-fun node))
1649     (find-free-function 'values "in a strange place"))
1650     (setf (combination-kind node) :full)
1651     (let ((args (combination-args use)))
1652     (dolist (arg args)
1653     (setf (continuation-dest arg) node))
1654     (setf (combination-args use) nil)
1655     (flush-dest list)
1656     (setf (combination-args node) args))
1657 ram 1.19 t)))
1658    
1659    
1660     ;;; VALUES IR1 transform -- Internal
1661     ;;;
1662     ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1663     ;;; PROG1. This allows the computation of the additional values to become dead
1664     ;;; code.
1665     ;;;
1666     (deftransform values ((&rest vals) * * :node node)
1667     (when (typep (continuation-dest (node-cont node))
1668     '(or creturn exit mv-combination))
1669     (give-up))
1670 ram 1.34 (setf (node-derived-type node) *wild-type*)
1671 ram 1.33 (if vals
1672     (let ((dummies (loop repeat (1- (length vals))
1673 ram 1.19 collect (gensym))))
1674 ram 1.33 `(lambda (val ,@dummies)
1675     (declare (ignore ,@dummies))
1676     val))
1677     'nil))

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