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Revision 1.55 - (hide annotations)
Thu Sep 24 16:41:49 1992 UTC (21 years, 7 months ago) by ram
Branch: MAIN
Changes since 1.54: +9 -1 lines
Added a hack to IF-IF optimization to hopefully prevent some spurious
unreachable code notes.
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     ;;; If you want to use this code or any part of CMU Common Lisp, please contact
7     ;;; Scott Fahlman or slisp-group@cs.cmu.edu.
8     ;;;
9     (ext:file-comment
10 ram 1.55 "$Header: /tiger/var/lib/cvsroots/cmucl/src/compiler/ir1opt.lisp,v 1.55 1992/09/24 16:41:49 ram Exp $")
11 ram 1.24 ;;;
12 wlott 1.1 ;;; **********************************************************************
13     ;;;
14     ;;; This file implements the IR1 optimization phase of the compiler. IR1
15     ;;; optimization is a grab-bag of optimizations that don't make major changes
16     ;;; to the block-level control flow and don't use flow analysis. These
17     ;;; optimizations can mostly be classified as "meta-evaluation", but there is a
18     ;;; sizable top-down component as well.
19     ;;;
20     ;;; Written by Rob MacLachlan
21     ;;;
22 ram 1.46 (in-package :c)
23 wlott 1.1
24    
25     ;;;; Interface for obtaining results of constant folding:
26    
27     ;;; Constant-Continuation-P -- Interface
28     ;;;
29     ;;; Return true if the sole use of Cont is a reference to a constant leaf.
30     ;;;
31     (proclaim '(function constant-continuation-p (continuation) boolean))
32     (defun constant-continuation-p (cont)
33     (let ((use (continuation-use cont)))
34     (and (ref-p use)
35     (constant-p (ref-leaf use)))))
36    
37    
38     ;;; Continuation-Value -- Interface
39     ;;;
40     ;;; Return the constant value for a continuation whose only use is a
41     ;;; constant node.
42     ;;;
43     (proclaim '(function continuation-value (continuation) t))
44     (defun continuation-value (cont)
45 ram 1.10 (assert (constant-continuation-p cont))
46 wlott 1.1 (constant-value (ref-leaf (continuation-use cont))))
47    
48    
49     ;;;; Interface for obtaining results of type inference:
50    
51     ;;; CONTINUATION-PROVEN-TYPE -- Interface
52     ;;;
53     ;;; Return a (possibly values) type that describes what we have proven about
54     ;;; the type of Cont without taking any type assertions into consideration.
55     ;;; This is just the union of the NODE-DERIVED-TYPE of all the uses. Most
56     ;;; often people use CONTINUATION-DERIVED-TYPE or CONTINUATION-TYPE instead of
57     ;;; using this function directly.
58     ;;;
59     (defun continuation-proven-type (cont)
60     (declare (type continuation cont))
61     (ecase (continuation-kind cont)
62     ((:block-start :deleted-block-start)
63     (let ((uses (block-start-uses (continuation-block cont))))
64     (if uses
65     (do ((res (node-derived-type (first uses))
66     (values-type-union (node-derived-type (first current))
67     res))
68     (current (rest uses) (rest current)))
69     ((null current) res))
70     *empty-type*)))
71     (:inside-block
72     (node-derived-type (continuation-use cont)))))
73    
74    
75     ;;; Continuation-Derived-Type -- Interface
76     ;;;
77     ;;; Our best guess for the type of this continuation's value. Note that
78     ;;; this may be Values or Function type, which cannot be passed as an argument
79     ;;; to the normal type operations. See Continuation-Type. This may be called
80     ;;; on deleted continuations, always returning *.
81     ;;;
82     ;;; What we do is call CONTINUATION-PROVEN-TYPE and check whether the result
83     ;;; is a subtype of the assertion. If so, return the proven type and set
84     ;;; TYPE-CHECK to nil. Otherwise, return the intersection of the asserted and
85     ;;; proven types, and set TYPE-CHECK T. If TYPE-CHECK already has a non-null
86     ;;; value, then preserve it. Only in the somewhat unusual circumstance of
87     ;;; a newly discovered assertion will we change TYPE-CHECK from NIL to T.
88     ;;;
89     ;;; The result value is cached in the Continuation-%Derived-Type. If the
90     ;;; slot is true, just return that value, otherwise recompute and stash the
91     ;;; value there.
92     ;;;
93     (proclaim '(inline continuation-derived-type))
94     (defun continuation-derived-type (cont)
95     (declare (type continuation cont))
96     (or (continuation-%derived-type cont)
97     (%continuation-derived-type cont)))
98     ;;;
99     (defun %continuation-derived-type (cont)
100     (declare (type continuation cont))
101     (let ((proven (continuation-proven-type cont))
102     (asserted (continuation-asserted-type cont)))
103     (cond ((values-subtypep proven asserted)
104     (setf (continuation-%type-check cont) nil)
105     (setf (continuation-%derived-type cont) proven))
106     (t
107     (unless (or (continuation-%type-check cont)
108     (not (continuation-dest cont))
109     (eq asserted *universal-type*))
110     (setf (continuation-%type-check cont) t))
111    
112     (setf (continuation-%derived-type cont)
113     (values-type-intersection asserted proven))))))
114    
115    
116     ;;; CONTINUATION-TYPE-CHECK -- Interface
117     ;;;
118     ;;; Call CONTINUATION-DERIVED-TYPE to make sure the slot is up to date, then
119     ;;; return it.
120     ;;;
121     (proclaim '(inline continuation-type-check))
122     (defun continuation-type-check (cont)
123     (declare (type continuation cont))
124     (continuation-derived-type cont)
125     (continuation-%type-check cont))
126    
127    
128     ;;; Continuation-Type -- Interface
129     ;;;
130     ;;; Return the derived type for Cont's first value. This is guaranteed not
131     ;;; to be a Values or Function type.
132     ;;;
133 wlott 1.14 (proclaim '(function continuation-type (continuation) ctype))
134 wlott 1.1 (defun continuation-type (cont)
135     (single-value-type (continuation-derived-type cont)))
136    
137    
138     ;;;; Interface routines used by optimizers:
139    
140     ;;; Reoptimize-Continuation -- Interface
141     ;;;
142     ;;; This function is called by optimizers to indicate that something
143     ;;; interesting has happened to the value of Cont. Optimizers must make sure
144     ;;; that they don't call for reoptimization when nothing has happened, since
145     ;;; optimization will fail to terminate.
146     ;;;
147     ;;; We clear any cached type for the continuation and set the reoptimize
148     ;;; flags on everything in sight, unless the continuation is deleted (in which
149     ;;; case we do nothing.)
150     ;;;
151     ;;; Since this can get called curing IR1 conversion, we have to be careful
152     ;;; not to fly into space when the Dest's Prev is missing.
153     ;;;
154     (defun reoptimize-continuation (cont)
155     (declare (type continuation cont))
156 ram 1.29 (unless (member (continuation-kind cont) '(:deleted :unused))
157 wlott 1.1 (setf (continuation-%derived-type cont) nil)
158     (let ((dest (continuation-dest cont)))
159     (when dest
160     (setf (continuation-reoptimize cont) t)
161     (setf (node-reoptimize dest) t)
162     (let ((prev (node-prev dest)))
163     (when prev
164     (let* ((block (continuation-block prev))
165     (component (block-component block)))
166 ram 1.18 (when (typep dest 'cif)
167     (setf (block-test-modified block) t))
168 wlott 1.1 (setf (block-reoptimize block) t)
169     (setf (component-reoptimize component) t))))))
170     (do-uses (node cont)
171     (setf (block-type-check (node-block node)) t)))
172     (undefined-value))
173    
174    
175     ;;; Derive-Node-Type -- Interface
176     ;;;
177     ;;; Annotate Node to indicate that its result has been proven to be typep to
178     ;;; RType. After IR1 conversion has happened, this is the only correct way to
179     ;;; supply information discovered about a node's type. If you fuck with the
180     ;;; Node-Derived-Type directly, then information may be lost and reoptimization
181     ;;; may not happen.
182     ;;;
183     ;;; What we do is intersect Rtype with Node's Derived-Type. If the
184     ;;; intersection is different from the old type, then we do a
185     ;;; Reoptimize-Continuation on the Node-Cont.
186     ;;;
187     (defun derive-node-type (node rtype)
188     (declare (type node node) (type ctype rtype))
189     (let ((node-type (node-derived-type node)))
190     (unless (eq node-type rtype)
191     (let ((int (values-type-intersection node-type rtype)))
192     (when (type/= node-type int)
193 ram 1.38 (when (and *check-consistency*
194     (eq int *empty-type*)
195 ram 1.34 (not (eq rtype *empty-type*)))
196     (let ((*compiler-error-context* node))
197     (compiler-warning
198     "New inferred type ~S conflicts with old type:~
199     ~% ~S~%*** Bug?"
200     (type-specifier rtype) (type-specifier node-type))))
201 wlott 1.1 (setf (node-derived-type node) int)
202     (reoptimize-continuation (node-cont node))))))
203     (undefined-value))
204    
205 ram 1.50 (declaim (start-block assert-continuation-type assert-call-type))
206 wlott 1.1
207     ;;; Assert-Continuation-Type -- Interface
208     ;;;
209     ;;; Similar to Derive-Node-Type, but asserts that it is an error for Cont's
210     ;;; value not to be typep to Type. If we improve the assertion, we set
211 ram 1.11 ;;; TYPE-CHECK and TYPE-ASSERTED to guarantee that the new assertion will be
212     ;;; checked.
213 wlott 1.1 ;;;
214     (defun assert-continuation-type (cont type)
215     (declare (type continuation cont) (type ctype type))
216     (let ((cont-type (continuation-asserted-type cont)))
217     (unless (eq cont-type type)
218     (let ((int (values-type-intersection cont-type type)))
219     (when (type/= cont-type int)
220     (setf (continuation-asserted-type cont) int)
221     (do-uses (node cont)
222 ram 1.11 (setf (block-attributep (block-flags (node-block node))
223     type-check type-asserted)
224     t))
225 wlott 1.1 (reoptimize-continuation cont)))))
226     (undefined-value))
227    
228    
229     ;;; Assert-Call-Type -- Interface
230     ;;;
231     ;;; Assert that Call is to a function of the specified Type. It is assumed
232     ;;; that the call is legal and has only constants in the keyword positions.
233     ;;;
234     (defun assert-call-type (call type)
235     (declare (type combination call) (type function-type type))
236     (derive-node-type call (function-type-returns type))
237     (let ((args (combination-args call)))
238     (dolist (req (function-type-required type))
239     (when (null args) (return-from assert-call-type))
240     (let ((arg (pop args)))
241     (assert-continuation-type arg req)))
242     (dolist (opt (function-type-optional type))
243     (when (null args) (return-from assert-call-type))
244     (let ((arg (pop args)))
245     (assert-continuation-type arg opt)))
246    
247     (let ((rest (function-type-rest type)))
248     (when rest
249     (dolist (arg args)
250     (assert-continuation-type arg rest))))
251    
252     (dolist (key (function-type-keywords type))
253     (let ((name (key-info-name key)))
254     (do ((arg args (cddr arg)))
255     ((null arg))
256     (when (eq (continuation-value (first arg)) name)
257     (assert-continuation-type
258     (second arg) (key-info-type key)))))))
259     (undefined-value))
260    
261    
262 ram 1.50 ;;;; IR1-OPTIMIZE:
263    
264     (declaim (start-block ir1-optimize))
265    
266 wlott 1.1 ;;; IR1-Optimize -- Interface
267     ;;;
268     ;;; Do one forward pass over Component, deleting unreachable blocks and
269 ram 1.11 ;;; doing IR1 optimizations. We can ignore all blocks that don't have the
270     ;;; Reoptimize flag set. If Component-Reoptimize is true when we are done,
271 wlott 1.1 ;;; then another iteration would be beneficial.
272     ;;;
273     ;;; We delete blocks when there is either no predecessor or the block is in
274     ;;; a lambda that has been deleted. These blocks would eventually be deleted
275     ;;; by DFO recomputation, but doing it here immediately makes the effect
276     ;;; avaliable to IR1 optimization.
277     ;;;
278     (defun ir1-optimize (component)
279     (declare (type component component))
280     (setf (component-reoptimize component) nil)
281     (do-blocks (block component)
282     (cond
283     ((or (block-delete-p block)
284     (null (block-pred block))
285 ram 1.11 (eq (functional-kind (block-home-lambda block)) :deleted))
286 wlott 1.1 (delete-block block))
287     (t
288     (loop
289     (let ((succ (block-succ block)))
290     (unless (and succ (null (rest succ)))
291     (return)))
292    
293     (let ((last (block-last block)))
294     (typecase last
295     (cif
296     (flush-dest (if-test last))
297     (when (unlink-node last) (return)))
298     (exit
299     (when (maybe-delete-exit last) (return)))))
300    
301     (unless (join-successor-if-possible block)
302     (return)))
303    
304 ram 1.11 (when (and (block-reoptimize block) (block-component block))
305 wlott 1.1 (assert (not (block-delete-p block)))
306     (ir1-optimize-block block))
307    
308 ram 1.11 (when (and (block-flush-p block) (block-component block))
309 wlott 1.1 (assert (not (block-delete-p block)))
310     (flush-dead-code block)))))
311    
312     (undefined-value))
313    
314    
315     ;;; IR1-Optimize-Block -- Internal
316     ;;;
317     ;;; Loop over the nodes in Block, looking for stuff that needs to be
318     ;;; optimized. We dispatch off of the type of each node with its reoptimize
319     ;;; flag set:
320     ;;; -- With a combination, we call Propagate-Function-Change whenever the
321     ;;; function changes, and call IR1-Optimize-Combination if any argument
322     ;;; changes.
323     ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
324     ;;; propagate Cont's assertion to the Value, since if we did, this would
325     ;;; move the checking of Cont's assertion to the exit. This wouldn't work
326     ;;; with Catch and UWP, where the Exit node is just a placeholder for the
327     ;;; actual unknown exit.
328     ;;;
329     ;;; Note that we clear the node & block reoptimize flags *before* doing the
330     ;;; optimization. This ensures that the node or block will be reoptimized if
331 ram 1.19 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
332 wlott 1.1 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
333     ;;;
334     (defun ir1-optimize-block (block)
335     (declare (type cblock block))
336     (setf (block-reoptimize block) nil)
337 ram 1.19 (do-nodes (node cont block :restart-p t)
338 wlott 1.1 (when (node-reoptimize node)
339     (setf (node-reoptimize node) nil)
340     (typecase node
341     (ref)
342     (combination
343 ram 1.50 (ir1-optimize-combination node))
344 wlott 1.1 (cif
345     (ir1-optimize-if node))
346     (creturn
347     (setf (node-reoptimize node) t)
348     (ir1-optimize-return node))
349 ram 1.6 (mv-combination
350 ram 1.21 (ir1-optimize-mv-combination node))
351 wlott 1.1 (exit
352     (let ((value (exit-value node)))
353     (when value
354     (derive-node-type node (continuation-derived-type value)))))
355     (cset
356     (ir1-optimize-set node)))))
357     (undefined-value))
358    
359 ram 1.50
360 wlott 1.1 ;;; Join-Successor-If-Possible -- Internal
361     ;;;
362     ;;; We cannot combine with a successor block if:
363     ;;; 1] The successor has more than one predecessor.
364     ;;; 2] The last node's Cont is also used somewhere else.
365     ;;; 3] The successor is the current block (infinite loop).
366     ;;; 4] The next block has a different cleanup, and thus we may want to insert
367     ;;; cleanup code between the two blocks at some point.
368     ;;; 5] The next block has a different home lambda, and thus the control
369     ;;; transfer is a non-local exit.
370     ;;;
371     ;;; If we succeed, we return true, otherwise false.
372     ;;;
373     ;;; Joining is easy when the successor's Start continuation is the same from
374     ;;; our Last's Cont. If they differ, then we can still join when the last
375     ;;; continuation has no next and the next continuation has no uses. In this
376 ram 1.5 ;;; case, we replace the next continuation with the last before joining the
377 wlott 1.1 ;;; blocks.
378     ;;;
379     (defun join-successor-if-possible (block)
380     (declare (type cblock block))
381     (let ((next (first (block-succ block))))
382 ram 1.11 (when (block-start next)
383 wlott 1.1 (let* ((last (block-last block))
384     (last-cont (node-cont last))
385 ram 1.11 (next-cont (block-start next)))
386 wlott 1.1 (cond ((or (rest (block-pred next))
387 ram 1.5 (not (eq (continuation-use last-cont) last))
388 wlott 1.1 (eq next block)
389 ram 1.11 (not (eq (block-end-cleanup block)
390     (block-start-cleanup next)))
391     (not (eq (block-home-lambda block)
392     (block-home-lambda next))))
393 wlott 1.1 nil)
394 ram 1.5 ((eq last-cont next-cont)
395 wlott 1.1 (join-blocks block next)
396     t)
397 ram 1.5 ((and (null (block-start-uses next))
398     (eq (continuation-kind last-cont) :inside-block))
399     (let ((next-node (continuation-next next-cont)))
400 ram 1.30 ;;
401     ;; If next-cont does have a dest, it must be unreachable,
402     ;; since there are no uses. DELETE-CONTINUATION will mark the
403     ;; dest block as delete-p [and also this block, unless it is
404     ;; no longer backward reachable from the dest block.]
405 ram 1.5 (delete-continuation next-cont)
406     (setf (node-prev next-node) last-cont)
407     (setf (continuation-next last-cont) next-node)
408     (setf (block-start next) last-cont)
409     (join-blocks block next))
410 wlott 1.1 t)
411     (t
412     nil))))))
413    
414    
415     ;;; Join-Blocks -- Internal
416     ;;;
417     ;;; Join together two blocks which have the same ending/starting
418     ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
419 ram 1.11 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
420     ;;; that any indicated optimization gets done.
421 wlott 1.1 ;;;
422     (defun join-blocks (block1 block2)
423     (declare (type cblock block1 block2))
424     (let* ((last (block-last block2))
425     (last-cont (node-cont last))
426     (succ (block-succ block2))
427     (start2 (block-start block2)))
428     (do ((cont start2 (node-cont (continuation-next cont))))
429     ((eq cont last-cont)
430     (when (eq (continuation-kind last-cont) :inside-block)
431     (setf (continuation-block last-cont) block1)))
432     (setf (continuation-block cont) block1))
433    
434     (unlink-blocks block1 block2)
435     (dolist (block succ)
436     (unlink-blocks block2 block)
437     (link-blocks block1 block))
438    
439     (setf (block-last block1) last)
440     (setf (continuation-kind start2) :inside-block))
441    
442 ram 1.11 (setf (block-flags block1)
443     (attributes-union (block-flags block1)
444     (block-flags block2)
445     (block-attributes type-asserted test-modified)))
446 wlott 1.1
447     (let ((next (block-next block2))
448     (prev (block-prev block2)))
449     (setf (block-next prev) next)
450     (setf (block-prev next) prev))
451    
452     (undefined-value))
453    
454 ram 1.50 ;;; Flush-Dead-Code -- Internal
455     ;;;
456     ;;; Delete any nodes in Block whose value is unused and have no
457     ;;; side-effects. We can delete sets of lexical variables when the set
458     ;;; variable has no references.
459     ;;;
460     ;;; [### For now, don't delete potentially flushable calls when they have the
461     ;;; Call attribute. Someday we should look at the funcitonal args to determine
462     ;;; if they have any side-effects.]
463     ;;;
464     (defun flush-dead-code (block)
465     (declare (type cblock block))
466     (do-nodes-backwards (node cont block)
467     (unless (continuation-dest cont)
468     (typecase node
469     (ref
470     (delete-ref node)
471     (unlink-node node))
472     (combination
473     (let ((info (combination-kind node)))
474     (when (function-info-p info)
475     (let ((attr (function-info-attributes info)))
476     (when (and (ir1-attributep attr flushable)
477     (not (ir1-attributep attr call)))
478     (flush-dest (combination-fun node))
479     (dolist (arg (combination-args node))
480     (flush-dest arg))
481     (unlink-node node))))))
482     (mv-combination
483     (when (eq (basic-combination-kind node) :local)
484     (let ((fun (combination-lambda node)))
485     (when (dolist (var (lambda-vars fun) t)
486     (when (or (leaf-refs var)
487     (lambda-var-sets var))
488     (return nil)))
489     (flush-dest (first (basic-combination-args node)))
490     (delete-let fun)))))
491     (exit
492     (let ((value (exit-value node)))
493     (when value
494     (flush-dest value)
495     (setf (exit-value node) nil))))
496     (cset
497     (let ((var (set-var node)))
498     (when (and (lambda-var-p var)
499     (null (leaf-refs var)))
500     (flush-dest (set-value node))
501     (setf (basic-var-sets var)
502     (delete node (basic-var-sets var)))
503     (unlink-node node)))))))
504    
505     (setf (block-flush-p block) nil)
506     (undefined-value))
507    
508     (declaim (end-block))
509    
510 wlott 1.1
511     ;;;; Local call return type propagation:
512    
513     ;;; Find-Result-Type -- Internal
514     ;;;
515     ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
516     ;;; set. It iterates over the uses of the RESULT, looking for interesting
517 ram 1.46 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
518     ;;; its type together with the types of other such uses. We assign to the
519     ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
520     ;;; type. We can make this intersection now (potentially before type checking)
521     ;;; because this assertion on the result will eventually be checked (if
522     ;;; appropriate.)
523 wlott 1.1 ;;;
524 ram 1.46 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
525     ;;; which may change the succesor of the call to be the called function, and if
526     ;;; so, checks if the call can become an assignment.
527     ;;;
528     (defun find-result-type (node)
529 wlott 1.1 (declare (type creturn node))
530 ram 1.46 (let ((result (return-result node)))
531 wlott 1.1 (collect ((use-union *empty-type* values-type-union))
532     (do-uses (use result)
533 ram 1.34 (cond ((and (basic-combination-p use)
534 ram 1.46 (eq (basic-combination-kind use) :local))
535     (assert (eq (lambda-tail-set (node-home-lambda use))
536     (lambda-tail-set (combination-lambda use))))
537 ram 1.39 (when (combination-p use)
538     (maybe-convert-tail-local-call use)))
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     (setf (node-reoptimize node) nil)
572     (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     (inlinep (if (defined-function-p leaf)
852     (defined-function-inlinep leaf)
853     :no-chance)))
854     (cond
855     ((eq inlinep :notinline) (values nil nil))
856     ((not (and (global-var-p leaf)
857     (eq (global-var-kind leaf) :global-function)))
858     (values leaf nil))
859     ((and (ecase inlinep
860     (:inline t)
861     (:no-chance nil)
862     ((nil :maybe-inline) (policy call (zerop space))))
863     (defined-function-inline-expansion leaf)
864     (let ((fun (defined-function-functional leaf)))
865     (or (not fun)
866     (and (eq inlinep :inline) (functional-kind fun))))
867     (inline-expansion-ok call))
868     (flet ((frob ()
869     (let ((res (ir1-convert-lambda-for-defun
870     (defined-function-inline-expansion leaf)
871 ram 1.53 leaf t
872 ram 1.50 #'ir1-convert-inline-lambda
873     'labels)))
874     (setf (defined-function-functional leaf) res)
875     (change-ref-leaf ref res))))
876     (if ir1-p
877     (frob)
878     (with-ir1-environment call
879     (frob)
880     (local-call-analyze *current-component*))))
881 ram 1.53
882 ram 1.50 (values (ref-leaf (continuation-use (basic-combination-fun call)))
883     nil))
884     (t
885     (let* ((name (leaf-name leaf))
886     (info (info function info
887     (if (slot-accessor-p leaf)
888     (if (consp name) '%slot-setter '%slot-accessor)
889     name))))
890     (if info
891     (values leaf (setf (basic-combination-kind call) info))
892     (values leaf nil)))))))
893 wlott 1.1
894    
895 ram 1.50 ;;; VALIDATE-CALL-TYPE -- Internal
896     ;;;
897     ;;; Check if Call satisfies Type. If so, apply the type to the call, and do
898     ;;; MAYBE-TERMINATE-BLOCK and return the values of RECOGNIZE-KNOWN-CALL. If an
899     ;;; error, set the combination kind and return NIL, NIL.
900     ;;;
901     (defun validate-call-type (call type ir1-p)
902     (declare (type combination call) (type ctype type))
903     (cond ((not (function-type-p type)) (values nil nil))
904     ((valid-function-use call type
905     :argument-test #'always-subtypep
906     :result-test #'always-subtypep
907     :error-function #'compiler-warning
908     :warning-function #'compiler-note)
909     (assert-call-type call type)
910     (maybe-terminate-block call ir1-p)
911     (recognize-known-call call ir1-p))
912     (t
913     (setf (combination-kind call) :error)
914     (values nil nil))))
915    
916    
917 wlott 1.1 ;;; Propagate-Function-Change -- Internal
918     ;;;
919     ;;; Called by Ir1-Optimize when the function for a call has changed.
920 ram 1.50 ;;; If the call is local, we try to let-convert it, and derive the result type.
921     ;;; If it is a :FULL call, we validate it against the type, which recognizes
922     ;;; known calls, does inline expansion, etc. If a call to a predicate in a
923     ;;; non-conditional position or to a function with a source transform, then we
924     ;;; reconvert the form to give IR1 another chance.
925 wlott 1.1 ;;;
926     (defun propagate-function-change (call)
927     (declare (type combination call))
928 ram 1.50 (let ((*compiler-error-context* call)
929     (fun-cont (basic-combination-fun call)))
930     (setf (continuation-reoptimize fun-cont) nil)
931     (case (combination-kind call)
932     (:local
933     (let ((fun (combination-lambda call)))
934     (maybe-let-convert fun)
935     (unless (member (functional-kind fun) '(:let :assignment :deleted))
936     (derive-node-type call (tail-set-type (lambda-tail-set fun))))))
937     (:full
938     (multiple-value-bind
939     (leaf info)
940     (validate-call-type call (continuation-derived-type fun-cont) nil)
941     (cond ((functional-p leaf)
942     (convert-call-if-possible
943     (continuation-use (basic-combination-fun call))
944     call))
945     ((not leaf))
946     ((or (info function source-transform (leaf-name leaf))
947     (and info
948     (ir1-attributep (function-info-attributes info)
949     predicate)
950     (let ((dest (continuation-dest (node-cont call))))
951     (and dest (not (if-p dest))))))
952     (let ((name (leaf-name leaf)))
953     (when (symbolp name)
954     (let ((dums (loop repeat (length (combination-args call))
955     collect (gensym))))
956     (transform-call call
957     `(lambda ,dums
958     (,name ,@dums))))))))))))
959 wlott 1.1 (undefined-value))
960    
961    
962     ;;;; Known function optimization:
963    
964 ram 1.15
965     ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
966     ;;;
967 ram 1.50 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for Node, Fun
968 ram 1.28 ;;; and Args. If there is already a note for Node and Transform, replace it,
969 ram 1.15 ;;; otherwise add a new one.
970     ;;;
971 ram 1.28 (defun record-optimization-failure (node transform args)
972     (declare (type combination node) (type transform transform)
973 ram 1.15 (type (or function-type list) args))
974 ram 1.50 (let* ((table (component-failed-optimizations *compile-component*))
975     (found (assoc transform (gethash node table))))
976 ram 1.15 (if found
977     (setf (cdr found) args)
978 ram 1.50 (push (cons transform args) (gethash node table))))
979 ram 1.15 (undefined-value))
980    
981    
982 wlott 1.1 ;;; IR1-Transform -- Internal
983     ;;;
984     ;;; Attempt to transform Node using Function, subject to the call type
985     ;;; constraint Type. If we are inhibited from doing the transform for some
986     ;;; reason and Flame is true, then we make a note of the message in
987 ram 1.50 ;;; FAILED-OPTIMIZATIONS for IR1 finalize to pick up. We return true if
988 wlott 1.2 ;;; the transform failed, and thus further transformation should be
989     ;;; attempted. We return false if either the transform suceeded or was
990     ;;; aborted.
991 wlott 1.1 ;;;
992 ram 1.28 (defun ir1-transform (node transform)
993     (declare (type combination node) (type transform transform))
994     (let* ((type (transform-type transform))
995     (fun (transform-function transform))
996     (constrained (function-type-p type))
997 ram 1.50 (table (component-failed-optimizations *compile-component*))
998 wlott 1.41 (flame
999     (if (transform-important transform)
1000     (policy node (>= speed brevity))
1001     (policy node (> speed brevity))))
1002 ram 1.28 (*compiler-error-context* node))
1003 wlott 1.1 (cond ((or (not constrained)
1004 ram 1.19 (valid-function-use node type :strict-result t))
1005 wlott 1.1 (multiple-value-bind
1006     (severity args)
1007     (catch 'give-up
1008     (transform-call node (funcall fun node))
1009     (values :none nil))
1010     (ecase severity
1011 ram 1.15 (:none
1012 ram 1.50 (remhash node table)
1013 ram 1.15 nil)
1014 wlott 1.1 (:aborted
1015 ram 1.50 (setf (combination-kind node) :error)
1016 wlott 1.1 (when args
1017 wlott 1.2 (apply #'compiler-warning args))
1018 ram 1.50 (remhash node table)
1019 wlott 1.2 nil)
1020 wlott 1.1 (:failure
1021 ram 1.15 (if args
1022     (when flame
1023 ram 1.28 (record-optimization-failure node transform args))
1024 ram 1.50 (setf (gethash node table)
1025     (remove transform (gethash node table) :key #'car)))
1026 wlott 1.2 t))))
1027 wlott 1.1 ((and flame
1028     (valid-function-use node type
1029     :argument-test #'types-intersect
1030     :result-test #'values-types-intersect))
1031 ram 1.28 (record-optimization-failure node transform type)
1032 wlott 1.13 t)
1033     (t
1034 wlott 1.2 t))))
1035 wlott 1.1
1036 ram 1.50 (declaim (end-block))
1037 wlott 1.1
1038     ;;; GIVE-UP, ABORT-TRANSFORM -- Interface
1039     ;;;
1040     ;;; Just throw the severity and args...
1041     ;;;
1042     (proclaim '(function give-up (&rest t) nil))
1043     (defun give-up (&rest args)
1044     "This function is used to throw out of an IR1 transform, aborting this
1045     attempt to transform the call, but admitting the possibility that this or
1046     some other transform will later suceed. If arguments are supplied, they are
1047     format arguments for an efficiency note."
1048     (throw 'give-up (values :failure args)))
1049     ;;;
1050     (defun abort-transform (&rest args)
1051     "This function is used to throw out of an IR1 transform and force a normal
1052     call to the function at run time. No further optimizations will be
1053     attempted."
1054     (throw 'give-up (values :aborted args)))
1055    
1056    
1057     ;;; Transform-Call -- Internal
1058     ;;;
1059     ;;; Take the lambda-expression Res, IR1 convert it in the proper
1060     ;;; environment, and then install it as the function for the call Node. We do
1061     ;;; local call analysis so that the new function is integrated into the control
1062 ram 1.50 ;;; flow.
1063 wlott 1.1 ;;;
1064     (defun transform-call (node res)
1065     (declare (type combination node) (list res))
1066     (with-ir1-environment node
1067 ram 1.50 (let ((new-fun (ir1-convert-inline-lambda res))
1068 wlott 1.1 (ref (continuation-use (combination-fun node))))
1069     (change-ref-leaf ref new-fun)
1070     (setf (combination-kind node) :full)
1071     (local-call-analyze *current-component*)))
1072     (undefined-value))
1073    
1074    
1075     ;;; Constant-Fold-Call -- Internal
1076     ;;;
1077     ;;; Replace a call to a foldable function of constant arguments with the
1078     ;;; result of evaluating the form. We insert the resulting constant node after
1079     ;;; the call, stealing the call's continuation. We give the call a
1080     ;;; continuation with no Dest, which should cause it and its arguments to go
1081     ;;; away. If there is an error during the evaluation, we give a warning and
1082 ram 1.50 ;;; leave the call alone, making the call a :ERROR call.
1083 wlott 1.1 ;;;
1084 ram 1.50 ;;; If there is more than one value, then we transform the call into a
1085     ;;; values form.
1086 wlott 1.1 ;;;
1087     (defun constant-fold-call (call)
1088     (declare (type combination call))
1089     (let* ((args (mapcar #'continuation-value (combination-args call)))
1090     (ref (continuation-use (combination-fun call)))
1091     (fun (leaf-name (ref-leaf ref))))
1092    
1093     (multiple-value-bind (values win)
1094     (careful-call fun args call "constant folding")
1095     (cond
1096     ((not win)
1097 ram 1.50 (setf (combination-kind call) :error))
1098 wlott 1.1 ((= (length values) 1)
1099     (with-ir1-environment call
1100 wlott 1.37 (when (producing-fasl-file)
1101     (maybe-emit-make-load-forms (first values)))
1102 wlott 1.1 (let* ((leaf (find-constant (first values)))
1103 ram 1.50 (node (make-ref (leaf-type leaf) leaf))
1104 wlott 1.1 (dummy (make-continuation))
1105     (cont (node-cont call))
1106     (block (node-block call))
1107     (next (continuation-next cont)))
1108     (push node (leaf-refs leaf))
1109     (setf (leaf-ever-used leaf) t)
1110    
1111     (delete-continuation-use call)
1112     (add-continuation-use call dummy)
1113     (prev-link node dummy)
1114     (add-continuation-use node cont)
1115     (setf (continuation-next cont) next)
1116     (when (eq call (block-last block))
1117     (setf (block-last block) node))
1118 ram 1.19 (reoptimize-continuation cont))))
1119     (t
1120     (let ((dummies (loop repeat (length args)
1121     collect (gensym))))
1122     (transform-call
1123     call
1124     `(lambda ,dummies
1125     (declare (ignore ,@dummies))
1126     (values ,@(mapcar #'(lambda (x) `',x) values)))))))))
1127 wlott 1.1
1128     (undefined-value))
1129    
1130    
1131     ;;;; Local call optimization:
1132    
1133 ram 1.50 (declaim (start-block ir1-optimize-set constant-reference-p delete-let
1134     propagate-let-args propagate-local-call-args
1135 ram 1.52 propagate-to-refs propagate-from-sets
1136     ir1-optimize-mv-combination))
1137 ram 1.50
1138 wlott 1.1 ;;; Propagate-To-Refs -- Internal
1139     ;;;
1140     ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1141     ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1142     ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1143     ;;;
1144     (defun propagate-to-refs (leaf type)
1145     (declare (type leaf leaf) (type ctype type))
1146     (let ((var-type (leaf-type leaf)))
1147     (unless (function-type-p var-type)
1148     (let ((int (type-intersection var-type type)))
1149     (when (type/= int var-type)
1150     (setf (leaf-type leaf) int)
1151     (dolist (ref (leaf-refs leaf))
1152     (derive-node-type ref int))))
1153     (undefined-value))))
1154    
1155    
1156     ;;; PROPAGATE-FROM-SETS -- Internal
1157     ;;;
1158     ;;; Figure out the type of a LET variable that has sets. We compute the
1159     ;;; union of the initial value Type and the types of all the set values and to
1160     ;;; a PROPAGATE-TO-REFS with this type.
1161     ;;;
1162     (defun propagate-from-sets (var type)
1163 ram 1.6 (collect ((res type type-union))
1164 wlott 1.1 (dolist (set (basic-var-sets var))
1165     (res (continuation-type (set-value set)))
1166     (setf (node-reoptimize set) nil))
1167     (propagate-to-refs var (res)))
1168     (undefined-value))
1169    
1170    
1171     ;;; IR1-OPTIMIZE-SET -- Internal
1172     ;;;
1173     ;;; If a let variable, find the initial value's type and do
1174     ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1175     ;;;
1176     (defun ir1-optimize-set (node)
1177     (declare (type cset node))
1178     (let ((var (set-var node)))
1179     (when (and (lambda-var-p var) (leaf-refs var))
1180     (let ((home (lambda-var-home var)))
1181     (when (eq (functional-kind home) :let)
1182     (let ((iv (let-var-initial-value var)))
1183     (setf (continuation-reoptimize iv) nil)
1184     (propagate-from-sets var (continuation-type iv)))))))
1185    
1186     (derive-node-type node (continuation-type (set-value node)))
1187     (undefined-value))
1188    
1189    
1190 ram 1.17 ;;; CONSTANT-REFERENCE-P -- Interface
1191 ram 1.7 ;;;
1192     ;;; Return true if the value of Ref will always be the same (and is thus
1193 ram 1.50 ;;; legal to substitute.)
1194 ram 1.7 ;;;
1195     (defun constant-reference-p (ref)
1196     (declare (type ref ref))
1197     (let ((leaf (ref-leaf ref)))
1198     (typecase leaf
1199 ram 1.50 ((or constant functional) t)
1200 ram 1.7 (lambda-var
1201     (null (lambda-var-sets leaf)))
1202 ram 1.50 (defined-function
1203     (not (eq (defined-function-inlinep leaf) :notinline)))
1204 ram 1.7 (global-var
1205     (case (global-var-kind leaf)
1206 ram 1.50 (:global-function t)
1207 ram 1.7 (:constant t))))))
1208    
1209    
1210     ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1211     ;;;
1212     ;;; If we have a non-set let var with a single use, then (if possible)
1213     ;;; replace the variable reference's CONT with the arg continuation. This is
1214     ;;; inhibited when:
1215     ;;; -- CONT has other uses, or
1216     ;;; -- CONT receives multiple values, or
1217 ram 1.9 ;;; -- the reference is in a different environment from the variable, or
1218     ;;; -- either continuation has a funky TYPE-CHECK annotation.
1219 ram 1.43 ;;; -- the continuations have incompatible assertions, so the new asserted type
1220     ;;; would be NIL.
1221 ram 1.27 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1222 ram 1.7 ;;;
1223     ;;; We change the Ref to be a reference to NIL with unused value, and let it
1224     ;;; be flushed as dead code. A side-effect of this substitution is to delete
1225     ;;; the variable.
1226     ;;;
1227     (defun substitute-single-use-continuation (arg var)
1228     (declare (type continuation arg) (type lambda-var var))
1229     (let* ((ref (first (leaf-refs var)))
1230     (cont (node-cont ref))
1231 ram 1.43 (cont-atype (continuation-asserted-type cont))
1232 ram 1.7 (dest (continuation-dest cont)))
1233     (when (and (eq (continuation-use cont) ref)
1234     dest
1235     (not (typep dest '(or creturn exit mv-combination)))
1236 ram 1.11 (eq (node-home-lambda ref)
1237 ram 1.9 (lambda-home (lambda-var-home var)))
1238     (member (continuation-type-check arg) '(t nil))
1239 ram 1.27 (member (continuation-type-check cont) '(t nil))
1240 ram 1.43 (not (eq (values-type-intersection
1241     cont-atype
1242     (continuation-asserted-type arg))
1243     *empty-type*))
1244 ram 1.27 (eq (lexenv-cookie (node-lexenv dest))
1245     (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1246 ram 1.25 (assert (member (continuation-kind arg)
1247     '(:block-start :deleted-block-start :inside-block)))
1248 ram 1.43 (assert-continuation-type arg cont-atype)
1249 ram 1.34 (setf (node-derived-type ref) *wild-type*)
1250 ram 1.7 (change-ref-leaf ref (find-constant nil))
1251     (substitute-continuation arg cont)
1252     (reoptimize-continuation arg)
1253     t)))
1254    
1255    
1256 ram 1.19 ;;; DELETE-LET -- Interface
1257     ;;;
1258     ;;; Delete a Let, removing the call and bind nodes, and warning about any
1259     ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1260     ;;; away and delete the REF and then the lambda, since we flush the FUN
1261     ;;; continuation.
1262     ;;;
1263     (defun delete-let (fun)
1264     (declare (type clambda fun))
1265 ram 1.42 (assert (member (functional-kind fun) '(:let :mv-let)))
1266 ram 1.19 (note-unreferenced-vars fun)
1267     (let ((call (let-combination fun)))
1268 ram 1.42 (flush-dest (basic-combination-fun call))
1269 ram 1.19 (unlink-node call)
1270     (unlink-node (lambda-bind fun))
1271     (setf (lambda-bind fun) nil))
1272     (undefined-value))
1273    
1274    
1275 wlott 1.1 ;;; Propagate-Let-Args -- Internal
1276     ;;;
1277     ;;; This function is called when one of the arguments to a LET changes. We
1278     ;;; look at each changed argument. If the corresponding variable is set, then
1279     ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1280     ;;; variable, and also propagate derived-type information for the arg to all
1281     ;;; the Var's refs.
1282     ;;;
1283 ram 1.16 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1284     ;;; subtype of the argument's asserted type. This prevents type checking from
1285     ;;; being defeated, and also ensures that the best representation for the
1286     ;;; variable can be used.
1287 wlott 1.1 ;;;
1288 ram 1.26 ;;; Substitution of individual references is inhibited if the reference is
1289     ;;; in a different component from the home. This can only happen with closures
1290     ;;; over top-level lambda vars. In such cases, the references may have already
1291     ;;; been compiled, and thus can't be retroactively modified.
1292     ;;;
1293 ram 1.19 ;;; If all of the variables are deleted (have no references) when we are
1294     ;;; done, then we delete the let.
1295     ;;;
1296 wlott 1.1 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1297     ;;; flags.
1298     ;;;
1299     (defun propagate-let-args (call fun)
1300     (declare (type combination call) (type clambda fun))
1301 ram 1.19 (loop for arg in (combination-args call)
1302     and var in (lambda-vars fun) do
1303     (when (and arg (continuation-reoptimize arg))
1304     (setf (continuation-reoptimize arg) nil)
1305     (cond
1306     ((lambda-var-sets var)
1307     (propagate-from-sets var (continuation-type arg)))
1308     ((let ((use (continuation-use arg)))
1309     (when (ref-p use)
1310     (let ((leaf (ref-leaf use)))
1311     (when (and (constant-reference-p use)
1312     (values-subtypep (leaf-type leaf)
1313     (continuation-asserted-type arg)))
1314     (propagate-to-refs var (continuation-type arg))
1315 ram 1.26 (let ((this-comp (block-component (node-block use))))
1316     (substitute-leaf-if
1317     #'(lambda (ref)
1318     (cond ((eq (block-component (node-block ref))
1319     this-comp)
1320     t)
1321     (t
1322     (assert (eq (functional-kind (lambda-home fun))
1323     :top-level))
1324     nil)))
1325     leaf var))
1326 ram 1.19 t)))))
1327     ((and (null (rest (leaf-refs var)))
1328 wlott 1.47 (not *byte-compiling*)
1329 ram 1.19 (substitute-single-use-continuation arg var)))
1330     (t
1331     (propagate-to-refs var (continuation-type arg))))))
1332    
1333     (when (every #'null (combination-args call))
1334     (delete-let fun))
1335    
1336 wlott 1.1 (undefined-value))
1337    
1338    
1339     ;;; Propagate-Local-Call-Args -- Internal
1340     ;;;
1341     ;;; This function is called when one of the args to a non-let local call
1342     ;;; changes. For each changed argument corresponding to an unset variable, we
1343     ;;; compute the union of the types across all calls and propagate this type
1344     ;;; information to the var's refs.
1345     ;;;
1346     ;;; If the function has an XEP, then we don't do anything, since we won't
1347     ;;; discover anything.
1348     ;;;
1349     ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1350     ;;; corresponding to changed arguments in Call, since the only use in IR1
1351     ;;; optimization of the Reoptimize flag for local call args is right here.
1352     ;;;
1353     (defun propagate-local-call-args (call fun)
1354     (declare (type combination call) (type clambda fun))
1355    
1356     (unless (functional-entry-function fun)
1357     (let* ((vars (lambda-vars fun))
1358     (union (mapcar #'(lambda (arg var)
1359     (when (and arg
1360     (continuation-reoptimize arg)
1361     (null (basic-var-sets var)))
1362     (continuation-type arg)))
1363     (basic-combination-args call)
1364     vars))
1365     (this-ref (continuation-use (basic-combination-fun call))))
1366    
1367     (dolist (arg (basic-combination-args call))
1368     (when arg
1369     (setf (continuation-reoptimize arg) nil)))
1370    
1371     (dolist (ref (leaf-refs fun))
1372     (unless (eq ref this-ref)
1373     (setq union
1374     (mapcar #'(lambda (this-arg old)
1375     (when old
1376     (setf (continuation-reoptimize this-arg) nil)
1377     (type-union (continuation-type this-arg) old)))
1378     (basic-combination-args
1379     (continuation-dest (node-cont ref)))
1380     union))))
1381    
1382     (mapc #'(lambda (var type)
1383     (when type
1384     (propagate-to-refs var type)))
1385     vars union)))
1386    
1387 ram 1.6 (undefined-value))
1388    
1389 ram 1.50 (declaim (end-block))
1390    
1391 ram 1.6
1392 ram 1.19 ;;;; Multiple values optimization:
1393    
1394 ram 1.21 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1395     ;;;
1396 ram 1.32 ;;; Do stuff to notice a change to a MV combination node. There are two
1397     ;;; main branches here:
1398     ;;; -- If the call is local, then it is already a MV let, or should become one.
1399     ;;; Note that although all :LOCAL MV calls must eventually be converted to
1400     ;;; :MV-LETs, there can be a window when the call is local, but has not
1401     ;;; been let converted yet. This is because the entry-point lambdas may
1402     ;;; have stray references (in other entry points) that have not been
1403     ;;; deleted yet.
1404     ;;; -- The call is full. This case is somewhat similar to the non-MV
1405     ;;; combination optimization: we propagate return type information and
1406     ;;; notice non-returning calls. We also have an optimization
1407     ;;; which tries to convert MV-CALLs into MV-binds.
1408 ram 1.21 ;;;
1409     (defun ir1-optimize-mv-combination (node)
1410 ram 1.50 (ecase (basic-combination-kind node)
1411     (:local
1412 ram 1.54 (let ((fun-cont (basic-combination-fun node)))
1413     (when (continuation-reoptimize fun-cont)
1414     (setf (continuation-reoptimize fun-cont) nil)
1415 ram 1.50 (maybe-let-convert (combination-lambda node))))
1416     (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1417     (when (eq (functional-kind (combination-lambda node)) :mv-let)
1418     (unless (convert-mv-bind-to-let node)
1419     (ir1-optimize-mv-bind node))))
1420     (:full
1421     (let* ((fun (basic-combination-fun node))
1422     (fun-changed (continuation-reoptimize fun))
1423     (args (basic-combination-args node)))
1424     (when fun-changed
1425     (setf (continuation-reoptimize fun) nil)
1426     (let ((type (continuation-type fun)))
1427     (when (function-type-p type)
1428     (derive-node-type node (function-type-returns type))))
1429     (maybe-terminate-block node nil)
1430     (let ((use (continuation-use fun)))
1431     (when (and (ref-p use) (functional-p (ref-leaf use)))
1432     (convert-call-if-possible use node)
1433 ram 1.54 (when (eq (basic-combination-kind node) :local)
1434     (maybe-let-convert (ref-leaf use))))))
1435 ram 1.50 (unless (or (eq (basic-combination-kind node) :local)
1436     (eq (continuation-function-name fun) '%throw))
1437     (ir1-optimize-mv-call node))
1438     (dolist (arg args)
1439     (setf (continuation-reoptimize arg) nil))))
1440     (:error))
1441 ram 1.21 (undefined-value))
1442    
1443    
1444 ram 1.6 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1445     ;;;
1446     ;;; Propagate derived type info from the values continuation to the vars.
1447     ;;;
1448     (defun ir1-optimize-mv-bind (node)
1449     (declare (type mv-combination node))
1450     (let ((arg (first (basic-combination-args node)))
1451     (vars (lambda-vars (combination-lambda node))))
1452     (multiple-value-bind (types nvals)
1453     (values-types (continuation-derived-type arg))
1454     (unless (eq nvals :unknown)
1455     (mapc #'(lambda (var type)
1456     (if (basic-var-sets var)
1457     (propagate-from-sets var type)
1458     (propagate-to-refs var type)))
1459     vars
1460     (append types
1461     (make-list (max (- (length vars) nvals) 0)
1462     :initial-element *null-type*)))))
1463    
1464     (setf (continuation-reoptimize arg) nil))
1465 wlott 1.1 (undefined-value))
1466 ram 1.19
1467    
1468 ram 1.21 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1469 ram 1.19 ;;;
1470 ram 1.21 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1471     ;;; if:
1472 ram 1.22 ;;; -- The call has only one argument, and
1473 ram 1.21 ;;; -- The function has a known fixed number of arguments, or
1474 ram 1.22 ;;; -- The argument yields a known fixed number of values.
1475 ram 1.21 ;;;
1476     ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1477     ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1478     ;;; this call can be converted (the next time around.) This new lambda just
1479 ram 1.31 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1480     ;;; that this new MV bind is not let-converted immediately, as there are going
1481     ;;; to be stray references from the entry-point functions until they get
1482     ;;; deleted.
1483 ram 1.21 ;;;
1484     ;;; In order to avoid loss of argument count checking, we only do the
1485     ;;; transformation according to a known number of expected argument if safety
1486     ;;; is unimportant. We can always convert if we know the number of actual
1487     ;;; values, since the normal call that we build will still do any appropriate
1488     ;;; argument count checking.
1489     ;;;
1490     ;;; We only attempt the transformation if the called function is a constant
1491     ;;; reference. This allows us to just splice the leaf into the new function,
1492     ;;; instead of trying to somehow bind the function expression. The leaf must
1493     ;;; be constant because we are evaluating it again in a different place. This
1494     ;;; also has the effect of squelching multiple warnings when there is an
1495     ;;; argument count error.
1496     ;;;
1497     (defun ir1-optimize-mv-call (node)
1498     (let ((fun (basic-combination-fun node))
1499     (*compiler-error-context* node)
1500 ram 1.22 (ref (continuation-use (basic-combination-fun node)))
1501     (args (basic-combination-args node)))
1502 ram 1.21
1503 ram 1.22 (unless (and (ref-p ref) (constant-reference-p ref)
1504     args (null (rest args)))
1505 ram 1.21 (return-from ir1-optimize-mv-call))
1506    
1507     (multiple-value-bind (min max)
1508     (function-type-nargs (continuation-type fun))
1509 ram 1.22 (let ((total-nvals
1510     (multiple-value-bind
1511     (types nvals)
1512     (values-types (continuation-derived-type (first args)))
1513     (declare (ignore types))
1514     (if (eq nvals :unknown) nil nvals))))
1515 ram 1.21
1516 ram 1.22 (when total-nvals
1517     (when (and min (< total-nvals min))
1518     (compiler-warning
1519     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1520     at least ~R."
1521     total-nvals min)
1522 ram 1.50 (setf (basic-combination-kind node) :error)
1523 ram 1.22 (return-from ir1-optimize-mv-call))
1524     (when (and max (> total-nvals max))
1525     (compiler-warning
1526     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1527     at most ~R."
1528     total-nvals max)
1529 ram 1.50 (setf (basic-combination-kind node) :error)
1530 ram 1.22 (return-from ir1-optimize-mv-call)))
1531 ram 1.21
1532 ram 1.22 (let ((count (cond (total-nvals)
1533     ((and (policy node (zerop safety)) (eql min max))
1534     min)
1535     (t nil))))
1536     (when count
1537     (with-ir1-environment node
1538     (let* ((dums (loop repeat count collect (gensym)))
1539     (ignore (gensym))
1540     (fun (ir1-convert-lambda
1541     `(lambda (&optional ,@dums &rest ,ignore)
1542     (declare (ignore ,ignore))
1543     (funcall ,(ref-leaf ref) ,@dums)))))
1544     (change-ref-leaf ref fun)
1545     (assert (eq (basic-combination-kind node) :full))
1546     (local-call-analyze *current-component*)
1547 ram 1.23 (assert (eq (basic-combination-kind node) :local)))))))))
1548 ram 1.21 (undefined-value))
1549    
1550    
1551     ;;; CONVERT-MV-BIND-TO-LET -- Internal
1552     ;;;
1553 ram 1.19 ;;; If we see:
1554     ;;; (multiple-value-bind (x y)
1555     ;;; (values xx yy)
1556     ;;; ...)
1557     ;;; Convert to:
1558     ;;; (let ((x xx)
1559     ;;; (y yy))
1560     ;;; ...)
1561     ;;;
1562     ;;; What we actually do is convert the VALUES combination into a normal let
1563 ram 1.31 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1564 ram 1.19 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1565     ;;; args, insert references to NIL.
1566     ;;;
1567 ram 1.21 (defun convert-mv-bind-to-let (call)
1568     (declare (type mv-combination call))
1569     (let* ((arg (first (basic-combination-args call)))
1570     (use (continuation-use arg)))
1571     (when (and (combination-p use)
1572     (eq (continuation-function-name (combination-fun use))
1573     'values))
1574     (let* ((fun (combination-lambda call))
1575 ram 1.19 (vars (lambda-vars fun))
1576 ram 1.21 (vals (combination-args use))
1577 ram 1.19 (nvars (length vars))
1578     (nvals (length vals)))
1579     (cond ((> nvals nvars)
1580     (mapc #'flush-dest (subseq vals nvars))
1581     (setq vals (subseq vals 0 nvars)))
1582     ((< nvals nvars)
1583 ram 1.21 (with-ir1-environment use
1584     (let ((node-prev (node-prev use)))
1585     (setf (node-prev use) nil)
1586 ram 1.19 (setf (continuation-next node-prev) nil)
1587     (collect ((res vals))
1588 ram 1.21 (loop as cont = (make-continuation use)
1589 ram 1.19 and prev = node-prev then cont
1590     repeat (- nvars nvals)
1591     do (reference-constant prev cont nil)
1592     (res cont))
1593     (setq vals (res)))
1594 ram 1.21 (prev-link use (car (last vals)))))))
1595     (setf (combination-args use) vals)
1596     (flush-dest (combination-fun use))
1597     (let ((fun-cont (basic-combination-fun call)))
1598     (setf (continuation-dest fun-cont) use)
1599     (setf (combination-fun use) fun-cont))
1600     (setf (combination-kind use) :local)
1601 ram 1.19 (setf (functional-kind fun) :let)
1602 ram 1.21 (flush-dest (first (basic-combination-args call)))
1603     (unlink-node call)
1604 ram 1.19 (when vals
1605 ram 1.20 (reoptimize-continuation (first vals)))
1606 ram 1.21 (propagate-to-args use fun))
1607     t)))
1608    
1609    
1610     ;;; VALUES-LIST IR1 optimizer -- Internal
1611     ;;;
1612     ;;; If we see:
1613     ;;; (values-list (list x y z))
1614     ;;;
1615     ;;; Convert to:
1616     ;;; (values x y z)
1617     ;;;
1618     ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1619     ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1620     ;;; the old argument continuation (allowing the LIST to be flushed.)
1621     ;;;
1622     (defoptimizer (values-list optimizer) ((list) node)
1623     (let ((use (continuation-use list)))
1624     (when (and (combination-p use)
1625     (eq (continuation-function-name (combination-fun use))
1626     'list))
1627     (change-ref-leaf (continuation-use (combination-fun node))
1628     (find-free-function 'values "in a strange place"))
1629     (setf (combination-kind node) :full)
1630     (let ((args (combination-args use)))
1631     (dolist (arg args)
1632     (setf (continuation-dest arg) node))
1633     (setf (combination-args use) nil)
1634     (flush-dest list)
1635     (setf (combination-args node) args))
1636 ram 1.19 t)))
1637    
1638    
1639     ;;; VALUES IR1 transform -- Internal
1640     ;;;
1641     ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1642     ;;; PROG1. This allows the computation of the additional values to become dead
1643     ;;; code.
1644     ;;;
1645     (deftransform values ((&rest vals) * * :node node)
1646     (when (typep (continuation-dest (node-cont node))
1647     '(or creturn exit mv-combination))
1648     (give-up))
1649 ram 1.34 (setf (node-derived-type node) *wild-type*)
1650 ram 1.33 (if vals
1651     (let ((dummies (loop repeat (1- (length vals))
1652 ram 1.19 collect (gensym))))
1653 ram 1.33 `(lambda (val ,@dummies)
1654     (declare (ignore ,@dummies))
1655     val))
1656     'nil))

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