/[cmucl]/src/compiler/ir1opt.lisp
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Revision 1.46 - (hide annotations)
Thu Jun 4 17:48:53 1992 UTC (21 years, 10 months ago) by ram
Branch: MAIN
Branch point for: patch_16
Changes since 1.45: +39 -69 lines
Moved tail-set merging out of IR1-OPTIMIZE-RETURN into LTN.  Changed
MAYBE-DELETE-EXIT to call MERGE-TAIL-SETS.
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 1.46 "$Header: /tiger/var/lib/cvsroots/cmucl/src/compiler/ir1opt.lisp,v 1.46 1992/06/04 17:48:53 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    
206     ;;; Assert-Continuation-Type -- Interface
207     ;;;
208     ;;; Similar to Derive-Node-Type, but asserts that it is an error for Cont's
209     ;;; value not to be typep to Type. If we improve the assertion, we set
210 ram 1.11 ;;; TYPE-CHECK and TYPE-ASSERTED to guarantee that the new assertion will be
211     ;;; checked.
212 wlott 1.1 ;;;
213     (defun assert-continuation-type (cont type)
214     (declare (type continuation cont) (type ctype type))
215     (let ((cont-type (continuation-asserted-type cont)))
216     (unless (eq cont-type type)
217     (let ((int (values-type-intersection cont-type type)))
218     (when (type/= cont-type int)
219     (setf (continuation-asserted-type cont) int)
220     (do-uses (node cont)
221 ram 1.11 (setf (block-attributep (block-flags (node-block node))
222     type-check type-asserted)
223     t))
224 wlott 1.1 (reoptimize-continuation cont)))))
225     (undefined-value))
226    
227    
228     ;;; Assert-Call-Type -- Interface
229     ;;;
230     ;;; Assert that Call is to a function of the specified Type. It is assumed
231     ;;; that the call is legal and has only constants in the keyword positions.
232     ;;;
233     (defun assert-call-type (call type)
234     (declare (type combination call) (type function-type type))
235     (derive-node-type call (function-type-returns type))
236     (let ((args (combination-args call)))
237     (dolist (req (function-type-required type))
238     (when (null args) (return-from assert-call-type))
239     (let ((arg (pop args)))
240     (assert-continuation-type arg req)))
241     (dolist (opt (function-type-optional type))
242     (when (null args) (return-from assert-call-type))
243     (let ((arg (pop args)))
244     (assert-continuation-type arg opt)))
245    
246     (let ((rest (function-type-rest type)))
247     (when rest
248     (dolist (arg args)
249     (assert-continuation-type arg rest))))
250    
251     (dolist (key (function-type-keywords type))
252     (let ((name (key-info-name key)))
253     (do ((arg args (cddr arg)))
254     ((null arg))
255     (when (eq (continuation-value (first arg)) name)
256     (assert-continuation-type
257     (second arg) (key-info-type key)))))))
258     (undefined-value))
259    
260    
261     ;;; IR1-Optimize -- Interface
262     ;;;
263     ;;; Do one forward pass over Component, deleting unreachable blocks and
264 ram 1.11 ;;; doing IR1 optimizations. We can ignore all blocks that don't have the
265     ;;; Reoptimize flag set. If Component-Reoptimize is true when we are done,
266 wlott 1.1 ;;; then another iteration would be beneficial.
267     ;;;
268     ;;; We delete blocks when there is either no predecessor or the block is in
269     ;;; a lambda that has been deleted. These blocks would eventually be deleted
270     ;;; by DFO recomputation, but doing it here immediately makes the effect
271     ;;; avaliable to IR1 optimization.
272     ;;;
273     (defun ir1-optimize (component)
274     (declare (type component component))
275     (setf (component-reoptimize component) nil)
276     (do-blocks (block component)
277     (cond
278     ((or (block-delete-p block)
279     (null (block-pred block))
280 ram 1.11 (eq (functional-kind (block-home-lambda block)) :deleted))
281 wlott 1.1 (delete-block block))
282     (t
283     (loop
284     (let ((succ (block-succ block)))
285     (unless (and succ (null (rest succ)))
286     (return)))
287    
288     (let ((last (block-last block)))
289     (typecase last
290     (cif
291     (flush-dest (if-test last))
292     (when (unlink-node last) (return)))
293     (exit
294     (when (maybe-delete-exit last) (return)))))
295    
296     (unless (join-successor-if-possible block)
297     (return)))
298    
299 ram 1.11 (when (and (block-reoptimize block) (block-component block))
300 wlott 1.1 (assert (not (block-delete-p block)))
301     (ir1-optimize-block block))
302    
303 ram 1.11 (when (and (block-flush-p block) (block-component block))
304 wlott 1.1 (assert (not (block-delete-p block)))
305     (flush-dead-code block)))))
306    
307     (undefined-value))
308    
309    
310     ;;; IR1-Optimize-Block -- Internal
311     ;;;
312     ;;; Loop over the nodes in Block, looking for stuff that needs to be
313     ;;; optimized. We dispatch off of the type of each node with its reoptimize
314     ;;; flag set:
315     ;;; -- With a combination, we call Propagate-Function-Change whenever the
316     ;;; function changes, and call IR1-Optimize-Combination if any argument
317     ;;; changes.
318     ;;; -- With an Exit, we derive the node's type from the Value's type. We don't
319     ;;; propagate Cont's assertion to the Value, since if we did, this would
320     ;;; move the checking of Cont's assertion to the exit. This wouldn't work
321     ;;; with Catch and UWP, where the Exit node is just a placeholder for the
322     ;;; actual unknown exit.
323     ;;;
324     ;;; Note that we clear the node & block reoptimize flags *before* doing the
325     ;;; optimization. This ensures that the node or block will be reoptimized if
326 ram 1.19 ;;; necessary. We leave the NODE-OPTIMIZE flag set going into
327 wlott 1.1 ;;; IR1-OPTIMIZE-RETURN, since it wants to clear the flag itself.
328     ;;;
329     (defun ir1-optimize-block (block)
330     (declare (type cblock block))
331     (setf (block-reoptimize block) nil)
332 ram 1.19 (do-nodes (node cont block :restart-p t)
333 wlott 1.1 (when (node-reoptimize node)
334     (setf (node-reoptimize node) nil)
335     (typecase node
336     (ref)
337     (combination
338     (when (continuation-reoptimize (basic-combination-fun node))
339     (propagate-function-change node))
340 ram 1.30 (ir1-optimize-combination node)
341 ram 1.29 (unless (node-deleted node)
342 ram 1.30 (maybe-terminate-block node nil)))
343 wlott 1.1 (cif
344     (ir1-optimize-if node))
345     (creturn
346     (setf (node-reoptimize node) t)
347     (ir1-optimize-return node))
348 ram 1.6 (mv-combination
349 ram 1.21 (ir1-optimize-mv-combination node))
350 wlott 1.1 (exit
351     (let ((value (exit-value node)))
352     (when value
353     (derive-node-type node (continuation-derived-type value)))))
354     (cset
355     (ir1-optimize-set node)))))
356     (undefined-value))
357    
358    
359     ;;; Join-Successor-If-Possible -- Internal
360     ;;;
361     ;;; We cannot combine with a successor block if:
362     ;;; 1] The successor has more than one predecessor.
363     ;;; 2] The last node's Cont is also used somewhere else.
364     ;;; 3] The successor is the current block (infinite loop).
365     ;;; 4] The next block has a different cleanup, and thus we may want to insert
366     ;;; cleanup code between the two blocks at some point.
367     ;;; 5] The next block has a different home lambda, and thus the control
368     ;;; transfer is a non-local exit.
369     ;;;
370     ;;; If we succeed, we return true, otherwise false.
371     ;;;
372     ;;; Joining is easy when the successor's Start continuation is the same from
373     ;;; our Last's Cont. If they differ, then we can still join when the last
374     ;;; continuation has no next and the next continuation has no uses. In this
375 ram 1.5 ;;; case, we replace the next continuation with the last before joining the
376 wlott 1.1 ;;; blocks.
377     ;;;
378     (defun join-successor-if-possible (block)
379     (declare (type cblock block))
380     (let ((next (first (block-succ block))))
381 ram 1.11 (when (block-start next)
382 wlott 1.1 (let* ((last (block-last block))
383     (last-cont (node-cont last))
384 ram 1.11 (next-cont (block-start next)))
385 wlott 1.1 (cond ((or (rest (block-pred next))
386 ram 1.5 (not (eq (continuation-use last-cont) last))
387 wlott 1.1 (eq next block)
388 ram 1.11 (not (eq (block-end-cleanup block)
389     (block-start-cleanup next)))
390     (not (eq (block-home-lambda block)
391     (block-home-lambda next))))
392 wlott 1.1 nil)
393 ram 1.5 ((eq last-cont next-cont)
394 wlott 1.1 (join-blocks block next)
395     t)
396 ram 1.5 ((and (null (block-start-uses next))
397     (eq (continuation-kind last-cont) :inside-block))
398     (let ((next-node (continuation-next next-cont)))
399 ram 1.30 ;;
400     ;; If next-cont does have a dest, it must be unreachable,
401     ;; since there are no uses. DELETE-CONTINUATION will mark the
402     ;; dest block as delete-p [and also this block, unless it is
403     ;; no longer backward reachable from the dest block.]
404 ram 1.5 (delete-continuation next-cont)
405     (setf (node-prev next-node) last-cont)
406     (setf (continuation-next last-cont) next-node)
407     (setf (block-start next) last-cont)
408     (join-blocks block next))
409 wlott 1.1 t)
410     (t
411     nil))))))
412    
413    
414     ;;; Join-Blocks -- Internal
415     ;;;
416     ;;; Join together two blocks which have the same ending/starting
417     ;;; continuation. The code in Block2 is moved into Block1 and Block2 is
418 ram 1.11 ;;; deleted from the DFO. We combine the optimize flags for the two blocks so
419     ;;; that any indicated optimization gets done.
420 wlott 1.1 ;;;
421     (defun join-blocks (block1 block2)
422     (declare (type cblock block1 block2))
423     (let* ((last (block-last block2))
424     (last-cont (node-cont last))
425     (succ (block-succ block2))
426     (start2 (block-start block2)))
427     (do ((cont start2 (node-cont (continuation-next cont))))
428     ((eq cont last-cont)
429     (when (eq (continuation-kind last-cont) :inside-block)
430     (setf (continuation-block last-cont) block1)))
431     (setf (continuation-block cont) block1))
432    
433     (unlink-blocks block1 block2)
434     (dolist (block succ)
435     (unlink-blocks block2 block)
436     (link-blocks block1 block))
437    
438     (setf (block-last block1) last)
439     (setf (continuation-kind start2) :inside-block))
440    
441 ram 1.11 (setf (block-flags block1)
442     (attributes-union (block-flags block1)
443     (block-flags block2)
444     (block-attributes type-asserted test-modified)))
445 wlott 1.1
446     (let ((next (block-next block2))
447     (prev (block-prev block2)))
448     (setf (block-next prev) next)
449     (setf (block-prev next) prev))
450    
451     (undefined-value))
452    
453    
454     ;;;; Local call return type propagation:
455    
456     ;;; Find-Result-Type -- Internal
457     ;;;
458     ;;; This function is called on RETURN nodes that have their REOPTIMIZE flag
459     ;;; set. It iterates over the uses of the RESULT, looking for interesting
460 ram 1.46 ;;; stuff to update the TAIL-SET. If a use isn't a local call, then we union
461     ;;; its type together with the types of other such uses. We assign to the
462     ;;; RETURN-RESULT-TYPE the intersection of this type with the RESULT's asserted
463     ;;; type. We can make this intersection now (potentially before type checking)
464     ;;; because this assertion on the result will eventually be checked (if
465     ;;; appropriate.)
466 wlott 1.1 ;;;
467 ram 1.46 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV combination,
468     ;;; which may change the succesor of the call to be the called function, and if
469     ;;; so, checks if the call can become an assignment.
470     ;;;
471     (defun find-result-type (node)
472 wlott 1.1 (declare (type creturn node))
473 ram 1.46 (let ((result (return-result node)))
474 wlott 1.1 (collect ((use-union *empty-type* values-type-union))
475     (do-uses (use result)
476 ram 1.34 (cond ((and (basic-combination-p use)
477 ram 1.46 (eq (basic-combination-kind use) :local))
478     (assert (eq (lambda-tail-set (node-home-lambda use))
479     (lambda-tail-set (combination-lambda use))))
480 ram 1.39 (when (combination-p use)
481     (maybe-convert-tail-local-call use)))
482 ram 1.34 (t
483     (use-union (node-derived-type use)))))
484 wlott 1.1 (let ((int (values-type-intersection
485     (continuation-asserted-type result)
486     (use-union))))
487 ram 1.46 (setf (return-result-type node) int))))
488     (undefined-value))
489 wlott 1.1
490    
491     ;;; IR1-Optimize-Return -- Internal
492     ;;;
493     ;;; Do stuff to realize that something has changed about the value delivered
494     ;;; to a return node. Since we consider the return values of all functions in
495     ;;; the tail set to be equivalent, this amounts to bringing the entire tail set
496     ;;; up to date. We iterate over the returns for all the functions in the tail
497     ;;; set, reanalyzing them all (not treating Node specially.)
498     ;;;
499     ;;; When we are done, we check if the new type is different from the old
500     ;;; TAIL-SET-TYPE. If so, we set the type and also reoptimize all the
501     ;;; continuations for references to functions in the tail set. This will
502     ;;; cause IR1-OPTIMIZE-COMBINATION to derive the new type as the results of the
503     ;;; calls.
504     ;;;
505     (defun ir1-optimize-return (node)
506     (declare (type creturn node))
507 ram 1.46 (let* ((tails (lambda-tail-set (return-lambda node)))
508     (funs (tail-set-functions tails)))
509 wlott 1.1 (collect ((res *empty-type* values-type-union))
510 ram 1.46 (dolist (fun funs)
511     (let ((return (lambda-return fun)))
512     (when return
513     (when (node-reoptimize return)
514     (setf (node-reoptimize node) nil)
515     (find-result-type return))
516     (res (return-result-type return)))))
517 wlott 1.1
518     (when (type/= (res) (tail-set-type tails))
519     (setf (tail-set-type tails) (res))
520     (dolist (fun (tail-set-functions tails))
521     (dolist (ref (leaf-refs fun))
522     (reoptimize-continuation (node-cont ref)))))))
523    
524     (undefined-value))
525    
526    
527     ;;; IR1-Optimize-If -- Internal
528     ;;;
529     ;;; If the test has multiple uses, replicate the node when possible. Also
530     ;;; check if the predicate is known to be true or false, deleting the IF node
531     ;;; in favor of the appropriate branch when this is the case.
532     ;;;
533     (defun ir1-optimize-if (node)
534     (declare (type cif node))
535     (let ((test (if-test node))
536     (block (node-block node)))
537    
538     (when (and (eq (block-start block) test)
539     (eq (continuation-next test) node)
540     (rest (block-start-uses block)))
541     (do-uses (use test)
542     (when (immediately-used-p test use)
543     (convert-if-if use node)
544     (when (continuation-use test) (return)))))
545    
546     (let* ((type (continuation-type test))
547     (victim
548     (cond ((constant-continuation-p test)
549     (if (continuation-value test)
550     (if-alternative node)
551     (if-consequent node)))
552     ((not (types-intersect type *null-type*))
553     (if-alternative node))
554     ((type= type *null-type*)
555     (if-consequent node)))))
556     (when victim
557     (flush-dest test)
558     (when (rest (block-succ block))
559     (unlink-blocks block victim))
560     (setf (component-reanalyze (block-component (node-block node))) t)
561     (unlink-node node))))
562     (undefined-value))
563    
564    
565     ;;; Convert-If-If -- Internal
566     ;;;
567     ;;; Create a new copy of an IF Node that tests the value of the node Use.
568     ;;; The test must have >1 use, and must be immediately used by Use. Node must
569     ;;; be the only node in its block (implying that block-start = if-test).
570     ;;;
571     ;;; This optimization has an effect semantically similar to the
572     ;;; source-to-source transformation:
573     ;;; (IF (IF A B C) D E) ==>
574     ;;; (IF A (IF B D E) (IF C D E))
575     ;;;
576     (defun convert-if-if (use node)
577     (declare (type node use) (type cif node))
578     (with-ir1-environment node
579     (let* ((block (node-block node))
580     (test (if-test node))
581     (cblock (if-consequent node))
582     (ablock (if-alternative node))
583     (use-block (node-block use))
584     (dummy-cont (make-continuation))
585     (new-cont (make-continuation))
586 ram 1.11 (new-node (make-if :test new-cont
587 wlott 1.1 :consequent cblock :alternative ablock))
588     (new-block (continuation-starts-block new-cont)))
589     (prev-link new-node new-cont)
590     (setf (continuation-dest new-cont) new-node)
591     (add-continuation-use new-node dummy-cont)
592     (setf (block-last new-block) new-node)
593    
594     (unlink-blocks use-block block)
595     (delete-continuation-use use)
596     (add-continuation-use use new-cont)
597     (link-blocks use-block new-block)
598    
599     (link-blocks new-block cblock)
600     (link-blocks new-block ablock)
601    
602     (reoptimize-continuation test)
603     (reoptimize-continuation new-cont)
604     (setf (component-reanalyze *current-component*) t)))
605     (undefined-value))
606    
607    
608     ;;;; Exit IR1 optimization:
609    
610     ;;; Maybe-Delete-Exit -- Interface
611     ;;;
612     ;;; This function attempts to delete an exit node, returning true if it
613     ;;; deletes the block as a consequence:
614     ;;; -- If the exit is degenerate (has no Entry), then we don't do anything,
615     ;;; since there is nothing to be done.
616     ;;; -- If the exit node and its Entry have the same home lambda then we know
617     ;;; the exit is local, and can delete the exit. We change uses of the
618     ;;; Exit-Value to be uses of the original continuation, then unlink the
619 ram 1.46 ;;; node. If the exit is to a TR context, then we must do MERGE-TAIL-SETS
620     ;;; on any local calls which delivered their value to this exit.
621 wlott 1.1 ;;; -- If there is no value (as in a GO), then we skip the value semantics.
622     ;;;
623     ;;; This function is also called by environment analysis, since it wants all
624     ;;; exits to be optimized even if normal optimization was omitted.
625     ;;;
626     (defun maybe-delete-exit (node)
627     (declare (type exit node))
628     (let ((value (exit-value node))
629     (entry (exit-entry node))
630     (cont (node-cont node)))
631     (when (and entry
632 ram 1.11 (eq (node-home-lambda node) (node-home-lambda entry)))
633     (setf (entry-exits entry) (delete node (entry-exits entry)))
634 wlott 1.1 (prog1
635     (unlink-node node)
636     (when value
637 ram 1.46 (collect ((merges))
638     (when (return-p (continuation-dest cont))
639     (do-uses (use value)
640     (when (and (basic-combination-p use)
641     (eq (basic-combination-kind use) :local))
642     (merges use))))
643     (substitute-continuation-uses cont value)
644     (dolist (merge (merges))
645     (merge-tail-sets merge))))))))
646 wlott 1.1
647    
648     ;;;; Combination IR1 optimization:
649    
650     ;;; Ir1-Optimize-Combination -- Internal
651     ;;;
652     ;;; Do IR1 optimizations on a Combination node.
653     ;;;
654     (proclaim '(function ir1-optimize-combination (combination) void))
655     (defun ir1-optimize-combination (node)
656     (let ((args (basic-combination-args node))
657     (kind (basic-combination-kind node)))
658     (case kind
659     (:local
660     (let ((fun (combination-lambda node)))
661     (if (eq (functional-kind fun) :let)
662     (propagate-let-args node fun)
663     (propagate-local-call-args node fun))))
664     (:full
665     (dolist (arg args)
666     (when arg
667     (setf (continuation-reoptimize arg) nil))))
668     (t
669     (dolist (arg args)
670     (when arg
671     (setf (continuation-reoptimize arg) nil)))
672    
673     (let ((attr (function-info-attributes kind)))
674     (when (and (ir1-attributep attr foldable)
675     (not (ir1-attributep attr call))
676     (every #'constant-continuation-p args)
677     (continuation-dest (node-cont node)))
678     (constant-fold-call node)
679     (return-from ir1-optimize-combination)))
680 ram 1.18
681 wlott 1.1 (let ((fun (function-info-derive-type kind)))
682     (when fun
683     (let ((res (funcall fun node)))
684     (when res
685     (derive-node-type node res)))))
686 ram 1.18
687 wlott 1.1 (let ((fun (function-info-optimizer kind)))
688     (unless (and fun (funcall fun node))
689     (dolist (x (function-info-transforms kind))
690 ram 1.28 (unless (ir1-transform node x)
691 wlott 1.2 (return))))))))
692 wlott 1.1
693     (undefined-value))
694    
695    
696 ram 1.29 ;;; MAYBE-TERMINATE-BLOCK -- Interface
697     ;;;
698     ;;; If Call is to a function that doesn't return (type NIL), then terminate
699 ram 1.31 ;;; the block there, and link it to the component tail. We also change the
700     ;;; call's CONT to be a dummy continuation to prevent the use from confusing
701     ;;; things.
702 ram 1.29 ;;;
703 ram 1.30 ;;; Except when called during IR1, we delete the continuation if it has no
704     ;;; other uses. (If it does have other uses, we reoptimize.)
705     ;;;
706 ram 1.31 ;;; Termination on the basis of a continuation type assertion is inhibited
707     ;;; when:
708     ;;; -- The continuation is deleted (hence the assertion is spurious), or
709     ;;; -- We are in IR1 conversion (where THE assertions are subject to
710     ;;; weakening.)
711     ;;;
712 ram 1.30 (defun maybe-terminate-block (call ir1-p)
713 ram 1.29 (declare (type basic-combination call))
714 ram 1.32 (let* ((block (node-block call))
715     (cont (node-cont call))
716     (tail (component-tail (block-component block)))
717     (succ (first (block-succ block))))
718     (unless (or (and (eq call (block-last block)) (eq succ tail))
719     (block-delete-p block))
720     (when (or (and (eq (continuation-asserted-type cont) *empty-type*)
721     (not (or ir1-p (eq (continuation-kind cont) :deleted))))
722     (eq (node-derived-type call) *empty-type*))
723     (cond (ir1-p
724     (delete-continuation-use call)
725     (cond
726     ((block-last block)
727     (assert (and (eq (block-last block) call)
728     (eq (continuation-kind cont) :block-start))))
729     (t
730     (setf (block-last block) call)
731     (link-blocks block (continuation-starts-block cont)))))
732 ram 1.30 (t
733 ram 1.32 (node-ends-block call)
734     (delete-continuation-use call)
735     (if (eq (continuation-kind cont) :unused)
736     (delete-continuation cont)
737     (reoptimize-continuation cont))))
738    
739     (unlink-blocks block (first (block-succ block)))
740 ram 1.45 (setf (component-reanalyze (block-component block)) t)
741 ram 1.32 (assert (not (block-succ block)))
742     (link-blocks block tail)
743     (add-continuation-use call (make-continuation))
744     t))))
745 ram 1.30
746 ram 1.29
747 wlott 1.1 ;;; Recognize-Known-Call -- Interface
748     ;;;
749     ;;; If Call is a call to a known function, mark it as such by setting the
750     ;;; Kind. In addition to a direct check for the function name in the table, we
751     ;;; also must check for slot accessors. If the function is a slot accessor,
752     ;;; then we set the combination kind to the function info of %Slot-Setter or
753     ;;; %Slot-Accessor, as appropriate.
754     ;;;
755 ram 1.19 ;;; If convert-again is true, and the function has a source-transform or
756     ;;; inline-expansion, or if the function is conditional, and the destination of
757     ;;; the value is not an IF, then instead of making the existing call known, we
758     ;;; change it to be a call to a lambda that just re-calls the function. This
759     ;;; gives IR1 transformation another go at the call, in the case where the call
760     ;;; wasn't obviously known during the initial IR1 conversion.
761     ;;;
762     (defun recognize-known-call (call &optional convert-again)
763 wlott 1.1 (declare (type combination call))
764     (let* ((fun (basic-combination-fun call))
765     (name (continuation-function-name fun)))
766     (when name
767     (let ((info (info function info name)))
768 ram 1.19 (cond
769     ((and info convert-again
770     (or (info function source-transform name)
771     (info function inline-expansion name)
772     (and (ir1-attributep (function-info-attributes info)
773     predicate)
774     (let ((dest (continuation-dest (node-cont call))))
775     (and dest (not (if-p dest)))))))
776     (let ((dums (loop repeat (length (combination-args call))
777     collect (gensym))))
778     (transform-call call
779     `(lambda ,dums
780     (,name ,@dums)))))
781     (info
782     (setf (basic-combination-kind call) info))
783     ((slot-accessor-p (ref-leaf (continuation-use fun)))
784     (setf (basic-combination-kind call)
785     (info function info
786     (if (consp name)
787     '%slot-setter
788     '%slot-accessor))))))))
789 wlott 1.1 (undefined-value))
790    
791    
792     ;;; Propagate-Function-Change -- Internal
793     ;;;
794     ;;; Called by Ir1-Optimize when the function for a call has changed.
795     ;;; If the call is to a functional, then we attempt to convert it to a local
796     ;;; call, otherwise we check the call for legality with respect to the new
797     ;;; type; if it is illegal, we mark the Ref as :Notline and punt.
798     ;;;
799     ;;; If we do have a good type for the call, we propagate type information from
800     ;;; the type to the arg and result continuations. If we discover that the call
801     ;;; is to a known global function, then we mark the combination as known.
802     ;;;
803     (defun propagate-function-change (call)
804     (declare (type combination call))
805     (let* ((fun (combination-fun call))
806     (use (continuation-use fun))
807     (type (continuation-derived-type fun))
808     (*compiler-error-context* call))
809     (setf (continuation-reoptimize fun) nil)
810     (cond ((or (not (ref-p use))
811     (eq (ref-inlinep use) :notinline)))
812     ((functional-p (ref-leaf use))
813     (let ((leaf (ref-leaf use)))
814     (cond ((eq (combination-kind call) :local)
815 ram 1.34 (unless (member (functional-kind leaf)
816 ram 1.40 '(:let :assignment :deleted))
817 ram 1.34 (derive-node-type
818     call (tail-set-type (lambda-tail-set leaf)))))
819 wlott 1.1 ((not (eq (ref-inlinep use) :notinline))
820     (convert-call-if-possible use call)
821     (maybe-let-convert leaf)))))
822     ((not (function-type-p type)))
823     ((valid-function-use call type
824     :argument-test #'always-subtypep
825     :result-test #'always-subtypep
826     :error-function #'compiler-warning
827     :warning-function #'compiler-note)
828     (assert-call-type call type)
829 ram 1.19 (recognize-known-call call t))
830 wlott 1.1 (t
831     (setf (ref-inlinep use) :notinline))))
832    
833     (undefined-value))
834    
835    
836     ;;;; Known function optimization:
837    
838 ram 1.15 ;;;
839     ;;; A hashtable from combination nodes to things describing how an
840 ram 1.28 ;;; optimization of the node failed. The value is an alist (Transform . Args),
841     ;;; where Transform is the structure describing the transform that failed, and
842     ;;; Args is either a list of format arguments for the note, or the
843     ;;; FUNCTION-TYPE that would have enabled the transformation but failed to
844     ;;; match.
845 ram 1.15 ;;;
846     (defvar *failed-optimizations* (make-hash-table :test #'eq))
847    
848    
849     ;;; RECORD-OPTIMIZATION-FAILURE -- Internal
850     ;;;
851     ;;; Add a failed optimization note to *FAILED-OPTIMZATIONS* for Node, Fun
852 ram 1.28 ;;; and Args. If there is already a note for Node and Transform, replace it,
853 ram 1.15 ;;; otherwise add a new one.
854     ;;;
855 ram 1.28 (defun record-optimization-failure (node transform args)
856     (declare (type combination node) (type transform transform)
857 ram 1.15 (type (or function-type list) args))
858 ram 1.28 (let ((found (assoc transform (gethash node *failed-optimizations*))))
859 ram 1.15 (if found
860     (setf (cdr found) args)
861 ram 1.28 (push (cons transform args)
862 ram 1.15 (gethash node *failed-optimizations*))))
863     (undefined-value))
864    
865    
866 wlott 1.1 ;;; IR1-Transform -- Internal
867     ;;;
868     ;;; Attempt to transform Node using Function, subject to the call type
869     ;;; constraint Type. If we are inhibited from doing the transform for some
870     ;;; reason and Flame is true, then we make a note of the message in
871 wlott 1.2 ;;; *failed-optimizations* for IR1 finalize to pick up. We return true if
872     ;;; the transform failed, and thus further transformation should be
873     ;;; attempted. We return false if either the transform suceeded or was
874     ;;; aborted.
875 wlott 1.1 ;;;
876 ram 1.28 (defun ir1-transform (node transform)
877     (declare (type combination node) (type transform transform))
878     (let* ((type (transform-type transform))
879     (fun (transform-function transform))
880     (constrained (function-type-p type))
881 wlott 1.41 (flame
882     (if (transform-important transform)
883     (policy node (>= speed brevity))
884     (policy node (> speed brevity))))
885 ram 1.28 (*compiler-error-context* node))
886 wlott 1.1 (cond ((or (not constrained)
887 ram 1.19 (valid-function-use node type :strict-result t))
888 wlott 1.1 (multiple-value-bind
889     (severity args)
890     (catch 'give-up
891     (transform-call node (funcall fun node))
892     (values :none nil))
893     (ecase severity
894 ram 1.15 (:none
895     (remhash node *failed-optimizations*)
896     nil)
897 wlott 1.1 (:aborted
898     (setf (combination-kind node) :full)
899     (setf (ref-inlinep (continuation-use (combination-fun node)))
900     :notinline)
901     (when args
902 wlott 1.2 (apply #'compiler-warning args))
903 ram 1.15 (remhash node *failed-optimizations*)
904 wlott 1.2 nil)
905 wlott 1.1 (:failure
906 ram 1.15 (if args
907     (when flame
908 ram 1.28 (record-optimization-failure node transform args))
909 ram 1.15 (setf (gethash node *failed-optimizations*)
910 ram 1.28 (remove transform
911     (gethash node *failed-optimizations*)
912 ram 1.15 :key #'car)))
913 wlott 1.2 t))))
914 wlott 1.1 ((and flame
915     (valid-function-use node type
916     :argument-test #'types-intersect
917     :result-test #'values-types-intersect))
918 ram 1.28 (record-optimization-failure node transform type)
919 wlott 1.13 t)
920     (t
921 wlott 1.2 t))))
922 wlott 1.1
923    
924     ;;; GIVE-UP, ABORT-TRANSFORM -- Interface
925     ;;;
926     ;;; Just throw the severity and args...
927     ;;;
928     (proclaim '(function give-up (&rest t) nil))
929     (defun give-up (&rest args)
930     "This function is used to throw out of an IR1 transform, aborting this
931     attempt to transform the call, but admitting the possibility that this or
932     some other transform will later suceed. If arguments are supplied, they are
933     format arguments for an efficiency note."
934     (throw 'give-up (values :failure args)))
935     ;;;
936     (defun abort-transform (&rest args)
937     "This function is used to throw out of an IR1 transform and force a normal
938     call to the function at run time. No further optimizations will be
939     attempted."
940     (throw 'give-up (values :aborted args)))
941    
942    
943     ;;; Transform-Call -- Internal
944     ;;;
945     ;;; Take the lambda-expression Res, IR1 convert it in the proper
946     ;;; environment, and then install it as the function for the call Node. We do
947     ;;; local call analysis so that the new function is integrated into the control
948     ;;; flow. We set the Reanalyze flag in the component to cause the DFO to be
949     ;;; recomputed at soonest convenience.
950     ;;;
951     (defun transform-call (node res)
952     (declare (type combination node) (list res))
953     (with-ir1-environment node
954 ram 1.11 (let ((new-fun (ir1-convert-global-lambda res))
955 wlott 1.1 (ref (continuation-use (combination-fun node))))
956     (change-ref-leaf ref new-fun)
957     (setf (combination-kind node) :full)
958     (local-call-analyze *current-component*)))
959     (undefined-value))
960    
961    
962     ;;; Constant-Fold-Call -- Internal
963     ;;;
964     ;;; Replace a call to a foldable function of constant arguments with the
965     ;;; result of evaluating the form. We insert the resulting constant node after
966     ;;; the call, stealing the call's continuation. We give the call a
967     ;;; continuation with no Dest, which should cause it and its arguments to go
968     ;;; away. If there is an error during the evaluation, we give a warning and
969     ;;; leave the call alone, making the call a full call and marking it as
970     ;;; :notinline to make sure that it stays that way.
971     ;;;
972     ;;; For now, if the result is other than one value, we don't fold it.
973     ;;;
974     (defun constant-fold-call (call)
975     (declare (type combination call))
976     (let* ((args (mapcar #'continuation-value (combination-args call)))
977     (ref (continuation-use (combination-fun call)))
978     (fun (leaf-name (ref-leaf ref))))
979    
980     (multiple-value-bind (values win)
981     (careful-call fun args call "constant folding")
982     (cond
983     ((not win)
984     (setf (ref-inlinep ref) :notinline)
985     (setf (combination-kind call) :full))
986     ((= (length values) 1)
987     (with-ir1-environment call
988 wlott 1.37 (when (producing-fasl-file)
989     (maybe-emit-make-load-forms (first values)))
990 wlott 1.1 (let* ((leaf (find-constant (first values)))
991     (node (make-ref (leaf-type leaf)
992     leaf
993     nil))
994     (dummy (make-continuation))
995     (cont (node-cont call))
996     (block (node-block call))
997     (next (continuation-next cont)))
998     (push node (leaf-refs leaf))
999     (setf (leaf-ever-used leaf) t)
1000    
1001     (delete-continuation-use call)
1002     (add-continuation-use call dummy)
1003     (prev-link node dummy)
1004     (add-continuation-use node cont)
1005     (setf (continuation-next cont) next)
1006     (when (eq call (block-last block))
1007     (setf (block-last block) node))
1008 ram 1.19 (reoptimize-continuation cont))))
1009     (t
1010     (let ((dummies (loop repeat (length args)
1011     collect (gensym))))
1012     (transform-call
1013     call
1014     `(lambda ,dummies
1015     (declare (ignore ,@dummies))
1016     (values ,@(mapcar #'(lambda (x) `',x) values)))))))))
1017 wlott 1.1
1018     (undefined-value))
1019    
1020    
1021     ;;;; Local call optimization:
1022    
1023     ;;; Propagate-To-Refs -- Internal
1024     ;;;
1025     ;;; Propagate Type to Leaf and its Refs, marking things changed. If the
1026     ;;; leaf type is a function type, then just leave it alone, since TYPE is never
1027     ;;; going to be more specific than that (and TYPE-INTERSECTION would choke.)
1028     ;;;
1029     (defun propagate-to-refs (leaf type)
1030     (declare (type leaf leaf) (type ctype type))
1031     (let ((var-type (leaf-type leaf)))
1032     (unless (function-type-p var-type)
1033     (let ((int (type-intersection var-type type)))
1034     (when (type/= int var-type)
1035     (setf (leaf-type leaf) int)
1036     (dolist (ref (leaf-refs leaf))
1037     (derive-node-type ref int))))
1038     (undefined-value))))
1039    
1040    
1041     ;;; PROPAGATE-FROM-SETS -- Internal
1042     ;;;
1043     ;;; Figure out the type of a LET variable that has sets. We compute the
1044     ;;; union of the initial value Type and the types of all the set values and to
1045     ;;; a PROPAGATE-TO-REFS with this type.
1046     ;;;
1047     (defun propagate-from-sets (var type)
1048 ram 1.6 (collect ((res type type-union))
1049 wlott 1.1 (dolist (set (basic-var-sets var))
1050     (res (continuation-type (set-value set)))
1051     (setf (node-reoptimize set) nil))
1052     (propagate-to-refs var (res)))
1053     (undefined-value))
1054    
1055    
1056     ;;; IR1-OPTIMIZE-SET -- Internal
1057     ;;;
1058     ;;; If a let variable, find the initial value's type and do
1059     ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's type.
1060     ;;;
1061     (defun ir1-optimize-set (node)
1062     (declare (type cset node))
1063     (let ((var (set-var node)))
1064     (when (and (lambda-var-p var) (leaf-refs var))
1065     (let ((home (lambda-var-home var)))
1066     (when (eq (functional-kind home) :let)
1067     (let ((iv (let-var-initial-value var)))
1068     (setf (continuation-reoptimize iv) nil)
1069     (propagate-from-sets var (continuation-type iv)))))))
1070    
1071     (derive-node-type node (continuation-type (set-value node)))
1072     (undefined-value))
1073    
1074    
1075 ram 1.17 ;;; CONSTANT-REFERENCE-P -- Interface
1076 ram 1.7 ;;;
1077     ;;; Return true if the value of Ref will always be the same (and is thus
1078 ram 1.44 ;;; legal to substitute.) Even though the value of a FUNCTIONAL really can't
1079     ;;; change, we consider it non-constant when it is marker :NOTINLINE, since
1080     ;;; this is used as a flag to inhibit local call conversion, and must not be
1081     ;;; lost.
1082 ram 1.7 ;;;
1083     (defun constant-reference-p (ref)
1084     (declare (type ref ref))
1085     (let ((leaf (ref-leaf ref)))
1086     (typecase leaf
1087     (constant t)
1088 ram 1.44 (functional
1089     (not (eq (ref-inlinep ref) :notinline)))
1090 ram 1.7 (lambda-var
1091     (null (lambda-var-sets leaf)))
1092     (global-var
1093     (case (global-var-kind leaf)
1094     (:global-function
1095     (not (eq (ref-inlinep ref) :notinline)))
1096     (:constant t))))))
1097    
1098    
1099     ;;; SUBSTITUTE-SINGLE-USE-CONTINUATION -- Internal
1100     ;;;
1101     ;;; If we have a non-set let var with a single use, then (if possible)
1102     ;;; replace the variable reference's CONT with the arg continuation. This is
1103     ;;; inhibited when:
1104     ;;; -- CONT has other uses, or
1105     ;;; -- CONT receives multiple values, or
1106 ram 1.9 ;;; -- the reference is in a different environment from the variable, or
1107     ;;; -- either continuation has a funky TYPE-CHECK annotation.
1108 ram 1.43 ;;; -- the continuations have incompatible assertions, so the new asserted type
1109     ;;; would be NIL.
1110 ram 1.27 ;;; -- the var's DEST has a different policy than the ARG's (think safety).
1111 ram 1.7 ;;;
1112     ;;; We change the Ref to be a reference to NIL with unused value, and let it
1113     ;;; be flushed as dead code. A side-effect of this substitution is to delete
1114     ;;; the variable.
1115     ;;;
1116     (defun substitute-single-use-continuation (arg var)
1117     (declare (type continuation arg) (type lambda-var var))
1118     (let* ((ref (first (leaf-refs var)))
1119     (cont (node-cont ref))
1120 ram 1.43 (cont-atype (continuation-asserted-type cont))
1121 ram 1.7 (dest (continuation-dest cont)))
1122     (when (and (eq (continuation-use cont) ref)
1123     dest
1124     (not (typep dest '(or creturn exit mv-combination)))
1125 ram 1.11 (eq (node-home-lambda ref)
1126 ram 1.9 (lambda-home (lambda-var-home var)))
1127     (member (continuation-type-check arg) '(t nil))
1128 ram 1.27 (member (continuation-type-check cont) '(t nil))
1129 ram 1.43 (not (eq (values-type-intersection
1130     cont-atype
1131     (continuation-asserted-type arg))
1132     *empty-type*))
1133 ram 1.27 (eq (lexenv-cookie (node-lexenv dest))
1134     (lexenv-cookie (node-lexenv (continuation-dest arg)))))
1135 ram 1.25 (assert (member (continuation-kind arg)
1136     '(:block-start :deleted-block-start :inside-block)))
1137 ram 1.43 (assert-continuation-type arg cont-atype)
1138 ram 1.34 (setf (node-derived-type ref) *wild-type*)
1139 ram 1.7 (change-ref-leaf ref (find-constant nil))
1140     (substitute-continuation arg cont)
1141     (reoptimize-continuation arg)
1142     t)))
1143    
1144    
1145 ram 1.19 ;;; DELETE-LET -- Interface
1146     ;;;
1147     ;;; Delete a Let, removing the call and bind nodes, and warning about any
1148     ;;; unreferenced variables. Note that FLUSH-DEAD-CODE will come along right
1149     ;;; away and delete the REF and then the lambda, since we flush the FUN
1150     ;;; continuation.
1151     ;;;
1152     (defun delete-let (fun)
1153     (declare (type clambda fun))
1154 ram 1.42 (assert (member (functional-kind fun) '(:let :mv-let)))
1155 ram 1.19 (note-unreferenced-vars fun)
1156     (let ((call (let-combination fun)))
1157 ram 1.42 (flush-dest (basic-combination-fun call))
1158 ram 1.19 (unlink-node call)
1159     (unlink-node (lambda-bind fun))
1160     (setf (lambda-bind fun) nil))
1161     (undefined-value))
1162    
1163    
1164 wlott 1.1 ;;; Propagate-Let-Args -- Internal
1165     ;;;
1166     ;;; This function is called when one of the arguments to a LET changes. We
1167     ;;; look at each changed argument. If the corresponding variable is set, then
1168     ;;; we call PROPAGATE-FROM-SETS. Otherwise, we consider substituting for the
1169     ;;; variable, and also propagate derived-type information for the arg to all
1170     ;;; the Var's refs.
1171     ;;;
1172 ram 1.16 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1173     ;;; subtype of the argument's asserted type. This prevents type checking from
1174     ;;; being defeated, and also ensures that the best representation for the
1175     ;;; variable can be used.
1176 wlott 1.1 ;;;
1177 ram 1.26 ;;; Substitution of individual references is inhibited if the reference is
1178     ;;; in a different component from the home. This can only happen with closures
1179     ;;; over top-level lambda vars. In such cases, the references may have already
1180     ;;; been compiled, and thus can't be retroactively modified.
1181     ;;;
1182 ram 1.19 ;;; If all of the variables are deleted (have no references) when we are
1183     ;;; done, then we delete the let.
1184     ;;;
1185 wlott 1.1 ;;; Note that we are responsible for clearing the Continuation-Reoptimize
1186     ;;; flags.
1187     ;;;
1188     (defun propagate-let-args (call fun)
1189     (declare (type combination call) (type clambda fun))
1190 ram 1.19 (loop for arg in (combination-args call)
1191     and var in (lambda-vars fun) do
1192     (when (and arg (continuation-reoptimize arg))
1193     (setf (continuation-reoptimize arg) nil)
1194     (cond
1195     ((lambda-var-sets var)
1196     (propagate-from-sets var (continuation-type arg)))
1197     ((let ((use (continuation-use arg)))
1198     (when (ref-p use)
1199     (let ((leaf (ref-leaf use)))
1200     (when (and (constant-reference-p use)
1201     (values-subtypep (leaf-type leaf)
1202     (continuation-asserted-type arg)))
1203     (propagate-to-refs var (continuation-type arg))
1204 ram 1.26 (let ((this-comp (block-component (node-block use))))
1205     (substitute-leaf-if
1206     #'(lambda (ref)
1207     (cond ((eq (block-component (node-block ref))
1208     this-comp)
1209     t)
1210     (t
1211     (assert (eq (functional-kind (lambda-home fun))
1212     :top-level))
1213     nil)))
1214     leaf var))
1215 ram 1.19 t)))))
1216     ((and (null (rest (leaf-refs var)))
1217     (substitute-single-use-continuation arg var)))
1218     (t
1219     (propagate-to-refs var (continuation-type arg))))))
1220    
1221     (when (every #'null (combination-args call))
1222     (delete-let fun))
1223    
1224 wlott 1.1 (undefined-value))
1225    
1226    
1227     ;;; Propagate-Local-Call-Args -- Internal
1228     ;;;
1229     ;;; This function is called when one of the args to a non-let local call
1230     ;;; changes. For each changed argument corresponding to an unset variable, we
1231     ;;; compute the union of the types across all calls and propagate this type
1232     ;;; information to the var's refs.
1233     ;;;
1234     ;;; If the function has an XEP, then we don't do anything, since we won't
1235     ;;; discover anything.
1236     ;;;
1237     ;;; We can clear the Continuation-Reoptimize flags for arguments in all calls
1238     ;;; corresponding to changed arguments in Call, since the only use in IR1
1239     ;;; optimization of the Reoptimize flag for local call args is right here.
1240     ;;;
1241     (defun propagate-local-call-args (call fun)
1242     (declare (type combination call) (type clambda fun))
1243    
1244     (unless (functional-entry-function fun)
1245     (let* ((vars (lambda-vars fun))
1246     (union (mapcar #'(lambda (arg var)
1247     (when (and arg
1248     (continuation-reoptimize arg)
1249     (null (basic-var-sets var)))
1250     (continuation-type arg)))
1251     (basic-combination-args call)
1252     vars))
1253     (this-ref (continuation-use (basic-combination-fun call))))
1254    
1255     (dolist (arg (basic-combination-args call))
1256     (when arg
1257     (setf (continuation-reoptimize arg) nil)))
1258    
1259     (dolist (ref (leaf-refs fun))
1260     (unless (eq ref this-ref)
1261     (setq union
1262     (mapcar #'(lambda (this-arg old)
1263     (when old
1264     (setf (continuation-reoptimize this-arg) nil)
1265     (type-union (continuation-type this-arg) old)))
1266     (basic-combination-args
1267     (continuation-dest (node-cont ref)))
1268     union))))
1269    
1270     (mapc #'(lambda (var type)
1271     (when type
1272     (propagate-to-refs var type)))
1273     vars union)))
1274    
1275 ram 1.6 (undefined-value))
1276    
1277    
1278 ram 1.19 ;;;; Multiple values optimization:
1279    
1280 ram 1.21 ;;; IR1-OPTIMIZE-MV-COMBINATION -- Internal
1281     ;;;
1282 ram 1.32 ;;; Do stuff to notice a change to a MV combination node. There are two
1283     ;;; main branches here:
1284     ;;; -- If the call is local, then it is already a MV let, or should become one.
1285     ;;; Note that although all :LOCAL MV calls must eventually be converted to
1286     ;;; :MV-LETs, there can be a window when the call is local, but has not
1287     ;;; been let converted yet. This is because the entry-point lambdas may
1288     ;;; have stray references (in other entry points) that have not been
1289     ;;; deleted yet.
1290     ;;; -- The call is full. This case is somewhat similar to the non-MV
1291     ;;; combination optimization: we propagate return type information and
1292     ;;; notice non-returning calls. We also have an optimization
1293     ;;; which tries to convert MV-CALLs into MV-binds.
1294 ram 1.21 ;;;
1295     (defun ir1-optimize-mv-combination (node)
1296 ram 1.31 (cond
1297     ((eq (basic-combination-kind node) :local)
1298     (let ((fun (basic-combination-fun node)))
1299     (when (continuation-reoptimize fun)
1300     (setf (continuation-reoptimize fun) nil)
1301     (maybe-let-convert (combination-lambda node))))
1302     (setf (continuation-reoptimize (first (basic-combination-args node))) nil)
1303 ram 1.32 (when (eq (functional-kind (combination-lambda node)) :mv-let)
1304     (unless (convert-mv-bind-to-let node)
1305     (ir1-optimize-mv-bind node))))
1306 ram 1.31 (t
1307     (let* ((fun (basic-combination-fun node))
1308     (fun-changed (continuation-reoptimize fun))
1309     (args (basic-combination-args node)))
1310     (when fun-changed
1311     (setf (continuation-reoptimize fun) nil)
1312     (let ((type (continuation-type fun)))
1313     (when (function-type-p type)
1314     (derive-node-type node (function-type-returns type))))
1315     (maybe-terminate-block node nil)
1316     (let ((use (continuation-use fun)))
1317     (when (and (ref-p use) (functional-p (ref-leaf use))
1318     (not (eq (ref-inlinep use) :notinline)))
1319     (convert-call-if-possible use node)
1320     (maybe-let-convert (ref-leaf use)))))
1321     (unless (or (eq (basic-combination-kind node) :local)
1322     (eq (continuation-function-name fun) '%throw))
1323     (ir1-optimize-mv-call node))
1324     (dolist (arg args)
1325     (setf (continuation-reoptimize arg) nil)))))
1326 ram 1.21 (undefined-value))
1327    
1328    
1329 ram 1.6 ;;; IR1-OPTIMIZE-MV-BIND -- Internal
1330     ;;;
1331     ;;; Propagate derived type info from the values continuation to the vars.
1332     ;;;
1333     (defun ir1-optimize-mv-bind (node)
1334     (declare (type mv-combination node))
1335     (let ((arg (first (basic-combination-args node)))
1336     (vars (lambda-vars (combination-lambda node))))
1337     (multiple-value-bind (types nvals)
1338     (values-types (continuation-derived-type arg))
1339     (unless (eq nvals :unknown)
1340     (mapc #'(lambda (var type)
1341     (if (basic-var-sets var)
1342     (propagate-from-sets var type)
1343     (propagate-to-refs var type)))
1344     vars
1345     (append types
1346     (make-list (max (- (length vars) nvals) 0)
1347     :initial-element *null-type*)))))
1348    
1349     (setf (continuation-reoptimize arg) nil))
1350 wlott 1.1 (undefined-value))
1351 ram 1.19
1352    
1353 ram 1.21 ;;; IR1-OPTIMIZE-MV-CALL -- Internal
1354 ram 1.19 ;;;
1355 ram 1.21 ;;; If possible, convert a general MV call to an MV-BIND. We can do this
1356     ;;; if:
1357 ram 1.22 ;;; -- The call has only one argument, and
1358 ram 1.21 ;;; -- The function has a known fixed number of arguments, or
1359 ram 1.22 ;;; -- The argument yields a known fixed number of values.
1360 ram 1.21 ;;;
1361     ;;; What we do is change the function in the MV-CALL to be a lambda that "looks
1362     ;;; like an MV bind", which allows IR1-OPTIMIZE-MV-COMBINATION to notice that
1363     ;;; this call can be converted (the next time around.) This new lambda just
1364 ram 1.31 ;;; calls the actual function with the MV-BIND variables as arguments. Note
1365     ;;; that this new MV bind is not let-converted immediately, as there are going
1366     ;;; to be stray references from the entry-point functions until they get
1367     ;;; deleted.
1368 ram 1.21 ;;;
1369     ;;; In order to avoid loss of argument count checking, we only do the
1370     ;;; transformation according to a known number of expected argument if safety
1371     ;;; is unimportant. We can always convert if we know the number of actual
1372     ;;; values, since the normal call that we build will still do any appropriate
1373     ;;; argument count checking.
1374     ;;;
1375     ;;; We only attempt the transformation if the called function is a constant
1376     ;;; reference. This allows us to just splice the leaf into the new function,
1377     ;;; instead of trying to somehow bind the function expression. The leaf must
1378     ;;; be constant because we are evaluating it again in a different place. This
1379     ;;; also has the effect of squelching multiple warnings when there is an
1380     ;;; argument count error.
1381     ;;;
1382     (defun ir1-optimize-mv-call (node)
1383     (let ((fun (basic-combination-fun node))
1384     (*compiler-error-context* node)
1385 ram 1.22 (ref (continuation-use (basic-combination-fun node)))
1386     (args (basic-combination-args node)))
1387 ram 1.21
1388 ram 1.22 (unless (and (ref-p ref) (constant-reference-p ref)
1389     args (null (rest args)))
1390 ram 1.21 (return-from ir1-optimize-mv-call))
1391    
1392     (multiple-value-bind (min max)
1393     (function-type-nargs (continuation-type fun))
1394 ram 1.22 (let ((total-nvals
1395     (multiple-value-bind
1396     (types nvals)
1397     (values-types (continuation-derived-type (first args)))
1398     (declare (ignore types))
1399     (if (eq nvals :unknown) nil nvals))))
1400 ram 1.21
1401 ram 1.22 (when total-nvals
1402     (when (and min (< total-nvals min))
1403     (compiler-warning
1404     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1405     at least ~R."
1406     total-nvals min)
1407     (setf (ref-inlinep ref) :notinline)
1408     (return-from ir1-optimize-mv-call))
1409     (when (and max (> total-nvals max))
1410     (compiler-warning
1411     "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1412     at most ~R."
1413     total-nvals max)
1414     (setf (ref-inlinep ref) :notinline)
1415     (return-from ir1-optimize-mv-call)))
1416 ram 1.21
1417 ram 1.22 (let ((count (cond (total-nvals)
1418     ((and (policy node (zerop safety)) (eql min max))
1419     min)
1420     (t nil))))
1421     (when count
1422     (with-ir1-environment node
1423     (let* ((dums (loop repeat count collect (gensym)))
1424     (ignore (gensym))
1425     (fun (ir1-convert-lambda
1426     `(lambda (&optional ,@dums &rest ,ignore)
1427     (declare (ignore ,ignore))
1428     (funcall ,(ref-leaf ref) ,@dums)))))
1429     (change-ref-leaf ref fun)
1430     (assert (eq (basic-combination-kind node) :full))
1431     (local-call-analyze *current-component*)
1432 ram 1.23 (assert (eq (basic-combination-kind node) :local)))))))))
1433 ram 1.21 (undefined-value))
1434    
1435    
1436     ;;; CONVERT-MV-BIND-TO-LET -- Internal
1437     ;;;
1438 ram 1.19 ;;; If we see:
1439     ;;; (multiple-value-bind (x y)
1440     ;;; (values xx yy)
1441     ;;; ...)
1442     ;;; Convert to:
1443     ;;; (let ((x xx)
1444     ;;; (y yy))
1445     ;;; ...)
1446     ;;;
1447     ;;; What we actually do is convert the VALUES combination into a normal let
1448 ram 1.31 ;;; combination calling the original :MV-LET lambda. If there are extra args to
1449 ram 1.19 ;;; VALUES, discard the corresponding continuations. If there are insufficient
1450     ;;; args, insert references to NIL.
1451     ;;;
1452 ram 1.21 (defun convert-mv-bind-to-let (call)
1453     (declare (type mv-combination call))
1454     (let* ((arg (first (basic-combination-args call)))
1455     (use (continuation-use arg)))
1456     (when (and (combination-p use)
1457     (eq (continuation-function-name (combination-fun use))
1458     'values))
1459     (let* ((fun (combination-lambda call))
1460 ram 1.19 (vars (lambda-vars fun))
1461 ram 1.21 (vals (combination-args use))
1462 ram 1.19 (nvars (length vars))
1463     (nvals (length vals)))
1464     (cond ((> nvals nvars)
1465     (mapc #'flush-dest (subseq vals nvars))
1466     (setq vals (subseq vals 0 nvars)))
1467     ((< nvals nvars)
1468 ram 1.21 (with-ir1-environment use
1469     (let ((node-prev (node-prev use)))
1470     (setf (node-prev use) nil)
1471 ram 1.19 (setf (continuation-next node-prev) nil)
1472     (collect ((res vals))
1473 ram 1.21 (loop as cont = (make-continuation use)
1474 ram 1.19 and prev = node-prev then cont
1475     repeat (- nvars nvals)
1476     do (reference-constant prev cont nil)
1477     (res cont))
1478     (setq vals (res)))
1479 ram 1.21 (prev-link use (car (last vals)))))))
1480     (setf (combination-args use) vals)
1481     (flush-dest (combination-fun use))
1482     (let ((fun-cont (basic-combination-fun call)))
1483     (setf (continuation-dest fun-cont) use)
1484     (setf (combination-fun use) fun-cont))
1485     (setf (combination-kind use) :local)
1486 ram 1.19 (setf (functional-kind fun) :let)
1487 ram 1.21 (flush-dest (first (basic-combination-args call)))
1488     (unlink-node call)
1489 ram 1.19 (when vals
1490 ram 1.20 (reoptimize-continuation (first vals)))
1491 ram 1.21 (propagate-to-args use fun))
1492     t)))
1493    
1494    
1495     ;;; VALUES-LIST IR1 optimizer -- Internal
1496     ;;;
1497     ;;; If we see:
1498     ;;; (values-list (list x y z))
1499     ;;;
1500     ;;; Convert to:
1501     ;;; (values x y z)
1502     ;;;
1503     ;;; In implementation, this is somewhat similar to CONVERT-MV-BIND-TO-LET. We
1504     ;;; grab the args of LIST and make them args of the VALUES-LIST call, flushing
1505     ;;; the old argument continuation (allowing the LIST to be flushed.)
1506     ;;;
1507     (defoptimizer (values-list optimizer) ((list) node)
1508     (let ((use (continuation-use list)))
1509     (when (and (combination-p use)
1510     (eq (continuation-function-name (combination-fun use))
1511     'list))
1512     (change-ref-leaf (continuation-use (combination-fun node))
1513     (find-free-function 'values "in a strange place"))
1514     (setf (combination-kind node) :full)
1515     (let ((args (combination-args use)))
1516     (dolist (arg args)
1517     (setf (continuation-dest arg) node))
1518     (setf (combination-args use) nil)
1519     (flush-dest list)
1520     (setf (combination-args node) args))
1521 ram 1.19 t)))
1522    
1523    
1524     ;;; VALUES IR1 transform -- Internal
1525     ;;;
1526     ;;; If VALUES appears in a non-MV context, then effectively convert it to a
1527     ;;; PROG1. This allows the computation of the additional values to become dead
1528     ;;; code.
1529     ;;;
1530     (deftransform values ((&rest vals) * * :node node)
1531     (when (typep (continuation-dest (node-cont node))
1532     '(or creturn exit mv-combination))
1533     (give-up))
1534 ram 1.34 (setf (node-derived-type node) *wild-type*)
1535 ram 1.33 (if vals
1536     (let ((dummies (loop repeat (1- (length vals))
1537 ram 1.19 collect (gensym))))
1538 ram 1.33 `(lambda (val ,@dummies)
1539     (declare (ignore ,@dummies))
1540     val))
1541     'nil))
1542 wlott 1.1
1543    
1544     ;;; Flush-Dead-Code -- Internal
1545     ;;;
1546     ;;; Delete any nodes in Block whose value is unused and have no
1547     ;;; side-effects. We can delete sets of lexical variables when the set
1548     ;;; variable has no references.
1549     ;;;
1550     ;;; [### For now, don't delete potentially flushable calls when they have the
1551     ;;; Call attribute. Someday we should look at the funcitonal args to determine
1552     ;;; if they have any side-effects.]
1553     ;;;
1554     (defun flush-dead-code (block)
1555     (declare (type cblock block))
1556     (do-nodes-backwards (node cont block)
1557     (unless (continuation-dest cont)
1558     (typecase node
1559     (ref
1560     (delete-ref node)
1561     (unlink-node node))
1562     (combination
1563     (let ((info (combination-kind node)))
1564     (when (function-info-p info)
1565     (let ((attr (function-info-attributes info)))
1566     (when (and (ir1-attributep attr flushable)
1567     (not (ir1-attributep attr call)))
1568     (flush-dest (combination-fun node))
1569     (dolist (arg (combination-args node))
1570     (flush-dest arg))
1571     (unlink-node node))))))
1572 ram 1.42 (mv-combination
1573     (when (eq (basic-combination-kind node) :local)
1574     (let ((fun (combination-lambda node)))
1575     (when (dolist (var (lambda-vars fun) t)
1576     (when (or (leaf-refs var)
1577     (lambda-var-sets var))
1578     (return nil)))
1579     (flush-dest (first (basic-combination-args node)))
1580     (delete-let fun)))))
1581 wlott 1.1 (exit
1582     (let ((value (exit-value node)))
1583     (when value
1584     (flush-dest value)
1585     (setf (exit-value node) nil))))
1586     (cset
1587     (let ((var (set-var node)))
1588     (when (and (lambda-var-p var)
1589     (null (leaf-refs var)))
1590     (flush-dest (set-value node))
1591     (setf (basic-var-sets var)
1592     (delete node (basic-var-sets var)))
1593     (unlink-node node)))))))
1594    
1595     (setf (block-flush-p block) nil)
1596     (undefined-value))

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