1 ;;;; This file contains the code that finds the initial components and
2 ;;;; DFO, and recomputes the DFO if it is invalidated.
4 ;;;; This software is part of the SBCL system. See the README file for
7 ;;;; This software is derived from the CMU CL system, which was
8 ;;;; written at Carnegie Mellon University and released into the
9 ;;;; public domain. The software is in the public domain and is
10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
11 ;;;; files for more information.
15 ;;; Find the DFO for a component, deleting any unreached blocks and
16 ;;; merging any other components we reach. We repeatedly iterate over
17 ;;; the entry points, since new ones may show up during the walk.
18 (declaim (ftype (function (component) (values)) find-dfo))
19 (defun find-dfo (component)
20 (clear-flags component)
21 (setf (component-reanalyze component) nil)
22 (let ((head (component-head component)))
24 ((dolist (ep (block-succ head) t)
25 (unless (block-flag ep)
26 (find-dfo-aux ep head component)
30 (declare (fixnum num))
31 (do-blocks-backwards (block component :both)
32 (if (block-flag block)
33 (setf (block-number block) (incf num))
34 (setf (block-delete-p block) t)))
35 (do-blocks (block component)
36 (unless (block-flag block)
37 (delete-block block))))
40 ;;; Move all the code and entry points from OLD to NEW. The code in
41 ;;; OLD is inserted at the head of NEW. This is also called during LET
42 ;;; conversion when we are about in insert the body of a LET in a
43 ;;; different component. [A local call can be to a different component
44 ;;; before FIND-INITIAL-DFO runs.]
45 (declaim (ftype (function (component component) (values)) join-components))
46 (defun join-components (new old)
47 (aver (eq (component-kind new) (component-kind old)))
48 (let ((old-head (component-head old))
49 (old-tail (component-tail old))
50 (head (component-head new))
51 (tail (component-tail new)))
53 (do-blocks (block old)
54 (setf (block-flag block) nil)
55 (setf (block-component block) new))
57 (let ((old-next (block-next old-head))
58 (old-last (block-prev old-tail))
59 (next (block-next head)))
60 (unless (eq old-next old-tail)
61 (setf (block-next head) old-next)
62 (setf (block-prev old-next) head)
64 (setf (block-prev next) old-last)
65 (setf (block-next old-last) next))
67 (setf (block-next old-head) old-tail)
68 (setf (block-prev old-tail) old-head))
70 (setf (component-lambdas new)
71 (nconc (component-lambdas old) (component-lambdas new)))
72 (setf (component-lambdas old) nil)
73 (setf (component-new-funs new) (nconc (component-new-funs old)
74 (component-new-funs new))
75 (component-new-funs old) nil)
77 (dolist (xp (block-pred old-tail))
78 (unlink-blocks xp old-tail)
79 (link-blocks xp tail))
80 (dolist (ep (block-succ old-head))
81 (unlink-blocks old-head ep)
82 (link-blocks head ep)))
85 ;;; Do a depth-first walk from BLOCK, inserting ourself in the DFO
86 ;;; after HEAD. If we somehow find ourselves in another component,
87 ;;; then we join that component to our component.
88 (declaim (ftype (function (cblock cblock component) (values)) find-dfo-aux))
89 (defun find-dfo-aux (block head component)
90 (unless (eq (block-component block) component)
91 (join-components component (block-component block)))
93 (unless (block-flag block)
94 (setf (block-flag block) t)
95 (dolist (succ (block-succ block))
96 (find-dfo-aux succ head component))
98 (remove-from-dfo block)
99 (add-to-dfo block head))
102 ;;; This function is called on each block by FIND-INITIAL-DFO-AUX
103 ;;; before it walks the successors. It looks at the home lambda's bind
104 ;;; block to see whether that block is in some other component:
106 ;;; -- If the block is in the initial component, then do
107 ;;; DFO-WALK-CALL-GRAPH on the home function to move it
109 ;;; -- If the block is in some other component, join COMPONENT into
110 ;;; it and return that component.
111 ;;; -- If the home function is deleted, do nothing. BLOCK must
112 ;;; eventually be discovered to be unreachable as well. This can
113 ;;; happen when we have a NLX into a function with no references.
114 ;;; The escape function still has refs (in the deleted function).
116 ;;; This ensures that all the blocks in a given environment will be in
117 ;;; the same component, even when they might not seem reachable from
118 ;;; the environment entry. Consider the case of code that is only
119 ;;; reachable from a non-local exit.
120 (defun walk-home-call-graph (block component)
121 (declare (type cblock block) (type component component))
122 (let ((home-lambda (block-home-lambda block)))
123 (if (eq (functional-kind home-lambda) :deleted)
125 (let ((home-component (lambda-component home-lambda)))
126 (cond ((eq (component-kind home-component) :initial)
127 (dfo-scavenge-call-graph home-lambda component))
128 ((eq home-component component)
131 (join-components home-component component)
134 ;;; This is somewhat similar to FIND-DFO-AUX, except that it merges
135 ;;; the current component with any strange component, rather than the
136 ;;; other way around. This is more efficient in the common case where
137 ;;; the current component doesn't have much stuff in it.
139 ;;; We return the current component as a result, allowing the caller
140 ;;; to detect when the old current component has been merged with
143 ;;; We walk blocks in initial components as though they were already
144 ;;; in the current component, moving them to the current component in
145 ;;; the process. The blocks are inserted at the head of the current
147 (defun find-initial-dfo-aux (block component)
148 (declare (type cblock block) (type component component))
149 (let ((this (block-component block)))
151 ((not (or (eq this component)
152 (eq (component-kind this) :initial)))
153 (join-components this component)
155 ((block-flag block) component)
157 (setf (block-flag block) t)
158 (let ((current (walk-home-call-graph block component)))
159 (dolist (succ (block-succ block))
160 (setq current (find-initial-dfo-aux succ current)))
162 (remove-from-dfo block)
163 (add-to-dfo block (component-head current))
166 ;;; Return a list of all the home lambdas that reference FUN (may
167 ;;; contain duplications).
169 ;;; References to functions which local call analysis could not (or
170 ;;; were chosen not) to local call convert will appear as references
171 ;;; to XEP lambdas. We can ignore references to XEPs that appear in
172 ;;; :TOPLEVEL components, since environment analysis goes to special
173 ;;; effort to allow closing over of values from a separate top level
174 ;;; component. (And now that HAS-EXTERNAL-REFERENCES-P-ness
175 ;;; generalizes :TOPLEVEL-ness, we ignore those too.) All other
176 ;;; references must cause components to be joined.
178 ;;; References in deleted functions are also ignored, since this code
179 ;;; will be deleted eventually.
180 (defun find-reference-funs (fun)
182 (dolist (ref (leaf-refs fun))
183 (let* ((home (node-home-lambda ref))
184 (home-kind (functional-kind home))
185 (home-externally-visible-p
186 (or (eq home-kind :toplevel)
187 (functional-has-external-references-p home))))
188 (unless (or (and home-externally-visible-p
189 (eq (functional-kind fun) :external))
190 (eq home-kind :deleted))
194 ;;; Move the code for FUN and all functions called by it into
195 ;;; COMPONENT. If FUN is already in COMPONENT, then we just return
198 ;;; If the function is in an initial component, then we move its head
199 ;;; and tail to COMPONENT and add it to COMPONENT's lambdas. It is
200 ;;; harmless to move the tail (even though the return might be
201 ;;; unreachable) because if the return is unreachable it (and its
202 ;;; successor link) will be deleted in the post-deletion pass.
204 ;;; We then do a FIND-DFO-AUX starting at the head of FUN. If this
205 ;;; flow-graph walk encounters another component (which can only
206 ;;; happen due to a non-local exit), then we move code into that
207 ;;; component instead. We then recurse on all functions called from
208 ;;; FUN, moving code into whichever component the preceding call
211 ;;; If FUN is in the initial component, but the BLOCK-FLAG is set in
212 ;;; the bind block, then we just return COMPONENT, since we must have
213 ;;; already reached this function in the current walk (or the
214 ;;; component would have been changed).
216 ;;; If the function is an XEP, then we also walk all functions that
217 ;;; contain references to the XEP. This is done so that environment
218 ;;; analysis doesn't need to cross component boundaries. This also
219 ;;; ensures that conversion of a full call to a local call won't
220 ;;; result in a need to join components, since the components will
222 (defun dfo-scavenge-call-graph (fun component)
223 (declare (type clambda fun) (type component component))
224 (/show "entering DFO-SCAVENGE-CALL-GRAPH" fun component)
225 (let* ((bind-block (node-block (lambda-bind fun)))
226 (old-lambda-component (block-component bind-block))
227 (return (lambda-return fun)))
229 ((eq old-lambda-component component)
230 (/show "LAMBDA is already in COMPONENT")
232 ((not (eq (component-kind old-lambda-component) :initial))
233 (/show "joining COMPONENTs")
234 (join-components old-lambda-component component)
235 old-lambda-component)
236 ((block-flag bind-block)
237 (/show "do-nothing (BLOCK-FLAG BIND-BLOCK) case")
240 (/show "full scavenge case")
241 (push fun (component-lambdas component))
242 (setf (component-lambdas old-lambda-component)
243 (delete fun (component-lambdas old-lambda-component)))
244 (link-blocks (component-head component) bind-block)
245 (unlink-blocks (component-head old-lambda-component) bind-block)
247 (let ((return-block (node-block return)))
248 (link-blocks return-block (component-tail component))
249 (unlink-blocks return-block (component-tail old-lambda-component))))
251 (/show (functional-kind fun))
252 (/show (lambda-calls fun))
253 (when (eq (functional-kind fun) :external)
254 (/show (find-reference-funs fun)))
256 (let ((calls (if (eq (functional-kind fun) :external)
257 (append (find-reference-funs fun)
259 (lambda-calls fun))))
260 (do ((res (find-initial-dfo-aux bind-block component)
261 (dfo-scavenge-call-graph (first funs) res))
262 (funs calls (rest funs)))
264 (declare (type component res))))))))
266 ;;; Return true if FUN is either an XEP or has EXITS to some of its
268 (defun has-xep-or-nlx (fun)
269 (declare (type clambda fun))
270 (or (eq (functional-kind fun) :external)
271 (let ((entries (lambda-entries fun)))
273 (find-if #'entry-exits entries)))))
275 ;;; Compute the result of FIND-INITIAL-DFO given the list of all
276 ;;; resulting components. Components with a :TOPLEVEL lambda, but no
277 ;;; normal XEPs or potential non-local exits are marked as :TOPLEVEL.
278 ;;; If there is a :TOPLEVEL lambda, and also a normal XEP, then we
279 ;;; treat the component as normal, but also return such components in
280 ;;; a list as the third value. Components with no entry of any sort
282 (defun separate-toplevelish-components (components)
283 (declare (list components))
287 (dolist (component components)
288 (unless (eq (block-next (component-head component))
289 (component-tail component))
290 (let* ((funs (component-lambdas component))
291 (has-top (find :toplevel funs :key #'functional-kind))
292 (has-external-references
293 (some #'functional-has-external-references-p funs)))
294 (cond (;; The FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P concept
295 ;; is newer than the rest of this function, and
296 ;; doesn't really seem to fit into its mindset. Here
297 ;; we mark components which contain such FUNCTIONs
298 ;; them as :COMPLEX-TOPLEVEL, since they do get
299 ;; executed at run time, and since it's not valid to
300 ;; delete them just because they don't have any
301 ;; references from pure :TOPLEVEL components. -- WHN
302 has-external-references
303 (setf (component-kind component) :complex-toplevel)
305 (real-top component))
306 ((or (some #'has-xep-or-nlx funs)
307 (and has-top (rest funs)))
308 (setf (component-name component)
309 (find-component-name component))
312 (setf (component-kind component) :complex-toplevel)
313 (real-top component)))
315 (setf (component-kind component) :toplevel)
316 (setf (component-name component) "top level form")
319 (delete-component component))))))
321 (values (real) (top) (real-top))))
323 ;; COMPONENTs want strings for names, LEAF-DEBUG-NAMEs mightn't be
325 (defun component-name-from-functional-debug-name (functional)
326 (declare (type functional functional))
327 (let ((leaf-debug-name (leaf-debug-name functional)))
329 (if (stringp leaf-debug-name)
331 (debug-namify "function ~S" leaf-debug-name)))))
333 ;;; Given a list of top level lambdas, return
334 ;;; (VALUES NONTOP-COMPONENTS TOP-COMPONENTS HAIRY-TOP-COMPONENTS).
335 ;;; Each of the three values returned is a list of COMPONENTs:
336 ;;; NONTOP-COMPONENTS = non-top-level-ish COMPONENTs;
337 ;;; TOP-COMPONENTS = top-level-ish COMPONENTs;
338 ;;; HAIRY-TOP-COMPONENTS = a subset of NONTOP-COMPONENTS, those
339 ;;; elements which include a top-level-ish lambda.
341 ;;; We assign the DFO for each component, and delete any unreachable
342 ;;; blocks. We assume that the FLAGS have already been cleared.
343 (defun find-initial-dfo (toplevel-lambdas)
344 (declare (list toplevel-lambdas))
345 (/show "entering FIND-INITIAL-DFO" toplevel-lambdas)
346 (collect ((components))
347 ;; We iterate over the lambdas in each initial component, trying
348 ;; to put each function in its own component, but joining it to
349 ;; an existing component if we find that there are references
350 ;; between them. Any code that is left in an initial component
351 ;; must be unreachable, so we can delete it. Stray links to the
352 ;; initial component tail (due NIL function terminated blocks)
353 ;; are moved to the appropriate newc component tail.
354 (dolist (toplevel-lambda toplevel-lambdas)
355 (/show toplevel-lambda)
356 (let* ((block (lambda-block toplevel-lambda))
357 (old-component (block-component block))
358 (old-component-lambdas (component-lambdas old-component))
360 (/show old-component old-component-lambdas)
361 (aver (member toplevel-lambda old-component-lambdas))
362 (dolist (component-lambda old-component-lambdas)
363 (/show component-lambda)
364 (aver (member (functional-kind component-lambda)
365 '(:optional :external :toplevel nil :escape
367 (unless new-component
368 (setf new-component (make-empty-component))
369 (setf (component-name new-component)
370 ;; This isn't necessarily an ideal name for the
371 ;; component, since it might end up with multiple
372 ;; lambdas in it, not just this one, but it does
373 ;; seem a better name than just "<unknown>".
374 (component-name-from-functional-debug-name
376 (let ((res (dfo-scavenge-call-graph component-lambda new-component)))
377 (when (eq res new-component)
378 (/show "saving" new-component (component-lambdas new-component))
379 (aver (not (position new-component (components))))
380 (components new-component)
381 (setq new-component nil))))
382 (when (eq (component-kind old-component) :initial)
383 (aver (null (component-lambdas old-component)))
384 (/show "clearing/deleting OLD-COMPONENT because KIND=:INITIAL")
385 (let ((tail (component-tail old-component)))
386 (dolist (pred (block-pred tail))
387 (let ((pred-component (block-component pred)))
388 (unless (eq pred-component old-component)
389 (unlink-blocks pred tail)
390 (link-blocks pred (component-tail pred-component))))))
391 (delete-component old-component))))
393 ;; When we are done, we assign DFNs.
394 (dolist (component (components))
396 (declare (fixnum num))
397 (do-blocks-backwards (block component :both)
398 (setf (block-number block) (incf num)))))
400 ;; Pull out top-level-ish code.
401 (separate-toplevelish-components (components))))
403 ;;; Insert the code in LAMBDA at the end of RESULT-LAMBDA.
404 (defun merge-1-tl-lambda (result-lambda lambda)
405 (declare (type clambda result-lambda lambda))
407 ;; Delete the lambda, and combine the LETs and entries.
408 (setf (functional-kind lambda) :deleted)
409 (dolist (let (lambda-lets lambda))
410 (setf (lambda-home let) result-lambda)
411 (setf (lambda-physenv let) (lambda-physenv result-lambda))
412 (push let (lambda-lets result-lambda)))
413 (setf (lambda-entries result-lambda)
414 (nconc (lambda-entries result-lambda)
415 (lambda-entries lambda)))
417 (let* ((bind (lambda-bind lambda))
418 (bind-block (node-block bind))
419 (component (block-component bind-block))
420 (result-component (lambda-component result-lambda))
421 (result-return-block (node-block (lambda-return result-lambda))))
423 ;; Move blocks into the new COMPONENT, and move any nodes directly
424 ;; in the old LAMBDA into the new one (with LETs implicitly moved
425 ;; by changing their home.)
426 (do-blocks (block component)
427 (do-nodes (node cont block)
428 (let ((lexenv (node-lexenv node)))
429 (when (eq (lexenv-lambda lexenv) lambda)
430 (setf (lexenv-lambda lexenv) result-lambda))))
431 (setf (block-component block) result-component))
433 ;; Splice the blocks into the new DFO, and unlink them from the
434 ;; old component head and tail. Non-return blocks that jump to the
435 ;; tail (NIL-returning calls) are switched to go to the new tail.
436 (let* ((head (component-head component))
437 (first (block-next head))
438 (tail (component-tail component))
439 (last (block-prev tail))
440 (prev (block-prev result-return-block)))
441 (setf (block-next prev) first)
442 (setf (block-prev first) prev)
443 (setf (block-next last) result-return-block)
444 (setf (block-prev result-return-block) last)
445 (dolist (succ (block-succ head))
446 (unlink-blocks head succ))
447 (dolist (pred (block-pred tail))
448 (unlink-blocks pred tail)
449 (let ((last (block-last pred)))
450 (unless (return-p last)
451 (aver (basic-combination-p last))
452 (link-blocks pred (component-tail result-component))))))
454 (let ((lambdas (component-lambdas component)))
455 (aver (and (null (rest lambdas))
456 (eq (first lambdas) lambda))))
458 ;; Switch the end of the code from the return block to the start of
460 (dolist (pred (block-pred result-return-block))
461 (unlink-blocks pred result-return-block)
462 (link-blocks pred bind-block))
465 ;; If there is a return, then delete it (making the preceding node
466 ;; the last node) and link the block to the result return. There
467 ;; is always a preceding REF NIL node in top level lambdas.
468 (let ((return (lambda-return lambda)))
470 (let ((return-block (node-block return))
471 (result (return-result return)))
472 (setf (block-last return-block) (continuation-use result))
474 (delete-continuation result)
475 (link-blocks return-block result-return-block))))))
477 ;;; Given a non-empty list of top level LAMBDAs, smash them into a
478 ;;; top level lambda and component, returning these as values. We use
479 ;;; the first lambda and its component, putting the other code in that
480 ;;; component and deleting the other lambdas.
481 (defun merge-toplevel-lambdas (lambdas)
482 (declare (cons lambdas))
483 (let* ((result-lambda (first lambdas))
484 (result-return (lambda-return result-lambda)))
488 ;; Make sure the result's return node starts a block so that we
489 ;; can splice code in before it.
490 (let ((prev (node-prev
492 (return-result result-return)))))
493 (when (continuation-use prev)
494 (node-ends-block (continuation-use prev)))
496 (let ((new (make-continuation)))
497 (delete-continuation-use use)
498 (add-continuation-use use new))))
500 (dolist (lambda (rest lambdas))
501 (merge-1-tl-lambda result-lambda lambda)))
503 (dolist (lambda (rest lambdas))
504 (setf (functional-entry-fun lambda) nil)
505 (delete-component (lambda-component lambda)))))
507 (values (lambda-component result-lambda) result-lambda)))