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 CLAMBDA's
104 ;;; BIND block to see whether that block is in some other component:
105 ;;; -- If the block is in the initial component, then do
106 ;;; DFO-WALK-CALL-GRAPH on the home function to move it
108 ;;; -- If the block is in some other component, join COMPONENT into
109 ;;; it and return that component.
110 ;;; -- If the home function is deleted, do nothing. BLOCK must
111 ;;; eventually be discovered to be unreachable as well. This can
112 ;;; happen when we have a NLX into a function with no references.
113 ;;; The escape function still has refs (in the deleted function).
115 ;;; This ensures that all the blocks in a given environment will be in
116 ;;; the same component, even when they might not seem reachable from
117 ;;; the environment entry. Consider the case of code that is only
118 ;;; reachable from a non-local exit.
119 (defun walk-home-call-graph (block component)
120 (declare (type cblock block) (type component component))
121 (let ((home-lambda (block-home-lambda block)))
122 (if (eq (functional-kind home-lambda) :deleted)
124 (let ((home-component (lambda-component home-lambda)))
125 (cond ((eq (component-kind home-component) :initial)
126 (dfo-scavenge-call-graph home-lambda component))
127 ((eq home-component component)
130 (join-components home-component component)
133 ;;; This is somewhat similar to FIND-DFO-AUX, except that it merges
134 ;;; the current component with any strange component, rather than the
135 ;;; other way around. This is more efficient in the common case where
136 ;;; the current component doesn't have much stuff in it.
138 ;;; We return the current component as a result, allowing the caller
139 ;;; to detect when the old current component has been merged with
142 ;;; We walk blocks in initial components as though they were already
143 ;;; in the current component, moving them to the current component in
144 ;;; the process. The blocks are inserted at the head of the current
146 (defun find-initial-dfo-aux (block component)
147 (declare (type cblock block) (type component component))
148 (let ((this (block-component block)))
150 ((not (or (eq this component)
151 (eq (component-kind this) :initial)))
152 (join-components this component)
154 ((block-flag block) component)
156 (setf (block-flag block) t)
157 (let ((current (walk-home-call-graph block component)))
158 (dolist (succ (block-succ block))
159 (setq current (find-initial-dfo-aux succ current)))
161 (remove-from-dfo block)
162 (add-to-dfo block (component-head current))
165 ;;; Return a list of all the home lambdas that reference FUN (may
166 ;;; contain duplications).
168 ;;; References to functions which local call analysis could not (or
169 ;;; were chosen not) to local call convert will appear as references
170 ;;; to XEP lambdas. We can ignore references to XEPs that appear in
171 ;;; :TOPLEVEL components, since environment analysis goes to special
172 ;;; effort to allow closing over of values from a separate top level
173 ;;; component. (And now that HAS-EXTERNAL-REFERENCES-P-ness
174 ;;; generalizes :TOPLEVEL-ness, we ignore those too.) All other
175 ;;; references must cause components to be joined.
177 ;;; References in deleted functions are also ignored, since this code
178 ;;; will be deleted eventually.
179 (defun find-reference-funs (fun)
181 (dolist (ref (leaf-refs fun))
182 (let* ((home (node-home-lambda ref))
183 (home-kind (functional-kind home))
184 (home-externally-visible-p
185 (or (eq home-kind :toplevel)
186 (functional-has-external-references-p home))))
187 (unless (or (and home-externally-visible-p
188 (eq (functional-kind fun) :external))
189 (eq home-kind :deleted))
193 ;;; Move the code for FUN and all functions called by it into
194 ;;; COMPONENT. If FUN is already in COMPONENT, then we just return
197 ;;; If the function is in an initial component, then we move its head
198 ;;; and tail to COMPONENT and add it to COMPONENT's lambdas. It is
199 ;;; harmless to move the tail (even though the return might be
200 ;;; unreachable) because if the return is unreachable it (and its
201 ;;; successor link) will be deleted in the post-deletion pass.
203 ;;; We then do a FIND-DFO-AUX starting at the head of FUN. If this
204 ;;; flow-graph walk encounters another component (which can only
205 ;;; happen due to a non-local exit), then we move code into that
206 ;;; component instead. We then recurse on all functions called from
207 ;;; FUN, moving code into whichever component the preceding call
210 ;;; If FUN is in the initial component, but the BLOCK-FLAG is set in
211 ;;; the bind block, then we just return COMPONENT, since we must have
212 ;;; already reached this function in the current walk (or the
213 ;;; component would have been changed).
215 ;;; If the function is an XEP, then we also walk all functions that
216 ;;; contain references to the XEP. This is done so that environment
217 ;;; analysis doesn't need to cross component boundaries. This also
218 ;;; ensures that conversion of a full call to a local call won't
219 ;;; result in a need to join components, since the components will
221 (defun dfo-scavenge-call-graph (fun component)
222 (declare (type clambda fun) (type component component))
223 (let* ((bind-block (node-block (lambda-bind fun)))
224 (old-lambda-component (block-component bind-block))
225 (return (lambda-return fun)))
227 ((eq old-lambda-component component)
229 ((not (eq (component-kind old-lambda-component) :initial))
230 (join-components old-lambda-component component)
231 old-lambda-component)
232 ((block-flag bind-block)
235 (push fun (component-lambdas component))
236 (setf (component-lambdas old-lambda-component)
237 (delete fun (component-lambdas old-lambda-component)))
238 (link-blocks (component-head component) bind-block)
239 (unlink-blocks (component-head old-lambda-component) bind-block)
241 (let ((return-block (node-block return)))
242 (link-blocks return-block (component-tail component))
243 (unlink-blocks return-block (component-tail old-lambda-component))))
245 (let ((calls (if (eq (functional-kind fun) :external)
246 (append (find-reference-funs fun)
248 (lambda-calls fun))))
249 (do ((res (find-initial-dfo-aux bind-block component)
250 (dfo-scavenge-call-graph (first remaining-calls) res))
251 (remaining-calls calls (rest remaining-calls)))
252 ((null remaining-calls)
254 (declare (type component res))))))))
256 ;;; Return true if FUN is either an XEP or has EXITS to some of its
258 (defun has-xep-or-nlx (fun)
259 (declare (type clambda fun))
260 (or (eq (functional-kind fun) :external)
261 (let ((entries (lambda-entries fun)))
263 (find-if #'entry-exits entries)))))
265 ;;; Compute the result of FIND-INITIAL-DFO given the list of all
266 ;;; resulting components. Components with a :TOPLEVEL lambda, but no
267 ;;; normal XEPs or potential non-local exits are marked as :TOPLEVEL.
268 ;;; If there is a :TOPLEVEL lambda, and also a normal XEP, then we
269 ;;; treat the component as normal, but also return such components in
270 ;;; a list as the third value. Components with no entry of any sort
272 (defun separate-toplevelish-components (components)
273 (declare (list components))
277 (dolist (component components)
278 (unless (eq (block-next (component-head component))
279 (component-tail component))
280 (let* ((funs (component-lambdas component))
281 (has-top (find :toplevel funs :key #'functional-kind))
282 (has-external-references
283 (some #'functional-has-external-references-p funs)))
284 (cond (;; The FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P concept
285 ;; is newer than the rest of this function, and
286 ;; doesn't really seem to fit into its mindset. Here
287 ;; we mark components which contain such FUNCTIONs
288 ;; them as :COMPLEX-TOPLEVEL, since they do get
289 ;; executed at run time, and since it's not valid to
290 ;; delete them just because they don't have any
291 ;; references from pure :TOPLEVEL components. -- WHN
292 has-external-references
293 (setf (component-kind component) :complex-toplevel)
295 (real-top component))
296 ((or (some #'has-xep-or-nlx funs)
297 (and has-top (rest funs)))
298 (setf (component-name component)
299 (find-component-name component))
302 (setf (component-kind component) :complex-toplevel)
303 (real-top component)))
305 (setf (component-kind component) :toplevel)
306 (setf (component-name component) "top level form")
309 (delete-component component))))))
311 (values (real) (top) (real-top))))
313 ;; COMPONENTs want strings for names, LEAF-DEBUG-NAMEs mightn't be
315 (defun component-name-from-functional-debug-name (functional)
316 (declare (type functional functional))
317 (let ((leaf-debug-name (leaf-debug-name functional)))
319 (if (stringp leaf-debug-name)
321 (debug-namify "function ~S" leaf-debug-name)))))
323 ;;; Given a list of top level lambdas, return
324 ;;; (VALUES NONTOP-COMPONENTS TOP-COMPONENTS HAIRY-TOP-COMPONENTS).
325 ;;; Each of the three values returned is a list of COMPONENTs:
326 ;;; NONTOP-COMPONENTS = non-top-level-ish COMPONENTs;
327 ;;; TOP-COMPONENTS = top-level-ish COMPONENTs;
328 ;;; HAIRY-TOP-COMPONENTS = a subset of NONTOP-COMPONENTS, those
329 ;;; elements which include a top-level-ish lambda.
331 ;;; We assign the DFO for each component, and delete any unreachable
332 ;;; blocks. We assume that the FLAGS have already been cleared.
333 (defun find-initial-dfo (toplevel-lambdas)
334 (declare (list toplevel-lambdas))
335 (collect ((components))
336 ;; We iterate over the lambdas in each initial component, trying
337 ;; to put each function in its own component, but joining it to
338 ;; an existing component if we find that there are references
339 ;; between them. Any code that is left in an initial component
340 ;; must be unreachable, so we can delete it. Stray links to the
341 ;; initial component tail (due NIL function terminated blocks)
342 ;; are moved to the appropriate newc component tail.
343 (dolist (toplevel-lambda toplevel-lambdas)
344 (let* ((block (lambda-block toplevel-lambda))
345 (old-component (block-component block))
346 (old-component-lambdas (component-lambdas old-component))
348 (aver (member toplevel-lambda old-component-lambdas))
349 (dolist (component-lambda old-component-lambdas)
350 (aver (member (functional-kind component-lambda)
351 '(:optional :external :toplevel nil :escape
353 (unless new-component
354 (setf new-component (make-empty-component))
355 (setf (component-name new-component)
356 ;; This isn't necessarily an ideal name for the
357 ;; component, since it might end up with multiple
358 ;; lambdas in it, not just this one, but it does
359 ;; seem a better name than just "<unknown>".
360 (component-name-from-functional-debug-name
362 (let ((res (dfo-scavenge-call-graph component-lambda new-component)))
363 (when (eq res new-component)
364 (aver (not (position new-component (components))))
365 (components new-component)
366 (setq new-component nil))))
367 (when (eq (component-kind old-component) :initial)
368 (aver (null (component-lambdas old-component)))
369 (let ((tail (component-tail old-component)))
370 (dolist (pred (block-pred tail))
371 (let ((pred-component (block-component pred)))
372 (unless (eq pred-component old-component)
373 (unlink-blocks pred tail)
374 (link-blocks pred (component-tail pred-component))))))
375 (delete-component old-component))))
377 ;; When we are done, we assign DFNs.
378 (dolist (component (components))
380 (declare (fixnum num))
381 (do-blocks-backwards (block component :both)
382 (setf (block-number block) (incf num)))))
384 ;; Pull out top-level-ish code.
385 (separate-toplevelish-components (components))))
387 ;;; Insert the code in LAMBDA at the end of RESULT-LAMBDA.
388 (defun merge-1-toplevel-lambda (result-lambda lambda)
389 (declare (type clambda result-lambda lambda))
391 ;; Delete the lambda, and combine the LETs and entries.
392 (setf (functional-kind lambda) :deleted)
393 (dolist (let (lambda-lets lambda))
394 (setf (lambda-home let) result-lambda)
395 (setf (lambda-physenv let) (lambda-physenv result-lambda))
396 (push let (lambda-lets result-lambda)))
397 (setf (lambda-entries result-lambda)
398 (nconc (lambda-entries result-lambda)
399 (lambda-entries lambda)))
401 (let* ((bind (lambda-bind lambda))
402 (bind-block (node-block bind))
403 (component (block-component bind-block))
404 (result-component (lambda-component result-lambda))
405 (result-return-block (node-block (lambda-return result-lambda))))
407 ;; Move blocks into the new COMPONENT, and move any nodes directly
408 ;; in the old LAMBDA into the new one (with LETs implicitly moved
409 ;; by changing their home.)
410 (do-blocks (block component)
411 (do-nodes (node cont block)
412 (let ((lexenv (node-lexenv node)))
413 (when (eq (lexenv-lambda lexenv) lambda)
414 (setf (lexenv-lambda lexenv) result-lambda))))
415 (setf (block-component block) result-component))
417 ;; Splice the blocks into the new DFO, and unlink them from the
418 ;; old component head and tail. Non-return blocks that jump to the
419 ;; tail (NIL-returning calls) are switched to go to the new tail.
420 (let* ((head (component-head component))
421 (first (block-next head))
422 (tail (component-tail component))
423 (last (block-prev tail))
424 (prev (block-prev result-return-block)))
425 (setf (block-next prev) first)
426 (setf (block-prev first) prev)
427 (setf (block-next last) result-return-block)
428 (setf (block-prev result-return-block) last)
429 (dolist (succ (block-succ head))
430 (unlink-blocks head succ))
431 (dolist (pred (block-pred tail))
432 (unlink-blocks pred tail)
433 (let ((last (block-last pred)))
434 (unless (return-p last)
435 (aver (basic-combination-p last))
436 (link-blocks pred (component-tail result-component))))))
438 (let ((lambdas (component-lambdas component)))
439 (aver (and (null (rest lambdas))
440 (eq (first lambdas) lambda))))
442 ;; Switch the end of the code from the return block to the start of
444 (dolist (pred (block-pred result-return-block))
445 (unlink-blocks pred result-return-block)
446 (link-blocks pred bind-block))
449 ;; If there is a return, then delete it (making the preceding node
450 ;; the last node) and link the block to the result return. There
451 ;; is always a preceding REF NIL node in top level lambdas.
452 (let ((return (lambda-return lambda)))
454 (let ((return-block (node-block return))
455 (result (return-result return)))
456 (setf (block-last return-block) (continuation-use result))
458 (delete-continuation result)
459 (link-blocks return-block result-return-block))))))
461 ;;; Given a non-empty list of top level LAMBDAs, smash them into a
462 ;;; top level lambda and component, returning these as values. We use
463 ;;; the first lambda and its component, putting the other code in that
464 ;;; component and deleting the other lambdas.
465 (defun merge-toplevel-lambdas (lambdas)
466 (declare (cons lambdas))
467 (let* ((result-lambda (first lambdas))
468 (result-return (lambda-return result-lambda)))
472 ;; Make sure the result's return node starts a block so that we
473 ;; can splice code in before it.
474 (let ((prev (node-prev
476 (return-result result-return)))))
477 (when (continuation-use prev)
478 (node-ends-block (continuation-use prev)))
480 (let ((new (make-continuation)))
481 (delete-continuation-use use)
482 (add-continuation-use use new))))
484 (dolist (lambda (rest lambdas))
485 (merge-1-toplevel-lambda result-lambda lambda)))
487 (dolist (lambda (rest lambdas))
488 (setf (functional-entry-fun lambda) nil)
489 (delete-component (lambda-component lambda)))))
491 (values (lambda-component result-lambda) result-lambda)))