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) ())
73 (setf (component-new-functions new)
74 (nconc (component-new-functions old) (component-new-functions new)))
75 (setf (component-new-functions old) ())
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 (block-home-lambda block)))
123 (if (eq (functional-kind home) :deleted)
125 (let* ((bind-block (node-block (lambda-bind home)))
126 (home-component (block-component bind-block)))
127 (cond ((eq (component-kind home-component) :initial)
128 (dfo-walk-call-graph home component))
129 ((eq home-component component)
132 (join-components home-component component)
135 ;;; This is somewhat similar to FIND-DFO-AUX, except that it merges
136 ;;; the current component with any strange component, rather than the
137 ;;; other way around. This is more efficient in the common case where
138 ;;; the current component doesn't have much stuff in it.
140 ;;; We return the current component as a result, allowing the caller
141 ;;; to detect when the old current component has been merged with
144 ;;; We walk blocks in initial components as though they were already
145 ;;; in the current component, moving them to the current component in
146 ;;; the process. The blocks are inserted at the head of the current
148 (defun find-initial-dfo-aux (block component)
149 (declare (type cblock block) (type component component))
150 (let ((this (block-component block)))
152 ((not (or (eq this component)
153 (eq (component-kind this) :initial)))
154 (join-components this component)
156 ((block-flag block) component)
158 (setf (block-flag block) t)
159 (let ((current (walk-home-call-graph block component)))
160 (dolist (succ (block-succ block))
161 (setq current (find-initial-dfo-aux succ current)))
163 (remove-from-dfo block)
164 (add-to-dfo block (component-head current))
167 ;;; Return a list of all the home lambdas that reference FUN (may
168 ;;; contain duplications).
170 ;;; References to functions which local call analysis could not (or
171 ;;; were chosen not) to local call convert will appear as references
172 ;;; to XEP lambdas. We can ignore references to XEPs that appear in
173 ;;; :TOP-LEVEL components, since environment analysis goes to special
174 ;;; effort to allow closing over of values from a separate top-level
175 ;;; component. (And now that HAS-EXTERNAL-REFERENCES-P-ness
176 ;;; generalizes :TOP-LEVEL-ness, we ignore those too.) All other
177 ;;; references must cause components to be joined.
179 ;;; References in deleted functions are also ignored, since this code
180 ;;; will be deleted eventually.
181 (defun find-reference-functions (fun)
183 (dolist (ref (leaf-refs fun))
184 (let* ((home (node-home-lambda ref))
185 (home-kind (functional-kind home))
186 (home-externally-visible-p
187 (or (eq home-kind :top-level)
188 (functional-has-external-references-p home))))
189 (unless (or (and home-externally-visible-p
190 (eq (functional-kind fun) :external))
191 (eq home-kind :deleted))
195 ;;; Move the code for FUN and all functions called by it into
196 ;;; COMPONENT. If FUN is already in COMPONENT, then we just return
199 ;;; If the function is in an initial component, then we move its head
200 ;;; and tail to COMPONENT and add it to COMPONENT's lambdas. It is
201 ;;; harmless to move the tail (even though the return might be
202 ;;; unreachable) because if the return is unreachable it (and its
203 ;;; successor link) will be deleted in the post-deletion pass.
205 ;;; We then do a FIND-DFO-AUX starting at the head of FUN. If this
206 ;;; flow-graph walk encounters another component (which can only
207 ;;; happen due to a non-local exit), then we move code into that
208 ;;; component instead. We then recurse on all functions called from
209 ;;; FUN, moving code into whichever component the preceding call
212 ;;; If FUN is in the initial component, but the BLOCK-FLAG is set in
213 ;;; the bind block, then we just return COMPONENT, since we must have
214 ;;; already reached this function in the current walk (or the
215 ;;; component would have been changed).
217 ;;; If the function is an XEP, then we also walk all functions that
218 ;;; contain references to the XEP. This is done so that environment
219 ;;; analysis doesn't need to cross component boundaries. This also
220 ;;; ensures that conversion of a full call to a local call won't
221 ;;; result in a need to join components, since the components will
223 (defun dfo-walk-call-graph (fun component)
224 (declare (type clambda fun) (type component component))
225 (let* ((bind-block (node-block (lambda-bind fun)))
226 (this (block-component bind-block))
227 (return (lambda-return fun)))
229 ((eq this component) component)
230 ((not (eq (component-kind this) :initial))
231 (join-components this component)
233 ((block-flag bind-block)
236 (push fun (component-lambdas component))
237 (setf (component-lambdas this)
238 (delete fun (component-lambdas this)))
239 (link-blocks (component-head component) bind-block)
240 (unlink-blocks (component-head this) bind-block)
242 (let ((return-block (node-block return)))
243 (link-blocks return-block (component-tail component))
244 (unlink-blocks return-block (component-tail this))))
245 (let ((calls (if (eq (functional-kind fun) :external)
246 (append (find-reference-functions fun)
248 (lambda-calls fun))))
249 (do ((res (find-initial-dfo-aux bind-block component)
250 (dfo-walk-call-graph (first funs) res))
251 (funs calls (rest funs)))
253 (declare (type component res))))))))
255 ;;; Return true if FUN is either an XEP or has EXITS to some of its
257 (defun has-xep-or-nlx (fun)
258 (declare (type clambda fun))
259 (or (eq (functional-kind fun) :external)
260 (let ((entries (lambda-entries fun)))
262 (find-if #'entry-exits entries)))))
264 ;;; Compute the result of FIND-INITIAL-DFO given the list of all
265 ;;; resulting components. Components with a :TOP-LEVEL lambda, but no
266 ;;; normal XEPs or potential non-local exits are marked as :TOP-LEVEL.
267 ;;; If there is a :TOP-LEVEL lambda, and also a normal XEP, then we
268 ;;; treat the component as normal, but also return such components in
269 ;;; a list as the third value. Components with no entry of any sort
271 (defun find-top-level-components (components)
272 (declare (list components))
276 (dolist (com components)
277 (unless (eq (block-next (component-head com)) (component-tail com))
278 (let* ((funs (component-lambdas com))
279 (has-top (find :top-level funs :key #'functional-kind))
280 (has-external-references
281 (some #'functional-has-external-references-p funs)))
282 (cond (;; The FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P concept
283 ;; is newer than the rest of this function, and
284 ;; doesn't really seem to fit into its mindset. Here
285 ;; we mark components which contain such FUNCTIONs
286 ;; them as :COMPLEX-TOP-LEVEL, since they do get
287 ;; executed at run time, and since it's not valid to
288 ;; delete them just because they don't have any
289 ;; references from pure :TOP-LEVEL components. -- WHN
290 has-external-references
291 (setf (component-kind com) :complex-top-level)
294 ((or (some #'has-xep-or-nlx funs)
295 (and has-top (rest funs)))
296 (setf (component-name com) (find-component-name com))
299 (setf (component-kind com) :complex-top-level)
302 (setf (component-kind com) :top-level)
303 (setf (component-name com) "top-level form")
306 (delete-component com))))))
308 (values (real) (top) (real-top))))
310 ;;; Given a list of top-level lambdas, return three lists of
311 ;;; components representing the actual component division:
312 ;;; 1. the non-top-level components,
313 ;;; 2. and the second is the top-level components, and
314 ;;; 3. Components in [1] that also have a top-level lambda.
316 ;;; We assign the DFO for each component, and delete any unreachable
317 ;;; blocks. We assume that the Flags have already been cleared.
319 ;;; We iterate over the lambdas in each initial component, trying to
320 ;;; put each function in its own component, but joining it to an
321 ;;; existing component if we find that there are references between
322 ;;; them. Any code that is left in an initial component must be
323 ;;; unreachable, so we can delete it. Stray links to the initial
324 ;;; component tail (due NIL function terminated blocks) are moved to
325 ;;; the appropriate newc component tail.
327 ;;; When we are done, we assign DFNs and call
328 ;;; FIND-TOP-LEVEL-COMPONENTS to pull out top-level code.
329 (defun find-initial-dfo (lambdas)
330 (declare (list lambdas))
331 (collect ((components))
332 (let ((new (make-empty-component)))
333 (dolist (tll lambdas)
334 (let ((component (block-component (node-block (lambda-bind tll)))))
335 (dolist (fun (component-lambdas component))
336 (aver (member (functional-kind fun)
337 '(:optional :external :top-level nil :escape
339 (let ((res (dfo-walk-call-graph fun new)))
342 (setq new (make-empty-component)))))
343 (when (eq (component-kind component) :initial)
344 (aver (null (component-lambdas component)))
345 (let ((tail (component-tail component)))
346 (dolist (pred (block-pred tail))
347 (let ((pred-component (block-component pred)))
348 (unless (eq pred-component component)
349 (unlink-blocks pred tail)
350 (link-blocks pred (component-tail pred-component))))))
351 (delete-component component)))))
353 (dolist (com (components))
355 (declare (fixnum num))
356 (do-blocks-backwards (block com :both)
357 (setf (block-number block) (incf num)))))
359 (find-top-level-components (components))))
361 ;;; Insert the code in LAMBDA at the end of RESULT-LAMBDA.
362 (defun merge-1-tl-lambda (result-lambda lambda)
363 (declare (type clambda result-lambda lambda))
365 ;; Delete the lambda, and combine the LETs and entries.
366 (setf (functional-kind lambda) :deleted)
367 (dolist (let (lambda-lets lambda))
368 (setf (lambda-home let) result-lambda)
369 (setf (lambda-physenv let) (lambda-physenv result-lambda))
370 (push let (lambda-lets result-lambda)))
371 (setf (lambda-entries result-lambda)
372 (nconc (lambda-entries result-lambda)
373 (lambda-entries lambda)))
375 (let* ((bind (lambda-bind lambda))
376 (bind-block (node-block bind))
377 (component (block-component bind-block))
379 (block-component (node-block (lambda-bind result-lambda))))
380 (result-return-block (node-block (lambda-return result-lambda))))
382 ;; Move blocks into the new COMPONENT, and move any nodes directly
383 ;; in the old LAMBDA into the new one (with LETs implicitly moved
384 ;; by changing their home.)
385 (do-blocks (block component)
386 (do-nodes (node cont block)
387 (let ((lexenv (node-lexenv node)))
388 (when (eq (lexenv-lambda lexenv) lambda)
389 (setf (lexenv-lambda lexenv) result-lambda))))
390 (setf (block-component block) result-component))
392 ;; Splice the blocks into the new DFO, and unlink them from the
393 ;; old component head and tail. Non-return blocks that jump to the
394 ;; tail (NIL-returning calls) are switched to go to the new tail.
395 (let* ((head (component-head component))
396 (first (block-next head))
397 (tail (component-tail component))
398 (last (block-prev tail))
399 (prev (block-prev result-return-block)))
400 (setf (block-next prev) first)
401 (setf (block-prev first) prev)
402 (setf (block-next last) result-return-block)
403 (setf (block-prev result-return-block) last)
404 (dolist (succ (block-succ head))
405 (unlink-blocks head succ))
406 (dolist (pred (block-pred tail))
407 (unlink-blocks pred tail)
408 (let ((last (block-last pred)))
409 (unless (return-p last)
410 (aver (basic-combination-p last))
411 (link-blocks pred (component-tail result-component))))))
413 (let ((lambdas (component-lambdas component)))
414 (aver (and (null (rest lambdas))
415 (eq (first lambdas) lambda))))
417 ;; Switch the end of the code from the return block to the start of
419 (dolist (pred (block-pred result-return-block))
420 (unlink-blocks pred result-return-block)
421 (link-blocks pred bind-block))
424 ;; If there is a return, then delete it (making the preceding node
425 ;; the last node) and link the block to the result return. There
426 ;; is always a preceding REF NIL node in top-level lambdas.
427 (let ((return (lambda-return lambda)))
429 (let ((return-block (node-block return))
430 (result (return-result return)))
431 (setf (block-last return-block) (continuation-use result))
433 (delete-continuation result)
434 (link-blocks return-block result-return-block))))))
436 ;;; Given a non-empty list of top-level LAMBDAs, smash them into a
437 ;;; top-level lambda and component, returning these as values. We use
438 ;;; the first lambda and its component, putting the other code in that
439 ;;; component and deleting the other lambdas.
440 (defun merge-top-level-lambdas (lambdas)
441 (declare (cons lambdas))
442 (let* ((result-lambda (first lambdas))
443 (result-return (lambda-return result-lambda)))
447 ;; Make sure the result's return node starts a block so that we
448 ;; can splice code in before it.
449 (let ((prev (node-prev
451 (return-result result-return)))))
452 (when (continuation-use prev)
453 (node-ends-block (continuation-use prev)))
455 (let ((new (make-continuation)))
456 (delete-continuation-use use)
457 (add-continuation-use use new))))
459 (dolist (lambda (rest lambdas))
460 (merge-1-tl-lambda result-lambda lambda)))
462 (dolist (lambda (rest lambdas))
463 (setf (functional-entry-function lambda) nil)
466 (node-block (lambda-bind lambda)))))))
468 (values (block-component (node-block (lambda-bind result-lambda)))