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6e8ad823 AW |
1 | ;;; Continuation-passing style (CPS) intermediate language (IL) |
2 | ||
3 | ;; Copyright (C) 2013 Free Software Foundation, Inc. | |
4 | ||
5 | ;;;; This library is free software; you can redistribute it and/or | |
6 | ;;;; modify it under the terms of the GNU Lesser General Public | |
7 | ;;;; License as published by the Free Software Foundation; either | |
8 | ;;;; version 3 of the License, or (at your option) any later version. | |
9 | ;;;; | |
10 | ;;;; This library is distributed in the hope that it will be useful, | |
11 | ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | ;;;; Lesser General Public License for more details. | |
14 | ;;;; | |
15 | ;;;; You should have received a copy of the GNU Lesser General Public | |
16 | ;;;; License along with this library; if not, write to the Free Software | |
17 | ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | ||
19 | ;;; Commentary: | |
20 | ;;; | |
21 | ;;; Many passes rely on a local or global static analysis of a function. | |
22 | ;;; This module implements a simple data-flow graph (DFG) analysis, | |
23 | ;;; tracking the definitions and uses of variables and continuations. | |
f22979db | 24 | ;;; It also builds a table of continuations and scope links, to be able |
6e8ad823 AW |
25 | ;;; to easily determine if one continuation is in the scope of another, |
26 | ;;; and to get to the expression inside a continuation. | |
27 | ;;; | |
28 | ;;; Note that the data-flow graph of continuation labels is a | |
29 | ;;; control-flow graph. | |
30 | ;;; | |
31 | ;;; We currently don't expose details of the DFG type outside this | |
32 | ;;; module, preferring to only expose accessors. That may change in the | |
33 | ;;; future but it seems to work for now. | |
34 | ;;; | |
35 | ;;; Code: | |
36 | ||
37 | (define-module (language cps dfg) | |
38 | #:use-module (ice-9 match) | |
39 | #:use-module (srfi srfi-1) | |
40 | #:use-module (srfi srfi-9) | |
41 | #:use-module (srfi srfi-26) | |
42 | #:use-module (language cps) | |
43 | #:export (build-cont-table | |
44 | build-local-cont-table | |
45 | lookup-cont | |
46 | ||
47 | compute-dfg | |
48 | dfg-cont-table | |
49 | lookup-def | |
50 | lookup-uses | |
f22979db AW |
51 | lookup-predecessors |
52 | lookup-successors | |
c8ad7426 | 53 | lookup-block-scope |
6e8ad823 AW |
54 | find-call |
55 | call-expression | |
56 | find-expression | |
57 | find-defining-expression | |
58 | find-constant-value | |
f22979db | 59 | continuation-bound-in? |
d51fb1e6 | 60 | variable-free-in? |
6e8ad823 | 61 | constant-needs-allocation? |
e636f424 | 62 | control-point? |
db11440d AW |
63 | lookup-bound-syms |
64 | ||
65 | ;; Data flow analysis. | |
66 | compute-live-variables | |
67 | dfa-k-idx dfa-k-sym dfa-k-count dfa-k-in dfa-k-out | |
68 | dfa-var-idx dfa-var-name dfa-var-sym dfa-var-count | |
69 | print-dfa)) | |
6e8ad823 AW |
70 | |
71 | (define (build-cont-table fun) | |
72 | (fold-conts (lambda (k src cont table) | |
73 | (hashq-set! table k cont) | |
74 | table) | |
75 | (make-hash-table) | |
76 | fun)) | |
77 | ||
78 | (define (build-local-cont-table cont) | |
79 | (fold-local-conts (lambda (k src cont table) | |
80 | (hashq-set! table k cont) | |
81 | table) | |
82 | (make-hash-table) | |
83 | cont)) | |
84 | ||
85 | (define (lookup-cont sym conts) | |
86 | (let ((res (hashq-ref conts sym))) | |
87 | (unless res | |
88 | (error "Unknown continuation!" sym (hash-fold acons '() conts))) | |
89 | res)) | |
90 | ||
91 | ;; Data-flow graph for CPS: both for values and continuations. | |
92 | (define-record-type $dfg | |
f22979db | 93 | (make-dfg conts blocks use-maps) |
6e8ad823 | 94 | dfg? |
f22979db | 95 | ;; hash table of sym -> $kif, $kargs, etc |
6e8ad823 | 96 | (conts dfg-cont-table) |
f22979db AW |
97 | ;; hash table of sym -> $block |
98 | (blocks dfg-blocks) | |
6e8ad823 | 99 | ;; hash table of sym -> $use-map |
f22979db | 100 | (use-maps dfg-use-maps)) |
6e8ad823 AW |
101 | |
102 | (define-record-type $use-map | |
fc95a944 | 103 | (make-use-map name sym def uses) |
6e8ad823 | 104 | use-map? |
fc95a944 | 105 | (name use-map-name) |
6e8ad823 AW |
106 | (sym use-map-sym) |
107 | (def use-map-def) | |
108 | (uses use-map-uses set-use-map-uses!)) | |
109 | ||
f22979db | 110 | (define-record-type $block |
0e2446d4 AW |
111 | (%make-block scope scope-level preds succs |
112 | idom dom-level | |
113 | pdom pdom-level | |
114 | loop-header irreducible) | |
f22979db AW |
115 | block? |
116 | (scope block-scope set-block-scope!) | |
117 | (scope-level block-scope-level set-block-scope-level!) | |
118 | (preds block-preds set-block-preds!) | |
119 | (succs block-succs set-block-succs!) | |
120 | (idom block-idom set-block-idom!) | |
121 | (dom-level block-dom-level set-block-dom-level!) | |
366eb4d7 | 122 | |
0e2446d4 AW |
123 | (pdom block-pdom set-block-pdom!) |
124 | (pdom-level block-pdom-level set-block-pdom-level!) | |
125 | ||
366eb4d7 AW |
126 | ;; The loop header of this block, if this block is part of a reducible |
127 | ;; loop. Otherwise #f. | |
128 | (loop-header block-loop-header set-block-loop-header!) | |
129 | ||
130 | ;; Some sort of marker that this block is part of an irreducible | |
131 | ;; (multi-entry) loop. Otherwise #f. | |
132 | (irreducible block-irreducible set-block-irreducible!)) | |
f22979db AW |
133 | |
134 | (define (make-block scope scope-level) | |
0e2446d4 | 135 | (%make-block scope scope-level '() '() #f #f #f #f #f #f)) |
f22979db | 136 | |
0e2446d4 | 137 | (define (reverse-post-order k0 blocks accessor) |
3aee6cfd AW |
138 | (let ((order '()) |
139 | (visited? (make-hash-table))) | |
140 | (let visit ((k k0)) | |
141 | (hashq-set! visited? k #t) | |
0e2446d4 AW |
142 | (for-each (lambda (k) |
143 | (unless (hashq-ref visited? k) | |
144 | (visit k))) | |
145 | (accessor (lookup-block k blocks))) | |
146 | (set! order (cons k order))) | |
366eb4d7 | 147 | (list->vector order))) |
3aee6cfd | 148 | |
0e2446d4 | 149 | (define (convert-predecessors order blocks accessor) |
366eb4d7 AW |
150 | (let* ((mapping (make-hash-table)) |
151 | (preds-vec (make-vector (vector-length order) #f))) | |
152 | (let lp ((n 0)) | |
153 | (when (< n (vector-length order)) | |
154 | (hashq-set! mapping (vector-ref order n) n) | |
155 | (lp (1+ n)))) | |
156 | (let lp ((n 0)) | |
157 | (when (< n (vector-length order)) | |
0e2446d4 AW |
158 | (let ((preds (accessor (lookup-block (vector-ref order n) blocks)))) |
159 | (vector-set! preds-vec n | |
160 | ;; It's possible for a predecessor to not be in | |
161 | ;; the mapping, if the predecessor is not | |
162 | ;; reachable from the entry node. | |
163 | (filter-map (cut hashq-ref mapping <>) preds)) | |
164 | (lp (1+ n))))) | |
3aee6cfd AW |
165 | preds-vec)) |
166 | ||
366eb4d7 AW |
167 | (define (compute-dom-levels idoms) |
168 | (let ((dom-levels (make-vector (vector-length idoms) #f))) | |
3aee6cfd AW |
169 | (define (compute-dom-level n) |
170 | (or (vector-ref dom-levels n) | |
171 | (let ((dom-level (1+ (compute-dom-level (vector-ref idoms n))))) | |
172 | (vector-set! dom-levels n dom-level) | |
173 | dom-level))) | |
174 | (vector-set! dom-levels 0 0) | |
175 | (let lp ((n 0)) | |
366eb4d7 AW |
176 | (when (< n (vector-length idoms)) |
177 | (compute-dom-level n) | |
178 | (lp (1+ n)))) | |
179 | dom-levels)) | |
3aee6cfd | 180 | |
366eb4d7 AW |
181 | (define (compute-idoms preds) |
182 | (let ((idoms (make-vector (vector-length preds) 0))) | |
3aee6cfd AW |
183 | (define (common-idom d0 d1) |
184 | ;; We exploit the fact that a reverse post-order is a topological | |
185 | ;; sort, and so the idom of a node is always numerically less than | |
186 | ;; the node itself. | |
187 | (cond | |
188 | ((= d0 d1) d0) | |
189 | ((< d0 d1) (common-idom d0 (vector-ref idoms d1))) | |
190 | (else (common-idom (vector-ref idoms d0) d1)))) | |
191 | (define (compute-idom preds) | |
192 | (match preds | |
193 | (() 0) | |
194 | ((pred . preds) | |
195 | (let lp ((idom pred) (preds preds)) | |
196 | (match preds | |
197 | (() idom) | |
198 | ((pred . preds) | |
199 | (lp (common-idom idom pred) preds))))))) | |
200 | ;; This is the iterative O(n^2) fixpoint algorithm, originally from | |
201 | ;; Allen and Cocke ("Graph-theoretic constructs for program flow | |
202 | ;; analysis", 1972). See the discussion in Cooper, Harvey, and | |
203 | ;; Kennedy's "A Simple, Fast Dominance Algorithm", 2001. | |
204 | (let iterate ((n 0) (changed? #f)) | |
205 | (cond | |
206 | ((< n (vector-length preds)) | |
207 | (let ((idom (vector-ref idoms n)) | |
208 | (idom* (compute-idom (vector-ref preds n)))) | |
209 | (cond | |
210 | ((eqv? idom idom*) | |
211 | (iterate (1+ n) changed?)) | |
212 | (else | |
213 | (vector-set! idoms n idom*) | |
214 | (iterate (1+ n) #t))))) | |
215 | (changed? | |
216 | (iterate 0 #f)) | |
366eb4d7 AW |
217 | (else idoms))))) |
218 | ||
96b8027c AW |
219 | (define-inlinable (vector-push! vec idx val) |
220 | (let ((v vec) (i idx)) | |
221 | (vector-set! v i (cons val (vector-ref v i))))) | |
222 | ||
223 | ;; Compute a vector containing, for each node, a list of the nodes that | |
224 | ;; it immediately dominates. These are the "D" edges in the DJ tree. | |
225 | (define (compute-dom-edges idoms) | |
226 | (let ((doms (make-vector (vector-length idoms) '()))) | |
227 | (let lp ((n 0)) | |
228 | (when (< n (vector-length idoms)) | |
229 | (let ((idom (vector-ref idoms n))) | |
230 | (vector-push! doms idom n)) | |
231 | (lp (1+ n)))) | |
232 | doms)) | |
233 | ||
234 | ;; Compute a vector containing, for each node, a list of the successors | |
235 | ;; of that node that are not dominated by that node. These are the "J" | |
236 | ;; edges in the DJ tree. | |
237 | (define (compute-join-edges preds idoms) | |
238 | (define (dominates? n1 n2) | |
239 | (or (= n1 n2) | |
240 | (and (< n1 n2) | |
241 | (dominates? n1 (vector-ref idoms n2))))) | |
242 | (let ((joins (make-vector (vector-length idoms) '()))) | |
243 | (let lp ((n 0)) | |
244 | (when (< n (vector-length preds)) | |
245 | (for-each (lambda (pred) | |
246 | (unless (dominates? pred n) | |
247 | (vector-push! joins pred n))) | |
248 | (vector-ref preds n)) | |
249 | (lp (1+ n)))) | |
250 | joins)) | |
251 | ||
252 | ;; Compute a vector containing, for each node, a list of the back edges | |
253 | ;; to that node. If a node is not the entry of a reducible loop, that | |
254 | ;; list is empty. | |
255 | (define (compute-reducible-back-edges joins idoms) | |
256 | (define (dominates? n1 n2) | |
257 | (or (= n1 n2) | |
258 | (and (< n1 n2) | |
259 | (dominates? n1 (vector-ref idoms n2))))) | |
260 | (let ((back-edges (make-vector (vector-length idoms) '()))) | |
261 | (let lp ((n 0)) | |
262 | (when (< n (vector-length joins)) | |
263 | (for-each (lambda (succ) | |
264 | (when (dominates? succ n) | |
265 | (vector-push! back-edges succ n))) | |
266 | (vector-ref joins n)) | |
267 | (lp (1+ n)))) | |
268 | back-edges)) | |
269 | ||
270 | ;; Compute the levels in the dominator tree at which there are | |
271 | ;; irreducible loops, as an integer. If a bit N is set in the integer, | |
272 | ;; that indicates that at level N in the dominator tree, there is at | |
273 | ;; least one irreducible loop. | |
274 | (define (compute-irreducible-dom-levels doms joins idoms dom-levels) | |
366eb4d7 AW |
275 | (define (dominates? n1 n2) |
276 | (or (= n1 n2) | |
277 | (and (< n1 n2) | |
278 | (dominates? n1 (vector-ref idoms n2))))) | |
96b8027c AW |
279 | (let ((pre-order (make-vector (vector-length doms) #f)) |
280 | (last-pre-order (make-vector (vector-length doms) #f)) | |
281 | (res 0) | |
282 | (count 0)) | |
283 | ;; Is MAYBE-PARENT an ancestor of N on the depth-first spanning tree | |
284 | ;; computed from the DJ graph? See Havlak 1997, "Nesting of | |
285 | ;; Reducible and Irreducible Loops". | |
286 | (define (ancestor? a b) | |
287 | (let ((w (vector-ref pre-order a)) | |
288 | (v (vector-ref pre-order b))) | |
289 | (and (<= w v) | |
290 | (<= v (vector-ref last-pre-order w))))) | |
291 | ;; Compute depth-first spanning tree of DJ graph. | |
292 | (define (recurse n) | |
293 | (unless (vector-ref pre-order n) | |
294 | (visit n))) | |
295 | (define (visit n) | |
296 | ;; Pre-order visitation index. | |
297 | (vector-set! pre-order n count) | |
298 | (set! count (1+ count)) | |
299 | (for-each recurse (vector-ref doms n)) | |
300 | (for-each recurse (vector-ref joins n)) | |
301 | ;; Pre-order visitation index of last descendant. | |
302 | (vector-set! last-pre-order (vector-ref pre-order n) (1- count))) | |
303 | ||
304 | (visit 0) | |
305 | ||
306 | (let lp ((n 0)) | |
307 | (when (< n (vector-length joins)) | |
308 | (for-each (lambda (succ) | |
309 | ;; If this join edge is not a loop back edge but it | |
310 | ;; does go to an ancestor on the DFST of the DJ | |
311 | ;; graph, then we have an irreducible loop. | |
312 | (when (and (not (dominates? succ n)) | |
313 | (ancestor? succ n)) | |
314 | (set! res (logior (ash 1 (vector-ref dom-levels succ)))))) | |
315 | (vector-ref joins n)) | |
316 | (lp (1+ n)))) | |
317 | ||
318 | res)) | |
319 | ||
320 | (define (compute-nodes-by-level dom-levels) | |
321 | (let* ((max-level (let lp ((n 0) (max-level 0)) | |
322 | (if (< n (vector-length dom-levels)) | |
323 | (lp (1+ n) (max (vector-ref dom-levels n) max-level)) | |
324 | max-level))) | |
325 | (nodes-by-level (make-vector (1+ max-level) '()))) | |
326 | (let lp ((n (1- (vector-length dom-levels)))) | |
327 | (when (>= n 0) | |
328 | (vector-push! nodes-by-level (vector-ref dom-levels n) n) | |
329 | (lp (1- n)))) | |
330 | nodes-by-level)) | |
331 | ||
332 | ;; Collect all predecessors to the back-nodes that are strictly | |
333 | ;; dominated by the loop header, and mark them as belonging to the loop. | |
334 | ;; If they already have a loop header, that means they are either in a | |
335 | ;; nested loop, or they have already been visited already. | |
336 | (define (mark-loop-body header back-nodes preds idoms loop-headers) | |
337 | (define (strictly-dominates? n1 n2) | |
338 | (and (< n1 n2) | |
339 | (let ((idom (vector-ref idoms n2))) | |
340 | (or (= n1 idom) | |
341 | (strictly-dominates? n1 idom))))) | |
342 | (define (visit node) | |
343 | (when (strictly-dominates? header node) | |
344 | (cond | |
345 | ((vector-ref loop-headers node) => visit) | |
346 | (else | |
347 | (vector-set! loop-headers node header) | |
348 | (for-each visit (vector-ref preds node)))))) | |
349 | (for-each visit back-nodes)) | |
350 | ||
351 | (define (mark-irreducible-loops level idoms dom-levels loop-headers) | |
352 | ;; FIXME: Identify strongly-connected components that are >= LEVEL in | |
353 | ;; the dominator tree, and somehow mark them as irreducible. | |
354 | (warn 'irreducible-loops-at-level level)) | |
355 | ||
356 | ;; "Identifying Loops Using DJ Graphs" by Sreedhar, Gao, and Lee, ACAPS | |
357 | ;; Technical Memo 98, 1995. | |
358 | (define (identify-loops preds idoms dom-levels) | |
359 | (let* ((doms (compute-dom-edges idoms)) | |
360 | (joins (compute-join-edges preds idoms)) | |
361 | (back-edges (compute-reducible-back-edges joins idoms)) | |
362 | (irreducible-levels | |
363 | (compute-irreducible-dom-levels doms joins idoms dom-levels)) | |
364 | (loop-headers (make-vector (vector-length preds) #f)) | |
365 | (nodes-by-level (compute-nodes-by-level dom-levels))) | |
366 | (let lp ((level (1- (vector-length nodes-by-level)))) | |
367 | (when (>= level 0) | |
368 | (for-each (lambda (n) | |
369 | (let ((edges (vector-ref back-edges n))) | |
370 | (unless (null? edges) | |
371 | (mark-loop-body n edges preds idoms loop-headers)))) | |
372 | (vector-ref nodes-by-level level)) | |
373 | (when (logbit? level irreducible-levels) | |
374 | (mark-irreducible-loops level idoms dom-levels loop-headers)) | |
375 | (lp (1- level)))) | |
376 | loop-headers)) | |
366eb4d7 | 377 | |
0e2446d4 AW |
378 | (define (analyze-control-flow! kentry kexit blocks) |
379 | ;; First go forward in the graph, computing dominators and loop | |
380 | ;; information. | |
381 | (let* ((order (reverse-post-order kentry blocks block-succs)) | |
382 | (preds (convert-predecessors order blocks block-preds)) | |
366eb4d7 AW |
383 | (idoms (compute-idoms preds)) |
384 | (dom-levels (compute-dom-levels idoms)) | |
385 | (loop-headers (identify-loops preds idoms dom-levels))) | |
386 | (let lp ((n 0)) | |
387 | (when (< n (vector-length order)) | |
388 | (let* ((k (vector-ref order n)) | |
389 | (idom (vector-ref idoms n)) | |
0e2446d4 | 390 | (dom-level (vector-ref dom-levels n)) |
366eb4d7 AW |
391 | (loop-header (vector-ref loop-headers n)) |
392 | (b (lookup-block k blocks))) | |
393 | (set-block-idom! b (vector-ref order idom)) | |
394 | (set-block-dom-level! b dom-level) | |
395 | (set-block-loop-header! b (and loop-header | |
396 | (vector-ref order loop-header))) | |
0e2446d4 AW |
397 | (lp (1+ n)))))) |
398 | ;; Then go backwards, computing post-dominators. | |
399 | (let* ((order (reverse-post-order kexit blocks block-preds)) | |
400 | (preds (convert-predecessors order blocks block-succs)) | |
401 | (idoms (compute-idoms preds)) | |
402 | (dom-levels (compute-dom-levels idoms))) | |
403 | (let lp ((n 0)) | |
404 | (when (< n (vector-length order)) | |
405 | (let* ((k (vector-ref order n)) | |
406 | (pdom (vector-ref idoms n)) | |
407 | (pdom-level (vector-ref dom-levels n)) | |
408 | (b (lookup-block k blocks))) | |
409 | (set-block-pdom! b (vector-ref order pdom)) | |
410 | (set-block-pdom-level! b pdom-level) | |
366eb4d7 | 411 | (lp (1+ n))))))) |
3aee6cfd | 412 | |
db11440d AW |
413 | |
414 | ;; Compute the maximum fixed point of the data-flow constraint problem. | |
415 | ;; | |
416 | ;; This always completes, as the graph is finite and the in and out sets | |
417 | ;; are complete semi-lattices. If the graph is reducible and the blocks | |
418 | ;; are sorted in reverse post-order, this completes in a maximum of LC + | |
419 | ;; 2 iterations, where LC is the loop connectedness number. See Hecht | |
420 | ;; and Ullman, "Analysis of a simple algorithm for global flow | |
421 | ;; problems", POPL 1973, or the recent summary in "Notes on graph | |
422 | ;; algorithms used in optimizing compilers", Offner 2013. | |
423 | (define (compute-maximum-fixed-point preds inv outv killv genv union?) | |
424 | (define (bitvector-copy! dst src) | |
425 | (bitvector-fill! dst #f) | |
426 | (bit-set*! dst src #t)) | |
427 | (define (bitvector-meet! accum src) | |
428 | (bit-set*! accum src union?)) | |
429 | (let lp ((n 0) (changed? #f)) | |
430 | (cond | |
431 | ((< n (vector-length preds)) | |
432 | (let ((in (vector-ref inv n)) | |
433 | (out (vector-ref outv n)) | |
434 | (kill (vector-ref killv n)) | |
435 | (gen (vector-ref genv n))) | |
436 | (let ((out-count (or changed? (bit-count #t out)))) | |
437 | (for-each | |
438 | (lambda (pred) | |
439 | (bitvector-meet! in (vector-ref outv pred))) | |
440 | (vector-ref preds n)) | |
441 | (bitvector-copy! out in) | |
442 | (for-each (cut bitvector-set! out <> #f) kill) | |
443 | (for-each (cut bitvector-set! out <> #t) gen) | |
444 | (lp (1+ n) | |
445 | (or changed? (not (eqv? out-count (bit-count #t out)))))))) | |
446 | (changed? | |
447 | (lp 0 #f))))) | |
448 | ||
449 | ;; Data-flow analysis. | |
450 | (define-record-type $dfa | |
451 | (make-dfa k->idx order var->idx names syms in out) | |
452 | dfa? | |
453 | ;; Function mapping k-sym -> k-idx | |
454 | (k->idx dfa-k->idx) | |
455 | ;; Vector of k-idx -> k-sym | |
456 | (order dfa-order) | |
457 | ;; Function mapping var-sym -> var-idx | |
458 | (var->idx dfa-var->idx) | |
459 | ;; Vector of var-idx -> name | |
460 | (names dfa-names) | |
461 | ;; Vector of var-idx -> var-sym | |
462 | (syms dfa-syms) | |
463 | ;; Vector of k-idx -> bitvector | |
464 | (in dfa-in) | |
465 | ;; Vector of k-idx -> bitvector | |
466 | (out dfa-out)) | |
467 | ||
468 | (define (dfa-k-idx dfa k) | |
469 | ((dfa-k->idx dfa) k)) | |
470 | ||
471 | (define (dfa-k-sym dfa idx) | |
472 | (vector-ref (dfa-order dfa) idx)) | |
473 | ||
474 | (define (dfa-k-count dfa) | |
475 | (vector-length (dfa-order dfa))) | |
476 | ||
477 | (define (dfa-var-idx dfa var) | |
478 | ((dfa-var->idx dfa) var)) | |
479 | ||
480 | (define (dfa-var-name dfa idx) | |
481 | (vector-ref (dfa-names dfa) idx)) | |
482 | ||
483 | (define (dfa-var-sym dfa idx) | |
484 | (vector-ref (dfa-syms dfa) idx)) | |
485 | ||
486 | (define (dfa-var-count dfa) | |
487 | (vector-length (dfa-syms dfa))) | |
488 | ||
489 | (define (dfa-k-in dfa idx) | |
490 | (vector-ref (dfa-in dfa) idx)) | |
491 | ||
492 | (define (dfa-k-out dfa idx) | |
493 | (vector-ref (dfa-out dfa) idx)) | |
494 | ||
495 | (define (compute-live-variables ktail dfg) | |
496 | (define (make-variable-mapper use-maps) | |
497 | (let ((mapping (make-hash-table)) | |
498 | (n 0)) | |
499 | (hash-for-each (lambda (sym use-map) | |
500 | (hashq-set! mapping sym n) | |
501 | (set! n (1+ n))) | |
502 | use-maps) | |
503 | (values (lambda (sym) | |
504 | (or (hashq-ref mapping sym) | |
505 | (error "unknown sym" sym))) | |
506 | n))) | |
507 | (define (make-block-mapper order) | |
508 | (let ((mapping (make-hash-table))) | |
509 | (let lp ((n 0)) | |
510 | (when (< n (vector-length order)) | |
511 | (hashq-set! mapping (vector-ref order n) n) | |
512 | (lp (1+ n)))) | |
513 | (lambda (k) | |
514 | (or (hashq-ref mapping k) | |
515 | (error "unknown k" k))))) | |
516 | ||
517 | (call-with-values (lambda () (make-variable-mapper (dfg-use-maps dfg))) | |
518 | (lambda (var->idx nvars) | |
519 | (let* ((blocks (dfg-blocks dfg)) | |
520 | (order (reverse-post-order ktail blocks block-preds)) | |
521 | (succs (convert-predecessors order blocks block-succs)) | |
522 | (k->idx (make-block-mapper order)) | |
523 | (syms (make-vector nvars #f)) | |
524 | (names (make-vector nvars #f)) | |
525 | (usev (make-vector (vector-length order) '())) | |
526 | (defv (make-vector (vector-length order) '())) | |
527 | (live-in (make-vector (vector-length order) #f)) | |
528 | (live-out (make-vector (vector-length order) #f))) | |
529 | ;; Initialize syms, names, defv, and usev. | |
530 | (hash-for-each | |
531 | (lambda (sym use-map) | |
532 | (match use-map | |
533 | (($ $use-map name sym def uses) | |
534 | (let ((v (var->idx sym))) | |
535 | (vector-set! syms v sym) | |
536 | (vector-set! names v name) | |
537 | (for-each (lambda (def) | |
538 | (vector-push! defv (k->idx def) v)) | |
539 | (block-preds (lookup-block def blocks))) | |
540 | (for-each (lambda (use) | |
541 | (vector-push! usev (k->idx use) v)) | |
542 | uses))))) | |
543 | (dfg-use-maps dfg)) | |
544 | ||
545 | ;; Initialize live-in and live-out sets. | |
546 | (let lp ((n 0)) | |
547 | (when (< n (vector-length live-out)) | |
548 | (vector-set! live-in n (make-bitvector nvars #f)) | |
549 | (vector-set! live-out n (make-bitvector nvars #f)) | |
550 | (lp (1+ n)))) | |
551 | ||
552 | ;; Liveness is a reverse data-flow problem, so we give | |
553 | ;; compute-maximum-fixed-point a reversed graph, swapping in and | |
554 | ;; out, usev and defv, using successors instead of predecessors, | |
555 | ;; and starting with ktail instead of the entry. | |
556 | (compute-maximum-fixed-point succs live-out live-in defv usev #t) | |
557 | ||
558 | (make-dfa k->idx order var->idx names syms live-in live-out))))) | |
559 | ||
560 | (define (print-dfa dfa) | |
561 | (match dfa | |
562 | (($ $dfa k->idx order var->idx names syms in out) | |
563 | (define (print-var-set bv) | |
564 | (let lp ((n 0)) | |
565 | (let ((n (bit-position #t bv n))) | |
566 | (when n | |
567 | (format #t " ~A" (vector-ref syms n)) | |
568 | (lp (1+ n)))))) | |
569 | (let lp ((n 0)) | |
570 | (when (< n (vector-length order)) | |
571 | (format #t "~A:\n" (vector-ref order n)) | |
572 | (format #t " in:") | |
573 | (print-var-set (vector-ref in n)) | |
574 | (newline) | |
575 | (format #t " out:") | |
576 | (print-var-set (vector-ref out n)) | |
577 | (newline) | |
578 | (lp (1+ n))))))) | |
579 | ||
f22979db | 580 | (define (visit-fun fun conts blocks use-maps global?) |
fc95a944 | 581 | (define (add-def! name sym def-k) |
6e8ad823 AW |
582 | (unless def-k |
583 | (error "Term outside labelled continuation?")) | |
fc95a944 | 584 | (hashq-set! use-maps sym (make-use-map name sym def-k '()))) |
6e8ad823 AW |
585 | |
586 | (define (add-use! sym use-k) | |
587 | (match (hashq-ref use-maps sym) | |
588 | (#f (error "Symbol out of scope?" sym)) | |
fc95a944 | 589 | ((and use-map ($ $use-map name sym def uses)) |
6e8ad823 AW |
590 | (set-use-map-uses! use-map (cons use-k uses))))) |
591 | ||
f22979db AW |
592 | (define* (declare-block! label cont parent |
593 | #:optional (level | |
594 | (1+ (lookup-scope-level parent blocks)))) | |
595 | (hashq-set! conts label cont) | |
596 | (hashq-set! blocks label (make-block parent level))) | |
597 | ||
598 | (define (link-blocks! pred succ) | |
599 | (let ((pred-block (hashq-ref blocks pred)) | |
600 | (succ-block (hashq-ref blocks succ))) | |
601 | (unless (and pred-block succ-block) | |
c8ad7426 | 602 | (error "internal error" pred-block succ-block)) |
f22979db AW |
603 | (set-block-succs! pred-block (cons succ (block-succs pred-block))) |
604 | (set-block-preds! succ-block (cons pred (block-preds succ-block))))) | |
6e8ad823 AW |
605 | |
606 | (define (visit exp exp-k) | |
fc95a944 AW |
607 | (define (def! name sym) |
608 | (add-def! name sym exp-k)) | |
6e8ad823 AW |
609 | (define (use! sym) |
610 | (add-use! sym exp-k)) | |
3aee6cfd AW |
611 | (define (use-k! k) |
612 | (link-blocks! exp-k k)) | |
6e8ad823 AW |
613 | (define (recur exp) |
614 | (visit exp exp-k)) | |
615 | (match exp | |
616 | (($ $letk (($ $cont k src cont) ...) body) | |
617 | ;; Set up recursive environment before visiting cont bodies. | |
618 | (for-each (lambda (cont k) | |
f22979db | 619 | (declare-block! k cont exp-k)) |
6e8ad823 AW |
620 | cont k) |
621 | (for-each visit cont k) | |
622 | (recur body)) | |
623 | ||
624 | (($ $kargs names syms body) | |
fc95a944 | 625 | (for-each def! names syms) |
6e8ad823 AW |
626 | (recur body)) |
627 | ||
628 | (($ $kif kt kf) | |
f22979db AW |
629 | (use-k! kt) |
630 | (use-k! kf)) | |
6e8ad823 AW |
631 | |
632 | (($ $ktrunc arity k) | |
f22979db | 633 | (use-k! k)) |
6e8ad823 AW |
634 | |
635 | (($ $letrec names syms funs body) | |
636 | (unless global? | |
637 | (error "$letrec should not be present when building a local DFG")) | |
fc95a944 | 638 | (for-each def! names syms) |
f22979db | 639 | (for-each (cut visit-fun <> conts blocks use-maps global?) funs) |
6e8ad823 AW |
640 | (visit body exp-k)) |
641 | ||
642 | (($ $continue k exp) | |
f22979db | 643 | (use-k! k) |
6e8ad823 AW |
644 | (match exp |
645 | (($ $var sym) | |
646 | (use! sym)) | |
647 | ||
648 | (($ $call proc args) | |
649 | (use! proc) | |
650 | (for-each use! args)) | |
651 | ||
652 | (($ $primcall name args) | |
653 | (for-each use! args)) | |
654 | ||
655 | (($ $values args) | |
656 | (for-each use! args)) | |
657 | ||
658 | (($ $prompt escape? tag handler) | |
659 | (use! tag) | |
f22979db | 660 | (use-k! handler)) |
6e8ad823 AW |
661 | |
662 | (($ $fun) | |
663 | (when global? | |
f22979db | 664 | (visit-fun exp conts blocks use-maps global?))) |
6e8ad823 AW |
665 | |
666 | (_ #f))))) | |
667 | ||
668 | (match fun | |
669 | (($ $fun meta free | |
670 | ($ $cont kentry src | |
671 | (and entry | |
672 | ($ $kentry self ($ $cont ktail _ tail) clauses)))) | |
f22979db | 673 | (declare-block! kentry entry #f 0) |
fc95a944 | 674 | (add-def! #f self kentry) |
6e8ad823 | 675 | |
f22979db | 676 | (declare-block! ktail tail kentry) |
6e8ad823 AW |
677 | |
678 | (for-each | |
679 | (match-lambda | |
680 | (($ $cont kclause _ | |
681 | (and clause ($ $kclause arity ($ $cont kbody _ body)))) | |
f22979db AW |
682 | (declare-block! kclause clause kentry) |
683 | (link-blocks! kentry kclause) | |
6e8ad823 | 684 | |
f22979db AW |
685 | (declare-block! kbody body kclause) |
686 | (link-blocks! kclause kbody) | |
6e8ad823 AW |
687 | |
688 | (visit body kbody))) | |
3aee6cfd | 689 | clauses) |
f22979db | 690 | |
0e2446d4 | 691 | (analyze-control-flow! kentry ktail blocks)))) |
6e8ad823 AW |
692 | |
693 | (define* (compute-dfg fun #:key (global? #t)) | |
694 | (let* ((conts (make-hash-table)) | |
f22979db AW |
695 | (blocks (make-hash-table)) |
696 | (use-maps (make-hash-table))) | |
697 | (visit-fun fun conts blocks use-maps global?) | |
698 | (make-dfg conts blocks use-maps))) | |
6e8ad823 | 699 | |
f22979db AW |
700 | (define (lookup-block k blocks) |
701 | (let ((res (hashq-ref blocks k))) | |
6e8ad823 | 702 | (unless res |
f22979db | 703 | (error "Unknown continuation!" k (hash-fold acons '() blocks))) |
6e8ad823 AW |
704 | res)) |
705 | ||
f22979db AW |
706 | (define (lookup-scope-level k blocks) |
707 | (match (lookup-block k blocks) | |
708 | (($ $block _ scope-level) scope-level))) | |
709 | ||
6e8ad823 AW |
710 | (define (lookup-use-map sym use-maps) |
711 | (let ((res (hashq-ref use-maps sym))) | |
712 | (unless res | |
713 | (error "Unknown lexical!" sym (hash-fold acons '() use-maps))) | |
714 | res)) | |
715 | ||
716 | (define (lookup-def sym dfg) | |
717 | (match dfg | |
f22979db | 718 | (($ $dfg conts blocks use-maps) |
6e8ad823 | 719 | (match (lookup-use-map sym use-maps) |
fc95a944 | 720 | (($ $use-map name sym def uses) |
6e8ad823 AW |
721 | def))))) |
722 | ||
723 | (define (lookup-uses sym dfg) | |
724 | (match dfg | |
f22979db | 725 | (($ $dfg conts blocks use-maps) |
6e8ad823 | 726 | (match (lookup-use-map sym use-maps) |
fc95a944 | 727 | (($ $use-map name sym def uses) |
6e8ad823 AW |
728 | uses))))) |
729 | ||
c8ad7426 AW |
730 | (define (lookup-block-scope k dfg) |
731 | (block-scope (lookup-block k (dfg-blocks dfg)))) | |
732 | ||
f22979db AW |
733 | (define (lookup-predecessors k dfg) |
734 | (match (lookup-block k (dfg-blocks dfg)) | |
735 | (($ $block _ _ preds succs) preds))) | |
736 | ||
737 | (define (lookup-successors k dfg) | |
738 | (match (lookup-block k (dfg-blocks dfg)) | |
739 | (($ $block _ _ preds succs) succs))) | |
740 | ||
6e8ad823 | 741 | (define (find-defining-term sym dfg) |
f22979db | 742 | (match (lookup-predecessors (lookup-def sym dfg) dfg) |
6e8ad823 AW |
743 | ((def-exp-k) |
744 | (lookup-cont def-exp-k (dfg-cont-table dfg))) | |
745 | (else #f))) | |
746 | ||
747 | (define (find-call term) | |
748 | (match term | |
749 | (($ $kargs names syms body) (find-call body)) | |
750 | (($ $letk conts body) (find-call body)) | |
751 | (($ $letrec names syms funs body) (find-call body)) | |
752 | (($ $continue) term))) | |
753 | ||
754 | (define (call-expression call) | |
755 | (match call | |
756 | (($ $continue k exp) exp))) | |
757 | ||
758 | (define (find-expression term) | |
759 | (call-expression (find-call term))) | |
760 | ||
761 | (define (find-defining-expression sym dfg) | |
762 | (match (find-defining-term sym dfg) | |
763 | (#f #f) | |
764 | (($ $ktrunc) #f) | |
f22979db | 765 | (($ $kclause) #f) |
6e8ad823 AW |
766 | (term (find-expression term)))) |
767 | ||
768 | (define (find-constant-value sym dfg) | |
769 | (match (find-defining-expression sym dfg) | |
770 | (($ $const val) | |
771 | (values #t val)) | |
772 | (($ $continue k ($ $void)) | |
773 | (values #t *unspecified*)) | |
774 | (else | |
775 | (values #f #f)))) | |
776 | ||
777 | (define (constant-needs-allocation? sym val dfg) | |
607fe5a6 AW |
778 | (define (immediate-u8? val) |
779 | (and (integer? val) (exact? val) (<= 0 val 255))) | |
780 | ||
6e8ad823 AW |
781 | (define (find-exp term) |
782 | (match term | |
783 | (($ $kargs names syms body) (find-exp body)) | |
784 | (($ $letk conts body) (find-exp body)) | |
785 | (else term))) | |
786 | (match dfg | |
f22979db | 787 | (($ $dfg conts blocks use-maps) |
6e8ad823 | 788 | (match (lookup-use-map sym use-maps) |
fc95a944 | 789 | (($ $use-map _ _ def uses) |
6e8ad823 AW |
790 | (or-map |
791 | (lambda (use) | |
792 | (match (find-expression (lookup-cont use conts)) | |
793 | (($ $call) #f) | |
794 | (($ $values) #f) | |
795 | (($ $primcall 'free-ref (closure slot)) | |
796 | (not (eq? sym slot))) | |
797 | (($ $primcall 'free-set! (closure slot value)) | |
798 | (not (eq? sym slot))) | |
799 | (($ $primcall 'cache-current-module! (mod . _)) | |
800 | (eq? sym mod)) | |
801 | (($ $primcall 'cached-toplevel-box _) | |
802 | #f) | |
803 | (($ $primcall 'cached-module-box _) | |
804 | #f) | |
805 | (($ $primcall 'resolve (name bound?)) | |
806 | (eq? sym name)) | |
607fe5a6 AW |
807 | (($ $primcall 'make-vector (len init)) |
808 | (not (and (eq? sym len) (immediate-u8? val)))) | |
8ba3f20c | 809 | (($ $primcall 'vector-ref (v i)) |
607fe5a6 | 810 | (not (and (eq? sym i) (immediate-u8? val)))) |
8ba3f20c | 811 | (($ $primcall 'vector-set! (v i x)) |
607fe5a6 | 812 | (not (and (eq? sym i) (immediate-u8? val)))) |
6e8ad823 AW |
813 | (_ #t))) |
814 | uses)))))) | |
815 | ||
f22979db AW |
816 | (define (continuation-scope-contains? scope-k k blocks) |
817 | (let ((scope-level (lookup-scope-level scope-k blocks))) | |
818 | (let lp ((k k)) | |
819 | (or (eq? scope-k k) | |
820 | (match (lookup-block k blocks) | |
821 | (($ $block scope level) | |
822 | (and (< scope-level level) | |
823 | (lp scope)))))))) | |
824 | ||
f22979db | 825 | (define (continuation-bound-in? k use-k dfg) |
d51fb1e6 | 826 | (match dfg |
f22979db AW |
827 | (($ $dfg conts blocks use-maps) |
828 | (match (lookup-block k blocks) | |
829 | (($ $block def-k) | |
830 | (continuation-scope-contains? def-k use-k blocks)))))) | |
d51fb1e6 AW |
831 | |
832 | (define (variable-free-in? var k dfg) | |
6e8ad823 | 833 | (match dfg |
f22979db | 834 | (($ $dfg conts blocks use-maps) |
6e8ad823 | 835 | (or-map (lambda (use) |
f22979db | 836 | (continuation-scope-contains? k use blocks)) |
6e8ad823 | 837 | (match (lookup-use-map var use-maps) |
fc95a944 | 838 | (($ $use-map name sym def uses) |
6e8ad823 AW |
839 | uses)))))) |
840 | ||
841 | ;; Does k1 dominate k2? | |
238ef4cf | 842 | (define (dominates? k1 k2 blocks) |
0e2446d4 AW |
843 | (let ((b1 (lookup-block k1 blocks)) |
844 | (b2 (lookup-block k2 blocks))) | |
845 | (let ((k1-level (block-dom-level b1)) | |
846 | (k2-level (block-dom-level b2))) | |
847 | (cond | |
848 | ((> k1-level k2-level) #f) | |
849 | ((< k1-level k2-level) (dominates? k1 (block-idom b2) blocks)) | |
850 | ((= k1-level k2-level) (eqv? k1 k2)))))) | |
851 | ||
852 | ;; Does k1 post-dominate k2? | |
853 | (define (post-dominates? k1 k2 blocks) | |
854 | (let ((b1 (lookup-block k1 blocks)) | |
855 | (b2 (lookup-block k2 blocks))) | |
856 | (let ((k1-level (block-pdom-level b1)) | |
857 | (k2-level (block-pdom-level b2))) | |
858 | (cond | |
859 | ((> k1-level k2-level) #f) | |
860 | ((< k1-level k2-level) (post-dominates? k1 (block-pdom b2) blocks)) | |
861 | ((= k1-level k2-level) (eqv? k1 k2)))))) | |
6e8ad823 | 862 | |
b8da548f AW |
863 | (define (lookup-loop-header k blocks) |
864 | (block-loop-header (lookup-block k blocks))) | |
865 | ||
e636f424 AW |
866 | ;; A continuation is a control point if it has multiple predecessors, or |
867 | ;; if its single predecessor has multiple successors. | |
868 | (define (control-point? k dfg) | |
869 | (match (lookup-predecessors k dfg) | |
870 | ((pred) | |
871 | (match (lookup-successors pred dfg) | |
872 | ((_) #f) | |
873 | (_ #t))) | |
874 | (_ #t))) | |
6e8ad823 AW |
875 | |
876 | (define (lookup-bound-syms k dfg) | |
877 | (match dfg | |
f22979db | 878 | (($ $dfg conts blocks use-maps) |
6e8ad823 AW |
879 | (match (lookup-cont k conts) |
880 | (($ $kargs names syms body) | |
881 | syms))))) |