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b275fb26 AW |
1 | ;;; Tree-IL partial evaluator |
2 | ||
3 | ;; Copyright (C) 2011 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 | (define-module (language tree-il peval) | |
20 | #:use-module (language tree-il) | |
21 | #:use-module (language tree-il primitives) | |
22 | #:use-module (ice-9 vlist) | |
23 | #:use-module (ice-9 match) | |
24 | #:use-module (srfi srfi-1) | |
25 | #:use-module (srfi srfi-9) | |
26 | #:use-module (srfi srfi-11) | |
27 | #:use-module (srfi srfi-26) | |
28 | #:export (peval)) | |
29 | ||
30 | ;;; | |
47974c30 AW |
31 | ;;; Partial evaluation is Guile's most important source-to-source |
32 | ;;; optimization pass. It performs copy propagation, dead code | |
33 | ;;; elimination, inlining, and constant folding, all while preserving | |
34 | ;;; the order of effects in the residual program. | |
35 | ;;; | |
36 | ;;; For more on partial evaluation, see William Cook’s excellent | |
37 | ;;; tutorial on partial evaluation at DSL 2011, called “Build your own | |
38 | ;;; partial evaluator in 90 minutes”[0]. | |
39 | ;;; | |
40 | ;;; Our implementation of this algorithm was heavily influenced by | |
41 | ;;; Waddell and Dybvig's paper, "Fast and Effective Procedure Inlining", | |
42 | ;;; IU CS Dept. TR 484. | |
43 | ;;; | |
44 | ;;; [0] http://www.cs.utexas.edu/~wcook/tutorial/. | |
b275fb26 AW |
45 | ;;; |
46 | ||
47974c30 AW |
47 | ;; First, some helpers. |
48 | ;; | |
30669991 AW |
49 | (define-syntax *logging* (identifier-syntax #f)) |
50 | ||
41d43584 | 51 | ;; For efficiency we define *logging* to inline to #f, so that the call |
30669991 AW |
52 | ;; to log* gets optimized out. If you want to log, uncomment these |
53 | ;; lines: | |
41d43584 | 54 | ;; |
30669991 AW |
55 | ;; (define %logging #f) |
56 | ;; (define-syntax *logging* (identifier-syntax %logging)) | |
41d43584 AW |
57 | ;; |
58 | ;; Then you can change %logging at runtime. | |
41d43584 AW |
59 | |
60 | (define-syntax log | |
61 | (syntax-rules (quote) | |
62 | ((log 'event arg ...) | |
63 | (if (and *logging* | |
64 | (or (eq? *logging* #t) | |
65 | (memq 'event *logging*))) | |
66 | (log* 'event arg ...))))) | |
67 | ||
68 | (define (log* event . args) | |
69 | (let ((pp (module-ref (resolve-interface '(ice-9 pretty-print)) | |
70 | 'pretty-print))) | |
71 | (pp `(log ,event . ,args)) | |
72 | (newline) | |
73 | (values))) | |
74 | ||
b275fb26 AW |
75 | (define-syntax-rule (let/ec k e e* ...) |
76 | (let ((tag (make-prompt-tag))) | |
77 | (call-with-prompt | |
78 | tag | |
79 | (lambda () | |
80 | (let ((k (lambda args (apply abort-to-prompt tag args)))) | |
81 | e e* ...)) | |
82 | (lambda (_ res) res)))) | |
83 | ||
84 | (define (tree-il-any proc exp) | |
85 | (let/ec k | |
86 | (tree-il-fold (lambda (exp res) | |
87 | (let ((res (proc exp))) | |
88 | (if res (k res) #f))) | |
89 | (lambda (exp res) | |
90 | (let ((res (proc exp))) | |
91 | (if res (k res) #f))) | |
92 | (lambda (exp res) #f) | |
93 | #f exp))) | |
94 | ||
95 | (define (vlist-any proc vlist) | |
96 | (let ((len (vlist-length vlist))) | |
97 | (let lp ((i 0)) | |
98 | (and (< i len) | |
99 | (or (proc (vlist-ref vlist i)) | |
100 | (lp (1+ i))))))) | |
101 | ||
47974c30 AW |
102 | ;; Peval will do a one-pass analysis on the source program to determine |
103 | ;; the set of assigned lexicals, and to identify unreferenced and | |
104 | ;; singly-referenced lexicals. | |
105 | ;; | |
b275fb26 AW |
106 | (define-record-type <var> |
107 | (make-var name gensym refcount set?) | |
108 | var? | |
109 | (name var-name) | |
110 | (gensym var-gensym) | |
111 | (refcount var-refcount set-var-refcount!) | |
112 | (set? var-set? set-var-set?!)) | |
113 | ||
114 | (define* (build-var-table exp #:optional (table vlist-null)) | |
115 | (tree-il-fold | |
116 | (lambda (exp res) | |
117 | (match exp | |
118 | (($ <lexical-ref> src name gensym) | |
75170872 AW |
119 | (let ((var (cdr (vhash-assq gensym res)))) |
120 | (set-var-refcount! var (1+ (var-refcount var))) | |
121 | res)) | |
b275fb26 AW |
122 | (_ res))) |
123 | (lambda (exp res) | |
124 | (match exp | |
75170872 AW |
125 | (($ <lambda-case> src req opt rest kw init gensyms body alt) |
126 | (fold (lambda (name sym res) | |
127 | (vhash-consq sym (make-var name sym 0 #f) res)) | |
128 | res | |
129 | (append req (or opt '()) (if rest (list rest) '()) | |
130 | (match kw | |
131 | ((aok? (kw name sym) ...) name) | |
132 | (_ '()))) | |
133 | gensyms)) | |
134 | (($ <let> src names gensyms vals body) | |
135 | (fold (lambda (name sym res) | |
136 | (vhash-consq sym (make-var name sym 0 #f) res)) | |
137 | res names gensyms)) | |
138 | (($ <letrec> src in-order? names gensyms vals body) | |
139 | (fold (lambda (name sym res) | |
140 | (vhash-consq sym (make-var name sym 0 #f) res)) | |
141 | res names gensyms)) | |
142 | (($ <fix> src names gensyms vals body) | |
143 | (fold (lambda (name sym res) | |
144 | (vhash-consq sym (make-var name sym 0 #f) res)) | |
145 | res names gensyms)) | |
b275fb26 | 146 | (($ <lexical-set> src name gensym exp) |
75170872 AW |
147 | (set-var-set?! (cdr (vhash-assq gensym res)) #t) |
148 | res) | |
b275fb26 AW |
149 | (_ res))) |
150 | (lambda (exp res) res) | |
151 | table exp)) | |
152 | ||
47974c30 AW |
153 | ;; Counters are data structures used to limit the effort that peval |
154 | ;; spends on particular inlining attempts. Each call site in the source | |
155 | ;; program is allocated some amount of effort. If peval exceeds the | |
156 | ;; effort counter while attempting to inline a call site, it aborts the | |
157 | ;; inlining attempt and residualizes a call instead. | |
158 | ;; | |
159 | ;; As there is a fixed number of call sites, that makes `peval' O(N) in | |
160 | ;; the number of call sites in the source program. | |
161 | ;; | |
162 | ;; Counters should limit the size of the residual program as well, but | |
163 | ;; currently this is not implemented. | |
164 | ;; | |
165 | ;; At the top level, before seeing any peval call, there is no counter, | |
166 | ;; because inlining will terminate as there is no recursion. When peval | |
167 | ;; sees a call at the top level, it will make a new counter, allocating | |
168 | ;; it some amount of effort and size. | |
169 | ;; | |
170 | ;; This top-level effort counter effectively "prints money". Within a | |
171 | ;; toplevel counter, no more effort is printed ex nihilo; for a nested | |
172 | ;; inlining attempt to proceed, effort must be transferred from the | |
173 | ;; toplevel counter to the nested counter. | |
174 | ;; | |
175 | ;; Via `data' and `prev', counters form a linked list, terminating in a | |
176 | ;; toplevel counter. In practice `data' will be the a pointer to the | |
177 | ;; source expression of the procedure being inlined. | |
178 | ;; | |
179 | ;; In this way peval can detect a recursive inlining attempt, by walking | |
180 | ;; back on the `prev' links looking for matching `data'. Recursive | |
181 | ;; counters receive a more limited effort allocation, as we don't want | |
182 | ;; to spend all of the effort for a toplevel inlining site on loops. | |
183 | ;; Also, recursive counters don't need a prompt at each inlining site: | |
184 | ;; either the call chain folds entirely, or it will be residualized at | |
185 | ;; its original call. | |
186 | ;; | |
b275fb26 AW |
187 | (define-record-type <counter> |
188 | (%make-counter effort size continuation recursive? data prev) | |
189 | counter? | |
190 | (effort effort-counter) | |
191 | (size size-counter) | |
192 | (continuation counter-continuation) | |
75170872 | 193 | (recursive? counter-recursive? set-counter-recursive?!) |
b275fb26 AW |
194 | (data counter-data) |
195 | (prev counter-prev)) | |
196 | ||
197 | (define (abort-counter c) | |
198 | ((counter-continuation c))) | |
199 | ||
200 | (define (record-effort! c) | |
201 | (let ((e (effort-counter c))) | |
202 | (if (zero? (variable-ref e)) | |
203 | (abort-counter c) | |
204 | (variable-set! e (1- (variable-ref e)))))) | |
205 | ||
206 | (define (record-size! c) | |
207 | (let ((s (size-counter c))) | |
208 | (if (zero? (variable-ref s)) | |
209 | (abort-counter c) | |
210 | (variable-set! s (1- (variable-ref s)))))) | |
211 | ||
212 | (define (find-counter data counter) | |
213 | (and counter | |
214 | (if (eq? data (counter-data counter)) | |
215 | counter | |
216 | (find-counter data (counter-prev counter))))) | |
217 | ||
218 | (define* (transfer! from to #:optional | |
219 | (effort (variable-ref (effort-counter from))) | |
220 | (size (variable-ref (size-counter from)))) | |
221 | (define (transfer-counter! from-v to-v amount) | |
222 | (let* ((from-balance (variable-ref from-v)) | |
223 | (to-balance (variable-ref to-v)) | |
224 | (amount (min amount from-balance))) | |
225 | (variable-set! from-v (- from-balance amount)) | |
226 | (variable-set! to-v (+ to-balance amount)))) | |
227 | ||
228 | (transfer-counter! (effort-counter from) (effort-counter to) effort) | |
229 | (transfer-counter! (size-counter from) (size-counter to) size)) | |
230 | ||
231 | (define (make-top-counter effort-limit size-limit continuation data) | |
232 | (%make-counter (make-variable effort-limit) | |
233 | (make-variable size-limit) | |
234 | continuation | |
235 | #t | |
236 | data | |
237 | #f)) | |
238 | ||
239 | (define (make-nested-counter continuation data current) | |
240 | (let ((c (%make-counter (make-variable 0) | |
241 | (make-variable 0) | |
242 | continuation | |
243 | #f | |
244 | data | |
245 | current))) | |
246 | (transfer! current c) | |
247 | c)) | |
248 | ||
249 | (define (make-recursive-counter effort-limit size-limit orig current) | |
250 | (let ((c (%make-counter (make-variable 0) | |
251 | (make-variable 0) | |
252 | (counter-continuation orig) | |
253 | #t | |
254 | (counter-data orig) | |
255 | current))) | |
256 | (transfer! current c effort-limit size-limit) | |
257 | c)) | |
258 | ||
580a59e7 AW |
259 | ;; Operand structures allow bindings to be processed lazily instead of |
260 | ;; eagerly. By doing so, hopefully we can get process them in a way | |
261 | ;; appropriate to their use contexts. Operands also prevent values from | |
262 | ;; being visited multiple times, wasting effort. | |
75170872 AW |
263 | ;; |
264 | ;; TODO: Record value size in operand structure? | |
580a59e7 AW |
265 | ;; |
266 | (define-record-type <operand> | |
267 | (%make-operand var sym visit source visit-count residualize? | |
268 | copyable? residual-value constant-value) | |
269 | operand? | |
270 | (var operand-var) | |
271 | (sym operand-sym) | |
272 | (visit %operand-visit) | |
273 | (source operand-source) | |
274 | (visit-count operand-visit-count set-operand-visit-count!) | |
275 | (residualize? operand-residualize? set-operand-residualize?!) | |
276 | (copyable? operand-copyable? set-operand-copyable?!) | |
277 | (residual-value operand-residual-value set-operand-residual-value!) | |
278 | (constant-value operand-constant-value set-operand-constant-value!)) | |
279 | ||
280 | (define* (make-operand var sym #:optional source visit) | |
281 | ;; Bound operands are considered copyable until we prove otherwise. | |
282 | (%make-operand var sym visit source 0 #f (and source #t) #f #f)) | |
283 | ||
284 | (define (make-bound-operands vars syms sources visit) | |
285 | (map (lambda (x y z) (make-operand x y z visit)) vars syms sources)) | |
286 | ||
287 | (define (make-unbound-operands vars syms) | |
288 | (map make-operand vars syms)) | |
289 | ||
290 | (define* (visit-operand op counter ctx #:optional effort-limit size-limit) | |
291 | ;; Peval is O(N) in call sites of the source program. However, | |
292 | ;; visiting an operand can introduce new call sites. If we visit an | |
293 | ;; operand outside a counter -- i.e., outside an inlining attempt -- | |
294 | ;; this can lead to divergence. So, if we are visiting an operand to | |
295 | ;; try to copy it, and there is no counter, make a new one. | |
296 | ;; | |
297 | ;; This will only happen at most as many times as there are lexical | |
298 | ;; references in the source program. | |
299 | (and (zero? (operand-visit-count op)) | |
300 | (dynamic-wind | |
301 | (lambda () | |
302 | (set-operand-visit-count! op (1+ (operand-visit-count op)))) | |
303 | (lambda () | |
304 | (and (operand-source op) | |
305 | (if (or counter (and (not effort-limit) (not size-limit))) | |
306 | ((%operand-visit op) (operand-source op) counter ctx) | |
307 | (let/ec k | |
308 | (define (abort) (k #f)) | |
309 | ((%operand-visit op) | |
310 | (operand-source op) | |
311 | (make-top-counter effort-limit size-limit abort op) | |
312 | ctx))))) | |
313 | (lambda () | |
314 | (set-operand-visit-count! op (1- (operand-visit-count op))))))) | |
315 | ||
316 | ;; A helper for constant folding. | |
317 | ;; | |
b275fb26 AW |
318 | (define (types-check? primitive-name args) |
319 | (case primitive-name | |
320 | ((values) #t) | |
321 | ((not pair? null? list? symbol? vector? struct?) | |
322 | (= (length args) 1)) | |
323 | ((eq? eqv? equal?) | |
324 | (= (length args) 2)) | |
325 | ;; FIXME: add more cases? | |
326 | (else #f))) | |
327 | ||
328 | (define* (peval exp #:optional (cenv (current-module)) (env vlist-null) | |
329 | #:key | |
330 | (operator-size-limit 40) | |
331 | (operand-size-limit 20) | |
332 | (value-size-limit 10) | |
333 | (effort-limit 500) | |
334 | (recursive-effort-limit 100)) | |
335 | "Partially evaluate EXP in compilation environment CENV, with | |
47974c30 | 336 | top-level bindings from ENV and return the resulting expression." |
b275fb26 AW |
337 | |
338 | ;; This is a simple partial evaluator. It effectively performs | |
339 | ;; constant folding, copy propagation, dead code elimination, and | |
47974c30 AW |
340 | ;; inlining. |
341 | ||
342 | ;; TODO: | |
343 | ;; | |
344 | ;; Propagate copies across toplevel bindings, if we can prove the | |
345 | ;; bindings to be immutable. | |
b275fb26 | 346 | ;; |
47974c30 | 347 | ;; Specialize lambda expressions with invariant arguments. |
b275fb26 AW |
348 | |
349 | (define local-toplevel-env | |
350 | ;; The top-level environment of the module being compiled. | |
351 | (match exp | |
352 | (($ <toplevel-define> _ name) | |
353 | (vhash-consq name #t env)) | |
354 | (($ <sequence> _ exps) | |
355 | (fold (lambda (x r) | |
356 | (match x | |
357 | (($ <toplevel-define> _ name) | |
358 | (vhash-consq name #t r)) | |
359 | (_ r))) | |
360 | env | |
361 | exps)) | |
362 | (_ env))) | |
363 | ||
364 | (define (local-toplevel? name) | |
365 | (vhash-assq name local-toplevel-env)) | |
366 | ||
47974c30 AW |
367 | ;; gensym -> <var> |
368 | ;; renamed-term -> original-term | |
369 | ;; | |
b275fb26 AW |
370 | (define store (build-var-table exp)) |
371 | ||
4bf9e928 AW |
372 | (define (record-new-temporary! name sym refcount) |
373 | (set! store (vhash-consq sym (make-var name sym refcount #f) store))) | |
374 | ||
75170872 | 375 | (define (lookup-var sym) |
b275fb26 | 376 | (let ((v (vhash-assq sym store))) |
75170872 AW |
377 | (if v (cdr v) (error "unbound var" sym (vlist->list store))))) |
378 | ||
379 | (define (fresh-gensyms vars) | |
380 | (map (lambda (var) | |
381 | (let ((new (gensym (string-append (symbol->string (var-name var)) | |
382 | " ")))) | |
383 | (set! store (vhash-consq new var store)) | |
384 | new)) | |
385 | vars)) | |
386 | ||
387 | (define (assigned-lexical? sym) | |
388 | (var-set? (lookup-var sym))) | |
b275fb26 AW |
389 | |
390 | (define (lexical-refcount sym) | |
75170872 | 391 | (var-refcount (lookup-var sym))) |
b275fb26 | 392 | |
47974c30 AW |
393 | ;; ORIG has been alpha-renamed to NEW. Analyze NEW and record a link |
394 | ;; from it to ORIG. | |
395 | ;; | |
b275fb26 | 396 | (define (record-source-expression! orig new) |
75170872 | 397 | (set! store (vhash-consq new (source-expression orig) store)) |
b275fb26 AW |
398 | new) |
399 | ||
47974c30 AW |
400 | ;; Find the source expression corresponding to NEW. Used to detect |
401 | ;; recursive inlining attempts. | |
402 | ;; | |
b275fb26 AW |
403 | (define (source-expression new) |
404 | (let ((x (vhash-assq new store))) | |
405 | (if x (cdr x) new))) | |
406 | ||
75170872 AW |
407 | (define* (residualize-lexical op #:optional ctx val) |
408 | (log 'residualize op) | |
409 | (set-operand-residualize?! op #t) | |
410 | (if (eq? ctx 'value) | |
411 | (set-operand-residual-value! op val)) | |
412 | (make-lexical-ref #f (var-name (operand-var op)) (operand-sym op))) | |
b275fb26 AW |
413 | |
414 | (define (apply-primitive name args) | |
415 | ;; todo: further optimize commutative primitives | |
416 | (catch #t | |
417 | (lambda () | |
418 | (call-with-values | |
419 | (lambda () | |
420 | (apply (module-ref the-scm-module name) args)) | |
421 | (lambda results | |
422 | (values #t results)))) | |
423 | (lambda _ | |
424 | (values #f '())))) | |
425 | ||
30fcf30f AW |
426 | (define (make-values src values) |
427 | (match values | |
428 | ((single) single) ; 1 value | |
429 | ((_ ...) ; 0, or 2 or more values | |
430 | (make-application src (make-primitive-ref src 'values) | |
431 | values)))) | |
432 | ||
433 | (define (fold-constants src name args ctx) | |
434 | (define (residualize-call) | |
435 | (make-application src (make-primitive-ref #f name) args)) | |
436 | (cond | |
437 | ((every const? args) | |
438 | (let-values (((success? values) | |
439 | (apply-primitive name (map const-exp args)))) | |
440 | (log 'fold success? values name args) | |
441 | (if success? | |
442 | (case ctx | |
443 | ((effect) (make-void src)) | |
444 | ((test) | |
445 | ;; Values truncation: only take the first | |
446 | ;; value. | |
447 | (if (pair? values) | |
448 | (make-const src (car values)) | |
449 | (make-values src '()))) | |
450 | (else | |
451 | (make-values src (map (cut make-const src <>) values)))) | |
452 | (residualize-call)))) | |
453 | ((and (eq? ctx 'effect) (types-check? name args)) | |
454 | (make-void #f)) | |
455 | (else | |
456 | (residualize-call)))) | |
457 | ||
b275fb26 AW |
458 | (define (inline-values exp src names gensyms body) |
459 | (let loop ((exp exp)) | |
460 | (match exp | |
461 | ;; Some expression types are always singly-valued. | |
462 | ((or ($ <const>) | |
463 | ($ <void>) | |
464 | ($ <lambda>) | |
465 | ($ <lexical-ref>) | |
466 | ($ <toplevel-ref>) | |
467 | ($ <module-ref>) | |
468 | ($ <primitive-ref>) | |
469 | ($ <dynref>) | |
470 | ($ <lexical-set>) ; FIXME: these set! expressions | |
471 | ($ <toplevel-set>) ; could return zero values in | |
472 | ($ <toplevel-define>) ; the future | |
473 | ($ <module-set>) ; | |
474 | ($ <dynset>)) ; | |
475 | (and (= (length names) 1) | |
476 | (make-let src names gensyms (list exp) body))) | |
477 | (($ <application> src | |
478 | ($ <primitive-ref> _ (? singly-valued-primitive? name))) | |
479 | (and (= (length names) 1) | |
480 | (make-let src names gensyms (list exp) body))) | |
481 | ||
482 | ;; Statically-known number of values. | |
483 | (($ <application> src ($ <primitive-ref> _ 'values) vals) | |
484 | (and (= (length names) (length vals)) | |
485 | (make-let src names gensyms vals body))) | |
486 | ||
487 | ;; Not going to copy code into both branches. | |
488 | (($ <conditional>) #f) | |
489 | ||
490 | ;; Bail on other applications. | |
491 | (($ <application>) #f) | |
492 | ||
493 | ;; Bail on prompt and abort. | |
494 | (($ <prompt>) #f) | |
495 | (($ <abort>) #f) | |
496 | ||
497 | ;; Propagate to tail positions. | |
498 | (($ <let> src names gensyms vals body) | |
499 | (let ((body (loop body))) | |
500 | (and body | |
501 | (make-let src names gensyms vals body)))) | |
502 | (($ <letrec> src in-order? names gensyms vals body) | |
503 | (let ((body (loop body))) | |
504 | (and body | |
505 | (make-letrec src in-order? names gensyms vals body)))) | |
506 | (($ <fix> src names gensyms vals body) | |
507 | (let ((body (loop body))) | |
508 | (and body | |
509 | (make-fix src names gensyms vals body)))) | |
510 | (($ <let-values> src exp | |
511 | ($ <lambda-case> src2 req opt rest kw inits gensyms body #f)) | |
512 | (let ((body (loop body))) | |
513 | (and body | |
514 | (make-let-values src exp | |
515 | (make-lambda-case src2 req opt rest kw | |
516 | inits gensyms body #f))))) | |
517 | (($ <dynwind> src winder body unwinder) | |
518 | (let ((body (loop body))) | |
519 | (and body | |
520 | (make-dynwind src winder body unwinder)))) | |
521 | (($ <dynlet> src fluids vals body) | |
522 | (let ((body (loop body))) | |
523 | (and body | |
524 | (make-dynlet src fluids vals body)))) | |
525 | (($ <sequence> src exps) | |
526 | (match exps | |
527 | ((head ... tail) | |
528 | (let ((tail (loop tail))) | |
529 | (and tail | |
530 | (make-sequence src (append head (list tail))))))))))) | |
531 | ||
b275fb26 | 532 | (define (constant-expression? x) |
16d3e013 AW |
533 | ;; Return true if X is constant, for the purposes of copying or |
534 | ;; elision---i.e., if it is known to have no effects, does not | |
535 | ;; allocate storage for a mutable object, and does not access | |
536 | ;; mutable data (like `car' or toplevel references). | |
b275fb26 AW |
537 | (let loop ((x x)) |
538 | (match x | |
539 | (($ <void>) #t) | |
540 | (($ <const>) #t) | |
541 | (($ <lambda>) #t) | |
16d3e013 AW |
542 | (($ <lambda-case> _ req opt rest kw inits syms body alternate) |
543 | (and (not (any assigned-lexical? syms)) | |
544 | (every loop inits) (loop body) | |
1082cbba | 545 | (or (not alternate) (loop alternate)))) |
b275fb26 AW |
546 | (($ <lexical-ref> _ _ gensym) |
547 | (not (assigned-lexical? gensym))) | |
548 | (($ <primitive-ref>) #t) | |
549 | (($ <conditional> _ condition subsequent alternate) | |
550 | (and (loop condition) (loop subsequent) (loop alternate))) | |
551 | (($ <application> _ ($ <primitive-ref> _ name) args) | |
552 | (and (effect-free-primitive? name) | |
553 | (not (constructor-primitive? name)) | |
f26c3a93 | 554 | (not (accessor-primitive? name)) |
b275fb26 AW |
555 | (types-check? name args) |
556 | (every loop args))) | |
557 | (($ <application> _ ($ <lambda> _ _ body) args) | |
558 | (and (loop body) (every loop args))) | |
559 | (($ <sequence> _ exps) | |
560 | (every loop exps)) | |
16d3e013 AW |
561 | (($ <let> _ _ syms vals body) |
562 | (and (not (any assigned-lexical? syms)) | |
563 | (every loop vals) (loop body))) | |
564 | (($ <letrec> _ _ _ syms vals body) | |
565 | (and (not (any assigned-lexical? syms)) | |
566 | (every loop vals) (loop body))) | |
b275fb26 AW |
567 | (($ <fix> _ _ _ vals body) |
568 | (and (every loop vals) (loop body))) | |
569 | (($ <let-values> _ exp body) | |
570 | (and (loop exp) (loop body))) | |
571 | (($ <prompt> _ tag body handler) | |
572 | (and (loop tag) (loop body) (loop handler))) | |
573 | (_ #f)))) | |
574 | ||
75170872 AW |
575 | (define (prune-bindings ops in-order? body counter ctx build-result) |
576 | ;; This helper handles both `let' and `letrec'/`fix'. In the latter | |
577 | ;; cases we need to make sure that if referenced binding A needs | |
578 | ;; as-yet-unreferenced binding B, that B is processed for value. | |
579 | ;; Likewise if C, when processed for effect, needs otherwise | |
580 | ;; unreferenced D, then D needs to be processed for value too. | |
581 | ;; | |
582 | (define (referenced? op) | |
583 | ;; When we visit lambdas in operator context, we just copy them, | |
584 | ;; as we will process their body later. However this does have | |
585 | ;; the problem that any free var referenced by the lambda is not | |
586 | ;; marked as needing residualization. Here we hack around this | |
587 | ;; and treat all bindings as referenced if we are in operator | |
588 | ;; context. | |
589 | (or (eq? ctx 'operator) (operand-residualize? op))) | |
590 | ||
591 | ;; values := (op ...) | |
592 | ;; effects := (op ...) | |
593 | (define (residualize values effects) | |
594 | ;; Note, values and effects are reversed. | |
595 | (cond | |
596 | (in-order? | |
597 | (let ((values (filter operand-residual-value ops))) | |
598 | (if (null? values) | |
b275fb26 | 599 | body |
75170872 AW |
600 | (build-result (map (compose var-name operand-var) values) |
601 | (map operand-sym values) | |
602 | (map operand-residual-value values) | |
603 | body)))) | |
604 | (else | |
605 | (let ((body | |
606 | (if (null? effects) | |
607 | body | |
608 | (let ((effect-vals (map operand-residual-value effects))) | |
609 | (make-sequence #f (reverse (cons body effect-vals))))))) | |
610 | (if (null? values) | |
611 | body | |
612 | (let ((values (reverse values))) | |
613 | (build-result (map (compose var-name operand-var) values) | |
614 | (map operand-sym values) | |
615 | (map operand-residual-value values) | |
616 | body))))))) | |
617 | ||
618 | ;; old := (bool ...) | |
619 | ;; values := (op ...) | |
620 | ;; effects := ((op . value) ...) | |
621 | (let prune ((old (map referenced? ops)) (values '()) (effects '())) | |
622 | (let lp ((ops* ops) (values values) (effects effects)) | |
623 | (cond | |
624 | ((null? ops*) | |
625 | (let ((new (map referenced? ops))) | |
626 | (if (not (equal? new old)) | |
627 | (prune new values '()) | |
628 | (residualize values | |
629 | (map (lambda (op val) | |
630 | (set-operand-residual-value! op val) | |
631 | op) | |
632 | (map car effects) (map cdr effects)))))) | |
633 | (else | |
634 | (let ((op (car ops*))) | |
635 | (cond | |
636 | ((memq op values) | |
637 | (lp (cdr ops*) values effects)) | |
638 | ((operand-residual-value op) | |
639 | (lp (cdr ops*) (cons op values) effects)) | |
640 | ((referenced? op) | |
641 | (set-operand-residual-value! op (visit-operand op counter 'value)) | |
642 | (lp (cdr ops*) (cons op values) effects)) | |
643 | (else | |
644 | (lp (cdr ops*) | |
645 | values | |
646 | (let ((effect (visit-operand op counter 'effect))) | |
647 | (if (void? effect) | |
648 | effects | |
649 | (acons op effect effects)))))))))))) | |
b275fb26 AW |
650 | |
651 | (define (small-expression? x limit) | |
652 | (let/ec k | |
653 | (tree-il-fold | |
654 | (lambda (x res) ; leaf | |
655 | (1+ res)) | |
656 | (lambda (x res) ; down | |
657 | (1+ res)) | |
658 | (lambda (x res) ; up | |
659 | (if (< res limit) | |
660 | res | |
661 | (k #f))) | |
662 | 0 x) | |
663 | #t)) | |
664 | ||
75170872 AW |
665 | (define (extend-env sym op env) |
666 | (vhash-consq (operand-sym op) op (vhash-consq sym op env))) | |
667 | ||
b275fb26 | 668 | (let loop ((exp exp) |
75170872 | 669 | (env vlist-null) ; vhash of gensym -> <operand> |
b275fb26 | 670 | (counter #f) ; inlined call stack |
75170872 | 671 | (ctx 'value)) ; effect, value, test, operator, or call |
b275fb26 | 672 | (define (lookup var) |
75170872 AW |
673 | (cond |
674 | ((vhash-assq var env) => cdr) | |
675 | (else (error "unbound var" var)))) | |
b275fb26 | 676 | |
904981ee | 677 | (define (visit exp ctx) |
b275fb26 AW |
678 | (loop exp env counter ctx)) |
679 | ||
904981ee | 680 | (define (for-value exp) (visit exp 'value)) |
904981ee AW |
681 | (define (for-test exp) (visit exp 'test)) |
682 | (define (for-effect exp) (visit exp 'effect)) | |
75170872 | 683 | (define (for-call exp) (visit exp 'call)) |
904981ee AW |
684 | (define (for-tail exp) (visit exp ctx)) |
685 | ||
b275fb26 AW |
686 | (if counter |
687 | (record-effort! counter)) | |
688 | ||
41d43584 AW |
689 | (log 'visit ctx (and=> counter effort-counter) |
690 | (unparse-tree-il exp)) | |
691 | ||
b275fb26 AW |
692 | (match exp |
693 | (($ <const>) | |
694 | (case ctx | |
695 | ((effect) (make-void #f)) | |
696 | (else exp))) | |
697 | (($ <void>) | |
698 | (case ctx | |
699 | ((test) (make-const #f #t)) | |
700 | (else exp))) | |
701 | (($ <lexical-ref> _ _ gensym) | |
75170872 AW |
702 | (log 'begin-copy gensym) |
703 | (let ((op (lookup gensym))) | |
704 | (cond | |
705 | ((eq? ctx 'effect) | |
706 | (log 'lexical-for-effect gensym) | |
707 | (make-void #f)) | |
708 | ((eq? ctx 'call) | |
709 | ;; Don't propagate copies if we are residualizing a call. | |
710 | (log 'residualize-lexical-call gensym op) | |
711 | (residualize-lexical op)) | |
712 | ((var-set? (operand-var op)) | |
713 | ;; Assigned lexicals don't copy-propagate. | |
714 | (log 'assigned-var gensym op) | |
715 | (residualize-lexical op)) | |
716 | ((not (operand-copyable? op)) | |
717 | ;; We already know that this operand is not copyable. | |
718 | (log 'not-copyable gensym op) | |
719 | (residualize-lexical op)) | |
720 | ((and=> (operand-constant-value op) | |
721 | (lambda (x) (or (const? x) (void? x) (primitive-ref? x)))) | |
722 | ;; A cache hit. | |
723 | (let ((val (operand-constant-value op))) | |
724 | (log 'memoized-constant gensym val) | |
725 | (for-tail val))) | |
726 | ((visit-operand op counter ctx recursive-effort-limit operand-size-limit) | |
727 | => | |
728 | ;; If we end up deciding to residualize this value instead of | |
729 | ;; copying it, save that residualized value. | |
730 | (lambda (val) | |
731 | (cond | |
732 | ((not (constant-expression? val)) | |
733 | (log 'not-constant gensym op) | |
734 | ;; At this point, ctx is operator, test, or value. A | |
735 | ;; value that is non-constant in one context will be | |
736 | ;; non-constant in the others, so it's safe to record | |
737 | ;; that here, and avoid future visits. | |
738 | (set-operand-copyable?! op #f) | |
739 | (residualize-lexical op ctx val)) | |
740 | ((or (const? val) | |
741 | (void? val) | |
742 | (primitive-ref? val)) | |
743 | ;; Always propagate simple values that cannot lead to | |
744 | ;; code bloat. | |
745 | (log 'copy-simple gensym val) | |
746 | ;; It could be this constant is the result of folding. | |
747 | ;; If that is the case, cache it. This helps loop | |
748 | ;; unrolling get farther. | |
749 | (if (eq? ctx 'value) | |
750 | (begin | |
751 | (log 'memoize-constant gensym val) | |
752 | (set-operand-constant-value! op val))) | |
753 | val) | |
754 | ((= 1 (var-refcount (operand-var op))) | |
755 | ;; Always propagate values referenced only once. | |
756 | (log 'copy-single gensym val) | |
757 | val) | |
758 | ;; FIXME: do demand-driven size accounting rather than | |
759 | ;; these heuristics. | |
760 | ((eq? ctx 'operator) | |
761 | ;; A pure expression in the operator position. Inline | |
762 | ;; if it's a lambda that's small enough. | |
763 | (if (and (lambda? val) | |
764 | (small-expression? val operator-size-limit)) | |
765 | (begin | |
766 | (log 'copy-operator gensym val) | |
767 | val) | |
768 | (begin | |
769 | (log 'too-big-for-operator gensym val) | |
770 | (residualize-lexical op ctx val)))) | |
771 | (else | |
772 | ;; A pure expression, processed for call or for value. | |
773 | ;; Don't inline lambdas, because they will probably won't | |
774 | ;; fold because we don't know the operator. | |
775 | (if (and (small-expression? val value-size-limit) | |
776 | (not (tree-il-any lambda? val))) | |
777 | (begin | |
778 | (log 'copy-value gensym val) | |
779 | val) | |
780 | (begin | |
781 | (log 'too-big-or-has-lambda gensym val) | |
782 | (residualize-lexical op ctx val))))))) | |
783 | (else | |
784 | ;; Visit failed. Either the operand isn't bound, as in | |
785 | ;; lambda formal parameters, or the copy was aborted. | |
786 | (log 'unbound-or-aborted gensym op) | |
787 | (residualize-lexical op))))) | |
b275fb26 | 788 | (($ <lexical-set> src name gensym exp) |
75170872 AW |
789 | (let ((op (lookup gensym))) |
790 | (if (zero? (var-refcount (operand-var op))) | |
791 | (let ((exp (for-effect exp))) | |
792 | (if (void? exp) | |
793 | exp | |
794 | (make-sequence src (list exp (make-void #f))))) | |
795 | (begin | |
796 | (set-operand-residualize?! op #t) | |
797 | (make-lexical-set src name (operand-sym op) (for-value exp)))))) | |
b275fb26 | 798 | (($ <let> src names gensyms vals body) |
75170872 AW |
799 | (let* ((vars (map lookup-var gensyms)) |
800 | (new (fresh-gensyms vars)) | |
801 | (ops (make-bound-operands vars new vals | |
802 | (lambda (exp counter ctx) | |
803 | (loop exp env counter ctx)))) | |
804 | (env (fold extend-env env gensyms ops)) | |
805 | (body (loop body env counter ctx))) | |
b275fb26 AW |
806 | (cond |
807 | ((const? body) | |
808 | (for-tail (make-sequence src (append vals (list body))))) | |
809 | ((and (lexical-ref? body) | |
75170872 | 810 | (memq (lexical-ref-gensym body) new)) |
b275fb26 | 811 | (let ((sym (lexical-ref-gensym body)) |
75170872 | 812 | (pairs (map cons new vals))) |
b275fb26 AW |
813 | ;; (let ((x foo) (y bar) ...) x) => (begin bar ... foo) |
814 | (for-tail | |
815 | (make-sequence | |
816 | src | |
817 | (append (map cdr (alist-delete sym pairs eq?)) | |
818 | (list (assq-ref pairs sym))))))) | |
819 | (else | |
820 | ;; Only include bindings for which lexical references | |
821 | ;; have been residualized. | |
75170872 | 822 | (prune-bindings ops #f body counter ctx |
b275fb26 AW |
823 | (lambda (names gensyms vals body) |
824 | (if (null? names) (error "what!" names)) | |
825 | (make-let src names gensyms vals body))))))) | |
826 | (($ <letrec> src in-order? names gensyms vals body) | |
75170872 AW |
827 | ;; Note the difference from the `let' case: here we use letrec* |
828 | ;; so that the `visit' procedure for the new operands closes over | |
829 | ;; an environment that includes the operands. | |
830 | (letrec* ((visit (lambda (exp counter ctx) | |
831 | (loop exp env* counter ctx))) | |
832 | (vars (map lookup-var gensyms)) | |
833 | (new (fresh-gensyms vars)) | |
834 | (ops (make-bound-operands vars new vals visit)) | |
835 | (env* (fold extend-env env gensyms ops)) | |
836 | (body* (visit body counter ctx))) | |
16d3e013 AW |
837 | (if (and (const? body*) (every constant-expression? vals)) |
838 | ;; We may have folded a loop completely, even though there | |
839 | ;; might be cyclical references between the bound values. | |
840 | ;; Handle this degenerate case specially. | |
75170872 AW |
841 | body* |
842 | (prune-bindings ops in-order? body* counter ctx | |
b275fb26 AW |
843 | (lambda (names gensyms vals body) |
844 | (make-letrec src in-order? | |
845 | names gensyms vals body)))))) | |
846 | (($ <fix> src names gensyms vals body) | |
75170872 AW |
847 | (letrec* ((visit (lambda (exp counter ctx) |
848 | (loop exp env* counter ctx))) | |
849 | (vars (map lookup-var gensyms)) | |
850 | (new (fresh-gensyms vars)) | |
851 | (ops (make-bound-operands vars new vals visit)) | |
852 | (env* (fold extend-env env gensyms ops)) | |
853 | (body* (visit body counter ctx))) | |
854 | (if (const? body*) | |
855 | body* | |
856 | (prune-bindings ops #f body* counter ctx | |
b275fb26 AW |
857 | (lambda (names gensyms vals body) |
858 | (make-fix src names gensyms vals body)))))) | |
859 | (($ <let-values> lv-src producer consumer) | |
860 | ;; Peval the producer, then try to inline the consumer into | |
861 | ;; the producer. If that succeeds, peval again. Otherwise | |
862 | ;; reconstruct the let-values, pevaling the consumer. | |
863 | (let ((producer (for-value producer))) | |
864 | (or (match consumer | |
865 | (($ <lambda-case> src req #f #f #f () gensyms body #f) | |
866 | (cond | |
867 | ((inline-values producer src req gensyms body) | |
868 | => for-tail) | |
869 | (else #f))) | |
870 | (_ #f)) | |
871 | (make-let-values lv-src producer (for-tail consumer))))) | |
872 | (($ <dynwind> src winder body unwinder) | |
873 | (make-dynwind src (for-value winder) (for-tail body) | |
874 | (for-value unwinder))) | |
875 | (($ <dynlet> src fluids vals body) | |
876 | (make-dynlet src (map for-value fluids) (map for-value vals) | |
877 | (for-tail body))) | |
878 | (($ <dynref> src fluid) | |
879 | (make-dynref src (for-value fluid))) | |
880 | (($ <dynset> src fluid exp) | |
881 | (make-dynset src (for-value fluid) (for-value exp))) | |
882 | (($ <toplevel-ref> src (? effect-free-primitive? name)) | |
883 | (if (local-toplevel? name) | |
884 | exp | |
75170872 AW |
885 | (let ((exp (resolve-primitives! exp cenv))) |
886 | (if (primitive-ref? exp) | |
887 | (for-tail exp) | |
888 | exp)))) | |
b275fb26 AW |
889 | (($ <toplevel-ref>) |
890 | ;; todo: open private local bindings. | |
891 | exp) | |
16d50b8e LC |
892 | (($ <module-ref> src module (? effect-free-primitive? name) #f) |
893 | (let ((module (false-if-exception | |
894 | (resolve-module module #:ensure #f)))) | |
895 | (if (module? module) | |
896 | (let ((var (module-variable module name))) | |
897 | (if (eq? var (module-variable the-scm-module name)) | |
898 | (make-primitive-ref src name) | |
899 | exp)) | |
900 | exp))) | |
b275fb26 AW |
901 | (($ <module-ref>) |
902 | exp) | |
903 | (($ <module-set> src mod name public? exp) | |
904 | (make-module-set src mod name public? (for-value exp))) | |
905 | (($ <toplevel-define> src name exp) | |
906 | (make-toplevel-define src name (for-value exp))) | |
907 | (($ <toplevel-set> src name exp) | |
908 | (make-toplevel-set src name (for-value exp))) | |
909 | (($ <primitive-ref>) | |
910 | (case ctx | |
911 | ((effect) (make-void #f)) | |
912 | ((test) (make-const #f #t)) | |
913 | (else exp))) | |
914 | (($ <conditional> src condition subsequent alternate) | |
915 | (let ((condition (for-test condition))) | |
916 | (if (const? condition) | |
917 | (if (const-exp condition) | |
918 | (for-tail subsequent) | |
919 | (for-tail alternate)) | |
920 | (make-conditional src condition | |
921 | (for-tail subsequent) | |
922 | (for-tail alternate))))) | |
923 | (($ <application> src | |
924 | ($ <primitive-ref> _ '@call-with-values) | |
925 | (producer | |
926 | ($ <lambda> _ _ | |
927 | (and consumer | |
928 | ;; No optional or kwargs. | |
929 | ($ <lambda-case> | |
930 | _ req #f rest #f () gensyms body #f))))) | |
931 | (for-tail (make-let-values src (make-application src producer '()) | |
932 | consumer))) | |
933 | ||
934 | (($ <application> src orig-proc orig-args) | |
935 | ;; todo: augment the global env with specialized functions | |
75170872 | 936 | (let ((proc (visit orig-proc 'operator))) |
b275fb26 AW |
937 | (match proc |
938 | (($ <primitive-ref> _ (? constructor-primitive? name)) | |
75170872 AW |
939 | (cond |
940 | ((and (memq ctx '(effect test)) | |
941 | (match (cons name orig-args) | |
942 | ((or ('cons _ _) | |
943 | ('list . _) | |
944 | ('vector . _) | |
945 | ('make-prompt-tag) | |
946 | ('make-prompt-tag ($ <const> _ (? string?)))) | |
947 | #t) | |
948 | (_ #f))) | |
949 | ;; Some expressions can be folded without visiting the | |
950 | ;; arguments for value. | |
951 | (let ((res (if (eq? ctx 'effect) | |
952 | (make-void #f) | |
953 | (make-const #f #t)))) | |
954 | (for-tail (make-sequence src (append orig-args (list res)))))) | |
955 | (else | |
956 | (match (cons name (map for-value orig-args)) | |
957 | (('cons head tail) | |
958 | (match tail | |
959 | (($ <const> src ()) | |
960 | (make-application src (make-primitive-ref #f 'list) | |
961 | (list head))) | |
962 | (($ <application> src ($ <primitive-ref> _ 'list) elts) | |
963 | (make-application src (make-primitive-ref #f 'list) | |
964 | (cons head elts))) | |
f26c3a93 | 965 | (_ (make-application src proc (list head tail))))) |
75170872 AW |
966 | ((_ . args) |
967 | (make-application src proc args)))))) | |
f26c3a93 AW |
968 | (($ <primitive-ref> _ (? accessor-primitive? name)) |
969 | (match (cons name (map for-value orig-args)) | |
970 | ;; FIXME: these for-tail recursions could take place outside | |
971 | ;; an effort counter. | |
972 | (('car ($ <application> src ($ <primitive-ref> _ 'cons) (head tail))) | |
973 | (for-tail (make-sequence src (list tail head)))) | |
974 | (('cdr ($ <application> src ($ <primitive-ref> _ 'cons) (head tail))) | |
975 | (for-tail (make-sequence src (list head tail)))) | |
976 | (('car ($ <application> src ($ <primitive-ref> _ 'list) (head . tail))) | |
977 | (for-tail (make-sequence src (append tail (list head))))) | |
978 | (('cdr ($ <application> src ($ <primitive-ref> _ 'list) (head . tail))) | |
979 | (for-tail (make-sequence | |
980 | src | |
981 | (list head | |
982 | (make-application | |
983 | src (make-primitive-ref #f 'list) tail))))) | |
984 | ||
985 | (('car ($ <const> src (head . tail))) | |
986 | (for-tail (make-const src head))) | |
987 | (('cdr ($ <const> src (head . tail))) | |
988 | (for-tail (make-const src tail))) | |
4bf9e928 AW |
989 | (((or 'memq 'memv) k ($ <const> _ (elts ...))) |
990 | ;; FIXME: factor | |
991 | (case ctx | |
992 | ((effect) | |
993 | (for-tail | |
994 | (make-sequence src (list k (make-void #f))))) | |
995 | ((test) | |
996 | (cond | |
997 | ((const? k) | |
998 | ;; A shortcut. The `else' case would handle it, but | |
999 | ;; this way is faster. | |
1000 | (let ((member (case name ((memq) memq) ((memv) memv)))) | |
1001 | (make-const #f (and (member (const-exp k) elts) #t)))) | |
1002 | ((null? elts) | |
1003 | (for-tail | |
1004 | (make-sequence src (list k (make-const #f #f))))) | |
1005 | (else | |
1006 | (let ((t (gensym "t ")) | |
1007 | (eq (if (eq? name 'memq) 'eq? 'eqv?))) | |
1008 | (record-new-temporary! 't t (length elts)) | |
1009 | (for-tail | |
1010 | (make-let | |
1011 | src (list 't) (list t) (list k) | |
1012 | (let lp ((elts elts)) | |
1013 | (define test | |
1014 | (make-application | |
1015 | #f (make-primitive-ref #f eq) | |
1016 | (list (make-lexical-ref #f 't t) | |
1017 | (make-const #f (car elts))))) | |
1018 | (if (null? (cdr elts)) | |
1019 | test | |
1020 | (make-conditional src test | |
1021 | (make-const #f #t) | |
1022 | (lp (cdr elts))))))))))) | |
1023 | (else | |
1024 | (cond | |
1025 | ((const? k) | |
1026 | (let ((member (case name ((memq) memq) ((memv) memv)))) | |
1027 | (make-const #f (member (const-exp k) elts)))) | |
1028 | ((null? elts) | |
1029 | (for-tail (make-sequence src (list k (make-const #f #f))))) | |
1030 | (else | |
1031 | (make-application src proc (list k (make-const #f elts)))))))) | |
f26c3a93 | 1032 | ((_ . args) |
30fcf30f AW |
1033 | (or (fold-constants src name args ctx) |
1034 | (make-application src proc args))))) | |
b275fb26 AW |
1035 | (($ <primitive-ref> _ (? effect-free-primitive? name)) |
1036 | (let ((args (map for-value orig-args))) | |
30fcf30f AW |
1037 | (or (fold-constants src name args ctx) |
1038 | (make-application src proc args)))) | |
b275fb26 AW |
1039 | (($ <lambda> _ _ |
1040 | ($ <lambda-case> _ req opt #f #f inits gensyms body #f)) | |
1041 | ;; Simple case: no rest, no keyword arguments. | |
1042 | ;; todo: handle the more complex cases | |
1043 | (let* ((nargs (length orig-args)) | |
1044 | (nreq (length req)) | |
1045 | (nopt (if opt (length opt) 0)) | |
1046 | (key (source-expression proc))) | |
1047 | (cond | |
1048 | ((or (< nargs nreq) (> nargs (+ nreq nopt))) | |
1049 | ;; An error, or effecting arguments. | |
75170872 | 1050 | (make-application src (for-call orig-proc) |
b275fb26 AW |
1051 | (map for-value orig-args))) |
1052 | ((or (and=> (find-counter key counter) counter-recursive?) | |
1053 | (lambda? orig-proc)) | |
1054 | ;; A recursive call, or a lambda in the operator | |
1055 | ;; position of the source expression. Process again in | |
1056 | ;; tail context. | |
75170872 AW |
1057 | ;; |
1058 | ;; In the recursive case, mark intervening counters as | |
1059 | ;; recursive, so we can handle a toplevel counter that | |
1060 | ;; recurses mutually with some other procedure. | |
1061 | ;; Otherwise, the next time we see the other procedure, | |
1062 | ;; the effort limit would be clamped to 100. | |
1063 | ;; | |
1064 | (let ((found (find-counter key counter))) | |
1065 | (if (and found (counter-recursive? found)) | |
1066 | (let lp ((counter counter)) | |
1067 | (if (not (eq? counter found)) | |
1068 | (begin | |
1069 | (set-counter-recursive?! counter #t) | |
1070 | (lp (counter-prev counter))))))) | |
1071 | ||
41d43584 | 1072 | (log 'inline-recurse key) |
b275fb26 AW |
1073 | (loop (make-let src (append req (or opt '())) |
1074 | gensyms | |
1075 | (append orig-args | |
1076 | (drop inits (- nargs nreq))) | |
1077 | body) | |
1078 | env counter ctx)) | |
1079 | (else | |
1080 | ;; An integration at the top-level, the first | |
1081 | ;; recursion of a recursive procedure, or a nested | |
1082 | ;; integration of a procedure that hasn't been seen | |
1083 | ;; yet. | |
41d43584 | 1084 | (log 'inline-begin exp) |
b275fb26 AW |
1085 | (let/ec k |
1086 | (define (abort) | |
41d43584 | 1087 | (log 'inline-abort exp) |
75170872 | 1088 | (k (make-application src (for-call orig-proc) |
b275fb26 AW |
1089 | (map for-value orig-args)))) |
1090 | (define new-counter | |
1091 | (cond | |
1092 | ;; These first two cases will transfer effort | |
1093 | ;; from the current counter into the new | |
1094 | ;; counter. | |
1095 | ((find-counter key counter) | |
1096 | => (lambda (prev) | |
1097 | (make-recursive-counter recursive-effort-limit | |
1098 | operand-size-limit | |
1099 | prev counter))) | |
1100 | (counter | |
1101 | (make-nested-counter abort key counter)) | |
1102 | ;; This case opens a new account, effectively | |
1103 | ;; printing money. It should only do so once | |
1104 | ;; for each call site in the source program. | |
1105 | (else | |
1106 | (make-top-counter effort-limit operand-size-limit | |
1107 | abort key)))) | |
1108 | (define result | |
1109 | (loop (make-let src (append req (or opt '())) | |
1110 | gensyms | |
1111 | (append orig-args | |
1112 | (drop inits (- nargs nreq))) | |
1113 | body) | |
1114 | env new-counter ctx)) | |
1115 | ||
1116 | (if counter | |
1117 | ;; The nested inlining attempt succeeded. | |
1118 | ;; Deposit the unspent effort and size back | |
1119 | ;; into the current counter. | |
1120 | (transfer! new-counter counter)) | |
1121 | ||
41d43584 | 1122 | (log 'inline-end result exp) |
b275fb26 AW |
1123 | result))))) |
1124 | (_ | |
75170872 | 1125 | (make-application src (for-call orig-proc) |
b275fb26 AW |
1126 | (map for-value orig-args)))))) |
1127 | (($ <lambda> src meta body) | |
1128 | (case ctx | |
1129 | ((effect) (make-void #f)) | |
1130 | ((test) (make-const #f #t)) | |
1131 | ((operator) exp) | |
75170872 AW |
1132 | (else (record-source-expression! |
1133 | exp | |
1134 | (make-lambda src meta (for-tail body)))))) | |
b275fb26 | 1135 | (($ <lambda-case> src req opt rest kw inits gensyms body alt) |
75170872 AW |
1136 | (let* ((vars (map lookup-var gensyms)) |
1137 | (new (fresh-gensyms vars)) | |
1138 | (env (fold extend-env env gensyms | |
1139 | (make-unbound-operands vars new))) | |
1140 | (new-sym (lambda (old) | |
1141 | (operand-sym (cdr (vhash-assq old env)))))) | |
1142 | (make-lambda-case src req opt rest | |
1143 | (match kw | |
1144 | ((aok? (kw name old) ...) | |
1145 | (cons aok? (map list kw name (map new-sym old)))) | |
1146 | (_ #f)) | |
1147 | (map (cut loop <> env counter 'value) inits) | |
1148 | new | |
1149 | (loop body env counter ctx) | |
1150 | (and alt (for-tail alt))))) | |
b275fb26 AW |
1151 | (($ <sequence> src exps) |
1152 | (let lp ((exps exps) (effects '())) | |
1153 | (match exps | |
1154 | ((last) | |
1155 | (if (null? effects) | |
1156 | (for-tail last) | |
1157 | (make-sequence | |
1158 | src | |
1159 | (reverse (cons (for-tail last) effects))))) | |
1160 | ((head . rest) | |
1161 | (let ((head (for-effect head))) | |
1162 | (cond | |
1163 | ((sequence? head) | |
1164 | (lp (append (sequence-exps head) rest) effects)) | |
1165 | ((void? head) | |
1166 | (lp rest effects)) | |
1167 | (else | |
1168 | (lp rest (cons head effects))))))))) | |
1169 | (($ <prompt> src tag body handler) | |
1170 | (define (singly-used-definition x) | |
1171 | (cond | |
1172 | ((and (lexical-ref? x) | |
1173 | ;; Only fetch definitions with single uses. | |
1174 | (= (lexical-refcount (lexical-ref-gensym x)) 1) | |
1175 | (lookup (lexical-ref-gensym x))) | |
75170872 AW |
1176 | => (lambda (x) |
1177 | (singly-used-definition (visit-operand x counter 'value 10 10)))) | |
b275fb26 AW |
1178 | (else x))) |
1179 | (match (singly-used-definition tag) | |
1180 | (($ <application> _ ($ <primitive-ref> _ 'make-prompt-tag) | |
1181 | (or () ((? constant-expression?)))) | |
1182 | ;; There is no way that an <abort> could know the tag | |
1183 | ;; for this <prompt>, so we can elide the <prompt> | |
1184 | ;; entirely. | |
1185 | (for-tail body)) | |
1186 | (_ | |
1187 | (make-prompt src (for-value tag) (for-tail body) | |
1188 | (for-value handler))))) | |
1189 | (($ <abort> src tag args tail) | |
1190 | (make-abort src (for-value tag) (map for-value args) | |
1191 | (for-value tail)))))) |