File size: 18,876 Bytes
3dcad1f |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 |
;;; Guile VM frame functions
;;; Copyright (C) 2001, 2005, 2009-2016, 2018 Free Software Foundation, Inc.
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;; Code:
(define-module (system vm frame)
#:use-module (system vm program)
#:use-module (system vm debug)
#:use-module (system vm disassembler)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 match)
#:export (binding-index
binding-name
binding-slot
binding-representation
frame-bindings
frame-lookup-binding
binding-ref binding-set!
frame-call-representation
frame-return-values
frame-environment
frame-object-binding frame-object-name))
(eval-when (expand compile load eval)
(load-extension (string-append "libguile-" (effective-version))
"scm_init_frames_builtins"))
(define-record-type <binding>
(make-binding frame idx name slot representation)
binding?
(frame binding-frame)
(idx binding-index)
(name binding-name)
(slot binding-slot)
(representation binding-representation))
(define (parse-code code)
(let ((len (bytevector-length code)))
(let lp ((pos 0) (out '()))
(cond
((< pos len)
(let* ((inst-len (instruction-length code pos))
(pos (+ pos inst-len)))
(unless (<= pos len)
(error "Failed to parse codestream"))
(lp pos (cons inst-len out))))
(else
(list->vector (reverse out)))))))
(define (compute-predecessors code parsed)
(let ((preds (make-vector (vector-length parsed) '())))
(define (add-pred! from target)
(let lp ((to from) (target target))
(cond
((negative? target)
(lp (1- to) (+ target (vector-ref parsed (1- to)))))
((positive? target)
(lp (1+ to) (- target (vector-ref parsed to))))
((= to (vector-length preds))
;; This can happen when an arity fails to match. Just ignore
;; this case.
#t)
(else
(vector-set! preds to (cons from (vector-ref preds to)))))))
(let lp ((n 0) (pos 0))
(when (< n (vector-length preds))
(when (instruction-has-fallthrough? code pos)
(add-pred! n (vector-ref parsed n)))
(for-each (lambda (target)
(add-pred! n target))
(instruction-relative-jump-targets code pos))
(lp (1+ n) (+ pos (vector-ref parsed n)))))
preds))
(define (compute-frame-sizes code parsed initial-size)
(let ((in-sizes (make-vector (vector-length parsed) #f))
(out-sizes (make-vector (vector-length parsed) #f)))
;; This only computes all possible valid stack sizes if the bytecode
;; is sorted topologically. Guiles' compiler does this currently,
;; but if that changes we should do a proper pre-order visit. Of
;; course the bytecode has to be valid too.
(define (find-idx n diff)
(let lp ((n n) (diff diff))
(cond
((= n (vector-length parsed))
;; Possible for jumps to alternate arities.
#f)
((negative? diff)
(lp (1- n) (+ diff (vector-ref parsed (1- n)))))
((positive? diff)
(lp (1+ n) (- diff (vector-ref parsed n))))
(else n))))
(vector-set! in-sizes 0 initial-size)
(let lp ((n 0) (pos 0))
(define (offset->idx target)
(call-with-values (lambda ()
(if (>= target pos)
(values n pos)
(values 0 0)))
(lambda (n pos)
(let lp ((n n) (pos pos))
(cond
((= pos target) n)
((< pos target) (lp (1+ n) (+ pos (vector-ref parsed n))))
(else (error "bad target" target)))))))
(when (< n (vector-length parsed))
(let* ((in (vector-ref in-sizes n))
(out (instruction-stack-size-after code pos in)))
(vector-set! out-sizes n out)
(when out
(when (instruction-has-fallthrough? code pos)
(vector-set! in-sizes (1+ n) out))
(for-each (lambda (target)
(let ((idx (find-idx n target)))
(when idx
(vector-set! in-sizes idx out))))
(instruction-relative-jump-targets code pos))))
(lp (1+ n) (+ pos (vector-ref parsed n)))))
(values in-sizes out-sizes)))
(define (compute-genv parsed defs)
(let ((genv (make-vector (vector-length parsed) '())))
(define (add-def! pos var)
(vector-set! genv pos (cons var (vector-ref genv pos))))
(let lp ((var 0) (pos 0) (pc-offset 0))
(when (< var (vector-length defs))
(match (vector-ref defs var)
(#(name offset slot representation)
(when (< offset pc-offset)
(error "mismatch between def offsets and parsed code"))
(cond
((< pc-offset offset)
(lp var (1+ pos) (+ pc-offset (vector-ref parsed pos))))
(else
(add-def! pos var)
(lp (1+ var) pos pc-offset)))))))
genv))
(define (compute-defs-by-slot defs)
(let* ((nslots (match defs
(#(#(_ _ slot _) ...) (1+ (apply max slot)))))
(by-slot (make-vector nslots #f)))
(let lp ((n 0))
(when (< n nslots)
(vector-set! by-slot n (make-bitvector (vector-length defs) #f))
(lp (1+ n))))
(let lp ((n 0))
(when (< n (vector-length defs))
(match (vector-ref defs n)
(#(_ _ slot _)
(bitvector-set-bit! (vector-ref by-slot slot) n)
(lp (1+ n))))))
by-slot))
(define (compute-killv code parsed defs)
(let*-values (((defs-by-slot) (compute-defs-by-slot defs))
((initial-frame-size) (vector-length defs-by-slot))
((in-sizes out-sizes)
(compute-frame-sizes code parsed initial-frame-size))
((killv) (make-vector (vector-length parsed) #f)))
(define (kill-slot! n slot)
(bitvector-set-bits! (vector-ref killv n)
(vector-ref defs-by-slot slot)))
(let lp ((n 0))
(when (< n (vector-length killv))
(vector-set! killv n (make-bitvector (vector-length defs) #f))
(lp (1+ n))))
;; Some defs get into place without explicit instructions -- this is
;; the case if no shuffling need occur, for example. In any case,
;; mark them as killing any previous definitions at that slot.
(let lp ((var 0) (pos 0) (pc-offset 0))
(when (< var (vector-length defs))
(match (vector-ref defs var)
(#(name offset slot representation)
(when (< offset pc-offset)
(error "mismatch between def offsets and parsed code"))
(cond
((< pc-offset offset)
(lp var (1+ pos) (+ pc-offset (vector-ref parsed pos))))
(else
(kill-slot! pos slot)
(lp (1+ var) pos pc-offset)))))))
(let lp ((n 0) (pos 0))
(when (< n (vector-length parsed))
(for-each (lambda (slot)
(when (< slot (vector-length defs-by-slot))
(kill-slot! n slot)))
(let ((in (vector-ref in-sizes n))
(out (vector-ref out-sizes n)))
(instruction-slot-clobbers code pos in out)))
(lp (1+ n) (+ pos (vector-ref parsed n)))))
killv))
(define (available-bindings frame arity ip top-frame?)
(let* ((defs (list->vector (arity-definitions arity)))
(code (arity-code arity))
(parsed (parse-code code))
(len (vector-length parsed))
(preds (compute-predecessors code parsed))
(genv (compute-genv parsed defs))
(killv (compute-killv code parsed defs))
(inv (make-vector len #f))
(outv (make-vector len #f))
(tmp (make-bitvector (vector-length defs) #f)))
(define (bitvector-copy! dst src)
(bitvector-clear-all-bits! dst)
(bitvector-set-bits! dst src))
(define (bitvector-meet! accum src)
(bitvector-copy! tmp src)
(bitvector-flip-all-bits! tmp)
(bitvector-clear-bits! accum tmp))
(let lp ((n 0))
(when (< n len)
(vector-set! inv n (make-bitvector (vector-length defs) #f))
(vector-set! outv n (make-bitvector (vector-length defs) #f))
(lp (1+ n))))
(let lp ((n 0) (first? #t) (changed? #f))
(cond
((< n len)
(let ((in (vector-ref inv n))
(out (vector-ref outv n))
(kill (vector-ref killv n))
(gen (vector-ref genv n)))
(let ((out-count (or changed? (bitvector-count out))))
(if (zero? n)
(bitvector-clear-all-bits! in)
(bitvector-set-all-bits! in))
(let lp ((preds (vector-ref preds n)))
(match preds
(() #t)
((pred . preds)
(unless (and first? (<= n pred))
(bitvector-meet! in (vector-ref outv pred)))
(lp preds))))
(bitvector-copy! out in)
(bitvector-clear-bits! out kill)
(for-each (lambda (def)
(bitvector-set-bit! out def))
gen)
(lp (1+ n) first?
(or changed? (not (eqv? out-count (bitvector-count out))))))))
((or changed? first?)
(lp 0 #f #f))))
(let lp ((n 0) (offset (- ip (arity-low-pc arity))))
(when (< offset 0)
(error "ip did not correspond to an instruction boundary?"))
(if (zero? offset)
;; It shouldn't be the case that both OFFSET and N are zero
;; but TOP-FRAME? is false. Still, it could happen, as is
;; currently the case in frame-arguments.
(let ((live (if (or top-frame? (zero? n))
(vector-ref inv n)
;; If we're not at a top frame, the IP points
;; to the continuation -- but we haven't
;; returned and defined its values yet. The
;; set of live variables is the set that was
;; live going into the call, minus the set
;; killed by the call, but not including
;; values defined by the call.
(begin
(bitvector-copy! tmp (vector-ref inv (1- n)))
(bitvector-clear-bits! tmp (vector-ref killv (1- n)))
tmp))))
(let lp ((n 0))
(let ((n (bitvector-position live #t n)))
(if n
(match (vector-ref defs n)
(#(name def-offset slot representation)
(cons (make-binding frame n name slot representation)
(lp (1+ n)))))
'()))))
(lp (1+ n) (- offset (vector-ref parsed n)))))))
(define* (frame-bindings frame #:optional top-frame?)
(let ((ip (frame-instruction-pointer frame)))
(cond
((find-program-arity ip)
=> (lambda (arity)
(available-bindings frame arity ip top-frame?)))
(else '()))))
(define (frame-lookup-binding frame var)
(let lp ((bindings (frame-bindings frame)))
(cond ((null? bindings)
#f)
((eq? (binding-name (car bindings)) var)
(car bindings))
(else
(lp (cdr bindings))))))
(define (binding-ref binding)
(frame-local-ref (or (binding-frame binding)
(error "binding has no frame" binding))
(binding-slot binding)
(binding-representation binding)))
(define (binding-set! binding val)
(frame-local-set! (or (binding-frame binding)
(error "binding has no frame" binding))
(binding-slot binding)
val
(binding-representation binding)))
(define* (frame-procedure-name frame #:key
(info (find-program-debug-info
(frame-instruction-pointer frame))))
(if info
(program-debug-info-name info)
(primitive-code-name (frame-instruction-pointer frame))))
;; This function is always called to get some sort of representation of the
;; frame to present to the user, so let's do the logical thing and dispatch to
;; frame-call-representation.
(define (frame-arguments frame)
(cdr (frame-call-representation frame)))
;;;
;;; Pretty printing
;;;
;; Basically there are three cases to deal with here:
;;
;; 1. We've already parsed the arguments, and bound them to local
;; variables. In a standard (lambda (a b c) ...) call, this doesn't
;; involve any argument shuffling; but with rest, optional, or
;; keyword arguments, the arguments as given to the procedure may
;; not correspond to what's on the stack. We reconstruct the
;; arguments using e.g. for the case above: `(,a ,b ,c). This works
;; for rest arguments too: (a b . c) => `(,a ,b . ,c)
;;
;; 2. We have failed to parse the arguments. Perhaps it's the wrong
;; number of arguments, or perhaps we're doing a typed dispatch and
;; the types don't match. In that case the arguments are all on the
;; stack, and nothing else is on the stack.
;;
;; 3. Alternately it's possible that we're between a primitive call
;; and its associated return. In that case, we won't be able to
;; say anything at all.
(define* (frame-call-representation frame #:key top-frame?)
(let* ((ip (frame-instruction-pointer frame))
(info (find-program-debug-info ip))
(nlocals (frame-num-locals frame)))
(define (find-slot i bindings)
(match bindings
(() #f)
(((and binding ($ <binding> frame idx name slot)) . bindings)
(if (< idx i)
(find-slot i bindings)
(and (= idx i) binding)))))
(define (local-ref i bindings)
(cond
((not bindings)
;; This case is only hit for primitives and application
;; arguments.
(frame-local-ref frame i 'scm))
((find-slot i bindings)
=> (lambda (binding)
(let* ((slot (binding-slot binding))
;; HACK: Avoid out-of-range from frame-local-ref.
;; Some frames have bindings beyond nlocals. That
;; is probably a bug somewhere else, but at least
;; this workaround allows them to be printed.
(val (if (< slot nlocals)
(frame-local-ref frame slot
(binding-representation binding))
;; else #<unspecified>
)))
;; It could be that there's a value that isn't clobbered
;; by a call but that isn't live after a call either. In
;; that case, if GC runs during the call, the value will
;; be collected, and on the stack it will be replaced
;; with the unspecified value. Assume that clobbering
;; values is more likely than passing the unspecified
;; value as an argument, and replace unspecified with _,
;; as if the binding were not available.
(if (unspecified? val) '_ val))))
(else
'_)))
(define (application-arguments)
;; Case 1.
(map (lambda (local) (local-ref local #f))
;; Cdr past the 0th local, which is the procedure.
(cdr (iota nlocals))))
(define (reconstruct-arguments bindings nreq nopt kw has-rest? local)
;; Case 2.
(cond
((positive? nreq)
(cons (local-ref local bindings)
(reconstruct-arguments bindings
(1- nreq) nopt kw has-rest? (1+ local))))
((positive? nopt)
(cons (local-ref local bindings)
(reconstruct-arguments bindings
nreq (1- nopt) kw has-rest? (1+ local))))
((pair? kw)
(cons* (caar kw) (local-ref (cdar kw) bindings)
(reconstruct-arguments bindings
nreq nopt (cdr kw) has-rest? (1+ local))))
(has-rest?
(local-ref local bindings))
(else
'())))
(cons
(or (frame-procedure-name frame #:info info) '_)
(cond
((find-program-arity ip)
=> (lambda (arity)
(if (and top-frame? (eqv? ip (arity-low-pc arity)))
(application-arguments)
(reconstruct-arguments
(available-bindings frame arity ip top-frame?)
(arity-nreq arity)
(arity-nopt arity)
(arity-keyword-args arity)
(arity-has-rest? arity)
(if (arity-has-closure? arity) 1 0)))))
((and (primitive-code? ip)
(program-arguments-alist (frame-local-ref frame 0 'scm) ip))
=> (lambda (args)
(match args
((('required . req)
('optional . opt)
('keyword . kw)
('allow-other-keys? . _)
('rest . rest))
(reconstruct-arguments #f
(length req) (length opt) kw rest 1)))))
(else
(application-arguments))))))
;;; Misc
;;;
(define (frame-environment frame)
(map (lambda (binding)
(cons (binding-name binding) (binding-ref binding)))
(frame-bindings frame)))
(define (frame-object-binding frame obj)
(do ((bs (frame-bindings frame) (cdr bs)))
((or (null? bs) (eq? obj (binding-ref (car bs))))
(and (pair? bs) (car bs)))))
(define (frame-object-name frame obj)
(cond ((frame-object-binding frame obj) => binding-name)
(else #f)))
|