1 ;;;; This file implements type check generation. This is a phase that
2 ;;;; runs at the very end of IR1. If a type check is too complex for
3 ;;;; the back end to directly emit in-line, then we transform the check
4 ;;;; into an explicit conditional using TYPEP.
6 ;;;; This software is part of the SBCL system. See the README file for
9 ;;;; This software is derived from the CMU CL system, which was
10 ;;;; written at Carnegie Mellon University and released into the
11 ;;;; public domain. The software is in the public domain and is
12 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
13 ;;;; files for more information.
19 ;;; Return some sort of guess about the cost of a call to a function.
20 ;;; If the function has some templates, we return the cost of the
21 ;;; cheapest one, otherwise we return the cost of CALL-NAMED. Calling
22 ;;; this with functions that have transforms can result in relatively
23 ;;; meaningless results (exaggerated costs.)
25 ;;; We special-case NULL, since it does have a source tranform and is
26 ;;; interesting to us.
27 (defun function-cost (name)
28 (declare (symbol name))
29 (let ((info (info :function :info name))
30 (call-cost (template-cost (template-or-lose 'call-named))))
32 (let ((templates (function-info-templates info)))
34 (template-cost (first templates))
36 (null (template-cost (template-or-lose 'if-eq)))
40 ;;; Return some sort of guess for the cost of doing a test against
41 ;;; TYPE. The result need not be precise as long as it isn't way out
42 ;;; in space. The units are based on the costs specified for various
43 ;;; templates in the VM definition.
44 (defun type-test-cost (type)
45 (declare (type ctype type))
46 (or (let ((check (type-check-template type)))
49 (let ((found (cdr (assoc type *backend-type-predicates*
52 (+ (function-cost found) (function-cost 'eq))
57 (dolist (mem (union-type-types type))
58 (res (type-test-cost mem)))
61 (* (length (member-type-members type))
64 (* (if (numeric-type-complexp type) 2 1)
66 (if (csubtypep type (specifier-type 'fixnum)) 'fixnump 'numberp))
68 (if (numeric-type-low type) 1 0)
69 (if (numeric-type-high type) 1 0))))
71 (+ (type-test-cost (specifier-type 'cons))
73 (type-test-cost (cons-type-car-type type))
75 (type-test-cost (cons-type-cdr-type type))))
77 (function-cost 'typep)))))
79 ;;;; checking strategy determination
81 ;;; Return the type we should test for when we really want to check
82 ;;; for TYPE. If speed, space or compilation speed is more important
83 ;;; than safety, then we return a weaker type if it is easier to
84 ;;; check. First we try the defined type weakenings, then look for any
85 ;;; predicate that is cheaper.
87 ;;; If the supertype is equal in cost to the type, we prefer the
88 ;;; supertype. This produces a closer approximation of the right thing
89 ;;; in the presence of poor cost info.
90 (defun maybe-weaken-check (type cont)
91 (declare (type ctype type) (type continuation cont))
92 (cond ((policy (continuation-dest cont)
93 (<= speed safety) (<= space safety) (<= cspeed safety))
96 (let ((min-cost (type-test-cost type))
99 (dolist (x *backend-type-predicates*)
100 (let ((stype (car x)))
101 (when (and (csubtypep type stype)
102 (not (union-type-p stype)))
103 (let ((stype-cost (type-test-cost stype)))
104 (when (or (< stype-cost min-cost)
108 min-cost stype-cost))))))
111 *universal-type*)))))
113 ;;; Like VALUES-TYPES, only mash any complex function types to FUNCTION.
114 (defun no-function-values-types (type)
115 (declare (type ctype type))
116 (multiple-value-bind (res count) (values-types type)
117 (values (mapcar #'(lambda (type)
118 (if (function-type-p type)
119 (specifier-type 'function)
124 ;;; Switch to disable check complementing, for evaluation.
125 (defvar *complement-type-checks* t)
127 ;;; CONT is a continuation we are doing a type check on and TYPES is a
128 ;;; list of types that we are checking its values against. If we have
129 ;;; proven that CONT generates a fixed number of values, then for each
130 ;;; value, we check whether it is cheaper to then difference between
131 ;;; the proven type and the corresponding type in TYPES. If so, we opt
132 ;;; for a :HAIRY check with that test negated. Otherwise, we try to do
133 ;;; a simple test, and if that is impossible, we do a hairy test with
134 ;;; non-negated types. If true, Force-Hairy forces a hairy type check.
136 ;;; When doing a non-negated check, we call MAYBE-WEAKEN-CHECK to
137 ;;; weaken the test to a convenient supertype (conditional on policy.)
138 ;;; If SPEED is 3, or DEBUG-INFO is not particularly important (DEBUG
139 ;;; <= 1), then we allow weakened checks to be simple, resulting in
140 ;;; less informative error messages, but saving space and possibly
143 ;;; FIXME: I don't quite understand this, but it looks as though
144 ;;; that means type checks are weakened when SPEED=3 regardless of
145 ;;; the SAFETY level, which is not the right thing to do.
146 (defun maybe-negate-check (cont types force-hairy)
147 (declare (type continuation cont) (list types))
148 (multiple-value-bind (ptypes count)
149 (no-function-values-types (continuation-proven-type cont))
150 (if (eq count :unknown)
151 (if (and (every #'type-check-template types) (not force-hairy))
152 (values :simple types)
154 (mapcar #'(lambda (x)
155 (list nil (maybe-weaken-check x cont) x))
157 (let ((res (mapcar #'(lambda (p c)
158 (let ((diff (type-difference p c))
159 (weak (maybe-weaken-check c cont)))
161 (< (type-test-cost diff)
162 (type-test-cost weak))
163 *complement-type-checks*)
167 (cond ((or force-hairy (find-if #'first res))
169 ((every #'type-check-template types)
170 (values :simple types))
171 ((policy (continuation-dest cont)
172 (or (<= debug 1) (and (= speed 3) (/= debug 3))))
173 (let ((weakened (mapcar #'second res)))
174 (if (every #'type-check-template weakened)
175 (values :simple weakened)
176 (values :hairy res))))
178 (values :hairy res)))))))
180 ;;; Determines whether CONT's assertion is:
181 ;;; -- checkable by the back end (:SIMPLE), or
182 ;;; -- not checkable by the back end, but checkable via an explicit
183 ;;; test in type check conversion (:HAIRY), or
184 ;;; -- not reasonably checkable at all (:TOO-HAIRY).
186 ;;; A type is checkable if it either represents a fixed number of
187 ;;; values (as determined by VALUES-TYPES), or it is the assertion for
188 ;;; an MV-Bind. A type is simply checkable if all the type assertions
189 ;;; have a TYPE-CHECK-TEMPLATE. In this :SIMPLE case, the second value
190 ;;; is a list of the type restrictions specified for the leading
191 ;;; positional values.
193 ;;; We force a check to be hairy even when there are fixed values if
194 ;;; we are in a context where we may be forced to use the unknown
195 ;;; values convention anyway. This is because IR2tran can't generate
196 ;;; type checks for unknown values continuations but people could
197 ;;; still be depending on the check being done. We only care about
198 ;;; EXIT and RETURN (not MV-COMBINATION) since these are the only
199 ;;; contexts where the ultimate values receiver
201 ;;; In the :HAIRY case, the second value is a list of triples of
203 ;;; (NOT-P TYPE ORIGINAL-TYPE)
205 ;;; If true, the NOT-P flag indicates a test that the corresponding
206 ;;; value is *not* of the specified TYPE. ORIGINAL-TYPE is the type
207 ;;; asserted on this value in the continuation, for use in error
208 ;;; messages. When NOT-P is true, this will be different from TYPE.
210 ;;; This allows us to take what has been proven about CONT's type into
211 ;;; consideration. If it is cheaper to test for the difference between
212 ;;; the derived type and the asserted type, then we check for the
213 ;;; negation of this type instead.
214 (defun continuation-check-types (cont)
215 (declare (type continuation cont))
216 (let ((type (continuation-asserted-type cont))
217 (dest (continuation-dest cont)))
218 (assert (not (eq type *wild-type*)))
219 (multiple-value-bind (types count) (no-function-values-types type)
220 (cond ((not (eq count :unknown))
221 (if (or (exit-p dest)
223 (multiple-value-bind (ignore count)
224 (values-types (return-result-type dest))
225 (declare (ignore ignore))
226 (eq count :unknown))))
227 (maybe-negate-check cont types t)
228 (maybe-negate-check cont types nil)))
229 ((and (mv-combination-p dest)
230 (eq (basic-combination-kind dest) :local))
231 (assert (values-type-p type))
232 (maybe-negate-check cont (args-type-optional type) nil))
234 (values :too-hairy nil))))))
236 ;;; Return true if CONT is a continuation whose type the back end is
237 ;;; likely to want to check. Since we don't know what template the
238 ;;; back end is going to choose to implement the continuation's DEST,
239 ;;; we use a heuristic. We always return T unless:
240 ;;; -- nobody uses the value, or
241 ;;; -- safety is totally unimportant, or
242 ;;; -- the continuation is an argument to an unknown function, or
243 ;;; -- the continuation is an argument to a known function that has
244 ;;; no IR2-Convert method or :FAST-SAFE templates that are
245 ;;; compatible with the call's type.
247 ;;; We must only return NIL when it is *certain* that a check will not
248 ;;; be done, since if we pass up this chance to do the check, it will
249 ;;; be too late. The penalty for being too conservative is duplicated
252 ;;; If there is a compile-time type error, then we always return true
253 ;;; unless the DEST is a full call. With a full call, the theory is
254 ;;; that the type error is probably from a declaration in (or on) the
255 ;;; callee, so the callee should be able to do the check. We want to
256 ;;; let the callee do the check, because it is possible that the error
257 ;;; is really in the callee, not the caller. We don't want to make
258 ;;; people recompile all calls to a function when they were originally
259 ;;; compiled with a bad declaration (or an old type assertion derived
260 ;;; from a definition appearing after the call.)
261 (defun probable-type-check-p (cont)
262 (declare (type continuation cont))
263 (let ((dest (continuation-dest cont)))
264 (cond ((eq (continuation-type-check cont) :error)
265 (if (and (combination-p dest) (eq (combination-kind dest) :error))
269 (policy dest (zerop safety)))
271 ((basic-combination-p dest)
272 (let ((kind (basic-combination-kind dest)))
273 (cond ((eq cont (basic-combination-fun dest)) t)
275 ((member kind '(:full :error)) nil)
276 ((function-info-ir2-convert kind) t)
278 (dolist (template (function-info-templates kind) nil)
279 (when (eq (template-policy template) :fast-safe)
280 (multiple-value-bind (val win)
281 (valid-function-use dest (template-type template))
282 (when (or val (not win)) (return t)))))))))
285 ;;; Return a form that we can convert to do a hairy type check of the
286 ;;; specified TYPES. TYPES is a list of the format returned by
287 ;;; CONTINUATION-CHECK-TYPES in the :HAIRY case. In place of the
288 ;;; actual value(s) we are to check, we use 'DUMMY. This constant
289 ;;; reference is later replaced with the actual values continuation.
291 ;;; Note that we don't attempt to check for required values being
292 ;;; unsupplied. Such checking is impossible to efficiently do at the
293 ;;; source level because our fixed-values conventions are optimized
294 ;;; for the common MV-BIND case.
296 ;;; We can always use MULTIPLE-VALUE-BIND, since the macro is clever
297 ;;; about binding a single variable.
298 (defun make-type-check-form (types)
299 (let ((temps (make-gensym-list (length types))))
300 `(multiple-value-bind ,temps 'dummy
301 ,@(mapcar #'(lambda (temp type)
303 (let ((*unparse-function-type-simplify* t))
304 (type-specifier (second type))))
305 (test (if (first type) `(not ,spec) spec)))
306 `(unless (typep ,temp ',test)
309 ',(type-specifier (third type))))))
314 ;;; Splice in explicit type check code immediately before the node
315 ;;; which is CONT's DEST. This code receives the value(s) that were
316 ;;; being passed to CONT, checks the type(s) of the value(s), then
317 ;;; passes them on to CONT.
318 (defun convert-type-check (cont types)
319 (declare (type continuation cont) (type list types))
320 (with-ir1-environment (continuation-dest cont)
322 ;; Ensuring that CONT starts a block lets us freely manipulate its uses.
323 (ensure-block-start cont)
325 ;; Make a new continuation and move CONT's uses to it.
326 (let* ((new-start (make-continuation))
327 (dest (continuation-dest cont))
328 (prev (node-prev dest)))
329 (continuation-starts-block new-start)
330 (substitute-continuation-uses new-start cont)
332 ;; Setting TYPE-CHECK in CONT to :DELETED indicates that the
333 ;; check has been done.
334 (setf (continuation-%type-check cont) :deleted)
336 ;; Make the DEST node start its block so that we can splice in
337 ;; the type check code.
338 (when (continuation-use prev)
339 (node-ends-block (continuation-use prev)))
341 (let* ((prev-block (continuation-block prev))
342 (new-block (continuation-block new-start))
343 (dummy (make-continuation)))
345 ;; Splice in the new block before DEST, giving the new block
346 ;; all of DEST's predecessors.
347 (dolist (block (block-pred prev-block))
348 (change-block-successor block prev-block new-block))
350 ;; Convert the check form, using the new block start as START
351 ;; and a dummy continuation as CONT.
352 (ir1-convert new-start dummy (make-type-check-form types))
354 ;; TO DO: Why should this be true? -- WHN 19990601
355 (assert (eq (continuation-block dummy) new-block))
357 ;; KLUDGE: Comments at the head of this function in CMU CL
358 ;; said that somewhere in here we
359 ;; Set the new block's start and end cleanups to the *start*
360 ;; cleanup of PREV's block. This overrides the incorrect
361 ;; default from WITH-IR1-ENVIRONMENT.
362 ;; Unfortunately I can't find any code which corresponds to this.
363 ;; Perhaps it was a stale comment? Or perhaps I just don't
364 ;; understand.. -- WHN 19990521
366 (let ((node (continuation-use dummy)))
367 (setf (block-last new-block) node)
368 ;; Change the use to a use of CONT. (We need to use the
369 ;; dummy continuation to get the control transfer right,
370 ;; because we want to go to PREV's block, not CONT's.)
371 (delete-continuation-use node)
372 (add-continuation-use node cont))
373 ;; Link the new block to PREV's block.
374 (link-blocks new-block prev-block))
376 ;; MAKE-TYPE-CHECK-FORM generated a form which checked the type
377 ;; of 'DUMMY, not a real form. At this point we convert to the
378 ;; real form by finding 'DUMMY and overwriting it with the new
379 ;; continuation. (We can find 'DUMMY because no LET conversion
380 ;; has been done yet.) The [mv-]combination code from the
381 ;; mv-bind in the check form will be the use of the new check
382 ;; continuation. We substitute for the first argument of this
384 (let* ((node (continuation-use cont))
385 (args (basic-combination-args node))
386 (victim (first args)))
387 (assert (and (= (length args) 1)
390 (continuation-use victim)))
392 (substitute-continuation new-start victim)))
394 ;; Invoking local call analysis converts this call to a LET.
395 (local-call-analyze *current-component*))
399 ;;; Emit a type warning for NODE. If the value of NODE is being used
400 ;;; for a variable binding, we figure out which one for source
401 ;;; context. If the value is a constant, we print it specially. We
402 ;;; ignore nodes whose type is NIL, since they are supposed to never
404 (defun do-type-warning (node)
405 (declare (type node node))
406 (let* ((*compiler-error-context* node)
407 (cont (node-cont node))
408 (atype-spec (type-specifier (continuation-asserted-type cont)))
409 (dtype (node-derived-type node))
410 (dest (continuation-dest cont))
411 (what (when (and (combination-p dest)
412 (eq (combination-kind dest) :local))
413 (let ((lambda (combination-lambda dest))
414 (pos (position-or-lose cont (combination-args dest))))
415 (format nil "~:[A possible~;The~] binding of ~S"
416 (and (continuation-use cont)
417 (eq (functional-kind lambda) :let))
418 (leaf-name (elt (lambda-vars lambda) pos)))))))
419 (cond ((eq dtype *empty-type*))
420 ((and (ref-p node) (constant-p (ref-leaf node)))
421 (compiler-warning "~:[This~;~:*~A~] is not a ~<~%~9T~:;~S:~>~% ~S"
422 what atype-spec (constant-value (ref-leaf node))))
425 "~:[Result~;~:*~A~] is a ~S, ~<~%~9T~:;not a ~S.~>"
426 what (type-specifier dtype) atype-spec))))
429 ;;; Mark CONT as being a continuation with a manifest type error. We
430 ;;; set the kind to :ERROR, and clear any FUNCTION-INFO if the
431 ;;; continuation is an argument to a known call. The last is done so
432 ;;; that the back end doesn't have to worry about type errors in
433 ;;; arguments to known functions. This clearing is inhibited for
434 ;;; things with IR2-CONVERT methods, since we can't do a full call to
436 (defun mark-error-continuation (cont)
437 (declare (type continuation cont))
438 (setf (continuation-%type-check cont) :error)
439 (let ((dest (continuation-dest cont)))
440 (when (and (combination-p dest)
441 (let ((kind (basic-combination-kind dest)))
443 (and (function-info-p kind)
444 (not (function-info-ir2-convert kind))))))
445 (setf (basic-combination-kind dest) :error)))
448 ;;; Loop over all blocks in Component that have TYPE-CHECK set,
449 ;;; looking for continuations with TYPE-CHECK T. We do two mostly
450 ;;; unrelated things: detect compile-time type errors and determine if
451 ;;; and how to do run-time type checks.
453 ;;; If there is a compile-time type error, then we mark the
454 ;;; continuation and emit a warning if appropriate. This part loops
455 ;;; over all the uses of the continuation, since after we convert the
456 ;;; check, the :DELETED kind will inhibit warnings about the types of
459 ;;; If a continuation is too complex to be checked by the back end, or
460 ;;; is better checked with explicit code, then convert to an explicit
461 ;;; test. Assertions that can checked by the back end are passed
462 ;;; through. Assertions that can't be tested are flamed about and
463 ;;; marked as not needing to be checked.
465 ;;; If we determine that a type check won't be done, then we set
466 ;;; TYPE-CHECK to :NO-CHECK. In the non-hairy cases, this is just to
467 ;;; prevent us from wasting time coming to the same conclusion again
468 ;;; on a later iteration. In the hairy case, we must indicate to LTN
469 ;;; that it must choose a safe implementation, since IR2 conversion
470 ;;; will choke on the check.
472 ;;; The generation of the type checks is delayed until all the type
473 ;;; check decisions have been made because the generation of the type
474 ;;; checks creates new nodes whose derived types aren't always updated
475 ;;; which may lead to inappropriate template choices due to the
476 ;;; modification of argument types.
477 (defun generate-type-checks (component)
479 (do-blocks (block component)
480 (when (block-type-check block)
481 (do-nodes (node cont block)
482 (let ((type-check (continuation-type-check cont)))
483 (unless (member type-check '(nil :error :deleted))
484 (let ((atype (continuation-asserted-type cont)))
486 (unless (values-types-intersect (node-derived-type use)
488 (mark-error-continuation cont)
489 (unless (policy node (= brevity 3))
490 (do-type-warning use))))))
491 (when (and (eq type-check t)
492 (not *byte-compiling*))
493 (cond ((probable-type-check-p cont)
496 (setf (continuation-%type-check cont) :no-check))))))
497 (setf (block-type-check block) nil)))
498 (dolist (cont (conts))
499 (multiple-value-bind (check types) (continuation-check-types cont)
503 (convert-type-check cont types))
505 (let* ((context (continuation-dest cont))
506 (*compiler-error-context* context))
507 (when (policy context (>= safety brevity))
509 "type assertion too complex to check:~% ~S."
510 (type-specifier (continuation-asserted-type cont)))))
511 (setf (continuation-%type-check cont) :deleted))))))