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 (and (<= speed safety)
98 (let ((min-cost (type-test-cost type))
101 (dolist (x *backend-type-predicates*)
102 (let ((stype (car x)))
103 (when (and (csubtypep type stype)
104 (not (union-type-p stype)))
105 (let ((stype-cost (type-test-cost stype)))
106 (when (or (< stype-cost min-cost)
110 min-cost stype-cost))))))
113 *universal-type*)))))
115 ;;; Like VALUES-TYPES, only mash any complex function types to FUNCTION.
116 (defun no-function-values-types (type)
117 (declare (type ctype type))
118 (multiple-value-bind (res count) (values-types type)
119 (values (mapcar #'(lambda (type)
120 (if (function-type-p type)
121 (specifier-type 'function)
126 ;;; Switch to disable check complementing, for evaluation.
127 (defvar *complement-type-checks* t)
129 ;;; CONT is a continuation we are doing a type check on and TYPES is a
130 ;;; list of types that we are checking its values against. If we have
131 ;;; proven that CONT generates a fixed number of values, then for each
132 ;;; value, we check whether it is cheaper to then difference between
133 ;;; the proven type and the corresponding type in TYPES. If so, we opt
134 ;;; for a :HAIRY check with that test negated. Otherwise, we try to do
135 ;;; a simple test, and if that is impossible, we do a hairy test with
136 ;;; non-negated types. If true, Force-Hairy forces a hairy type check.
138 ;;; When doing a non-negated check, we call MAYBE-WEAKEN-CHECK to
139 ;;; weaken the test to a convenient supertype (conditional on policy.)
140 ;;; If SPEED is 3, or DEBUG-INFO is not particularly important (DEBUG
141 ;;; <= 1), then we allow weakened checks to be simple, resulting in
142 ;;; less informative error messages, but saving space and possibly
145 ;;; FIXME: I don't quite understand this, but it looks as though
146 ;;; that means type checks are weakened when SPEED=3 regardless of
147 ;;; the SAFETY level, which is not the right thing to do.
148 (defun maybe-negate-check (cont types force-hairy)
149 (declare (type continuation cont) (list types))
150 (multiple-value-bind (ptypes count)
151 (no-function-values-types (continuation-proven-type cont))
152 (if (eq count :unknown)
153 (if (and (every #'type-check-template types) (not force-hairy))
154 (values :simple types)
156 (mapcar #'(lambda (x)
157 (list nil (maybe-weaken-check x cont) x))
159 (let ((res (mapcar #'(lambda (p c)
160 (let ((diff (type-difference p c))
161 (weak (maybe-weaken-check c cont)))
163 (< (type-test-cost diff)
164 (type-test-cost weak))
165 *complement-type-checks*)
169 (cond ((or force-hairy (find-if #'first res))
171 ((every #'type-check-template types)
172 (values :simple types))
173 ((policy (continuation-dest cont)
174 (or (<= debug 1) (and (= speed 3) (/= debug 3))))
175 (let ((weakened (mapcar #'second res)))
176 (if (every #'type-check-template weakened)
177 (values :simple weakened)
178 (values :hairy res))))
180 (values :hairy res)))))))
182 ;;; Determines whether CONT's assertion is:
183 ;;; -- checkable by the back end (:SIMPLE), or
184 ;;; -- not checkable by the back end, but checkable via an explicit
185 ;;; test in type check conversion (:HAIRY), or
186 ;;; -- not reasonably checkable at all (:TOO-HAIRY).
188 ;;; A type is checkable if it either represents a fixed number of
189 ;;; values (as determined by VALUES-TYPES), or it is the assertion for
190 ;;; an MV-Bind. A type is simply checkable if all the type assertions
191 ;;; have a TYPE-CHECK-TEMPLATE. In this :SIMPLE case, the second value
192 ;;; is a list of the type restrictions specified for the leading
193 ;;; positional values.
195 ;;; We force a check to be hairy even when there are fixed values if
196 ;;; we are in a context where we may be forced to use the unknown
197 ;;; values convention anyway. This is because IR2tran can't generate
198 ;;; type checks for unknown values continuations but people could
199 ;;; still be depending on the check being done. We only care about
200 ;;; EXIT and RETURN (not MV-COMBINATION) since these are the only
201 ;;; contexts where the ultimate values receiver
203 ;;; In the :HAIRY case, the second value is a list of triples of
205 ;;; (NOT-P TYPE ORIGINAL-TYPE)
207 ;;; If true, the NOT-P flag indicates a test that the corresponding
208 ;;; value is *not* of the specified TYPE. ORIGINAL-TYPE is the type
209 ;;; asserted on this value in the continuation, for use in error
210 ;;; messages. When NOT-P is true, this will be different from TYPE.
212 ;;; This allows us to take what has been proven about CONT's type into
213 ;;; consideration. If it is cheaper to test for the difference between
214 ;;; the derived type and the asserted type, then we check for the
215 ;;; negation of this type instead.
216 (defun continuation-check-types (cont)
217 (declare (type continuation cont))
218 (let ((type (continuation-asserted-type cont))
219 (dest (continuation-dest cont)))
220 (assert (not (eq type *wild-type*)))
221 (multiple-value-bind (types count) (no-function-values-types type)
222 (cond ((not (eq count :unknown))
223 (if (or (exit-p dest)
225 (multiple-value-bind (ignore count)
226 (values-types (return-result-type dest))
227 (declare (ignore ignore))
228 (eq count :unknown))))
229 (maybe-negate-check cont types t)
230 (maybe-negate-check cont types nil)))
231 ((and (mv-combination-p dest)
232 (eq (basic-combination-kind dest) :local))
233 (assert (values-type-p type))
234 (maybe-negate-check cont (args-type-optional type) nil))
236 (values :too-hairy nil))))))
238 ;;; Return true if CONT is a continuation whose type the back end is
239 ;;; likely to want to check. Since we don't know what template the
240 ;;; back end is going to choose to implement the continuation's DEST,
241 ;;; we use a heuristic. We always return T unless:
242 ;;; -- nobody uses the value, or
243 ;;; -- safety is totally unimportant, or
244 ;;; -- the continuation is an argument to an unknown function, or
245 ;;; -- the continuation is an argument to a known function that has
246 ;;; no IR2-Convert method or :FAST-SAFE templates that are
247 ;;; compatible with the call's type.
249 ;;; We must only return NIL when it is *certain* that a check will not
250 ;;; be done, since if we pass up this chance to do the check, it will
251 ;;; be too late. The penalty for being too conservative is duplicated
254 ;;; If there is a compile-time type error, then we always return true
255 ;;; unless the DEST is a full call. With a full call, the theory is
256 ;;; that the type error is probably from a declaration in (or on) the
257 ;;; callee, so the callee should be able to do the check. We want to
258 ;;; let the callee do the check, because it is possible that the error
259 ;;; is really in the callee, not the caller. We don't want to make
260 ;;; people recompile all calls to a function when they were originally
261 ;;; compiled with a bad declaration (or an old type assertion derived
262 ;;; from a definition appearing after the call.)
263 (defun probable-type-check-p (cont)
264 (declare (type continuation cont))
265 (let ((dest (continuation-dest cont)))
266 (cond ((eq (continuation-type-check cont) :error)
267 (if (and (combination-p dest) (eq (combination-kind dest) :error))
271 (policy dest (zerop safety)))
273 ((basic-combination-p dest)
274 (let ((kind (basic-combination-kind dest)))
275 (cond ((eq cont (basic-combination-fun dest)) t)
277 ((member kind '(:full :error)) nil)
278 ((function-info-ir2-convert kind) t)
280 (dolist (template (function-info-templates kind) nil)
281 (when (eq (template-policy template) :fast-safe)
282 (multiple-value-bind (val win)
283 (valid-function-use dest (template-type template))
284 (when (or val (not win)) (return t)))))))))
287 ;;; Return a form that we can convert to do a hairy type check of the
288 ;;; specified TYPES. TYPES is a list of the format returned by
289 ;;; CONTINUATION-CHECK-TYPES in the :HAIRY case. In place of the
290 ;;; actual value(s) we are to check, we use 'DUMMY. This constant
291 ;;; reference is later replaced with the actual values continuation.
293 ;;; Note that we don't attempt to check for required values being
294 ;;; unsupplied. Such checking is impossible to efficiently do at the
295 ;;; source level because our fixed-values conventions are optimized
296 ;;; for the common MV-BIND case.
298 ;;; We can always use MULTIPLE-VALUE-BIND, since the macro is clever
299 ;;; about binding a single variable.
300 (defun make-type-check-form (types)
301 (let ((temps (make-gensym-list (length types))))
302 `(multiple-value-bind ,temps 'dummy
303 ,@(mapcar #'(lambda (temp type)
305 (let ((*unparse-function-type-simplify* t))
306 (type-specifier (second type))))
307 (test (if (first type) `(not ,spec) spec)))
308 `(unless (typep ,temp ',test)
311 ',(type-specifier (third type))))))
316 ;;; Splice in explicit type check code immediately before the node
317 ;;; which is CONT's DEST. This code receives the value(s) that were
318 ;;; being passed to CONT, checks the type(s) of the value(s), then
319 ;;; passes them on to CONT.
320 (defun convert-type-check (cont types)
321 (declare (type continuation cont) (type list types))
322 (with-ir1-environment (continuation-dest cont)
324 ;; Ensuring that CONT starts a block lets us freely manipulate its uses.
325 (ensure-block-start cont)
327 ;; Make a new continuation and move CONT's uses to it.
328 (let* ((new-start (make-continuation))
329 (dest (continuation-dest cont))
330 (prev (node-prev dest)))
331 (continuation-starts-block new-start)
332 (substitute-continuation-uses new-start cont)
334 ;; Setting TYPE-CHECK in CONT to :DELETED indicates that the
335 ;; check has been done.
336 (setf (continuation-%type-check cont) :deleted)
338 ;; Make the DEST node start its block so that we can splice in
339 ;; the type check code.
340 (when (continuation-use prev)
341 (node-ends-block (continuation-use prev)))
343 (let* ((prev-block (continuation-block prev))
344 (new-block (continuation-block new-start))
345 (dummy (make-continuation)))
347 ;; Splice in the new block before DEST, giving the new block
348 ;; all of DEST's predecessors.
349 (dolist (block (block-pred prev-block))
350 (change-block-successor block prev-block new-block))
352 ;; Convert the check form, using the new block start as START
353 ;; and a dummy continuation as CONT.
354 (ir1-convert new-start dummy (make-type-check-form types))
356 ;; TO DO: Why should this be true? -- WHN 19990601
357 (assert (eq (continuation-block dummy) new-block))
359 ;; KLUDGE: Comments at the head of this function in CMU CL
360 ;; said that somewhere in here we
361 ;; Set the new block's start and end cleanups to the *start*
362 ;; cleanup of PREV's block. This overrides the incorrect
363 ;; default from WITH-IR1-ENVIRONMENT.
364 ;; Unfortunately I can't find any code which corresponds to this.
365 ;; Perhaps it was a stale comment? Or perhaps I just don't
366 ;; understand.. -- WHN 19990521
368 (let ((node (continuation-use dummy)))
369 (setf (block-last new-block) node)
370 ;; Change the use to a use of CONT. (We need to use the
371 ;; dummy continuation to get the control transfer right,
372 ;; because we want to go to PREV's block, not CONT's.)
373 (delete-continuation-use node)
374 (add-continuation-use node cont))
375 ;; Link the new block to PREV's block.
376 (link-blocks new-block prev-block))
378 ;; MAKE-TYPE-CHECK-FORM generated a form which checked the type
379 ;; of 'DUMMY, not a real form. At this point we convert to the
380 ;; real form by finding 'DUMMY and overwriting it with the new
381 ;; continuation. (We can find 'DUMMY because no LET conversion
382 ;; has been done yet.) The [mv-]combination code from the
383 ;; mv-bind in the check form will be the use of the new check
384 ;; continuation. We substitute for the first argument of this
386 (let* ((node (continuation-use cont))
387 (args (basic-combination-args node))
388 (victim (first args)))
389 (assert (and (= (length args) 1)
392 (continuation-use victim)))
394 (substitute-continuation new-start victim)))
396 ;; Invoking local call analysis converts this call to a LET.
397 (local-call-analyze *current-component*))
401 ;;; Emit a type warning for NODE. If the value of NODE is being used
402 ;;; for a variable binding, we figure out which one for source
403 ;;; context. If the value is a constant, we print it specially. We
404 ;;; ignore nodes whose type is NIL, since they are supposed to never
406 (defun do-type-warning (node)
407 (declare (type node node))
408 (let* ((*compiler-error-context* node)
409 (cont (node-cont node))
410 (atype-spec (type-specifier (continuation-asserted-type cont)))
411 (dtype (node-derived-type node))
412 (dest (continuation-dest cont))
413 (what (when (and (combination-p dest)
414 (eq (combination-kind dest) :local))
415 (let ((lambda (combination-lambda dest))
416 (pos (position-or-lose cont (combination-args dest))))
417 (format nil "~:[A possible~;The~] binding of ~S"
418 (and (continuation-use cont)
419 (eq (functional-kind lambda) :let))
420 (leaf-name (elt (lambda-vars lambda) pos)))))))
421 (cond ((eq dtype *empty-type*))
422 ((and (ref-p node) (constant-p (ref-leaf node)))
423 (compiler-warning "~:[This~;~:*~A~] is not a ~<~%~9T~:;~S:~>~% ~S"
424 what atype-spec (constant-value (ref-leaf node))))
427 "~:[Result~;~:*~A~] is a ~S, ~<~%~9T~:;not a ~S.~>"
428 what (type-specifier dtype) atype-spec))))
431 ;;; Mark CONT as being a continuation with a manifest type error. We
432 ;;; set the kind to :ERROR, and clear any FUNCTION-INFO if the
433 ;;; continuation is an argument to a known call. The last is done so
434 ;;; that the back end doesn't have to worry about type errors in
435 ;;; arguments to known functions. This clearing is inhibited for
436 ;;; things with IR2-CONVERT methods, since we can't do a full call to
438 (defun mark-error-continuation (cont)
439 (declare (type continuation cont))
440 (setf (continuation-%type-check cont) :error)
441 (let ((dest (continuation-dest cont)))
442 (when (and (combination-p dest)
443 (let ((kind (basic-combination-kind dest)))
445 (and (function-info-p kind)
446 (not (function-info-ir2-convert kind))))))
447 (setf (basic-combination-kind dest) :error)))
450 ;;; Loop over all blocks in Component that have TYPE-CHECK set,
451 ;;; looking for continuations with TYPE-CHECK T. We do two mostly
452 ;;; unrelated things: detect compile-time type errors and determine if
453 ;;; and how to do run-time type checks.
455 ;;; If there is a compile-time type error, then we mark the
456 ;;; continuation and emit a warning if appropriate. This part loops
457 ;;; over all the uses of the continuation, since after we convert the
458 ;;; check, the :DELETED kind will inhibit warnings about the types of
461 ;;; If a continuation is too complex to be checked by the back end, or
462 ;;; is better checked with explicit code, then convert to an explicit
463 ;;; test. Assertions that can checked by the back end are passed
464 ;;; through. Assertions that can't be tested are flamed about and
465 ;;; marked as not needing to be checked.
467 ;;; If we determine that a type check won't be done, then we set
468 ;;; TYPE-CHECK to :NO-CHECK. In the non-hairy cases, this is just to
469 ;;; prevent us from wasting time coming to the same conclusion again
470 ;;; on a later iteration. In the hairy case, we must indicate to LTN
471 ;;; that it must choose a safe implementation, since IR2 conversion
472 ;;; will choke on the check.
474 ;;; The generation of the type checks is delayed until all the type
475 ;;; check decisions have been made because the generation of the type
476 ;;; checks creates new nodes whose derived types aren't always updated
477 ;;; which may lead to inappropriate template choices due to the
478 ;;; modification of argument types.
479 (defun generate-type-checks (component)
481 (do-blocks (block component)
482 (when (block-type-check block)
483 (do-nodes (node cont block)
484 (let ((type-check (continuation-type-check cont)))
485 (unless (member type-check '(nil :error :deleted))
486 (let ((atype (continuation-asserted-type cont)))
488 (unless (values-types-intersect (node-derived-type use)
490 (mark-error-continuation cont)
491 (unless (policy node (= brevity 3))
492 (do-type-warning use))))))
493 (when (and (eq type-check t)
494 (not *byte-compiling*))
495 (cond ((probable-type-check-p cont)
498 (setf (continuation-%type-check cont) :no-check))))))
499 (setf (block-type-check block) nil)))
500 (dolist (cont (conts))
501 (multiple-value-bind (check types) (continuation-check-types cont)
505 (convert-type-check cont types))
507 (let* ((context (continuation-dest cont))
508 (*compiler-error-context* context))
509 (when (policy context (>= safety brevity))
511 "type assertion too complex to check:~% ~S."
512 (type-specifier (continuation-asserted-type cont)))))
513 (setf (continuation-%type-check cont) :deleted))))))