/[cmucl]/src/compiler/checkgen.lisp
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Revision 1.14 - (hide annotations)
Wed Oct 17 03:52:02 1990 UTC (23 years, 6 months ago) by ram
Branch: MAIN
Changes since 1.13: +9 -14 lines
Changed DO-TYPE-WARNING to ignore uses whose type is NIL, and also
tweaked output format a bit.
1 wlott 1.1 ;;; -*- Package: C; Log: C.Log -*-
2     ;;;
3     ;;; **********************************************************************
4     ;;; This code was written as part of the Spice Lisp project at
5     ;;; Carnegie-Mellon University, and has been placed in the public domain.
6     ;;; If you want to use this code or any part of Spice Lisp, please contact
7     ;;; Scott Fahlman (FAHLMAN@CMUC).
8     ;;; **********************************************************************
9     ;;;
10     ;;; This file implements type check generation. This is a phase that runs
11     ;;; at the very end of IR1. If a type check is too complex for the back end to
12     ;;; directly emit in-line, then we transform the check into an explicit
13     ;;; conditional using TYPEP.
14     ;;;
15     ;;; Written by Rob MacLachlan
16     ;;;
17     (in-package 'c)
18    
19    
20     ;;;; Cost estimation:
21    
22    
23     ;;; Function-Cost -- Internal
24     ;;;
25     ;;; Return some sort of guess about the cost of a call to a function. If
26     ;;; the function has some templates, we return the cost of the cheapest one,
27     ;;; otherwise we return the cost of CALL-NAMED. Calling this with functions
28     ;;; that have transforms can result in relatively meaningless results
29     ;;; (exaggerated costs.)
30     ;;;
31     ;;; We randomly special-case NULL, since it does have a source tranform and is
32     ;;; interesting to us.
33     ;;;
34     (defun function-cost (name)
35     (declare (symbol name))
36     (let ((info (info function info name))
37     (call-cost (template-cost (template-or-lose 'call-named))))
38     (if info
39     (let ((templates (function-info-templates info)))
40     (if templates
41     (template-cost (first templates))
42     (case name
43     (null (template-cost (template-or-lose 'if-eq)))
44     (t call-cost))))
45     call-cost)))
46    
47    
48     ;;; Type-Test-Cost -- Internal
49     ;;;
50     ;;; Return some sort of guess for the cost of doing a test against TYPE.
51     ;;; The result need not be precise as long as it isn't way out in space. The
52     ;;; units are based on the costs specified for various templates in the VM
53     ;;; definition.
54     ;;;
55     (defun type-test-cost (type)
56     (declare (type ctype type))
57     (or (let ((check (type-check-template type)))
58     (if check
59     (template-cost check)
60     (let ((found (cdr (assoc type *type-predicates* :test #'type=))))
61     (if found
62     (function-cost found)
63     nil))))
64     (typecase type
65     (union-type
66     (collect ((res 0 +))
67     (dolist (mem (union-type-types type))
68     (res (type-test-cost mem)))
69     (res)))
70     (member-type
71     (* (length (member-type-members type))
72     (function-cost 'eq)))
73     (numeric-type
74     (* (if (numeric-type-complexp type) 2 1)
75     (function-cost
76     (if (csubtypep type (specifier-type 'fixnum)) 'fixnump 'numberp))
77     (+ 1
78     (if (numeric-type-low type) 1 0)
79     (if (numeric-type-high type) 1 0))))
80     (t
81     (function-cost 'typep)))))
82    
83    
84     ;;;; Checking strategy determination:
85    
86    
87 ram 1.3 ;;; MAYBE-WEAKEN-CHECK -- Internal
88     ;;;
89     ;;; Return the type we should test for when we really want to check for
90     ;;; Type. If speed, space or compilation speed is more important than safety,
91     ;;; then we return a weaker type if it is easier to check. First we try the
92     ;;; defined type weakenings, then look for any predicate that is cheaper.
93     ;;;
94     ;;; If the supertype is equal in cost to the type, we prefer the supertype.
95     ;;; This produces a closer approximation of the right thing in the presence of
96     ;;; poor cost info.
97     ;;;
98     (defun maybe-weaken-check (type cont)
99     (declare (type ctype type) (type continuation cont))
100     (cond ((policy (continuation-dest cont)
101     (<= speed safety) (<= space safety) (<= cspeed safety))
102     type)
103     (t
104     (let ((min-cost (type-test-cost type))
105     (min-type type)
106     (found-super nil))
107     (dolist (x *type-predicates*)
108     (let ((stype (car x)))
109 ram 1.5 (when (and (csubtypep type stype)
110     (not (union-type-p stype))) ;Not #!% COMMON type.
111 ram 1.3 (let ((stype-cost (type-test-cost stype)))
112 ram 1.8 (when (or (< stype-cost min-cost)
113     (type= stype type))
114 ram 1.5 (setq found-super t)
115 ram 1.3 (setq min-type stype min-cost stype-cost))))))
116     (if found-super
117     min-type
118     *universal-type*)))))
119    
120    
121 ram 1.9 ;;; NO-FUNCTION-VALUES-TYPES -- Internal
122     ;;;
123     ;;; Like VALUES-TYPES, only mash any complex function types to FUNCTION.
124     ;;;
125     (defun no-function-values-types (type)
126     (declare (type ctype type))
127     (multiple-value-bind (res count)
128     (values-types type)
129     (values (mapcar #'(lambda (type)
130     (if (function-type-p type)
131     (specifier-type 'function)
132     type))
133     res)
134     count)))
135    
136    
137 wlott 1.1 ;;; MAYBE-NEGATE-CHECK -- Internal
138     ;;;
139     ;;; Cont is a continuation we are doing a type check on and Types is a list
140     ;;; of types that we are checking its values against. If we have proven
141     ;;; that Cont generates a fixed number of values, then for each value, we check
142     ;;; whether it is cheaper to then difference between the the proven type and
143     ;;; the corresponding type in Types. If so, we opt for a :HAIRY check with
144     ;;; that test negated. Otherwise, we try to do a simple test, and if that is
145 ram 1.13 ;;; impossible, we do a hairy test with non-negated types. If true,
146     ;;; Force-Hairy forces a hairy type check.
147 wlott 1.1 ;;;
148 ram 1.7 ;;; When doing a non-negated hairy check, we call MAYBE-WEAKEN-CHECK to
149     ;;; weaken the test to a convenient supertype (conditional on policy.)
150     ;;;
151 ram 1.13 (defun maybe-negate-check (cont types force-hairy)
152 wlott 1.1 (declare (type continuation cont) (list types))
153 ram 1.9 (multiple-value-bind
154     (ptypes count)
155     (no-function-values-types (continuation-proven-type cont))
156 wlott 1.1 (if (eq count :unknown)
157 ram 1.13 (if (and (every #'type-check-template types) (not force-hairy))
158 wlott 1.1 (values :simple types)
159 ram 1.3 (values :hairy
160     (mapcar #'(lambda (x)
161     (list nil (maybe-weaken-check x cont) x))
162     types)))
163 wlott 1.1 (let ((res (mapcar #'(lambda (p c)
164 ram 1.7 (let ((diff (type-difference p c))
165     (weak (maybe-weaken-check c cont)))
166 wlott 1.1 (if (and diff
167     (< (type-test-cost diff)
168 ram 1.7 (type-test-cost weak)))
169     (list t diff c)
170     (list nil weak c))))
171 wlott 1.1 ptypes types)))
172     (if (and (not (find-if #'first res))
173 ram 1.13 (every #'type-check-template types)
174     (not force-hairy))
175 wlott 1.1 (values :simple types)
176     (values :hairy res))))))
177    
178    
179     ;;; CONTINUATION-CHECK-TYPES -- Interface
180     ;;;
181     ;;; Determines whether Cont's assertion is:
182     ;;; -- Checkable by the back end (:SIMPLE), or
183     ;;; -- Not checkable by the back end, but checkable via an explicit test in
184     ;;; type check conversion (:HAIRY), or
185     ;;; -- not reasonably checkable at all (:TOO-HAIRY).
186     ;;;
187     ;;; A type is checkable if it either represents a fixed number of values (as
188     ;;; determined by VALUES-TYPES), or it is the assertion for an MV-Bind. A type
189     ;;; is simply checkable if all the type assertions have a TYPE-CHECK-TEMPLATE.
190     ;;; In this :SIMPLE case, the second value is a list of the type restrictions
191     ;;; specified for the leading positional values.
192     ;;;
193 ram 1.13 ;;; We force a check to be hairy even when there are fixed values if we are in
194     ;;; a context where we may be forced to use the unknown values convention
195     ;;; anyway. This is because IR2tran can't generate type checks for unknown
196     ;;; values continuations but people could still be depending on the check being
197     ;;; done. We only care about EXIT and RETURN (not MV-COMBINATION) since these
198     ;;; are the only contexts where the ultimate values receiver
199     ;;;
200 wlott 1.1 ;;; In the :HAIRY case, the second value is a list of triples of the form:
201     ;;; (Not-P Type Original-Type)
202     ;;;
203     ;;; If true, the Not-P flag indicates a test that the corresponding value is
204     ;;; *not* of the specified Type. Original-Type is the type asserted on this
205     ;;; value in the continuation, for use in error messages. When Not-P is true,
206     ;;; this will be different from Type.
207     ;;;
208     ;;; This allows us to take what has been proven about Cont's type into
209     ;;; consideration. If it is cheaper to test for the difference between the
210     ;;; derived type and the asserted type, then we check for the negation of this
211     ;;; type instead.
212     ;;;
213     (defun continuation-check-types (cont)
214     (declare (type continuation cont))
215     (let ((type (continuation-asserted-type cont))
216     (dest (continuation-dest cont)))
217     (assert (not (eq type *wild-type*)))
218     (multiple-value-bind (types count)
219 ram 1.9 (no-function-values-types type)
220 wlott 1.1 (cond ((not (eq count :unknown))
221 ram 1.13 (if (or (exit-p dest)
222     (and (return-p dest)
223     (multiple-value-bind
224     (ignore count)
225     (values-types (return-result-type dest))
226     (declare (ignore ignore))
227     (eq count :unknown))))
228     (maybe-negate-check cont types t)
229     (maybe-negate-check cont types nil)))
230 wlott 1.1 ((and (mv-combination-p dest)
231     (eq (basic-combination-kind dest) :local))
232     (assert (values-type-p type))
233 ram 1.13 (maybe-negate-check cont (args-type-optional type) nil))
234 wlott 1.1 (t
235     (values :too-hairy nil))))))
236    
237    
238     ;;; Probable-Type-Check-P -- Internal
239     ;;;
240     ;;; Return true if Cont is a continuation whose type the back end is likely
241     ;;; to want to check. Since we don't know what template the back end is going
242     ;;; to choose to implement the continuation's DEST, we use a heuristic. We
243     ;;; always return T unless:
244     ;;; -- Nobody uses the value, or
245 ram 1.3 ;;; -- Safety is totally unimportant, or
246 wlott 1.1 ;;; -- the continuation is an argument to an unknown function, or
247     ;;; -- the continuation is an argument to a known function that has no
248     ;;; IR2-Convert method or :fast-safe templates that are compatible with the
249     ;;; call's type.
250     ;;;
251     ;;; We must only return nil when it is *certain* that a check will not be done,
252     ;;; since if we pass up this chance to do the check, it will be too late. The
253     ;;; penalty for being too conservative is duplicated type checks.
254     ;;;
255 ram 1.13 ;;; If there is a compile-time type error, then we always return true unless
256     ;;; the DEST is a full call. With a full call, the theory is that the type
257     ;;; error is probably from a declaration in (or on) the callee, so the callee
258     ;;; should be able to do the check. We want to let the callee do the check,
259     ;;; because it is possible that the error is really in the callee, not the
260     ;;; caller. We don't want to make people recompile all calls to a function
261     ;;; when they were originally compiled with a bad declaration (or an old type
262     ;;; assertion derived from a definition appearing after the call.)
263 wlott 1.1 ;;;
264     (defun probable-type-check-p (cont)
265     (declare (type continuation cont))
266     (let ((dest (continuation-dest cont)))
267 ram 1.13 (cond ((eq (continuation-type-check cont) :error)
268     (if (and (combination-p dest) (eq (combination-kind dest) :full))
269     nil
270     t))
271 wlott 1.1 ((or (not dest)
272 ram 1.3 (policy dest (zerop safety)))
273 wlott 1.1 nil)
274     ((basic-combination-p dest)
275     (let ((kind (basic-combination-kind dest)))
276     (cond ((eq cont (basic-combination-fun dest)) t)
277     ((eq kind :local) t)
278     ((eq kind :full) nil)
279     ((function-info-ir2-convert kind) t)
280     (t
281     (dolist (template (function-info-templates kind) nil)
282 ram 1.6 (when (eq (template-policy template) :fast-safe)
283     (multiple-value-bind
284     (val win)
285     (valid-function-use dest (template-type template))
286     (when (or val (not win)) (return t)))))))))
287 wlott 1.1 (t t))))
288    
289    
290     ;;; Make-Type-Check-Form -- Internal
291     ;;;
292     ;;; Return a form that we can convert to do a hairy type check of the
293     ;;; specified Types. Types is a list of the format returned by
294     ;;; Continuation-Check-Types in the :HAIRY case. In place of the actual
295     ;;; value(s) we are to check, we use 'Dummy. This constant reference is later
296     ;;; replaced with the actual values continuation.
297     ;;;
298     ;;; Note that we don't attempt to check for required values being unsupplied.
299     ;;; Such checking is impossible to efficiently do at the source level because
300     ;;; our fixed-values conventions are optimized for the common MV-Bind case.
301     ;;;
302     ;;; We can always use Multiple-Value-Bind, since the macro is clever about
303     ;;; binding a single variable.
304     ;;;
305     (defun make-type-check-form (types)
306     (collect ((temps))
307     (dotimes (i (length types))
308     (temps (gensym)))
309    
310     `(multiple-value-bind ,(temps)
311     'dummy
312     ,@(mapcar #'(lambda (temp type)
313 ram 1.10 (let* ((spec
314     (let ((*unparse-function-type-simplify* t))
315     (type-specifier (second type))))
316 wlott 1.1 (test (if (first type) `(not ,spec) spec)))
317     `(unless (typep ,temp ',test)
318     (%type-check-error
319     ,temp
320     ',(type-specifier (third type))))))
321     (temps) types)
322     (values ,@(temps)))))
323    
324    
325     ;;; Convert-Type-Check -- Internal
326     ;;;
327     ;;; Splice in explicit type check code immediately before the node that its
328     ;;; Cont's Dest. This code receives the value(s) that were being passed to
329     ;;; Cont, checks the type(s) of the value(s), then passes them on to Cont.
330     ;;; We:
331     ;;; -- Ensure that Cont starts a block, so that we can freely manipulate its
332     ;;; uses.
333     ;;; -- Make a new continuation and move Cont's uses to it. Set type set
334     ;;; Type-Check in Cont to :DELETED to indicate that the check has been
335     ;;; done.
336     ;;; -- Make the Dest node start its block so that we can splice in the type
337     ;;; check code.
338     ;;; -- Splice in a new block before the Dest block, giving it all the Dest's
339     ;;; predecessors.
340     ;;; -- Convert the check form, using the new block start as Start and a dummy
341     ;;; continuation as Cont.
342     ;;; -- Set the new block's start and end cleanups to the *start* cleanup of
343     ;;; Prev's block. This overrides the incorrect default from
344     ;;; With-IR1-Environment.
345     ;;; -- Finish off the dummy continuation's block, and change the use to a use
346     ;;; of Cont. (we need to use the dummy continuation to get the control
347     ;;; transfer right, since we want to go to Prev's block, not Cont's.)
348     ;;; Link the new block to Prev's block.
349     ;;; -- Substitute the new continuation for the dummy placeholder argument.
350     ;;; Since no let conversion has been done yet, we can find the placeholder.
351     ;;; The [mv-]combination node from the mv-bind in the check form will be
352     ;;; the Use of the new check continuation. We substitute for the first
353     ;;; argument of this node.
354     ;;; -- Invoke local call analysis to convert the call to a let.
355     ;;;
356     (defun convert-type-check (cont types)
357     (declare (type continuation cont) (list types))
358     (with-ir1-environment (continuation-dest cont)
359     (ensure-block-start cont)
360     (let* ((new-start (make-continuation))
361     (dest (continuation-dest cont))
362     (prev (node-prev dest)))
363     (continuation-starts-block new-start)
364     (substitute-continuation-uses new-start cont)
365     (setf (continuation-%type-check cont) :deleted)
366    
367     (when (continuation-use prev)
368     (node-ends-block (continuation-use prev)))
369    
370     (let* ((prev-block (continuation-block prev))
371     (new-block (continuation-block new-start))
372     (dummy (make-continuation)))
373     (dolist (block (block-pred prev-block))
374     (change-block-successor block prev-block new-block))
375     (ir1-convert new-start dummy (make-type-check-form types))
376     (assert (eq (continuation-block dummy) new-block))
377    
378     (let ((node (continuation-use dummy)))
379     (setf (block-last new-block) node)
380     (delete-continuation-use node)
381     (add-continuation-use node cont))
382     (link-blocks new-block prev-block))
383    
384     (let* ((node (continuation-use cont))
385     (args (basic-combination-args node))
386     (victim (first args)))
387     (assert (and (= (length args) 1)
388     (eq (constant-value
389     (ref-leaf
390     (continuation-use victim)))
391     'dummy)))
392     (substitute-continuation new-start victim)))
393    
394     (local-call-analyze *current-component*))
395    
396     (undefined-value))
397    
398    
399 ram 1.13 ;;; DO-TYPE-WARNING -- Internal
400     ;;;
401     ;;; Emit a type warning for Node. If the value of node is being used for a
402     ;;; variable binding, we figure out which one for source context. If the value
403 ram 1.14 ;;; is a constant, we print it specially. We ignore nodes whose type is NIL,
404     ;;; since they are supposed to never return.
405 ram 1.13 ;;;
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 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 ram 1.14 (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 ram 1.13 what atype-spec (constant-value (ref-leaf node))))
425 ram 1.14 (t
426     (compiler-warning
427     "~:[Result~;~:*~A~] is a ~S, ~<~%~9T~:;not a ~S.~>"
428     what (type-specifier dtype) atype-spec))))
429 ram 1.13 (undefined-value))
430    
431    
432     ;;; MARK-ERROR-CONTINUATION -- Internal
433     ;;;
434     ;;; Mark Cont as being a continuation with a manifest type error. We set
435     ;;; the kind to :ERROR, and clear any FUNCTION-INFO if the continuation is an
436     ;;; argument to a known call. The last is done so that the back end doesn't
437     ;;; have to worry about type errors in arguments to known functions. This
438     ;;; clearing is inhibited for things with IR2-CONVERT methods, since we can't
439     ;;; do a full call to funny functions.
440     ;;;
441     (defun mark-error-continuation (cont)
442     (declare (type continuation cont))
443     (setf (continuation-%type-check cont) :error)
444     (let ((dest (continuation-dest cont)))
445     (when (and (combination-p dest)
446     (let ((info (basic-combination-kind dest)))
447     (and (function-info-p info)
448     (not (function-info-ir2-convert info)))))
449     (setf (basic-combination-kind dest) :full)))
450     (undefined-value))
451    
452    
453 wlott 1.1 ;;; Generate-Type-Checks -- Interface
454     ;;;
455     ;;; Loop over all blocks in Component that have TYPE-CHECK set, looking for
456     ;;; continuations with TYPE-CHECK T. We do two mostly unrelated things: detect
457     ;;; compile-time type errors and determine if and how to do run-time type
458     ;;; checks.
459     ;;;
460 ram 1.13 ;;; If there is a compile-time type error, then we mark the continuation and
461     ;;; emit a warning if appropriate. This part loops over all the uses of the
462     ;;; continuation, since after we convert the check, the :DELETED kind will
463     ;;; inhibit warnings about the types of other uses.
464 ram 1.2 ;;;
465 wlott 1.1 ;;; If a continuation is too complex to be checked by the back end, or is
466     ;;; better checked with explicit code, then convert to an explicit test.
467     ;;; Assertions that can checked by the back end are passed through. Assertions
468     ;;; that can't be tested are flamed about and marked as not needing to be
469     ;;; checked.
470     ;;;
471     ;;; If we determine that a type check won't be done, then we set TYPE-CHECK
472     ;;; to :NO-CHECK. In the non-hairy cases, this is just to prevent us from
473     ;;; wasting time coming to the same conclusion again on a later iteration. In
474     ;;; the hairy case, we must indicate to LTN that it must choose a safe
475     ;;; implementation, since IR2 conversion will choke on the check.
476     ;;;
477     (defun generate-type-checks (component)
478     (do-blocks (block component)
479     (when (block-type-check block)
480     (do-nodes (node cont block)
481 ram 1.12 (let ((type-check (continuation-type-check cont)))
482 ram 1.13 (unless (member type-check '(nil :error :deleted))
483     (let ((atype (continuation-asserted-type cont)))
484     (do-uses (use cont)
485     (unless (values-types-intersect (node-derived-type use)
486     atype)
487     (mark-error-continuation cont)
488     (unless (policy node (= brevity 3))
489     (do-type-warning use))))))
490    
491 ram 1.12 (when (eq type-check t)
492     (let ((check-p (probable-type-check-p cont)))
493     (multiple-value-bind (check types)
494     (continuation-check-types cont)
495     (ecase check
496     (:simple
497     (unless check-p
498 wlott 1.1 (setf (continuation-%type-check cont) :no-check)))
499 ram 1.12 (:hairy
500     (if check-p
501     (convert-type-check cont types)
502     (setf (continuation-%type-check cont) :no-check)))
503     (:too-hairy
504     (let* ((context (continuation-dest cont))
505     (*compiler-error-context* context))
506     (when (policy context (>= safety brevity))
507     (compiler-note
508     "Type assertion too complex to check:~% ~S."
509     (type-specifier (continuation-asserted-type cont)))))
510     (setf (continuation-%type-check cont) :deleted))))))))
511    
512 wlott 1.1 (setf (block-type-check block) nil)))
513 ram 1.12
514 wlott 1.1 (undefined-value))

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