1 ;;;; This file implements the constraint propagation phase of the
2 ;;;; compiler, which uses global flow analysis to obtain dynamic type
5 ;;;; This software is part of the SBCL system. See the README file for
8 ;;;; This software is derived from the CMU CL system, which was
9 ;;;; written at Carnegie Mellon University and released into the
10 ;;;; public domain. The software is in the public domain and is
11 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
12 ;;;; files for more information.
18 ;;; -- MV-BIND, :ASSIGNMENT
20 ;;; Note: The functions in this file that accept constraint sets are
21 ;;; actually receiving the constraint sets associated with nodes,
22 ;;; blocks, and lambda-vars. It might be make CP easier to understand
23 ;;; and work on if these functions traded in nodes, blocks, and
24 ;;; lambda-vars directly.
28 ;;; -- Constraint propagation badly interacts with bottom-up type
29 ;;; inference. Consider
31 ;;; (defun foo (n &aux (i 42))
32 ;;; (declare (optimize speed))
33 ;;; (declare (fixnum n)
34 ;;; #+nil (type (integer 0) i))
38 ;;; (when (>= i n) (go :exit))
43 ;;; In this case CP cannot even infer that I is of class INTEGER.
45 ;;; -- In the above example if we place the check after SETQ, CP will
46 ;;; fail to infer (< I FIXNUM): it does not understand that this
47 ;;; constraint follows from (TYPEP I (INTEGER 0 0)).
51 ;;; *CONSTRAINT-UNIVERSE* gets bound in IR1-PHASES to a fresh,
52 ;;; zero-length, non-zero-total-size vector-with-fill-pointer.
53 (declaim (type (and vector (not simple-vector)) *constraint-universe*))
54 (defvar *constraint-universe*)
56 (deftype constraint-y () '(or ctype lvar lambda-var constant))
58 (defstruct (constraint
59 (:include sset-element)
60 (:constructor make-constraint (number kind x y not-p))
62 ;; the kind of constraint we have:
65 ;; X is a LAMBDA-VAR and Y is a CTYPE. The value of X is
66 ;; constrained to be of type Y.
69 ;; X is a lambda-var and Y is a CTYPE. The relation holds
70 ;; between X and some object of type Y.
73 ;; X is a LAMBDA-VAR and Y is a LVAR, a LAMBDA-VAR or a CONSTANT.
74 ;; The relation is asserted to hold.
75 (kind nil :type (member typep < > eql))
76 ;; The operands to the relation.
77 (x nil :type lambda-var)
78 (y nil :type constraint-y)
79 ;; If true, negates the sense of the constraint, so the relation
81 (not-p nil :type boolean))
83 ;;; Historically, CMUCL and SBCL have used a sparse set implementation
84 ;;; for which most operations are O(n) (see sset.lisp), but at the
85 ;;; cost of at least a full word of pointer for each constraint set
86 ;;; element. Using bit-vectors instead of pointer structures saves a
87 ;;; lot of space and thus GC time (particularly on 64-bit machines),
88 ;;; and saves time on copy, union, intersection, and difference
89 ;;; operations; but makes iteration slower. Circa September 2008,
90 ;;; switching to bit-vectors gave a modest (5-10%) improvement in real
91 ;;; compile time for most Lisp systems, and as much as 20-30% for some
92 ;;; particularly CP-dependent systems.
94 ;;; It's bad to leave commented code in files, but if some clever
95 ;;; person comes along and makes SSETs better than bit-vectors as sets
96 ;;; for constraint propagation, or if bit-vectors on some XC host
97 ;;; really lose compared to SSETs, here's the conset API as a wrapper
101 (deftype conset () 'sset)
102 (declaim (ftype (sfunction (conset) boolean) conset-empty))
103 (declaim (ftype (sfunction (conset) conset) copy-conset))
104 (declaim (ftype (sfunction (constraint conset) boolean) conset-member))
105 (declaim (ftype (sfunction (constraint conset) boolean) conset-adjoin))
106 (declaim (ftype (sfunction (conset conset) boolean) conset=))
107 (declaim (ftype (sfunction (conset conset) (values)) conset-union))
108 (declaim (ftype (sfunction (conset conset) (values)) conset-intersection))
109 (declaim (ftype (sfunction (conset conset) (values)) conset-difference))
110 (defun make-conset () (make-sset))
111 (defmacro do-conset-elements ((constraint conset &optional result) &body body)
112 `(do-sset-elements (,constraint ,conset ,result) ,@body))
113 (defmacro do-conset-intersection
114 ((constraint conset1 conset2 &optional result) &body body)
115 `(do-conset-elements (,constraint ,conset1 ,result)
116 (when (conset-member ,constraint ,conset2)
118 (defun conset-empty (conset) (sset-empty conset))
119 (defun copy-conset (conset) (copy-sset conset))
120 (defun conset-member (constraint conset) (sset-member constraint conset))
121 (defun conset-adjoin (constraint conset) (sset-adjoin constraint conset))
122 (defun conset= (conset1 conset2) (sset= conset1 conset2))
123 ;; Note: CP doesn't ever care whether union, intersection, and
124 ;; difference change the first set. (This is an important degree of
125 ;; freedom, since some ways of implementing sets lose a great deal
126 ;; when these operations are required to track changes.)
127 (defun conset-union (conset1 conset2)
128 (sset-union conset1 conset2) (values))
129 (defun conset-intersection (conset1 conset2)
130 (sset-intersection conset1 conset2) (values))
131 (defun conset-difference (conset1 conset2)
132 (sset-difference conset1 conset2) (values)))
135 ;; This is performance critical for the compiler, and benefits
136 ;; from the following declarations. Probably you'll want to
137 ;; disable these declarations when debugging consets.
138 (declare #-sb-xc-host (optimize (speed 3) (safety 0) (space 0)))
139 (declaim (inline %constraint-number))
140 (defun %constraint-number (constraint)
141 (sset-element-number constraint))
143 (:constructor make-conset ())
144 (:copier %copy-conset))
146 ;; FIXME: make POWER-OF-TWO-CEILING available earlier?
147 (ash 1 (integer-length (1- (length *constraint-universe*))))
148 :element-type 'bit :initial-element 0)
149 :type simple-bit-vector)
150 ;; Bit-vectors win over lightweight hashes for copy, union,
151 ;; intersection, difference, but lose for iteration if you iterate
152 ;; over the whole vector. Tracking extrema helps a bit.
154 (max 0 :type fixnum))
156 (defmacro do-conset-elements ((constraint conset &optional result) &body body)
157 (with-unique-names (vector index start end
159 #-sb-xc-host constraint-universe-end)
160 (let* ((constraint-universe #+sb-xc-host '*constraint-universe*
161 #-sb-xc-host (sb!xc:gensym "UNIVERSE"))
163 #+sb-xc-host '(progn)
164 #-sb-xc-host `(with-array-data
165 ((,constraint-universe *constraint-universe*)
166 (,ignore 0) (,constraint-universe-end nil)
167 :check-fill-pointer t)
168 (declare (ignore ,ignore))
169 (aver (<= ,end ,constraint-universe-end)))))
170 `(let* ((,vector (conset-vector ,conset))
171 (,start (conset-min ,conset))
172 (,end (min (conset-max ,conset) (length ,vector))))
174 (do ((,index ,start (1+ ,index))) ((>= ,index ,end) ,result)
175 (when (plusp (sbit ,vector ,index))
176 (let ((,constraint (elt ,constraint-universe ,index)))
179 ;; Oddly, iterating just between the maximum of the two sets' minima
180 ;; and the minimum of the sets' maxima slowed down CP.
181 (defmacro do-conset-intersection
182 ((constraint conset1 conset2 &optional result) &body body)
183 `(do-conset-elements (,constraint ,conset1 ,result)
184 (when (conset-member ,constraint ,conset2)
187 (defun conset-empty (conset)
188 (or (= (conset-min conset) (conset-max conset))
189 ;; TODO: I bet FIND on bit-vectors can be optimized, if it
191 (not (find 1 (conset-vector conset)
192 :start (conset-min conset)
193 ;; By inspection, supplying :END here breaks the
194 ;; build with a "full call to
195 ;; DATA-VECTOR-REF-WITH-OFFSET" in the
196 ;; cross-compiler. If that should change, add
197 ;; :end (conset-max conset)
200 (defun copy-conset (conset)
201 (let ((ret (%copy-conset conset)))
202 (setf (conset-vector ret) (copy-seq (conset-vector conset)))
205 (defun %conset-grow (conset new-size)
206 (declare (type index new-size))
207 (setf (conset-vector conset)
208 (replace (the simple-bit-vector
210 (ash 1 (integer-length (1- new-size)))
213 (the simple-bit-vector
214 (conset-vector conset)))))
216 (declaim (inline conset-grow))
217 (defun conset-grow (conset new-size)
218 (declare (type index new-size))
219 (when (< (length (conset-vector conset)) new-size)
220 (%conset-grow conset new-size))
223 (defun conset-member (constraint conset)
224 (let ((number (%constraint-number constraint))
225 (vector (conset-vector conset)))
226 (when (< number (length vector))
227 (plusp (sbit vector number)))))
229 (defun conset-adjoin (constraint conset)
231 (not (conset-member constraint conset))
232 (let ((number (%constraint-number constraint)))
233 (conset-grow conset (1+ number))
234 (setf (sbit (conset-vector conset) number) 1)
235 (setf (conset-min conset) (min number (conset-min conset)))
236 (when (>= number (conset-max conset))
237 (setf (conset-max conset) (1+ number))))))
239 (defun conset= (conset1 conset2)
240 (let* ((vector1 (conset-vector conset1))
241 (vector2 (conset-vector conset2))
242 (length1 (length vector1))
243 (length2 (length vector2)))
244 (if (= length1 length2)
245 ;; When the lengths are the same, we can rely on EQUAL being
246 ;; nicely optimized on bit-vectors.
247 (equal vector1 vector2)
248 (multiple-value-bind (shorter longer)
249 (if (< length1 length2)
250 (values vector1 vector2)
251 (values vector2 vector1))
252 ;; FIXME: make MISMATCH fast on bit-vectors.
253 (dotimes (index (length shorter))
254 (when (/= (sbit vector1 index) (sbit vector2 index))
255 (return-from conset= nil)))
256 (if (find 1 longer :start (length shorter))
261 ((defconsetop (name bit-op)
262 `(defun ,name (conset-1 conset-2)
263 (declare (optimize (speed 3) (safety 0)))
264 (let* ((size-1 (length (conset-vector conset-1)))
265 (size-2 (length (conset-vector conset-2)))
266 (new-size (max size-1 size-2)))
267 (conset-grow conset-1 new-size)
268 (conset-grow conset-2 new-size))
269 (let ((vector1 (conset-vector conset-1))
270 (vector2 (conset-vector conset-2)))
271 (declare (simple-bit-vector vector1 vector2))
272 (setf (conset-vector conset-1) (,bit-op vector1 vector2 t))
273 ;; Update the extrema.
276 `(setf (conset-min conset-1)
277 (min (conset-min conset-1)
278 (conset-min conset-2))
279 (conset-max conset-1)
280 (max (conset-max conset-1)
281 (conset-max conset-2))))
282 ((conset-intersection)
283 `(let ((start (max (conset-min conset-1)
284 (conset-min conset-2)))
285 (end (min (conset-max conset-1)
286 (conset-max conset-2))))
287 (setf (conset-min conset-1)
290 (or (position 1 (conset-vector conset-1)
291 :start start :end end)
293 (conset-max conset-1)
298 1 (conset-vector conset-1)
299 :start start :end end :from-end t)))
304 `(setf (conset-min conset-1)
305 (or (position 1 (conset-vector conset-1)
306 :start (conset-min conset-1)
307 :end (conset-max conset-1))
309 (conset-max conset-1)
312 1 (conset-vector conset-1)
313 :start (conset-min conset-1)
314 :end (conset-max conset-1)
320 (defconsetop conset-union bit-ior)
321 (defconsetop conset-intersection bit-and)
322 (defconsetop conset-difference bit-andc2)))
324 ;;; Constraints are hash-consed. Unfortunately, types aren't, so we have
325 ;;; to over-approximate and then linear search through the potential hits.
326 ;;; LVARs can only be found in EQL (not-p = NIL) constraints, while constant
327 ;;; and lambda-vars can only be found in EQL constraints.
329 (defun find-constraint (kind x y not-p)
330 (declare (type lambda-var x) (type constraint-y y) (type boolean not-p))
333 (awhen (lambda-var-ctype-constraints x)
334 (dolist (con (gethash (sb!kernel::type-class-info y) it) nil)
335 (when (and (eq (constraint-kind con) kind)
336 (eq (constraint-not-p con) not-p)
337 (type= (constraint-y con) y))
338 (return-from find-constraint con)))
341 (awhen (lambda-var-eq-constraints x)
343 ((or constant lambda-var)
344 (awhen (lambda-var-eq-constraints x)
345 (let ((cache (gethash y it)))
346 (declare (type list cache))
347 (if not-p (cdr cache) (car cache)))))))
349 ;;; The most common operations on consets are iterating through the constraints
350 ;;; that are related to a certain variable in a given conset. Storing the
351 ;;; constraints related to each variable in vectors allows us to easily iterate
352 ;;; through the intersection of such constraints and the constraints in a conset.
354 ;;; EQL-var constraints assert that two lambda-vars are EQL.
355 ;;; Private constraints assert that a lambda-var is EQL or not EQL to a constant.
356 ;;; Inheritable constraints are constraints that may be propagated to EQL
357 ;;; lambda-vars (along with EQL-var constraints).
359 ;;; Lambda-var -- lvar EQL constraints only serve one purpose: remember whether
360 ;;; an lvar is (only) written to by a ref to that lambda-var, and aren't ever
363 (defun register-constraint (x con y)
364 (declare (type lambda-var x) (type constraint con) (type constraint-y y))
365 (conset-adjoin con (lambda-var-constraints x))
366 (macrolet ((ensuref (place default)
367 `(or ,place (setf ,place ,default)))
369 `(ensuref ,place (make-hash-table)))
371 `(ensuref ,place (make-array 8 :adjustable t :fill-pointer 0))))
374 (let ((index (ensure-hash (lambda-var-ctype-constraints x)))
375 (vec (ensure-vec (lambda-var-inheritable-constraints x))))
376 (push con (gethash (sb!kernel::type-class-info y) index))
377 (vector-push-extend con vec)))
379 (let ((index (ensure-hash (lambda-var-eq-constraints x))))
380 (setf (gethash y index) con)))
381 ((or constant lambda-var)
382 (let* ((index (ensure-hash (lambda-var-eq-constraints x)))
383 (cons (ensuref (gethash y index) (list nil))))
384 (if (constraint-not-p con)
385 (setf (cdr cons) con)
386 (setf (car cons) con)))
389 (let ((vec (ensure-vec (lambda-var-private-constraints x))))
390 (vector-push-extend con vec)))
392 (let ((vec (if (constraint-not-p con)
393 (ensure-vec (lambda-var-inheritable-constraints x))
394 (ensure-vec (lambda-var-eql-var-constraints x)))))
395 (vector-push-extend con vec)))))))
398 ;;; Return a constraint for the specified arguments. We only create a
399 ;;; new constraint if there isn't already an equivalent old one,
400 ;;; guaranteeing that all equivalent constraints are EQ. This
401 ;;; shouldn't be called on LAMBDA-VARs with no CONSTRAINTS set.
402 (defun find-or-create-constraint (kind x y not-p)
403 (declare (type lambda-var x) (type constraint-y y) (type boolean not-p))
404 (or (find-constraint kind x y not-p)
405 (let ((new (make-constraint (length *constraint-universe*)
407 (vector-push-extend new *constraint-universe*
408 (1+ (length *constraint-universe*)))
409 (register-constraint x new y)
410 (when (lambda-var-p y)
411 (register-constraint y new x))
414 ;;; If REF is to a LAMBDA-VAR with CONSTRAINTs (i.e. we can do flow
415 ;;; analysis on it), then return the LAMBDA-VAR, otherwise NIL.
416 #!-sb-fluid (declaim (inline ok-ref-lambda-var))
417 (defun ok-ref-lambda-var (ref)
418 (declare (type ref ref))
419 (let ((leaf (ref-leaf ref)))
420 (when (and (lambda-var-p leaf)
421 (lambda-var-constraints leaf))
424 ;;; See if LVAR's single USE is a REF to a LAMBDA-VAR and they are EQL
425 ;;; according to CONSTRAINTS. Return LAMBDA-VAR if so.
426 (defun ok-lvar-lambda-var (lvar constraints)
427 (declare (type lvar lvar))
428 (let ((use (lvar-uses lvar)))
430 (let ((lambda-var (ok-ref-lambda-var use)))
432 (let ((constraint (find-constraint 'eql lambda-var lvar nil)))
433 (when (and constraint (conset-member constraint constraints))
436 (ok-lvar-lambda-var (cast-value use) constraints)))))
438 (defmacro do-conset-constraints-intersection ((symbol (conset constraints) &optional result)
440 (let ((min (gensym "MIN"))
441 (max (gensym "MAX")))
442 (once-only ((conset conset)
443 (constraints constraints))
444 `(flet ((body (,symbol)
445 (declare (type constraint ,symbol))
448 (let ((,min (conset-min ,conset))
449 (,max (conset-max ,conset)))
450 (map nil (lambda (constraint)
451 (declare (type constraint constraint))
452 (let ((number (constraint-number constraint)))
453 (when (and (<= ,min number)
455 (conset-member constraint ,conset))
460 (defmacro do-eql-vars ((symbol (var constraints) &optional result) &body body)
461 (once-only ((var var)
462 (constraints constraints))
463 `(flet ((body-fun (,symbol)
466 (do-conset-constraints-intersection
467 (con (,constraints (lambda-var-eql-var-constraints ,var)) ,result)
468 (let ((x (constraint-x con))
469 (y (constraint-y con)))
470 (body-fun (if (eq ,var x) y x)))))))
472 (defmacro do-inheritable-constraints ((symbol (conset variable) &optional result)
474 (once-only ((conset conset)
477 (flet ((body-fun (,symbol)
479 (do-conset-constraints-intersection
480 (con (,conset (lambda-var-inheritable-constraints ,variable)))
482 (do-conset-constraints-intersection
483 (con (,conset (lambda-var-eql-var-constraints ,variable)) ,result)
486 (defmacro do-propagatable-constraints ((symbol (conset variable) &optional result)
488 (once-only ((conset conset)
491 (flet ((body-fun (,symbol)
493 (do-conset-constraints-intersection
494 (con (,conset (lambda-var-private-constraints ,variable)))
496 (do-conset-constraints-intersection
497 (con (,conset (lambda-var-eql-var-constraints ,variable)))
499 (do-conset-constraints-intersection
500 (con (,conset (lambda-var-inheritable-constraints ,variable)) ,result)
502 ;;;; Searching constraints
504 ;;; Add the indicated test constraint to BLOCK. We don't add the
505 ;;; constraint if the block has multiple predecessors, since it only
506 ;;; holds on this particular path.
507 (defun add-test-constraint (fun x y not-p constraints target)
508 (cond ((and (eq 'eql fun) (lambda-var-p y) (not not-p))
509 (add-eql-var-var-constraint x y constraints target))
511 (do-eql-vars (x (x constraints))
512 (let ((con (find-or-create-constraint fun x y not-p)))
513 (conset-adjoin con target)))))
516 ;;; Add complementary constraints to the consequent and alternative
517 ;;; blocks of IF. We do nothing if X is NIL.
518 (defun add-complement-constraints (fun x y not-p constraints
519 consequent-constraints
520 alternative-constraints)
522 (add-test-constraint fun x y not-p constraints
523 consequent-constraints)
524 (add-test-constraint fun x y (not not-p) constraints
525 alternative-constraints))
528 ;;; Add test constraints to the consequent and alternative blocks of
529 ;;; the test represented by USE.
530 (defun add-test-constraints (use if constraints)
531 (declare (type node use) (type cif if))
532 ;; Note: Even if we do (IF test exp exp) => (PROGN test exp)
533 ;; optimization, the *MAX-OPTIMIZE-ITERATIONS* cutoff means that we
534 ;; can't guarantee that the optimization will be done, so we still
535 ;; need to avoid barfing on this case.
536 (unless (eq (if-consequent if) (if-alternative if))
537 (let ((consequent-constraints (make-conset))
538 (alternative-constraints (make-conset)))
539 (macrolet ((add (fun x y not-p)
540 `(add-complement-constraints ,fun ,x ,y ,not-p
542 consequent-constraints
543 alternative-constraints)))
546 (add 'typep (ok-lvar-lambda-var (ref-lvar use) constraints)
547 (specifier-type 'null) t))
549 (unless (eq (combination-kind use)
551 (let ((name (lvar-fun-name
552 (basic-combination-fun use)))
553 (args (basic-combination-args use)))
555 ((%typep %instance-typep)
556 (let ((type (second args)))
557 (when (constant-lvar-p type)
558 (let ((val (lvar-value type)))
560 (ok-lvar-lambda-var (first args) constraints)
563 (let ((*compiler-error-context* use))
564 (specifier-type val)))
567 (let* ((arg1 (first args))
568 (var1 (ok-lvar-lambda-var arg1 constraints))
570 (var2 (ok-lvar-lambda-var arg2 constraints)))
571 ;; The code below assumes that the constant is the
572 ;; second argument in case of variable to constant
573 ;; comparision which is sometimes true (see source
574 ;; transformations for EQ, EQL and CHAR=). Fixing
575 ;; that would result in more constant substitutions
576 ;; which is not a universally good thing, thus the
577 ;; unnatural asymmetry of the tests.
580 (add-test-constraint 'typep var2 (lvar-type arg1)
582 consequent-constraints)))
584 (add 'eql var1 var2 nil))
585 ((constant-lvar-p arg2)
587 (let ((use (principal-lvar-use arg2)))
590 (find-constant (lvar-value arg2))))
593 (add-test-constraint 'typep var1 (lvar-type arg2)
595 consequent-constraints)))))
597 (let* ((arg1 (first args))
598 (var1 (ok-lvar-lambda-var arg1 constraints))
600 (var2 (ok-lvar-lambda-var arg2 constraints)))
602 (add name var1 (lvar-type arg2) nil))
604 (add (if (eq name '<) '> '<) var2 (lvar-type arg1) nil))))
606 (let ((ptype (gethash name *backend-predicate-types*)))
608 (add 'typep (ok-lvar-lambda-var (first args) constraints)
610 (values consequent-constraints alternative-constraints))))
612 ;;;; Applying constraints
614 ;;; Return true if X is an integer NUMERIC-TYPE.
615 (defun integer-type-p (x)
616 (declare (type ctype x))
617 (and (numeric-type-p x)
618 (eq (numeric-type-class x) 'integer)
619 (eq (numeric-type-complexp x) :real)))
621 ;;; Given that an inequality holds on values of type X and Y, return a
622 ;;; new type for X. If GREATER is true, then X was greater than Y,
623 ;;; otherwise less. If OR-EQUAL is true, then the inequality was
624 ;;; inclusive, i.e. >=.
626 ;;; If GREATER (or not), then we max (or min) in Y's lower (or upper)
627 ;;; bound into X and return that result. If not OR-EQUAL, we can go
628 ;;; one greater (less) than Y's bound.
629 (defun constrain-integer-type (x y greater or-equal)
630 (declare (type numeric-type x y))
637 (if greater (numeric-type-low x) (numeric-type-high x))))
638 (let* ((x-bound (bound x))
639 (y-bound (exclude (bound y)))
640 (new-bound (cond ((not x-bound) y-bound)
641 ((not y-bound) x-bound)
642 (greater (max x-bound y-bound))
643 (t (min x-bound y-bound)))))
645 (modified-numeric-type x :low new-bound)
646 (modified-numeric-type x :high new-bound)))))
648 ;;; Return true if X is a float NUMERIC-TYPE.
649 (defun float-type-p (x)
650 (declare (type ctype x))
651 (and (numeric-type-p x)
652 (eq (numeric-type-class x) 'float)
653 (eq (numeric-type-complexp x) :real)))
655 ;;; Exactly the same as CONSTRAIN-INTEGER-TYPE, but for float numbers.
656 (defun constrain-float-type (x y greater or-equal)
657 (declare (type numeric-type x y))
658 (declare (ignorable x y greater or-equal)) ; for CROSS-FLOAT-INFINITY-KLUDGE
660 (aver (eql (numeric-type-class x) 'float))
661 (aver (eql (numeric-type-class y) 'float))
662 #+sb-xc-host ; (See CROSS-FLOAT-INFINITY-KLUDGE.)
664 #-sb-xc-host ; (See CROSS-FLOAT-INFINITY-KLUDGE.)
665 (labels ((exclude (x)
673 (if greater (numeric-type-low x) (numeric-type-high x)))
678 (= (type-bound-number x) (type-bound-number ref)))
679 ;; X is tighter if REF is not an open bound and X is
680 (and (not (consp ref)) (consp x)))
682 (< (type-bound-number ref) (type-bound-number x)))
684 (> (type-bound-number ref) (type-bound-number x))))))
685 (let* ((x-bound (bound x))
686 (y-bound (exclude (bound y)))
687 (new-bound (cond ((not x-bound)
691 ((tighter-p y-bound x-bound)
696 (modified-numeric-type x :low new-bound)
697 (modified-numeric-type x :high new-bound)))))
699 ;;; Return true if LEAF is "visible" from NODE.
700 (defun leaf-visible-from-node-p (leaf node)
703 ;; A LAMBDA-VAR is visible iif it is homed in a CLAMBDA that is an
704 ;; ancestor for NODE.
705 (let ((leaf-lambda (lambda-var-home leaf)))
706 (loop for lambda = (node-home-lambda node)
707 then (lambda-parent lambda)
709 when (eq lambda leaf-lambda)
711 ;; FIXME: Check on FUNCTIONALs (CLAMBDAs and OPTIONAL-DISPATCHes),
712 ;; not just LAMBDA-VARs.
714 ;; Assume everything else is globally visible.
717 ;;; Given the set of CONSTRAINTS for a variable and the current set of
718 ;;; restrictions from flow analysis IN, set the type for REF
720 (defun constrain-ref-type (ref in)
721 (declare (type ref ref) (type conset in))
722 ;; KLUDGE: The NOT-SET and NOT-FPZ here are so that we don't need to
723 ;; cons up endless union types when propagating large number of EQL
724 ;; constraints -- eg. from large CASE forms -- instead we just
725 ;; directly accumulate one XSET, and a set of fp zeroes, which we at
726 ;; the end turn into a MEMBER-TYPE.
728 ;; Since massive symbol cases are an especially atrocious pattern
729 ;; and the (NOT (MEMBER ...ton of symbols...)) will never turn into
730 ;; a more useful type, don't propagate their negation except for NIL
731 ;; unless SPEED > COMPILATION-SPEED.
732 (let ((res (single-value-type (node-derived-type ref)))
733 (constrain-symbols (policy ref (> speed compilation-speed)))
734 (not-set (alloc-xset))
736 (not-res *empty-type*)
737 (leaf (ref-leaf ref)))
738 (declare (type lambda-var leaf))
742 (when (or constrain-symbols (null x) (not (symbolp x)))
743 (add-to-xset x not-set)))))
744 (do-propagatable-constraints (con (in leaf))
745 (let* ((x (constraint-x con))
746 (y (constraint-y con))
747 (not-p (constraint-not-p con))
748 (other (if (eq x leaf) y x))
749 (kind (constraint-kind con)))
753 (if (member-type-p other)
754 (mapc-member-type-members #'note-not other)
755 (setq not-res (type-union not-res other)))
756 (setq res (type-approx-intersection2 res other))))
758 (let ((other-type (leaf-type other)))
760 (when (and (constant-p other)
761 (member-type-p other-type))
762 (note-not (constant-value other)))
763 (let ((leaf-type (leaf-type leaf)))
765 ((or (constant-p other)
766 (and (leaf-refs other) ; protect from
768 (csubtypep other-type leaf-type)
769 (not (type= other-type leaf-type))
770 ;; Don't change to a LEAF not visible here.
771 (leaf-visible-from-node-p other ref)))
772 (change-ref-leaf ref other)
773 (when (constant-p other) (return)))
775 (setq res (type-approx-intersection2
776 res other-type))))))))
779 ((and (integer-type-p res) (integer-type-p y))
780 (let ((greater (eq kind '>)))
781 (let ((greater (if not-p (not greater) greater)))
783 (constrain-integer-type res y greater not-p)))))
784 ((and (float-type-p res) (float-type-p y))
785 (let ((greater (eq kind '>)))
786 (let ((greater (if not-p (not greater) greater)))
788 (constrain-float-type res y greater not-p)))))))))))
789 (cond ((and (if-p (node-dest ref))
790 (or (xset-member-p nil not-set)
791 (csubtypep (specifier-type 'null) not-res)))
792 (setf (node-derived-type ref) *wild-type*)
793 (change-ref-leaf ref (find-constant t)))
796 (type-union not-res (make-member-type :xset not-set :fp-zeroes not-fpz)))
797 (derive-node-type ref
798 (make-single-value-type
799 (or (type-difference res not-res)
801 (maybe-terminate-block ref nil))))
806 (defun maybe-add-eql-var-lvar-constraint (ref gen)
807 (let ((lvar (ref-lvar ref))
808 (leaf (ref-leaf ref)))
809 (when (and (lambda-var-p leaf) lvar)
810 (conset-adjoin (find-or-create-constraint 'eql leaf lvar nil)
813 ;;; Copy all CONSTRAINTS involving FROM-VAR - except the (EQL VAR
814 ;;; LVAR) ones - to all of the variables in the VARS list.
815 (defun inherit-constraints (vars from-var constraints target)
816 (do-inheritable-constraints (con (constraints from-var))
817 (let ((eq-x (eq from-var (constraint-x con)))
818 (eq-y (eq from-var (constraint-y con))))
820 (conset-adjoin (find-or-create-constraint
821 (constraint-kind con)
822 (if eq-x var (constraint-x con))
823 (if eq-y var (constraint-y con))
824 (constraint-not-p con))
827 ;; Add an (EQL LAMBDA-VAR LAMBDA-VAR) constraint on VAR1 and VAR2 and
828 ;; inherit each other's constraints.
829 (defun add-eql-var-var-constraint (var1 var2 constraints
830 &optional (target constraints))
831 (let ((con (find-or-create-constraint 'eql var1 var2 nil)))
832 (when (conset-adjoin con target)
833 (collect ((eql1) (eql2))
834 (do-eql-vars (var1 (var1 constraints))
836 (do-eql-vars (var2 (var2 constraints))
838 (inherit-constraints (eql1) var2 constraints target)
839 (inherit-constraints (eql2) var1 constraints target))
842 ;; Add an (EQL LAMBDA-VAR LAMBDA-VAR) constraint on VAR and LVAR's
843 ;; LAMBDA-VAR if possible.
844 (defun maybe-add-eql-var-var-constraint (var lvar constraints
845 &optional (target constraints))
846 (declare (type lambda-var var) (type lvar lvar))
847 (let ((lambda-var (ok-lvar-lambda-var lvar constraints)))
849 (add-eql-var-var-constraint var lambda-var constraints target))))
851 ;;; Local propagation
852 ;;; -- [TODO: For any LAMBDA-VAR ref with a type check, add that
854 ;;; -- For any LAMBDA-VAR set, delete all constraints on that var; add
855 ;;; a type constraint based on the new value type.
856 (declaim (ftype (function (cblock conset boolean)
858 constraint-propagate-in-block))
859 (defun constraint-propagate-in-block (block gen preprocess-refs-p)
860 (do-nodes (node lvar block)
863 (let ((fun (bind-lambda node)))
864 (when (eq (functional-kind fun) :let)
865 (loop with call = (lvar-dest (node-lvar (first (lambda-refs fun))))
866 for var in (lambda-vars fun)
867 and val in (combination-args call)
868 when (and val (lambda-var-constraints var))
869 do (let ((type (lvar-type val)))
870 (unless (eq type *universal-type*)
871 (let ((con (find-or-create-constraint 'typep var type nil)))
872 (conset-adjoin con gen))))
873 (maybe-add-eql-var-var-constraint var val gen)))))
875 (when (ok-ref-lambda-var node)
876 (maybe-add-eql-var-lvar-constraint node gen)
877 (when preprocess-refs-p
878 (constrain-ref-type node gen))))
880 (let ((lvar (cast-value node)))
881 (let ((var (ok-lvar-lambda-var lvar gen)))
883 (let ((atype (single-value-type (cast-derived-type node)))) ;FIXME
884 (unless (eq atype *universal-type*)
885 (do-eql-vars (var (var gen))
886 (let ((con (find-or-create-constraint 'typep var atype nil)))
887 (conset-adjoin con gen)))))))))
889 (binding* ((var (set-var node))
890 (nil (lambda-var-p var) :exit-if-null)
891 (cons (lambda-var-constraints var) :exit-if-null))
892 (conset-difference gen cons)
893 (let ((type (single-value-type (node-derived-type node))))
894 (unless (eq type *universal-type*)
895 (let ((con (find-or-create-constraint 'typep var type nil)))
896 (conset-adjoin con gen))))
897 (maybe-add-eql-var-var-constraint var (set-value node) gen)))))
900 (defun constraint-propagate-if (block gen)
901 (let ((node (block-last block)))
903 (let ((use (lvar-uses (if-test node))))
905 (add-test-constraints use node gen))))))
907 ;;; Starting from IN compute OUT and (consequent/alternative
908 ;;; constraints if the block ends with and IF). Return the list of
909 ;;; successors that may need to be recomputed.
910 (defun find-block-type-constraints (block final-pass-p)
911 (declare (type cblock block))
912 (let ((gen (constraint-propagate-in-block
916 (copy-conset (block-in block)))
918 (setf (block-gen block) gen)
919 (multiple-value-bind (consequent-constraints alternative-constraints)
920 (constraint-propagate-if block gen)
921 (if consequent-constraints
922 (let* ((node (block-last block))
923 (old-consequent-constraints (if-consequent-constraints node))
924 (old-alternative-constraints (if-alternative-constraints node))
926 ;; Add the consequent and alternative constraints to GEN.
927 (cond ((conset-empty consequent-constraints)
928 (setf (if-consequent-constraints node) gen)
929 (setf (if-alternative-constraints node) gen))
931 (setf (if-consequent-constraints node) (copy-conset gen))
932 (conset-union (if-consequent-constraints node)
933 consequent-constraints)
934 (setf (if-alternative-constraints node) gen)
935 (conset-union (if-alternative-constraints node)
936 alternative-constraints)))
937 ;; Has the consequent been changed?
938 (unless (and old-consequent-constraints
939 (conset= (if-consequent-constraints node)
940 old-consequent-constraints))
941 (push (if-consequent node) succ))
942 ;; Has the alternative been changed?
943 (unless (and old-alternative-constraints
944 (conset= (if-alternative-constraints node)
945 old-alternative-constraints))
946 (push (if-alternative node) succ))
949 (unless (and (block-out block)
950 (conset= gen (block-out block)))
951 (setf (block-out block) gen)
952 (block-succ block))))))
954 ;;; Deliver the results of constraint propagation to REFs in BLOCK.
955 ;;; During this pass, we also do local constraint propagation by
956 ;;; adding in constraints as we see them during the pass through the
958 (defun use-result-constraints (block)
959 (declare (type cblock block))
960 (constraint-propagate-in-block block (block-in block) t))
962 ;;; Give an empty constraints set to any var that doesn't have one and
963 ;;; isn't a set closure var. Since a var that we previously rejected
964 ;;; looks identical to one that is new, so we optimistically keep
965 ;;; hoping that vars stop being closed over or lose their sets.
966 (defun init-var-constraints (component)
967 (declare (type component component))
968 (dolist (fun (component-lambdas component))
970 (dolist (var (lambda-vars x))
971 (unless (lambda-var-constraints var)
972 (when (or (null (lambda-var-sets var))
973 (not (closure-var-p var)))
974 (setf (lambda-var-constraints var) (make-conset)))))))
976 (dolist (let (lambda-lets fun))
979 ;;; Return the constraints that flow from PRED to SUCC. This is
980 ;;; BLOCK-OUT unless PRED ends with an IF and test constraints were
982 (defun block-out-for-successor (pred succ)
983 (declare (type cblock pred succ))
984 (let ((last (block-last pred)))
985 (or (when (if-p last)
986 (cond ((eq succ (if-consequent last))
987 (if-consequent-constraints last))
988 ((eq succ (if-alternative last))
989 (if-alternative-constraints last))))
992 (defun compute-block-in (block)
994 (dolist (pred (block-pred block))
995 ;; If OUT has not been calculated, assume it to be the universal
997 (let ((out (block-out-for-successor pred block)))
1000 (conset-intersection in out)
1001 (setq in (copy-conset out))))))
1002 (or in (make-conset))))
1004 (defun update-block-in (block)
1005 (let ((in (compute-block-in block)))
1006 (cond ((and (block-in block) (conset= in (block-in block)))
1009 (setf (block-in block) in)))))
1011 ;;; Return two lists: one of blocks that precede all loops and
1012 ;;; therefore require only one constraint propagation pass and the
1013 ;;; rest. This implementation does not find all such blocks.
1015 ;;; A more complete implementation would be:
1017 ;;; (do-blocks (block component)
1018 ;;; (if (every #'(lambda (pred)
1019 ;;; (or (member pred leading-blocks)
1020 ;;; (eq pred head)))
1021 ;;; (block-pred block))
1022 ;;; (push block leading-blocks)
1023 ;;; (push block rest-of-blocks)))
1025 ;;; Trailing blocks that succeed all loops could be found and handled
1026 ;;; similarly. In practice though, these more complex solutions are
1027 ;;; slightly worse performancewise.
1028 (defun leading-component-blocks (component)
1029 (declare (type component component))
1030 (flet ((loopy-p (block)
1031 (let ((n (block-number block)))
1032 (dolist (pred (block-pred block))
1033 (unless (< n (block-number pred))
1035 (let ((leading-blocks ())
1038 (do-blocks (block component)
1039 (when (and (not seen-loop-p) (loopy-p block))
1040 (setq seen-loop-p t))
1042 (push block rest-of-blocks)
1043 (push block leading-blocks)))
1044 (values (nreverse leading-blocks) (nreverse rest-of-blocks)))))
1046 ;;; Append OBJ to the end of LIST as if by NCONC but only if it is not
1047 ;;; a member already.
1048 (defun nconc-new (obj list)
1049 (do ((x list (cdr x))
1053 (setf (cdr prev) (list obj))
1056 (when (eql (car x) obj)
1057 (return-from nconc-new list))))
1059 (defun find-and-propagate-constraints (component)
1060 (let ((blocks-to-process ()))
1061 (flet ((enqueue (blocks)
1062 (dolist (block blocks)
1063 (setq blocks-to-process (nconc-new block blocks-to-process)))))
1064 (multiple-value-bind (leading-blocks rest-of-blocks)
1065 (leading-component-blocks component)
1066 ;; Update every block once to account for changes in the
1067 ;; IR1. The constraints of the lead blocks cannot be changed
1068 ;; after the first pass so we might as well use them and skip
1069 ;; USE-RESULT-CONSTRAINTS later.
1070 (dolist (block leading-blocks)
1071 (setf (block-in block) (compute-block-in block))
1072 (find-block-type-constraints block t))
1073 (setq blocks-to-process (copy-list rest-of-blocks))
1074 ;; The rest of the blocks.
1075 (dolist (block rest-of-blocks)
1076 (aver (eq block (pop blocks-to-process)))
1077 (setf (block-in block) (compute-block-in block))
1078 (enqueue (find-block-type-constraints block nil)))
1079 ;; Propagate constraints
1080 (loop for block = (pop blocks-to-process)
1082 (unless (eq block (component-tail component))
1083 (when (update-block-in block)
1084 (enqueue (find-block-type-constraints block nil)))))
1087 (defun constraint-propagate (component)
1088 (declare (type component component))
1089 (init-var-constraints component)
1091 (unless (block-out (component-head component))
1092 (setf (block-out (component-head component)) (make-conset)))
1094 (dolist (block (find-and-propagate-constraints component))
1095 (unless (block-delete-p block)
1096 (use-result-constraints block)))