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
158 ignore constraint-universe-end)
159 (let* ((constraint-universe #+sb-xc-host '*constraint-universe*
160 #-sb-xc-host (gensym))
162 #+sb-xc-host '(progn)
163 #-sb-xc-host `(with-array-data
164 ((,constraint-universe *constraint-universe*)
165 (,ignore 0) (,constraint-universe-end nil)
166 :check-fill-pointer t)
167 (declare (ignore ,ignore))
168 (aver (<= ,end ,constraint-universe-end)))))
169 `(let* ((,vector (conset-vector ,conset))
170 (,start (conset-min ,conset))
171 (,end (min (conset-max ,conset) (length ,vector))))
173 (do ((,index ,start (1+ ,index))) ((>= ,index ,end) ,result)
174 (when (plusp (sbit ,vector ,index))
175 (let ((,constraint (elt ,constraint-universe ,index)))
178 ;; Oddly, iterating just between the maximum of the two sets' minima
179 ;; and the minimum of the sets' maxima slowed down CP.
180 (defmacro do-conset-intersection
181 ((constraint conset1 conset2 &optional result) &body body)
182 `(do-conset-elements (,constraint ,conset1 ,result)
183 (when (conset-member ,constraint ,conset2)
186 (defun conset-empty (conset)
187 (or (= (conset-min conset) (conset-max conset))
188 ;; TODO: I bet FIND on bit-vectors can be optimized, if it
190 (not (find 1 (conset-vector conset)
191 :start (conset-min conset)
192 ;; By inspection, supplying :END here breaks the
193 ;; build with a "full call to
194 ;; DATA-VECTOR-REF-WITH-OFFSET" in the
195 ;; cross-compiler. If that should change, add
196 ;; :end (conset-max conset)
199 (defun copy-conset (conset)
200 (let ((ret (%copy-conset conset)))
201 (setf (conset-vector ret) (copy-seq (conset-vector conset)))
204 (defun %conset-grow (conset new-size)
205 (declare (index new-size))
206 (setf (conset-vector conset)
207 (replace (the simple-bit-vector
209 (ash 1 (integer-length (1- new-size)))
212 (the simple-bit-vector
213 (conset-vector conset)))))
215 (declaim (inline conset-grow))
216 (defun conset-grow (conset new-size)
217 (declare (index new-size))
218 (when (< (length (conset-vector conset)) new-size)
219 (%conset-grow conset new-size))
222 (defun conset-member (constraint conset)
223 (let ((number (%constraint-number constraint))
224 (vector (conset-vector conset)))
225 (when (< number (length vector))
226 (plusp (sbit vector number)))))
228 (defun conset-adjoin (constraint conset)
230 (not (conset-member constraint conset))
231 (let ((number (%constraint-number constraint)))
232 (conset-grow conset (1+ number))
233 (setf (sbit (conset-vector conset) number) 1)
234 (setf (conset-min conset) (min number (conset-min conset)))
235 (when (>= number (conset-max conset))
236 (setf (conset-max conset) (1+ number))))))
238 (defun conset= (conset1 conset2)
239 (let* ((vector1 (conset-vector conset1))
240 (vector2 (conset-vector conset2))
241 (length1 (length vector1))
242 (length2 (length vector2)))
243 (if (= length1 length2)
244 ;; When the lengths are the same, we can rely on EQUAL being
245 ;; nicely optimized on bit-vectors.
246 (equal vector1 vector2)
247 (multiple-value-bind (shorter longer)
248 (if (< length1 length2)
249 (values vector1 vector2)
250 (values vector2 vector1))
251 ;; FIXME: make MISMATCH fast on bit-vectors.
252 (dotimes (index (length shorter))
253 (when (/= (sbit vector1 index) (sbit vector2 index))
254 (return-from conset= nil)))
255 (if (find 1 longer :start (length shorter))
260 ((defconsetop (name bit-op)
261 `(defun ,name (conset-1 conset-2)
262 (declare (optimize (speed 3) (safety 0)))
263 (let* ((size-1 (length (conset-vector conset-1)))
264 (size-2 (length (conset-vector conset-2)))
265 (new-size (max size-1 size-2)))
266 (conset-grow conset-1 new-size)
267 (conset-grow conset-2 new-size))
268 (let ((vector1 (conset-vector conset-1))
269 (vector2 (conset-vector conset-2)))
270 (declare (simple-bit-vector vector1 vector2))
271 (setf (conset-vector conset-1) (,bit-op vector1 vector2 t))
272 ;; Update the extrema.
275 `(setf (conset-min conset-1)
276 (min (conset-min conset-1)
277 (conset-min conset-2))
278 (conset-max conset-1)
279 (max (conset-max conset-1)
280 (conset-max conset-2))))
281 ((conset-intersection)
282 `(let ((start (max (conset-min conset-1)
283 (conset-min conset-2)))
284 (end (min (conset-max conset-1)
285 (conset-max conset-2))))
286 (setf (conset-min conset-1)
289 (or (position 1 (conset-vector conset-1)
290 :start start :end end)
292 (conset-max conset-1)
297 1 (conset-vector conset-1)
298 :start start :end end :from-end t)))
303 `(setf (conset-min conset-1)
304 (or (position 1 (conset-vector conset-1)
305 :start (conset-min conset-1)
306 :end (conset-max conset-1))
308 (conset-max conset-1)
311 1 (conset-vector conset-1)
312 :start (conset-min conset-1)
313 :end (conset-max conset-1)
319 (defconsetop conset-union bit-ior)
320 (defconsetop conset-intersection bit-and)
321 (defconsetop conset-difference bit-andc2)))
323 (defun find-constraint (kind x y not-p)
324 (declare (type lambda-var x) (type constraint-y y) (type boolean not-p))
327 (do-conset-elements (con (lambda-var-constraints x) nil)
328 (when (and (eq (constraint-kind con) kind)
329 (eq (constraint-not-p con) not-p)
330 (type= (constraint-y con) y))
333 (do-conset-elements (con (lambda-var-constraints x) nil)
334 (when (and (eq (constraint-kind con) kind)
335 (eq (constraint-not-p con) not-p)
336 (eq (constraint-y con) y))
339 (do-conset-elements (con (lambda-var-constraints x) nil)
340 (when (and (eq (constraint-kind con) kind)
341 (eq (constraint-not-p con) not-p)
342 (let ((cx (constraint-x con)))
349 ;;; Return a constraint for the specified arguments. We only create a
350 ;;; new constraint if there isn't already an equivalent old one,
351 ;;; guaranteeing that all equivalent constraints are EQ. This
352 ;;; shouldn't be called on LAMBDA-VARs with no CONSTRAINTS set.
353 (defun find-or-create-constraint (kind x y not-p)
354 (declare (type lambda-var x) (type constraint-y y) (type boolean not-p))
355 (or (find-constraint kind x y not-p)
356 (let ((new (make-constraint (length *constraint-universe*)
358 (vector-push-extend new *constraint-universe*
359 (* 2 (length *constraint-universe*)))
360 (conset-adjoin new (lambda-var-constraints x))
361 (when (lambda-var-p y)
362 (conset-adjoin new (lambda-var-constraints y)))
365 ;;; If REF is to a LAMBDA-VAR with CONSTRAINTs (i.e. we can do flow
366 ;;; analysis on it), then return the LAMBDA-VAR, otherwise NIL.
367 #!-sb-fluid (declaim (inline ok-ref-lambda-var))
368 (defun ok-ref-lambda-var (ref)
369 (declare (type ref ref))
370 (let ((leaf (ref-leaf ref)))
371 (when (and (lambda-var-p leaf)
372 (lambda-var-constraints leaf))
375 ;;; See if LVAR's single USE is a REF to a LAMBDA-VAR and they are EQL
376 ;;; according to CONSTRAINTS. Return LAMBDA-VAR if so.
377 (defun ok-lvar-lambda-var (lvar constraints)
378 (declare (type lvar lvar))
379 (let ((use (lvar-uses lvar)))
381 (let ((lambda-var (ok-ref-lambda-var use)))
383 (let ((constraint (find-constraint 'eql lambda-var lvar nil)))
384 (when (and constraint (conset-member constraint constraints))
387 (ok-lvar-lambda-var (cast-value use) constraints)))))
389 (defmacro do-eql-vars ((symbol (var constraints) &optional result) &body body)
390 (once-only ((var var))
391 `(let ((,symbol ,var))
395 (do-conset-elements (con ,constraints ,result)
396 (let ((other (and (eq (constraint-kind con) 'eql)
397 (eq (constraint-not-p con) nil)
398 (cond ((eq ,var (constraint-x con))
400 ((eq ,var (constraint-y con))
406 (when (lambda-var-p ,symbol)
409 ;;;; Searching constraints
411 ;;; Add the indicated test constraint to BLOCK. We don't add the
412 ;;; constraint if the block has multiple predecessors, since it only
413 ;;; holds on this particular path.
414 (defun add-test-constraint (fun x y not-p constraints target)
415 (cond ((and (eq 'eql fun) (lambda-var-p y) (not not-p))
416 (add-eql-var-var-constraint x y constraints target))
418 (do-eql-vars (x (x constraints))
419 (let ((con (find-or-create-constraint fun x y not-p)))
420 (conset-adjoin con target)))))
423 ;;; Add complementary constraints to the consequent and alternative
424 ;;; blocks of IF. We do nothing if X is NIL.
425 (defun add-complement-constraints (fun x y not-p constraints
426 consequent-constraints
427 alternative-constraints)
429 (add-test-constraint fun x y not-p constraints
430 consequent-constraints)
431 (add-test-constraint fun x y (not not-p) constraints
432 alternative-constraints))
435 ;;; Add test constraints to the consequent and alternative blocks of
436 ;;; the test represented by USE.
437 (defun add-test-constraints (use if constraints)
438 (declare (type node use) (type cif if))
439 ;; Note: Even if we do (IF test exp exp) => (PROGN test exp)
440 ;; optimization, the *MAX-OPTIMIZE-ITERATIONS* cutoff means that we
441 ;; can't guarantee that the optimization will be done, so we still
442 ;; need to avoid barfing on this case.
443 (unless (eq (if-consequent if) (if-alternative if))
444 (let ((consequent-constraints (make-conset))
445 (alternative-constraints (make-conset)))
446 (macrolet ((add (fun x y not-p)
447 `(add-complement-constraints ,fun ,x ,y ,not-p
449 consequent-constraints
450 alternative-constraints)))
453 (add 'typep (ok-lvar-lambda-var (ref-lvar use) constraints)
454 (specifier-type 'null) t))
456 (unless (eq (combination-kind use)
458 (let ((name (lvar-fun-name
459 (basic-combination-fun use)))
460 (args (basic-combination-args use)))
462 ((%typep %instance-typep)
463 (let ((type (second args)))
464 (when (constant-lvar-p type)
465 (let ((val (lvar-value type)))
467 (ok-lvar-lambda-var (first args) constraints)
470 (specifier-type val))
473 (let* ((arg1 (first args))
474 (var1 (ok-lvar-lambda-var arg1 constraints))
476 (var2 (ok-lvar-lambda-var arg2 constraints)))
477 ;; The code below assumes that the constant is the
478 ;; second argument in case of variable to constant
479 ;; comparision which is sometimes true (see source
480 ;; transformations for EQ, EQL and CHAR=). Fixing
481 ;; that would result in more constant substitutions
482 ;; which is not a universally good thing, thus the
483 ;; unnatural asymmetry of the tests.
486 (add-test-constraint 'typep var2 (lvar-type arg1)
488 consequent-constraints)))
490 (add 'eql var1 var2 nil))
491 ((constant-lvar-p arg2)
492 (add 'eql var1 (ref-leaf (principal-lvar-use arg2))
495 (add-test-constraint 'typep var1 (lvar-type arg2)
497 consequent-constraints)))))
499 (let* ((arg1 (first args))
500 (var1 (ok-lvar-lambda-var arg1 constraints))
502 (var2 (ok-lvar-lambda-var arg2 constraints)))
504 (add name var1 (lvar-type arg2) nil))
506 (add (if (eq name '<) '> '<) var2 (lvar-type arg1) nil))))
508 (let ((ptype (gethash name *backend-predicate-types*)))
510 (add 'typep (ok-lvar-lambda-var (first args) constraints)
512 (values consequent-constraints alternative-constraints))))
514 ;;;; Applying constraints
516 ;;; Return true if X is an integer NUMERIC-TYPE.
517 (defun integer-type-p (x)
518 (declare (type ctype x))
519 (and (numeric-type-p x)
520 (eq (numeric-type-class x) 'integer)
521 (eq (numeric-type-complexp x) :real)))
523 ;;; Given that an inequality holds on values of type X and Y, return a
524 ;;; new type for X. If GREATER is true, then X was greater than Y,
525 ;;; otherwise less. If OR-EQUAL is true, then the inequality was
526 ;;; inclusive, i.e. >=.
528 ;;; If GREATER (or not), then we max (or min) in Y's lower (or upper)
529 ;;; bound into X and return that result. If not OR-EQUAL, we can go
530 ;;; one greater (less) than Y's bound.
531 (defun constrain-integer-type (x y greater or-equal)
532 (declare (type numeric-type x y))
539 (if greater (numeric-type-low x) (numeric-type-high x))))
540 (let* ((x-bound (bound x))
541 (y-bound (exclude (bound y)))
542 (new-bound (cond ((not x-bound) y-bound)
543 ((not y-bound) x-bound)
544 (greater (max x-bound y-bound))
545 (t (min x-bound y-bound)))))
547 (modified-numeric-type x :low new-bound)
548 (modified-numeric-type x :high new-bound)))))
550 ;;; Return true if X is a float NUMERIC-TYPE.
551 (defun float-type-p (x)
552 (declare (type ctype x))
553 (and (numeric-type-p x)
554 (eq (numeric-type-class x) 'float)
555 (eq (numeric-type-complexp x) :real)))
557 ;;; Exactly the same as CONSTRAIN-INTEGER-TYPE, but for float numbers.
558 (defun constrain-float-type (x y greater or-equal)
559 (declare (type numeric-type x y))
560 (declare (ignorable x y greater or-equal)) ; for CROSS-FLOAT-INFINITY-KLUDGE
562 (aver (eql (numeric-type-class x) 'float))
563 (aver (eql (numeric-type-class y) 'float))
564 #+sb-xc-host ; (See CROSS-FLOAT-INFINITY-KLUDGE.)
566 #-sb-xc-host ; (See CROSS-FLOAT-INFINITY-KLUDGE.)
567 (labels ((exclude (x)
575 (if greater (numeric-type-low x) (numeric-type-high x)))
580 (= (type-bound-number x) (type-bound-number ref)))
581 ;; X is tighter if REF is not an open bound and X is
582 (and (not (consp ref)) (consp x)))
584 (< (type-bound-number ref) (type-bound-number x)))
586 (> (type-bound-number ref) (type-bound-number x))))))
587 (let* ((x-bound (bound x))
588 (y-bound (exclude (bound y)))
589 (new-bound (cond ((not x-bound)
593 ((tighter-p y-bound x-bound)
598 (modified-numeric-type x :low new-bound)
599 (modified-numeric-type x :high new-bound)))))
601 ;;; Given the set of CONSTRAINTS for a variable and the current set of
602 ;;; restrictions from flow analysis IN, set the type for REF
604 (defun constrain-ref-type (ref constraints in)
605 (declare (type ref ref) (type conset constraints in))
606 ;; KLUDGE: The NOT-SET and NOT-FPZ here are so that we don't need to
607 ;; cons up endless union types when propagating large number of EQL
608 ;; constraints -- eg. from large CASE forms -- instead we just
609 ;; directly accumulate one XSET, and a set of fp zeroes, which we at
610 ;; the end turn into a MEMBER-TYPE.
612 ;; Since massive symbol cases are an especially atrocious pattern
613 ;; and the (NOT (MEMBER ...ton of symbols...)) will never turn into
614 ;; a more useful type, don't propagate their negation except for NIL
615 ;; unless SPEED > COMPILATION-SPEED.
616 (let ((res (single-value-type (node-derived-type ref)))
617 (constrain-symbols (policy ref (> speed compilation-speed)))
618 (not-set (alloc-xset))
620 (not-res *empty-type*)
621 (leaf (ref-leaf ref)))
625 (when (or constrain-symbols (null x) (not (symbolp x)))
626 (add-to-xset x not-set)))))
627 ;; KLUDGE: the implementations of DO-CONSET-INTERSECTION will
628 ;; probably run faster when the smaller set comes first, so
629 ;; don't change the order here.
630 (do-conset-intersection (con constraints in)
631 (let* ((x (constraint-x con))
632 (y (constraint-y con))
633 (not-p (constraint-not-p con))
634 (other (if (eq x leaf) y x))
635 (kind (constraint-kind con)))
639 (if (member-type-p other)
640 (mapc-member-type-members #'note-not other)
641 (setq not-res (type-union not-res other)))
642 (setq res (type-approx-intersection2 res other))))
644 (unless (lvar-p other)
645 (let ((other-type (leaf-type other)))
647 (when (and (constant-p other)
648 (member-type-p other-type))
649 (note-not (constant-value other)))
650 (let ((leaf-type (leaf-type leaf)))
652 ((or (constant-p other)
653 (and (leaf-refs other) ; protect from
655 (csubtypep other-type leaf-type)
656 (not (type= other-type leaf-type))))
657 (change-ref-leaf ref other)
658 (when (constant-p other) (return)))
660 (setq res (type-approx-intersection2
661 res other-type)))))))))
664 ((and (integer-type-p res) (integer-type-p y))
665 (let ((greater (eq kind '>)))
666 (let ((greater (if not-p (not greater) greater)))
668 (constrain-integer-type res y greater not-p)))))
669 ((and (float-type-p res) (float-type-p y))
670 (let ((greater (eq kind '>)))
671 (let ((greater (if not-p (not greater) greater)))
673 (constrain-float-type res y greater not-p)))))))))))
674 (cond ((and (if-p (node-dest ref))
675 (or (xset-member-p nil not-set)
676 (csubtypep (specifier-type 'null) not-res)))
677 (setf (node-derived-type ref) *wild-type*)
678 (change-ref-leaf ref (find-constant t)))
681 (type-union not-res (make-member-type :xset not-set :fp-zeroes not-fpz)))
682 (derive-node-type ref
683 (make-single-value-type
684 (or (type-difference res not-res)
686 (maybe-terminate-block ref nil))))
691 (defun maybe-add-eql-var-lvar-constraint (ref gen)
692 (let ((lvar (ref-lvar ref))
693 (leaf (ref-leaf ref)))
694 (when (and (lambda-var-p leaf) lvar)
695 (conset-adjoin (find-or-create-constraint 'eql leaf lvar nil)
698 ;;; Copy all CONSTRAINTS involving FROM-VAR - except the (EQL VAR
699 ;;; LVAR) ones - to all of the variables in the VARS list.
700 (defun inherit-constraints (vars from-var constraints target)
701 (do-conset-elements (con constraints)
702 ;; Constant substitution is controversial.
703 (unless (constant-p (constraint-y con))
705 (let ((eq-x (eq from-var (constraint-x con)))
706 (eq-y (eq from-var (constraint-y con))))
707 (when (or (and eq-x (not (lvar-p (constraint-y con))))
709 (conset-adjoin (find-or-create-constraint
710 (constraint-kind con)
711 (if eq-x var (constraint-x con))
712 (if eq-y var (constraint-y con))
713 (constraint-not-p con))
716 ;; Add an (EQL LAMBDA-VAR LAMBDA-VAR) constraint on VAR1 and VAR2 and
717 ;; inherit each other's constraints.
718 (defun add-eql-var-var-constraint (var1 var2 constraints
719 &optional (target constraints))
720 (let ((con (find-or-create-constraint 'eql var1 var2 nil)))
721 (when (conset-adjoin con target)
722 (collect ((eql1) (eql2))
723 (do-eql-vars (var1 (var1 constraints))
725 (do-eql-vars (var2 (var2 constraints))
727 (inherit-constraints (eql1) var2 constraints target)
728 (inherit-constraints (eql2) var1 constraints target))
731 ;; Add an (EQL LAMBDA-VAR LAMBDA-VAR) constraint on VAR and LVAR's
732 ;; LAMBDA-VAR if possible.
733 (defun maybe-add-eql-var-var-constraint (var lvar constraints
734 &optional (target constraints))
735 (declare (type lambda-var var) (type lvar lvar))
736 (let ((lambda-var (ok-lvar-lambda-var lvar constraints)))
738 (add-eql-var-var-constraint var lambda-var constraints target))))
740 ;;; Local propagation
741 ;;; -- [TODO: For any LAMBDA-VAR ref with a type check, add that
743 ;;; -- For any LAMBDA-VAR set, delete all constraints on that var; add
744 ;;; a type constraint based on the new value type.
745 (declaim (ftype (function (cblock conset boolean)
747 constraint-propagate-in-block))
748 (defun constraint-propagate-in-block (block gen preprocess-refs-p)
749 (do-nodes (node lvar block)
752 (let ((fun (bind-lambda node)))
753 (when (eq (functional-kind fun) :let)
754 (loop with call = (lvar-dest (node-lvar (first (lambda-refs fun))))
755 for var in (lambda-vars fun)
756 and val in (combination-args call)
757 when (and val (lambda-var-constraints var))
758 do (let* ((type (lvar-type val))
759 (con (find-or-create-constraint 'typep var type
761 (conset-adjoin con gen))
762 (maybe-add-eql-var-var-constraint var val gen)))))
764 (when (ok-ref-lambda-var node)
765 (maybe-add-eql-var-lvar-constraint node gen)
766 (when preprocess-refs-p
767 (let* ((var (ref-leaf node))
768 (con (lambda-var-constraints var)))
769 (constrain-ref-type node con gen)))))
771 (let ((lvar (cast-value node)))
772 (let ((var (ok-lvar-lambda-var lvar gen)))
774 (let ((atype (single-value-type (cast-derived-type node)))) ;FIXME
775 (do-eql-vars (var (var gen))
776 (let ((con (find-or-create-constraint 'typep var atype nil)))
777 (conset-adjoin con gen))))))))
779 (binding* ((var (set-var node))
780 (nil (lambda-var-p var) :exit-if-null)
781 (cons (lambda-var-constraints var) :exit-if-null))
782 (conset-difference gen cons)
783 (let* ((type (single-value-type (node-derived-type node)))
784 (con (find-or-create-constraint 'typep var type nil)))
785 (conset-adjoin con gen))
786 (maybe-add-eql-var-var-constraint var (set-value node) gen)))))
789 (defun constraint-propagate-if (block gen)
790 (let ((node (block-last block)))
792 (let ((use (lvar-uses (if-test node))))
794 (add-test-constraints use node gen))))))
796 ;;; Starting from IN compute OUT and (consequent/alternative
797 ;;; constraints if the block ends with and IF). Return the list of
798 ;;; successors that may need to be recomputed.
799 (defun find-block-type-constraints (block final-pass-p)
800 (declare (type cblock block))
801 (let ((gen (constraint-propagate-in-block
805 (copy-conset (block-in block)))
807 (setf (block-gen block) gen)
808 (multiple-value-bind (consequent-constraints alternative-constraints)
809 (constraint-propagate-if block gen)
810 (if consequent-constraints
811 (let* ((node (block-last block))
812 (old-consequent-constraints (if-consequent-constraints node))
813 (old-alternative-constraints (if-alternative-constraints node))
815 ;; Add the consequent and alternative constraints to GEN.
816 (cond ((conset-empty consequent-constraints)
817 (setf (if-consequent-constraints node) gen)
818 (setf (if-alternative-constraints node) gen))
820 (setf (if-consequent-constraints node) (copy-conset gen))
821 (conset-union (if-consequent-constraints node)
822 consequent-constraints)
823 (setf (if-alternative-constraints node) gen)
824 (conset-union (if-alternative-constraints node)
825 alternative-constraints)))
826 ;; Has the consequent been changed?
827 (unless (and old-consequent-constraints
828 (conset= (if-consequent-constraints node)
829 old-consequent-constraints))
830 (push (if-consequent node) succ))
831 ;; Has the alternative been changed?
832 (unless (and old-alternative-constraints
833 (conset= (if-alternative-constraints node)
834 old-alternative-constraints))
835 (push (if-alternative node) succ))
838 (unless (and (block-out block)
839 (conset= gen (block-out block)))
840 (setf (block-out block) gen)
841 (block-succ block))))))
843 ;;; Deliver the results of constraint propagation to REFs in BLOCK.
844 ;;; During this pass, we also do local constraint propagation by
845 ;;; adding in constraints as we see them during the pass through the
847 (defun use-result-constraints (block)
848 (declare (type cblock block))
849 (constraint-propagate-in-block block (block-in block) t))
851 ;;; Give an empty constraints set to any var that doesn't have one and
852 ;;; isn't a set closure var. Since a var that we previously rejected
853 ;;; looks identical to one that is new, so we optimistically keep
854 ;;; hoping that vars stop being closed over or lose their sets.
855 (defun init-var-constraints (component)
856 (declare (type component component))
857 (dolist (fun (component-lambdas component))
859 (dolist (var (lambda-vars x))
860 (unless (lambda-var-constraints var)
861 (when (or (null (lambda-var-sets var))
862 (not (closure-var-p var)))
863 (setf (lambda-var-constraints var) (make-conset)))))))
865 (dolist (let (lambda-lets fun))
868 ;;; Return the constraints that flow from PRED to SUCC. This is
869 ;;; BLOCK-OUT unless PRED ends with an IF and test constraints were
871 (defun block-out-for-successor (pred succ)
872 (declare (type cblock pred succ))
873 (let ((last (block-last pred)))
874 (or (when (if-p last)
875 (cond ((eq succ (if-consequent last))
876 (if-consequent-constraints last))
877 ((eq succ (if-alternative last))
878 (if-alternative-constraints last))))
881 (defun compute-block-in (block)
883 (dolist (pred (block-pred block))
884 ;; If OUT has not been calculated, assume it to be the universal
886 (let ((out (block-out-for-successor pred block)))
889 (conset-intersection in out)
890 (setq in (copy-conset out))))))
891 (or in (make-conset))))
893 (defun update-block-in (block)
894 (let ((in (compute-block-in block)))
895 (cond ((and (block-in block) (conset= in (block-in block)))
898 (setf (block-in block) in)))))
900 ;;; Return two lists: one of blocks that precede all loops and
901 ;;; therefore require only one constraint propagation pass and the
902 ;;; rest. This implementation does not find all such blocks.
904 ;;; A more complete implementation would be:
906 ;;; (do-blocks (block component)
907 ;;; (if (every #'(lambda (pred)
908 ;;; (or (member pred leading-blocks)
910 ;;; (block-pred block))
911 ;;; (push block leading-blocks)
912 ;;; (push block rest-of-blocks)))
914 ;;; Trailing blocks that succeed all loops could be found and handled
915 ;;; similarly. In practice though, these more complex solutions are
916 ;;; slightly worse performancewise.
917 (defun leading-component-blocks (component)
918 (declare (type component component))
919 (flet ((loopy-p (block)
920 (let ((n (block-number block)))
921 (dolist (pred (block-pred block))
922 (unless (< n (block-number pred))
924 (let ((leading-blocks ())
927 (do-blocks (block component)
928 (when (and (not seen-loop-p) (loopy-p block))
929 (setq seen-loop-p t))
931 (push block rest-of-blocks)
932 (push block leading-blocks)))
933 (values (nreverse leading-blocks) (nreverse rest-of-blocks)))))
935 ;;; Append OBJ to the end of LIST as if by NCONC but only if it is not
936 ;;; a member already.
937 (defun nconc-new (obj list)
938 (do ((x list (cdr x))
942 (setf (cdr prev) (list obj))
945 (when (eql (car x) obj)
946 (return-from nconc-new list))))
948 (defun find-and-propagate-constraints (component)
949 (let ((blocks-to-process ()))
950 (flet ((enqueue (blocks)
951 (dolist (block blocks)
952 (setq blocks-to-process (nconc-new block blocks-to-process)))))
953 (multiple-value-bind (leading-blocks rest-of-blocks)
954 (leading-component-blocks component)
955 ;; Update every block once to account for changes in the
956 ;; IR1. The constraints of the lead blocks cannot be changed
957 ;; after the first pass so we might as well use them and skip
958 ;; USE-RESULT-CONSTRAINTS later.
959 (dolist (block leading-blocks)
960 (setf (block-in block) (compute-block-in block))
961 (find-block-type-constraints block t))
962 (setq blocks-to-process (copy-list rest-of-blocks))
963 ;; The rest of the blocks.
964 (dolist (block rest-of-blocks)
965 (aver (eq block (pop blocks-to-process)))
966 (setf (block-in block) (compute-block-in block))
967 (enqueue (find-block-type-constraints block nil)))
968 ;; Propagate constraints
969 (loop for block = (pop blocks-to-process)
971 (unless (eq block (component-tail component))
972 (when (update-block-in block)
973 (enqueue (find-block-type-constraints block nil)))))
976 (defun constraint-propagate (component)
977 (declare (type component component))
978 (init-var-constraints component)
980 (unless (block-out (component-head component))
981 (setf (block-out (component-head component)) (make-conset)))
983 (dolist (block (find-and-propagate-constraints component))
984 (unless (block-delete-p block)
985 (use-result-constraints block)))