;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.
+;;; TODO:
+;;;
+;;; -- documentation
+;;;
+;;; -- MV-BIND, :ASSIGNMENT
+
+;;; Problems:
+;;;
+;;; -- Constraint propagation badly interacts with bottom-up type
+;;; inference. Consider
+;;;
+;;; (defun foo (n &aux (i 42))
+;;; (declare (optimize speed))
+;;; (declare (fixnum n)
+;;; #+nil (type (integer 0) i))
+;;; (tagbody
+;;; (setq i 0)
+;;; :loop
+;;; (when (>= i n) (go :exit))
+;;; (setq i (1+ i))
+;;; (go :loop)
+;;; :exit))
+;;;
+;;; In this case CP cannot even infer that I is of class INTEGER.
+;;;
+;;; -- In the above example if we place the check after SETQ, CP will
+;;; fail to infer (< I FIXNUM): is does not understand that this
+;;; constraint follows from (TYPEP I (INTEGER 0 0)).
+
+;;; BUGS:
+;;;
+;;; -- this code does not check whether SET appears between REF and a
+;;; test (bug 233b)
+;;;
+;;; -- type check is assumed to be inserted immediately after a node
+;;; producing the value; it disagrees with the rest of Python (bug
+;;; 233a)
+
(in-package "SB!C")
(defstruct (constraint
;; the kind of constraint we have:
;;
;; TYPEP
- ;; X is a LAMBDA-VAR and Y is a CTYPE. The value of X is
+ ;; X is a LAMBDA-VAR and Y is a CTYPE. The value of X is
;; constrained to be of type Y.
;;
;; > or <
- ;; X is a lambda-var and Y is a CTYPE. The relation holds
+ ;; X is a lambda-var and Y is a CTYPE. The relation holds
;; between X and some object of type Y.
;;
;; EQL
;; The operands to the relation.
(x nil :type lambda-var)
(y nil :type (or ctype lambda-var constant))
- ;; If true, negates the sense of the constraint, so the relation
+ ;; If true, negates the sense of the constraint, so the relation
;; does *not* hold.
(not-p nil :type boolean))
(when (ref-p use)
(ok-ref-lambda-var use))))
+;;;; Searching constraints
+
;;; Add the indicated test constraint to BLOCK, marking the block as
;;; having a new assertion when the constriant was not already
;;; present. We don't add the constraint if the block has multiple
(setf (block-test-modified block) nil)
(values))
-;;; Compute the initial flow analysis sets for BLOCK:
-;;; -- For any lambda-var ref with a type check, add that constraint.
-;;; -- For any LAMBDA-VAR set, delete all constraints on that var, and add
-;;; those constraints to the set nuked by this block.
-(defun find-block-type-constraints (block)
- (declare (type cblock block))
- (let ((gen (make-sset)))
- (collect ((kill nil adjoin))
-
- (let ((test (block-test-constraint block)))
- (when test
- (sset-union gen test)))
-
- (do-nodes (node cont block)
- (typecase node
- (ref
- (when (continuation-type-check cont)
- (let ((var (ok-ref-lambda-var node)))
- (when var
- (let* ((atype (continuation-derived-type cont))
- (con (find-constraint 'typep var atype nil)))
- (sset-adjoin con gen))))))
- (cset
- (let ((var (set-var node)))
- (when (lambda-var-p var)
- (kill var)
- (let ((cons (lambda-var-constraints var)))
- (when cons
- (sset-difference gen cons))))))))
-
- (setf (block-in block) nil)
- (setf (block-gen block) gen)
- (setf (block-kill-list block) (kill))
- (setf (block-out block) (copy-sset gen))
- (setf (block-type-asserted block) nil)
- (values))))
+;;;; Applying constraints
;;; Return true if X is an integer NUMERIC-TYPE.
(defun integer-type-p (x)
(values))
+;;;; Flow analysis
+
+;;; Local propagation
+;;; -- [TODO: For any LAMBDA-VAR ref with a type check, add that
+;;; constraint.]
+;;; -- For any LAMBDA-VAR set, delete all constraints on that var; add
+;;; a type constraint based on the new value type.
+(declaim (ftype (function (cblock sset
+ &key (:ref-preprocessor function)
+ (:set-preprocessor function))
+ sset)
+ constraint-propagate-in-block))
+(defun constraint-propagate-in-block
+ (block gen &key ref-preprocessor set-preprocessor)
+
+ (let ((test (block-test-constraint block)))
+ (when test
+ (sset-union gen test)))
+
+ (do-nodes (node cont block)
+ (typecase node
+ (bind
+ (let ((fun (bind-lambda node)))
+ (when (eq (functional-kind fun) :let)
+ (loop with call = (continuation-dest
+ (node-cont (first (lambda-refs fun))))
+ for var in (lambda-vars fun)
+ and val in (combination-args call)
+ when (and val
+ (lambda-var-constraints var)
+ ;; if VAR has no SETs, type inference is
+ ;; fully performed by IR1 optimizer
+ (lambda-var-sets var))
+ do (let* ((type (continuation-type val))
+ (con (find-constraint 'typep var type nil)))
+ (sset-adjoin con gen))))))
+ (ref
+ (let ((var (ok-ref-lambda-var node)))
+ (when var
+ (when ref-preprocessor
+ (funcall ref-preprocessor node gen))
+ (when (continuation-type-check cont)
+ (let* ((atype (continuation-derived-type cont))
+ (con (find-constraint 'typep var atype nil)))
+ (sset-adjoin con gen))))))
+ (cset
+ (let ((var (set-var node)))
+ (when (lambda-var-p var)
+ (when set-preprocessor
+ (funcall set-preprocessor var))
+ (let ((cons (lambda-var-constraints var)))
+ (when cons
+ (sset-difference gen cons)
+ (let* ((type (node-derived-type node))
+ (con (find-constraint 'typep var type nil)))
+ (sset-adjoin con gen)))))))))
+
+ gen)
+
+;;; BLOCK-KILL is just a list of the LAMBDA-VARs killed, so we must
+;;; compute the kill set when there are any vars killed. We bum this a
+;;; bit by special-casing when only one var is killed, and just using
+;;; that var's constraints as the kill set. This set could possibly be
+;;; precomputed, but it would have to be invalidated whenever any
+;;; constraint is added, which would be a pain.
+(defun compute-block-out (block)
+ (declare (type cblock block))
+ (let ((in (block-in block))
+ (kill (block-kill block))
+ (out (copy-sset (block-gen block))))
+ (cond ((null kill)
+ (sset-union out in))
+ ((null (rest kill))
+ (let ((con (lambda-var-constraints (first kill))))
+ (if con
+ (sset-union-of-difference out in con)
+ (sset-union out in))))
+ (t
+ (let ((kill-set (make-sset)))
+ (dolist (var kill)
+ (let ((con (lambda-var-constraints var)))
+ (when con
+ (sset-union kill-set con))))
+ (sset-union-of-difference out in kill-set))))
+ out))
+
+;;; Compute the initial flow analysis sets for BLOCK:
+;;; -- Compute IN/OUT sets; if OUT of a predecessor is not yet
+;;; computed, assume it to be a universal set (this is only
+;;; possible in a loop)
+;;;
+;;; Return T if we have found a loop.
+(defun find-block-type-constraints (block)
+ (declare (type cblock block))
+ (collect ((kill nil adjoin))
+ (let ((gen (constraint-propagate-in-block
+ block (make-sset)
+ :set-preprocessor (lambda (var)
+ (kill var)))))
+ (setf (block-gen block) gen)
+ (setf (block-kill block) (kill))
+ (setf (block-type-asserted block) nil)
+ (let* ((n (block-number block))
+ (pred (block-pred block))
+ (in nil)
+ (loop-p nil))
+ (dolist (b pred)
+ (cond ((> (block-number b) n)
+ (if in
+ (sset-intersection in (block-out b))
+ (setq in (copy-sset (block-out b)))))
+ (t (setq loop-p t))))
+ (unless in
+ (bug "Unreachable code is found or flow graph is not ~
+ properly depth-first ordered."))
+ (setf (block-in block) in)
+ (setf (block-out block) (compute-block-out block))
+ loop-p))))
+
+;;; BLOCK-IN becomes the intersection of the OUT of the predecessors.
+;;; Our OUT is:
+;;; gen U (in - kill)
+;;;
+;;; Return True if we have done something.
+(defun flow-propagate-constraints (block)
+ (let* ((pred (block-pred block))
+ (in (progn (aver pred)
+ (let ((res (copy-sset (block-out (first pred)))))
+ (dolist (b (rest pred))
+ (sset-intersection res (block-out b)))
+ res))))
+ (setf (block-in block) in)
+ (let ((out (compute-block-out block)))
+ (if (sset= out (block-out block))
+ nil
+ (setf (block-out block) out)))))
+
;;; Deliver the results of constraint propagation to REFs in BLOCK.
;;; During this pass, we also do local constraint propagation by
;;; adding in constraints as we seem them during the pass through the
;;; block.
(defun use-result-constraints (block)
(declare (type cblock block))
- (let ((in (block-in block)))
-
- (let ((test (block-test-constraint block)))
- (when test
- (sset-union in test)))
-
- (do-nodes (node cont block)
- (typecase node
- (ref
- (let ((var (ref-leaf node)))
- (when (lambda-var-p var)
- (let ((con (lambda-var-constraints var)))
- (when con
- (constrain-ref-type node con in)
- (when (continuation-type-check cont)
- (sset-adjoin
- (find-constraint 'typep var
- (continuation-asserted-type cont)
- nil)
- in)))))))
- (cset
- (let ((var (set-var node)))
- (when (lambda-var-p var)
- (let ((cons (lambda-var-constraints var)))
- (when cons
- (sset-difference in cons))))))))))
+ (constraint-propagate-in-block
+ block (block-in block)
+ :ref-preprocessor (lambda (node cons)
+ (let ((var (ref-leaf node)))
+ (when (lambda-var-p var)
+ (let ((con (lambda-var-constraints var)))
+ (when con
+ (constrain-ref-type node con cons))))))))
;;; Return true if VAR would have to be closed over if environment
;;; analysis ran now (i.e. if there are any uses that have a different
(dolist (let (lambda-lets fun))
(frob let)))))
-;;; BLOCK-IN becomes the intersection of the OUT of the predecessors.
-;;; Our OUT is:
-;;; out U (in - kill)
-;;;
-;;; BLOCK-KILL-LIST is just a list of the LAMBDA-VARs killed, so we must
-;;; compute the kill set when there are any vars killed. We bum this a
-;;; bit by special-casing when only one var is killed, and just using
-;;; that var's constraints as the kill set. This set could possibly be
-;;; precomputed, but it would have to be invalidated whenever any
-;;; constraint is added, which would be a pain.
-(defun flow-propagate-constraints (block)
- (let* ((pred (block-pred block))
- (in (cond (pred
- (let ((res (copy-sset (block-out (first pred)))))
- (dolist (b (rest pred))
- (sset-intersection res (block-out b)))
- res))
- (t
- (let ((*compiler-error-context* (block-last block)))
- (compiler-warn
- "unreachable code in constraint ~
- propagation -- apparent compiler bug"))
- (make-sset))))
- (kill-list (block-kill-list block))
- (out (block-out block)))
-
- (setf (block-in block) in)
- (cond ((null kill-list)
- (sset-union (block-out block) in))
- ((null (rest kill-list))
- (let ((con (lambda-var-constraints (first kill-list))))
- (if con
- (sset-union-of-difference out in con)
- (sset-union out in))))
- (t
- (let ((kill-set (make-sset)))
- (dolist (var kill-list)
- (let ((con (lambda-var-constraints var)))
- (when con
- (sset-union kill-set con))))
- (sset-union-of-difference (block-out block) in kill-set))))))
-
;;; How many blocks does COMPONENT have?
(defun component-n-blocks (component)
(let ((result 0))
(incf result))
result))
-(defun constraint-propagate (component)
+(defun constraint-propagate (component &aux (loop-p nil))
(declare (type component component))
(init-var-constraints component)
(when (block-test-modified block)
(find-test-constraints block)))
+ (unless (block-out (component-head component))
+ (setf (block-out (component-head component)) (make-sset)))
+
(do-blocks (block component)
- (cond ((block-type-asserted block)
- (find-block-type-constraints block))
- (t
- (setf (block-in block) nil)
- (setf (block-out block) (copy-sset (block-gen block))))))
-
- (setf (block-out (component-head component)) (make-sset))
-
- (let (;; If we have to propagate changes more than this many times,
- ;; something is wrong.
- (max-n-changes-remaining (component-n-blocks component)))
- (declare (type fixnum max-n-changes-remaining))
- (loop (aver (plusp max-n-changes-remaining))
- (decf max-n-changes-remaining)
- (let ((did-something nil))
- (do-blocks (block component)
- (when (flow-propagate-constraints block)
- (setq did-something t)))
- (unless did-something
- (return)))))
+ (when (find-block-type-constraints block)
+ (setq loop-p t)))
+
+ (when loop-p
+ (let (;; If we have to propagate changes more than this many times,
+ ;; something is wrong.
+ (max-n-changes-remaining (component-n-blocks component)))
+ (declare (type fixnum max-n-changes-remaining))
+ (loop (aver (>= max-n-changes-remaining 0))
+ (decf max-n-changes-remaining)
+ (let ((did-something nil))
+ (do-blocks (block component)
+ (when (flow-propagate-constraints block)
+ (setq did-something t)))
+ (unless did-something
+ (return))))))
(do-blocks (block component)
(use-result-constraints block))
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