+(defun handle-nested-dynamic-extent-lvars (dx lvar)
+ (let ((uses (lvar-uses lvar)))
+ ;; DX value generators must end their blocks: see UPDATE-UVL-LIVE-SETS.
+ ;; Uses of mupltiple-use LVARs already end their blocks, so we just need
+ ;; to process uses of single-use LVARs.
+ (when (node-p uses)
+ (node-ends-block uses))
+ ;; If this LVAR's USE is good for DX, it is either a CAST, or it
+ ;; must be a regular combination whose arguments are potentially DX as well.
+ (flet ((recurse (use)
+ (etypecase use
+ (cast
+ (handle-nested-dynamic-extent-lvars dx (cast-value use)))
+ (combination
+ (loop for arg in (combination-args use)
+ ;; deleted args show up as NIL here
+ when (and arg (lvar-good-for-dx-p arg dx))
+ append (handle-nested-dynamic-extent-lvars dx arg)))
+ (ref
+ (let* ((other (trivial-lambda-var-ref-lvar use)))
+ (unless (eq other lvar)
+ (handle-nested-dynamic-extent-lvars dx other)))))))
+ (cons lvar
+ (if (listp uses)
+ (loop for use in uses
+ when (use-good-for-dx-p use dx)
+ nconc (recurse use))
+ (when (use-good-for-dx-p uses dx)
+ (recurse uses)))))))
+
+(defun recognize-dynamic-extent-lvars (call fun)
+ (declare (type combination call) (type clambda fun))
+ (loop for arg in (basic-combination-args call)
+ for var in (lambda-vars fun)
+ for dx = (lambda-var-dynamic-extent var)
+ when (and dx arg (not (lvar-dynamic-extent arg)))
+ append (handle-nested-dynamic-extent-lvars dx arg) into dx-lvars
+ finally (when dx-lvars
+ ;; Stack analysis requires that the CALL ends the block, so
+ ;; that MAP-BLOCK-NLXES sees the cleanup we insert here.
+ (node-ends-block call)
+ (let* ((entry (with-ir1-environment-from-node call
+ (make-entry)))
+ (cleanup (make-cleanup :kind :dynamic-extent
+ :mess-up entry
+ :info dx-lvars)))
+ (setf (entry-cleanup entry) cleanup)
+ (insert-node-before call entry)
+ (setf (node-lexenv call)
+ (make-lexenv :default (node-lexenv call)
+ :cleanup cleanup))
+ (push entry (lambda-entries (node-home-lambda entry)))
+ (dolist (lvar dx-lvars)
+ (setf (lvar-dynamic-extent lvar) cleanup)))))
+ (values))
+