+
+;;; Returns the defined (usually untrusted) type of the combination,
+;;; or NIL if we couldn't figure it out.
+(defun combination-defined-type (combination)
+ (let ((use (principal-lvar-use (basic-combination-fun combination))))
+ (or (when (ref-p use)
+ (let ((type (leaf-defined-type (ref-leaf use))))
+ (when (fun-type-p type)
+ (fun-type-returns type))))
+ *wild-type*)))
+
+;;; Return true if LVAR destination is executed after node with only
+;;; uninteresting nodes intervening.
+;;;
+;;; Uninteresting nodes are nodes in the same block which are either
+;;; REFs, external CASTs to the same destination, or known combinations
+;;; that never unwind.
+(defun almost-immediately-used-p (lvar node)
+ (declare (type lvar lvar)
+ (type node node))
+ (aver (eq (node-lvar node) lvar))
+ (let ((dest (lvar-dest lvar)))
+ (tagbody
+ :next
+ (let ((ctran (node-next node)))
+ (cond (ctran
+ (setf node (ctran-next ctran))
+ (if (eq node dest)
+ (return-from almost-immediately-used-p t)
+ (typecase node
+ (ref
+ (go :next))
+ (cast
+ (when (and (eq :external (cast-type-check node))
+ (eq dest (node-dest node)))
+ (go :next)))
+ (combination
+ ;; KLUDGE: Unfortunately we don't have an attribute for
+ ;; "never unwinds", so we just special case
+ ;; %ALLOCATE-CLOSURES: it is easy to run into with eg.
+ ;; FORMAT and a non-constant first argument.
+ (when (eq '%allocate-closures (combination-fun-source-name node nil))
+ (go :next))))))
+ (t
+ (when (eq (block-start (first (block-succ (node-block node))))
+ (node-prev dest))
+ (return-from almost-immediately-used-p t))))))))