;;; bound because ANSI specifies it as an exclusive bound.)
(def!type index () `(integer 0 (,sb!xc:array-dimension-limit)))
+;;; like INDEX, but only up to half the maximum. Used by hash-table
+;;; code that does plenty to (aref v (* 2 i)) and (aref v (1+ (* 2 i))).
+(def!type index/2 () `(integer 0 (,(floor sb!xc:array-dimension-limit 2))))
+
;;; like INDEX, but augmented with -1 (useful when using the index
;;; to count downwards to 0, e.g. LOOP FOR I FROM N DOWNTO 0, with
;;; an implementation which terminates the loop by testing for the
(* max-offset sb!vm:n-word-bytes))
scale)))
+#!+x86
+(defun displacement-bounds (lowtag element-size data-offset)
+ (let* ((adjustment (- (* data-offset sb!vm:n-word-bytes) lowtag))
+ (bytes-per-element (ceiling element-size sb!vm:n-byte-bits))
+ (min (truncate (+ sb!vm::minimum-immediate-offset adjustment)
+ bytes-per-element))
+ (max (truncate (+ sb!vm::maximum-immediate-offset adjustment)
+ bytes-per-element)))
+ (values min max)))
+
+#!+x86
+(def!type constant-displacement (lowtag element-size data-offset)
+ (flet ((integerify (x)
+ (etypecase x
+ (integer x)
+ (symbol (symbol-value x)))))
+ (let ((lowtag (integerify lowtag))
+ (element-size (integerify element-size))
+ (data-offset (integerify data-offset)))
+ (multiple-value-bind (min max) (displacement-bounds lowtag
+ element-size
+ data-offset)
+ `(integer ,min ,max)))))
+
;;; Similar to FUNCTION, but the result type is "exactly" specified:
;;; if it is an object type, then the function returns exactly one
;;; value, if it is a short form of VALUES, then this short form