(make-byte-tn value))
((sc-is value control-stack)
(make-ea :byte :base rbp-tn
- :disp (- (* (1+ (tn-offset value)) n-word-bytes))))
+ :disp (frame-byte-offset (tn-offset value))))
(t
value))
sb!vm::fixnum-tag-mask))
(inst mov tmp value)
(inst shr tmp n-positive-fixnum-bits)))
+(define-vop (fixnump/signed-byte-64 type-predicate)
+ (:args (value :scs (signed-reg)))
+ (:info)
+ (:conditional :z)
+ (:arg-types signed-num)
+ (:translate fixnump)
+ (:generator 5
+ ;; Hackers Delight, p. 53: signed
+ ;; a <= x <= a + 2^n - 1
+ ;; is equivalent to unsigned
+ ;; ((x-a) >> n) = 0
+ (inst mov rax-tn #.(- sb!xc:most-negative-fixnum))
+ (inst add rax-tn value)
+ (inst shr rax-tn #.(integer-length (- sb!xc:most-positive-fixnum
+ sb!xc:most-negative-fixnum)))))
+
;;; A (SIGNED-BYTE 64) can be represented with either fixnum or a bignum with
;;; exactly one digit.