ROTATE-BYTE on very large positions exhausts memory unnecessarily

[Paul F. Dietz]

Rotating bits far out in an integer, well past the last bit actually stored in its representation, leaves the integer unchanged. However, SB-ROTATE-BYTE:ROTATE-BYTE runs out of memory. It appears to expand the integer, perform the rotation, then normalize. Don't do that.

(sb-rotate-byte:rotate-byte 1 (byte 2 100000000000) 17) ==> memory exhausted

(sb-rotate-byte:rotate-byte 2 (byte 13 100000000000) (1- most-negative-fixnum)) ==> memory exhausted

[Stas Boukarev (stassats)]

rotate-byte shouldn't really be used with anything other than (byte 32/64 0) in any serious code.

[Christophe Rhodes (csr21-cantab)]

Agreed in general with Stas' comment, though mitigating this issue is straightforward I think.

There's a similar problem with e.g.

  (dpb -1 (byte 2 1000000000000) -1)