This reverts commit b0b3e3e1c7f6387eabc2ef9ff1fea311e63a4299. After thinking about this for a bit, I don't think this is correct. vscale being a power-of-2 only guarantees the canonical IV increment overflows to zero, but not overflows in general.
This reverts commit b0b3e3e1c7f6387eabc2ef9ff1fea311e63a4299. After thinking about this for a bit, I don't think this is correct. vscale being a power-of-2 only guarantees the canonical IV increment overflows to zero, but not overflows in general.