Function permlanex16_var 

pub unsafe extern "C" fn permlanex16_var(
    old: u32,
    src0: u32,
    src1: u32,
    fi: bool,
    bound_control: bool,
) -> u32

Performs arbitrary gather-style operation across two rows (16 contiguous lanes) of the second input operand.

In contrast to permlanex16_u32, allows each lane to specify its own gather lane.