    1. store_src_rg                   v0..1 = src.rg
    2. init_lane_masks                CondMask = LoopMask = RetMask = true
    3. store_device_xy01              sk_FragCoord = DeviceCoords.xy01
    4. copy_4_slots_unmasked          $0..3 = sk_FragCoord
    5. swizzle_2                      $0..1 = ($0..1).yx
    6. copy_constant                  $2 = 0x3F800000 (1.0)
    7. copy_constant                  $3 = 0x3F800000 (1.0)
    8. load_src                       src.rgba = $0..3