    1. store_src_rg                   coords = src.rg
    2. init_lane_masks                CondMask = LoopMask = RetMask = true
    3. copy_constant                  _4_ok = 0xFFFFFFFF
    4. copy_slot_unmasked             $4 = _4_ok
    5. branch_if_no_active_lanes_eq   branch +3 (label 0 at #8) if no lanes of $4 == 0xFFFFFFFF
    6. copy_4_constants               $0..3 = colorGreen
    7. jump                           jump +3 (label 1 at #10)
    8. label                          label 0x00000000
    9. copy_4_constants               $0..3 = colorRed
   10. label                          label 0x00000001
   11. load_src                       src.rgba = $0..3