7 instructions

store_src_rg                   coords = src.rg
init_lane_masks                CondMask = LoopMask = RetMask = true
copy_constant                  f = 0
copy_slot_unmasked             $0 = f
swizzle_4                      $0..3 = ($0..3).xxxx
copy_4_slots_unmasked          fv = $0..3
load_src                       src.rgba = $0..3