19 instructions

[immutable slots]
i0 = 0xFFFFFFFF

store_src_rg                   coords = src.rg
init_lane_masks                CondMask = LoopMask = RetMask = true
copy_4_uniforms                green = colorGreen
copy_4_uniforms                red = colorRed
copy_constant                  param = 0
copy_constant                  x = 0xFFFFFFFF
copy_constant                  $0 = 0
copy_slot_unmasked             param = x
label                          label 0
copy_constant                  call = 0xFFFFFFFF
copy_constant                  $0 = 0xFFFFFFFF
copy_slot_unmasked             $1 = param
bitwise_and_int                $0 &= $1
copy_slot_unmasked             $1 = call
bitwise_and_int                $0 &= $1
swizzle_4                      $0..3 = ($0..3).xxxx
copy_4_slots_unmasked          $4..7 = red
copy_4_slots_unmasked          $8..11 = green
mix_4_ints                     $0..3 = mix($4..7, $8..11, $0..3)
load_src                       src.rgba = $0..3