16 instructions

store_src_rg                   coords = src.rg
init_lane_masks                CondMask = LoopMask = RetMask = true
copy_constant                  _2_ok = 0xFFFFFFFF
copy_slot_unmasked             $0 = _2_ok
copy_4_uniforms                $1..4 = colorGreen
copy_4_uniforms                $5..8 = colorRed
cmpne_4_floats                 $1..4 = notEqual($1..4, $5..8)
bitwise_or_2_ints              $1..2 |= $3..4
bitwise_or_int                 $1 |= $2
bitwise_and_int                $0 &= $1
copy_slot_unmasked             _2_ok = $0
swizzle_4                      $0..3 = ($0..3).xxxx
copy_4_uniforms                $4..7 = colorRed
copy_4_uniforms                $8..11 = colorGreen
mix_4_ints                     $0..3 = mix($4..7, $8..11, $0..3)
load_src                       src.rgba = $0..3