static src_reg undef_src = src_reg(PROGRAM_UNDEFINED, 0, NULL);
static dst_reg undef_dst = dst_reg(PROGRAM_UNDEFINED, SWIZZLE_NOOP);
static src_reg undef_src = src_reg(PROGRAM_UNDEFINED, 0, NULL);
static dst_reg undef_dst = dst_reg(PROGRAM_UNDEFINED, SWIZZLE_NOOP);