adds various core builtin functions side-effect-free (read-only) to gain from dead instruction elimination
adds various core builtin functions side-effect-free (read-only) to gain from dead instruction elimination

christianparpart/x0,christianparpart/x0,christianparpart/x0,christianparpart/x0,xzero/x0,christianparpart/x0,xzero/x0,xzero/x0,christianparpart/x0,christianparpart/x0,xzero/x0,xzero/x0,xzero/x0