re PR middle-end/61409 (-Wmaybe-uninitialized false-positive with -O2)

re PR middle-end/61409 (-Wmaybe-uninitialized false-positive with -O2)

	PR middle-end/61409
	* tree-ssa-uninit.c: Define new global max_phi_args.
	(compute_uninit_opnds_pos): Use max_phi_args.
	(prune_uninit_phi_opnds): Same.
	(use_pred_not_overlap_with_undef_path_pred): Remove reference to
	missing NUM_PREDS in function comment.
	(can_one_predicate_be_invalidated_p): New.
	(can_chain_union_be_invalidated_p): New.
	(flatten_out_predicate_chains): New.
	(uninit_ops_invalidate_phi_use): New.
	(is_use_properly_guarded): Call uninit_ops_invalidate_phi_use.

From-SVN: r242639