re PR middle-end/78566 (gcc.dg/uninit-pred-6_[abc]*.c regressions on some non-x86...

re PR middle-end/78566 (gcc.dg/uninit-pred-6_[abc]*.c regressions on some non-x86 platforms)

	PR middle-end/78566
	* tree-ssa-uninit.c (can_one_predicate_be_invalidated_p): Change
	argument type to a pred_chain.
	(can_chain_union_be_invalidated_p): Use pred_chain instead of a
	worklist.
	(flatten_out_predicate_chains): Remove.
	(uninit_uses_cannot_happen): Rename from
	uninit_ops_invalidate_phi_use.
	Change logic so that we are checking that the PHI use will
	invalidate _ALL_ possibly uninitialized operands.
	(is_use_properly_guarded): Rename call to
	uninit_ops_invalidate_phi_use into uninit_uses_cannot_happen.

From-SVN: r243288