re PR tree-optimization/78899 (Vestorized loop with optmized mask stores motion is completely deleted after r242520.)

	PR tree-optimization/78899
	* tree-if-conv.c (version_loop_for_if_conversion): Instead of
	returning bool return struct loop *, NULL for failure and the new
	loop on success.
	(versionable_outer_loop_p): Don't version outer loop if it has
	dont_vectorized bit set.
	(tree_if_conversion): When versioning outer loop, ensure
	tree_if_conversion is performed also on the inner loop of the
	non-vectorizable outer loop copy.
	* tree-vectorizer.c (set_uid_loop_bbs): Formatting fix.  Fold
	LOOP_VECTORIZED in inner loop of the scalar outer loop and
	prevent vectorization of it.
	(vectorize_loops): For outer + inner LOOP_VECTORIZED, ensure
	the outer loop vectorization of the non-scalar version is attempted
	before vectorization of the inner loop in scalar version.  If
	outer LOOP_VECTORIZED guarded loop is not vectorized, prevent
	vectorization of its inner loop.
	* tree-vect-loop-manip.c (rename_variables_in_bb): If outer_loop
	has 2 inner loops, rename also on edges from bb whose single pred
	is outer_loop->header.  Fix typo in function comment.

	* gcc.target/i386/pr78899.c: New test.
	* gcc.dg/pr71077.c: New test.

From-SVN: r244238