Allow patterns in SLP reductions

The following removes the over-broad rejection of patterns for SLP
reductions which is done by removing them from LOOP_VINFO_REDUCTIONS
during pattern detection.  That's also insufficient in case the
pattern only appears on the reduction path.  Instead this implements
the proper correctness check in vectorizable_reduction and guides
SLP discovery to heuristically avoid forming later invalid groups.

I also couldn't find any testcase that FAILs when allowing the SLP
reductions to form so I've added one.

I came across this for single-lane SLP reductions with the all-SLP
work where we rely on patterns to properly vectorize COND_EXPR
reductions.

	* tree-vect-patterns.cc (vect_pattern_recog_1): Do not
	remove reductions involving patterns.
	* tree-vect-loop.cc (vectorizable_reduction): Reject SLP
	reduction groups with multiple lane-reducing reductions.
	* tree-vect-slp.cc (vect_analyze_slp_instance): When discovering
	SLP reduction groups avoid including lane-reducing ones.

	* gcc.dg/vect/vect-reduc-sad-9.c: New testcase.

0 files changed, 0 insertions, 0 deletions