2017-10-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/82436
	* tree-vect-slp.c (vect_supported_load_permutation_p): More
	conservatively choose the vectorization factor when checking
	whether we can perform the required load permutation.
	(vect_transform_slp_perm_load): Assert when we may not fail.

	* gcc.dg/vect/pr82436.c: New testcase.

From-SVN: r253473