2019-10-30  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/65930
	* tree-vect-loop.c (vect_is_simple_reduction): For reduction
	chains also allow a leading and trailing conversion.
	* tree-vect-slp.c (vect_get_and_check_slp_defs): Handle
	intermediate reduction chains.
	(vect_analyze_slp_instance): Likewise.  Build a SLP
	node for a trailing conversion manually.

	* gcc.dg/vect/pr65930-2.c: New testcase.

From-SVN: r277603