tree-vect-loop.c (vectorizable_reduction): Verify STMT_VINFO_REDUC_IDX on the to be vectorized stmts is set up correctly.

2019-10-25  Richard Biener  <rguenther@suse.de>

	* tree-vect-loop.c (vectorizable_reduction): Verify
	STMT_VINFO_REDUC_IDX on the to be vectorized stmts is set up
	correctly.
	* tree-vect-patterns.c (vect_mark_pattern_stmts): Transfer
	STMT_VINFO_REDUC_IDX from the original stmts to the pattern
	stmts.

From-SVN: r277437