re PR tree-optimization/80631 (Compiling with -O3 -mavx2 gives wrong code)

re PR tree-optimization/80631 (Compiling with -O3 -mavx2 gives wrong code)

	PR tree-optimization/80631
	* tree-vect-loop.c (get_initial_def_for_reduction): Fix comment typo.
	(vect_create_epilog_for_reduction): Add INDUC_VAL and INDUC_CODE
	arguments, for INTEGER_INDUC_COND_REDUCTION use INDUC_VAL instead of
	hardcoding zero as the value if COND_EXPR is never true.  For
	INTEGER_INDUC_COND_REDUCTION don't emit the final COND_EXPR if
	INDUC_VAL is equal to INITIAL_DEF, and use INDUC_CODE instead of
	hardcoding MAX_EXPR as the reduction operation.
	(is_nonwrapping_integer_induction): Allow negative step.
	(vectorizable_reduction): Compute INDUC_VAL and INDUC_CODE for
	vect_create_epilog_for_reduction, if no value is suitable, don't
	use INTEGER_INDUC_COND_REDUCTION for now.  Formatting fixes.

	* gcc.dg/vect/pr80631-1.c: New test.
	* gcc.dg/vect/pr80631-2.c: New test.
	* gcc.dg/vect/pr65947-13.c: Expect integer induc cond reduction
	vectorization.

From-SVN: r255574