[08/46] Add vec_info::lookup_def

[08/46] Add vec_info::lookup_def

This patch adds a vec_info helper for checking whether an operand is an
SSA_NAME that is defined in the vectorisable region.

2018-07-31  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vectorizer.h (vec_info::lookup_def): Declare.
	* tree-vectorizer.c (vec_info::lookup_def): New function.
	* tree-vect-patterns.c (vect_get_internal_def): Use it.
	(vect_widened_op_tree): Likewise.
	* tree-vect-stmts.c (vect_is_simple_use): Likewise.
	* tree-vect-loop.c (vect_analyze_loop_operations): Likewise.
	(vectorizable_reduction): Likewise.
	(vect_valid_reduction_input_p): Take a stmt_vec_info instead
	of a gimple *.
	(vect_is_slp_reduction): Update calls accordingly.  Use
	vec_info::lookup_def.
	(vect_is_simple_reduction): Likewise
	* tree-vect-slp.c (vect_detect_hybrid_slp_1): Use vec_info::lookup_def.

From-SVN: r263123