[27/46] Remove duplicated stmt_vec_info lookups

[27/46] Remove duplicated stmt_vec_info lookups

Various places called vect_dr_stmt or vinfo_for_stmt multiple times
on the same input.  This patch makes them reuse the earlier result.
It also splits a couple of single vinfo_for_stmt calls out into
separate statements so that they can be reused in later patches.

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

gcc/
	* tree-vect-data-refs.c (vect_analyze_data_ref_dependence)
	(vect_slp_analyze_node_dependences, vect_analyze_data_ref_accesses)
	(vect_permute_store_chain, vect_permute_load_chain)
	(vect_shift_permute_load_chain, vect_transform_grouped_load): Avoid
	repeated stmt_vec_info lookups.
	* tree-vect-loop-manip.c (vect_can_advance_ivs_p): Likewise.
	(vect_update_ivs_after_vectorizer): Likewise.
	* tree-vect-loop.c (vect_is_simple_reduction): Likewise.
	(vect_create_epilog_for_reduction, vectorizable_reduction): Likewise.
	* tree-vect-patterns.c (adjust_bool_stmts): Likewise.
	* tree-vect-slp.c (vect_analyze_slp_instance): Likewise.
	(vect_bb_slp_scalar_cost): Likewise.
	* tree-vect-stmts.c (get_group_alias_ptr_type): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@263142 138bc75d-0d04-0410-961f-82ee72b054a4