Introduce STMT_VINFO_VEC_STMTS

Introduce STMT_VINFO_VEC_STMTS

This gets rid of the linked list of STMT_VINFO_VECT_STMT and
STMT_VINFO_RELATED_STMT in preparation for vectorized stmts no
longer needing a stmt_vec_info (just for this chaining).  This
has ripple-down effects in all places we gather vectorized
defs.  For this new interfaces are introduced and used
throughout vectorization, simplifying code in a lot of places
and merging it with the SLP way of gathering vectorized
operands.  There is vect_get_vec_defs as the new recommended
unified interface and vect_get_vec_defs_for_operand as one
for non-SLP operation.  I've resorted to keep the structure
of the code the same where using vect_get_vec_defs would have
been too disruptive for this already large patch.

2020-06-10  Richard Biener  <rguenther@suse.de>

	* tree-vect-data-refs.c (vect_vfa_access_size): Adjust.
	(vect_record_grouped_load_vectors): Likewise.
	* tree-vect-loop.c (vect_create_epilog_for_reduction): Likewise.
	(vectorize_fold_left_reduction): Likewise.
	(vect_transform_reduction): Likewise.
	(vect_transform_cycle_phi): Likewise.
	(vectorizable_lc_phi): Likewise.
	(vectorizable_induction): Likewise.
	(vectorizable_live_operation): Likewise.
	(vect_transform_loop): Likewise.
	* tree-vect-slp.c (vect_get_slp_defs): New function, split out
	from overload.
	* tree-vect-stmts.c (vect_get_vec_def_for_operand_1): Remove.
	(vect_get_vec_def_for_operand): Likewise.
	(vect_get_vec_def_for_stmt_copy): Likewise.
	(vect_get_vec_defs_for_stmt_copy): Likewise.
	(vect_get_vec_defs_for_operand): New function.
	(vect_get_vec_defs): Likewise.
	(vect_build_gather_load_calls): Adjust.
	(vect_get_gather_scatter_ops): Likewise.
	(vectorizable_bswap): Likewise.
	(vectorizable_call): Likewise.
	(vectorizable_simd_clone_call): Likewise.
	(vect_get_loop_based_defs): Remove.
	(vect_create_vectorized_demotion_stmts): Adjust.
	(vectorizable_conversion): Likewise.
	(vectorizable_assignment): Likewise.
	(vectorizable_shift): Likewise.
	(vectorizable_operation): Likewise.
	(vectorizable_scan_store): Likewise.
	(vectorizable_store): Likewise.
	(vectorizable_load): Likewise.
	(vectorizable_condition): Likewise.
	(vectorizable_comparison): Likewise.
	(vect_transform_stmt): Adjust and remove no longer applicable
	sanity checks.
	* tree-vectorizer.c (vec_info::new_stmt_vec_info): Initialize
	STMT_VINFO_VEC_STMTS.
	(vec_info::free_stmt_vec_info): Relase it.
	* tree-vectorizer.h (_stmt_vec_info::vectorized_stmt): Remove.
	(_stmt_vec_info::vec_stmts): Add.
	(STMT_VINFO_VEC_STMT): Remove.
	(STMT_VINFO_VEC_STMTS): New.
	(vect_get_vec_def_for_operand_1): Remove.
	(vect_get_vec_def_for_operand): Likewise.
	(vect_get_vec_defs_for_stmt_copy): Likewise.
	(vect_get_vec_def_for_stmt_copy): Likewise.
	(vect_get_vec_defs): New overloads.
	(vect_get_vec_defs_for_operand): New.
	(vect_get_slp_defs): Declare.