vect: Add maskload else value support.

This patch adds an else operand to vectorized masked load calls.
The current implementation adds else-value arguments to the respective
target-querying functions that is used to supply the vectorizer with the
proper else value.

We query the target for its supported else operand and uses that for the
maskload call.  If necessary, i.e. if the mode has padding bits and if
the else operand is nonzero, a VEC_COND enforcing a zero else value is
emitted.

gcc/ChangeLog:

	* optabs-query.cc (supports_vec_convert_optab_p): Return icode.
	(get_supported_else_val): Return supported else value for
	optab's operand at index.
	(supports_vec_gather_load_p): Add else argument.
	(supports_vec_scatter_store_p): Ditto.
	* optabs-query.h (supports_vec_gather_load_p): Ditto.
	(get_supported_else_val): Ditto.
	* optabs-tree.cc (target_supports_mask_load_store_p): Ditto.
	(can_vec_mask_load_store_p): Ditto.
	(target_supports_len_load_store_p): Ditto.
	(get_len_load_store_mode): Ditto.
	* optabs-tree.h (target_supports_mask_load_store_p): Ditto.
	(can_vec_mask_load_store_p): Ditto.
	* tree-vect-data-refs.cc (vect_lanes_optab_supported_p): Ditto.
	(vect_gather_scatter_fn_p): Ditto.
	(vect_check_gather_scatter): Ditto.
	(vect_load_lanes_supported): Ditto.
	* tree-vect-patterns.cc (vect_recog_gather_scatter_pattern):
	Ditto.
	* tree-vect-slp.cc (vect_get_operand_map): Adjust indices for
	else operand.
	(vect_slp_analyze_node_operations): Skip undefined else operand.
	* tree-vect-stmts.cc (exist_non_indexing_operands_for_use_p):
	Add else operand handling.
	(vect_get_vec_defs_for_operand): Handle undefined else operand.
	(check_load_store_for_partial_vectors): Add else argument.
	(vect_truncate_gather_scatter_offset): Ditto.
	(vect_use_strided_gather_scatters_p): Ditto.
	(get_group_load_store_type): Ditto.
	(get_load_store_type): Ditto.
	(vect_get_mask_load_else): Ditto.
	(vect_get_else_val_from_tree): Ditto.
	(vect_build_one_gather_load_call): Add zero else operand.
	(vectorizable_load): Use else operand.
	* tree-vectorizer.h (vect_gather_scatter_fn_p): Add else
	argument.
	(vect_load_lanes_supported): Ditto.
	(vect_get_mask_load_else): Ditto.
	(vect_get_else_val_from_tree): Ditto.

1 files changed, 7 insertions, 3 deletions

diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index ebd1d89..dcad41d 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -2447,9 +2447,11 @@ extern bool vect_slp_analyze_instance_alignment (vec_info *, slp_instance);
 extern opt_result vect_analyze_data_ref_accesses (vec_info *, vec<int> *);
 extern opt_result vect_prune_runtime_alias_test_list (loop_vec_info);
 extern bool vect_gather_scatter_fn_p (vec_info *, bool, bool, tree, tree,
-				      tree, int, internal_fn *, tree *);
+				      tree, int, internal_fn *, tree *,
+				      vec<int> * = nullptr);
 extern bool vect_check_gather_scatter (stmt_vec_info, loop_vec_info,
-				       gather_scatter_info *);
+				       gather_scatter_info *,
+				       vec<int> * = nullptr);
 extern opt_result vect_find_stmt_data_reference (loop_p, gimple *,
 						 vec<data_reference_p> *,
 						 vec<int> *, int);
@@ -2467,7 +2469,8 @@ extern tree vect_create_destination_var (tree, tree);
 extern bool vect_grouped_store_supported (tree, unsigned HOST_WIDE_INT);
 extern internal_fn vect_store_lanes_supported (tree, unsigned HOST_WIDE_INT, bool);
 extern bool vect_grouped_load_supported (tree, bool, unsigned HOST_WIDE_INT);
-extern internal_fn vect_load_lanes_supported (tree, unsigned HOST_WIDE_INT, bool);
+extern internal_fn vect_load_lanes_supported (tree, unsigned HOST_WIDE_INT,
+					      bool, vec<int> * = nullptr);
 extern void vect_permute_store_chain (vec_info *, vec<tree> &,
 				      unsigned int, stmt_vec_info,
 				      gimple_stmt_iterator *, vec<tree> *);
@@ -2613,6 +2616,7 @@ extern int vect_slp_child_index_for_operand (const gimple *, int op, bool);
 
 extern tree prepare_vec_mask (loop_vec_info, tree, tree, tree,
 			      gimple_stmt_iterator *);
+extern tree vect_get_mask_load_else (int, tree);
 
 /* In tree-vect-patterns.cc.  */
 extern void