Refactor tree-loop-distribution.c for thread safety

This patch refactors tree-loop-distribution.c for thread safety without
use of C11 __thread feature. All global variables were moved to
`class loop_distribution` which is initialized at ::execute time.

From-SVN: r278421

gcc/ChangeLog

+2019-11-18  Giuliano Belinassi  <giuliano.belinassi@usp.br>
+
+	* cfgloop.c (get_loop_body_in_custom_order): New.
+	* cfgloop.h (get_loop_body_in_custom_order): New prototype.
+	* tree-loop-distribution.c (class loop_distribution): New.
+	(bb_top_order_cmp): Remove.
+	(bb_top_order_cmp_r): New.
+	(create_rdg_vertices): Move into class loop_distribution.
+	(stmts_from_loop): Same as above.
+	(update_for_merge): Same as above.
+	(partition_merge_into): Same as above.
+	(get_data_dependence): Same as above.
+	(data_dep_in_cycle_p): Same as above.
+	(update_type_for_merge): Same as above.
+	(build_rdg_partition_for-vertex): Same as above.
+	(classify_builtin_ldst): Same as above.
+	(classify_partition): Same as above.
+	(share_memory_accesses): Same as above.
+	(rdg_build_partitions): Same as above.
+	(pg_add_dependence_edges): Same as above.
+	(build_partition_graph): Same as above.
+	(merge_dep_scc_partitions): Same as above.
+	(break_alias_scc_partitions): Same as above.
+	(finalize_partitions): Same as above.
+	(distribute_loop): Same as above.
+	(bb_top_order_init): New method
+	(bb_top_order_destroy): New method.
+	(get_bb_top_order_index_size): New method.
+	(get_bb_top_order_index_index): New method.
+	(get_bb_top_order_index_index): New method.
+	(loop_distribution::execute): New method.
+	(pass_loop_distribution::execute): Instantiate loop_distribution.
+
 2019-11-18  Jan Hubicka  <jh@suse.cz>
 
 	PR ipa/92508

gcc/cfgloop.c

@@ -980,6 +980,19 @@ get_loop_body_in_custom_order (const class loop *loop,
   return bbs;
 }
 
+/* Same as above, but use gcc_sort_r instead of qsort.  */
+
+basic_block *
+get_loop_body_in_custom_order (const class loop *loop, void *data,
+			       int (*bb_comparator) (const void *, const void *, void *))
+{
+  basic_block *bbs = get_loop_body (loop);
+
+  gcc_sort_r (bbs, loop->num_nodes, sizeof (basic_block), bb_comparator, data);
+
+  return bbs;
+}
+
 /* Get body of a LOOP in breadth first sort order.  */
 
 basic_block *

gcc/cfgloop.h

@@ -376,6 +376,8 @@ extern basic_block *get_loop_body_in_dom_order (const class loop *);
 extern basic_block *get_loop_body_in_bfs_order (const class loop *);
 extern basic_block *get_loop_body_in_custom_order (const class loop *,
 			       int (*) (const void *, const void *));
+extern basic_block *get_loop_body_in_custom_order (const class loop *, void *,
+			       int (*) (const void *, const void *, void *));
 
 extern vec<edge> get_loop_exit_edges (const class loop *);
 extern edge single_exit (const class loop *);