tree-vrp.c (finalize_jump_threads): Do not care about dominance info.

	* tree-vrp.c (finalize_jump_threads): Do not care about dominance info.
	(execute_vrp): Preserve loops through jump threading.
	* tree-ssa-threadupdate.c (thread_single_edge,
	dbds_continue_enumeration_p, determine_bb_domination_status,
	thread_through_loop_header): New functions.
	(create_edge_and_update_destination_phis,
	create_edge_and_update_destination_phis): Set loops for the new blocks.
	(prune_undesirable_thread_requests): Removed.
	(redirect_edges): Do not pretend that redirect_edge_and_branch can
	create new blocks.
	(thread_block): Do not call prune_undesirable_thread_requests.
	Update loops.
	(mark_threaded_blocks): Select edges to thread here.
	(thread_through_all_blocks): Take may_peel_loop_headers argument.
	Thread edges through loop headers independently.
	* cfgloopmanip.c (create_preheader, mfb_keep_just): Export.
	* tree-pass.h (TODO_mark_first_instance): New.
	(first_pass_instance): Declare.
	* cfghooks.c (duplicate_block): Put the block to the original loop
	if copy is not specified.
	* tree-ssa-dom.c (tree_ssa_dominator_optimize): Preserve loops through
	jump threading.  Pass may_peel_loop_headers to
	thread_through_all_blocks according to first_pass_instance.
	* cfgloop.h (create_preheader): Declare.
	* tree-flow.h (thread_through_all_blocks): Declaration changed.
	* basic-block.h (mfb_keep_just, mfb_kj_edge): Declare.
	* passes.c (first_pass_instance): New variable.
	(next_pass_1): Set TODO_mark_first_instance.
	(execute_todo): Set first_pass_instance.

	* gcc.dg/tree-ssa/ssa-dom-thread-2.c: New test.
	* gcc.dg/vect/vect-102.c, gcc.dg/vect/vect-103.c,
	gcc.dg/vect/vect-104.c: Use more complex construction to prevent vectorizing.
	* gcc.dg/tree-ssa/pr21559.c: Update outcome.

From-SVN: r124786

1 files changed, 12 insertions, 0 deletions

diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index b772435..299255c 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -218,6 +218,9 @@ struct dump_file_info
    for the passes that are handed to register_dump_files.  */
 #define TODO_set_props			(1 << 15)
 
+/* Internally used for the first instance of a pass.  */
+#define TODO_mark_first_instance	(1 << 16)
+
 #define TODO_update_ssa_any		\
     (TODO_update_ssa			\
      | TODO_update_ssa_no_phi		\
@@ -417,4 +420,13 @@ extern struct tree_opt_pass *all_passes, *all_ipa_passes, *all_lowering_passes;
 extern void execute_pass_list (struct tree_opt_pass *);
 extern void execute_ipa_pass_list (struct tree_opt_pass *);
 
+/* Set to true if the pass is called the first time during compilation of the
+   current function.  Note that using this information in the optimization
+   passes is considered not to be clean, and it should be avoided if possible.
+   This flag is currently used to prevent loops from being peeled repeatedly
+   in jump threading; it will be removed once we preserve loop structures
+   throughout the compilation -- we will be able to mark the affected loops
+   directly in jump threading, and avoid peeling them next time.  */
+extern bool first_pass_instance;
+
 #endif /* GCC_TREE_PASS_H */