loop.texi: Document possibility not to perform disambiguation of loops with multiple latches.

	* doc/loop.texi: Document possibility not to perform disambiguation
	of loops with multiple latches.
	* cfgloopmanip.c (alp_enum_p): Removed.
	(add_loop): Handle subloops.  Use get_loop_body_with_size.
	(create_preheader): Do not allow ENTRY_BLOCK_PTR to be preheader.
	* cfghooks.c (redirect_edge_and_branch_force): Set dominator for
	the new forwarder block.
	(make_forwarder_block): Only call new_bb_cbk if it is not NULL.
	Handle the case latch is NULL.
	* tree-ssa-dom.c (tree_ssa_dominator_optimize): Avoid cfg modifications
	when marking loop exits.
	* ifcvt.c (if_convert): Ditto.  Mark loop exits even if cfg cannot
	be modified.
	* loop-init.c (loop_optimizer_init): Do not modify cfg.  Call
	disambiguate_loops_with_multiple_latches.
	* tree-cfgcleanup.c (cleanup_tree_cfg_loop): Calculate dominators
	before fix_loop_structure.
	* cfgloop.c: Include pointer-set.h and output.h.
	(canonicalize_loop_headers, HEADER_BLOCK, LATCH_EDGE,
	update_latch_info, mfb_keep_just, mfb_keep_nonlatch): Removed.
	(get_loop_latch_edges, find_subloop_latch_edge_by_profile,
	find_subloop_latch_edge_by_ivs, find_subloop_latch_edge,
	mfb_redirect_edges_in_set, form_subloop, merge_latch_edges,
	disambiguate_multiple_latches, get_loop_body_with_size,
	disambiguate_loops_with_multiple_latches): New functions.
	(flow_loop_dump): Dump multiple latch edges.
	(flow_loop_nodes_find): Handle loops with multiple latches.
	(flow_loops_find): Ditto. Do not call canonicalize_loop_headers.
	(glb_enum_p): Modified.
	(get_loop_body): Use get_loop_body_with_size.
	* cfgloop.h (LOOPS_HAVE_RECORDED_EXITS): New flag.
	(AVOID_CFG_MODIFICATIONS): New constant.
	(disambiguate_loops_with_multiple_latches, add_loop,
	get_loop_body_with_size): Declare.
	* Makefile.in (cfgloop.o): Add pointer-set.h and output.h.

	* gcc.dg/tree-ssa/loop-25.c: New test.

From-SVN: r121670

1 files changed, 7 insertions, 1 deletions

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index 4223a39c45f..09eef08ca3d 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -168,11 +168,13 @@ enum
   LOOPS_HAVE_PREHEADERS = 1,
   LOOPS_HAVE_SIMPLE_LATCHES = 2,
   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
-  LOOPS_HAVE_RECORDED_EXITS = 8
+  LOOPS_HAVE_RECORDED_EXITS = 8,
+  LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16
 };
 
 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 		      | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
+#define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 
 typedef struct loop *loop_p;
 DEF_VEC_P (loop_p);
@@ -198,6 +200,7 @@ struct loops
 
 /* Loop recognition.  */
 extern int flow_loops_find (struct loops *);
+extern void disambiguate_loops_with_multiple_latches (void);
 extern void flow_loops_free (struct loops *);
 extern void flow_loops_dump (FILE *,
 			     void (*)(const struct loop *, FILE *, int), int);
@@ -215,6 +218,7 @@ void rescan_loop_exit (edge, bool, bool);
 /* Loop data structure manipulation/querying.  */
 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 extern void flow_loop_tree_node_remove (struct loop *);
+extern void add_loop (struct loop *, struct loop *);
 extern bool flow_loop_nested_p	(const struct loop *, const struct loop *);
 extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
 extern struct loop * find_common_loop (struct loop *, struct loop *);
@@ -229,6 +233,8 @@ extern void mark_loop_exit_edges (void);
 
 /* Loops & cfg manipulation.  */
 extern basic_block *get_loop_body (const struct loop *);
+extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
+					 unsigned);
 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 extern VEC (edge, heap) *get_loop_exit_edges (const struct loop *);