middle-end: updated niters analysis to handle multiple exits.

This second part updates niters analysis to be able to analyze any number of
exits.  If we have multiple exits we determine the main exit by finding the
first counting IV.

The change allows the vectorizer to pass analysis for multiple loops, but we
later gracefully reject them.  It does however allow us to test if the exit
handling is using the right exit everywhere.

Additionally since we analyze all exits, we now return all conditions for them
and determine which condition belongs to the main exit.

The main condition is needed because the vectorizer needs to ignore the main IV
condition during vectorization as it will replace it during codegen.

To track versioned loops we extend the contract between ifcvt and the vectorizer
to store the exit number in aux so that we can match it up again during peeling.

gcc/ChangeLog:

	* tree-if-conv.cc (tree_if_conversion): Record exits in aux.
	* tree-vect-loop-manip.cc (slpeel_tree_duplicate_loop_to_edge_cfg): Use
	it.
	* tree-vect-loop.cc (vect_get_loop_niters): Determine main exit.
	(vec_init_loop_exit_info): Extend analysis when multiple exits.
	(vect_analyze_loop_form): Record conds and determine main cond.
	(vect_create_loop_vinfo): Extend bookkeeping of conds.
	(vect_analyze_loop): Release conds.
	* tree-vectorizer.h (LOOP_VINFO_LOOP_CONDS,
	LOOP_VINFO_LOOP_IV_COND):  New.
	(struct vect_loop_form_info): Add conds, alt_loop_conds;
	(struct loop_vec_info): Add conds, loop_iv_cond.

1 files changed, 9 insertions, 1 deletions

diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index a521608..605b6fd 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -888,6 +888,12 @@ public:
      we need to peel off iterations at the end to form an epilogue loop.  */
   bool peeling_for_niter;
 
+  /* List of loop additional IV conditionals found in the loop.  */
+  auto_vec<gcond *> conds;
+
+  /* Main loop IV cond.  */
+  gcond* loop_iv_cond;
+
   /* True if there are no loop carried data dependencies in the loop.
      If loop->safelen <= 1, then this is always true, either the loop
      didn't have any loop carried data dependencies, or the loop is being
@@ -990,6 +996,8 @@ public:
 #define LOOP_VINFO_REDUCTION_CHAINS(L)     (L)->reduction_chains
 #define LOOP_VINFO_PEELING_FOR_GAPS(L)     (L)->peeling_for_gaps
 #define LOOP_VINFO_PEELING_FOR_NITER(L)    (L)->peeling_for_niter
+#define LOOP_VINFO_LOOP_CONDS(L)           (L)->conds
+#define LOOP_VINFO_LOOP_IV_COND(L)         (L)->loop_iv_cond
 #define LOOP_VINFO_NO_DATA_DEPENDENCIES(L) (L)->no_data_dependencies
 #define LOOP_VINFO_SCALAR_LOOP(L)	   (L)->scalar_loop
 #define LOOP_VINFO_SCALAR_LOOP_SCALING(L)  (L)->scalar_loop_scaling
@@ -2379,7 +2387,7 @@ struct vect_loop_form_info
   tree number_of_iterations;
   tree number_of_iterationsm1;
   tree assumptions;
-  gcond *loop_cond;
+  auto_vec<gcond *> conds;
   gcond *inner_loop_cond;
   edge loop_exit;
 };