cfgloop.h (struct loop): Add comment.

	* cfgloop.h (struct loop): Add comment.  New field orig_loop_num.
	* cfgloopmanip.c (lv_adjust_loop_entry_edge): Comment change.
	* internal-fn.c (expand_LOOP_DIST_ALIAS): New function.
	* internal-fn.def (LOOP_DIST_ALIAS): New.
	* tree-vectorizer.c (fold_loop_vectorized_call): Rename to ...
	(fold_loop_internal_call): ... this.
	(vect_loop_dist_alias_call): New function.
	(set_uid_loop_bbs): Call fold_loop_internal_call.
	(vectorize_loops): Fold IFN_LOOP_VECTORIZED and IFN_LOOP_DIST_ALIAS
	internal calls.

From-SVN: r249983

1 files changed, 12 insertions, 1 deletions

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index a8bec1d..e7ffa23 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -114,7 +114,8 @@ struct GTY ((chain_next ("%h.next"))) control_iv {
 
 /* Structure to hold information for each natural loop.  */
 struct GTY ((chain_next ("%h.next"))) loop {
-  /* Index into loops array.  */
+  /* Index into loops array.  Note indices will never be reused after loop
+     is destroyed.  */
   int num;
 
   /* Number of loop insns.  */
@@ -225,6 +226,16 @@ struct GTY ((chain_next ("%h.next"))) loop {
      builtins.  */
   tree simduid;
 
+  /* In loop optimization, it's common to generate loops from the original
+     loop.  This field records the index of the original loop which can be
+     used to track the original loop from newly generated loops.  This can
+     be done by calling function get_loop (cfun, orig_loop_num).  Note the
+     original loop could be destroyed for various reasons thus no longer
+     exists, as a result, function call to get_loop returns NULL pointer.
+     In this case, this field should not be used and needs to be cleared
+     whenever possible.  */
+  int orig_loop_num;
+
   /* Upper bound on number of iterations of a loop.  */
   struct nb_iter_bound *bounds;