tree-optimization/99017 - be more forgiving in BB vect costing

This works around a SLP graph partitioning or cost collecting issue
by being more forgiving in vect_bb_vectorization_profitable_p.

2021-02-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/99017
	* tree-vect-slp.c (vect_bb_vectorization_profitable_p): Allow
	zero vector cost entries.

diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index b9f12c30fb834afc6f00cc6ac050d40a1cbd88ed..ea8a97b01c6371791ac66de3e1dabfedee69cb67 100644 (file)
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -4427,7 +4427,8 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo,
   /* Now cost the portions individually.  */
   unsigned vi = 0;
   unsigned si = 0;
-  do
+  while (si < li_scalar_costs.length ()
+        && vi < li_vector_costs.length ())
     {
       unsigned sl = li_scalar_costs[si].first;
       unsigned vl = li_vector_costs[vi].first;
@@ -4497,8 +4498,6 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo,
          return false;
        }
     }
-  while (si < li_scalar_costs.length ()
-        && vi < li_vector_costs.length ());
   if (vi < li_vector_costs.length ())
     {
       if (dump_enabled_p ())