diff --git a/gcc/dominance.c b/gcc/dominance.c
index 0e464cb7282..4943102ff1d 100644
--- a/gcc/dominance.c
+++ b/gcc/dominance.c
@@ -906,13 +906,13 @@ get_dominated_by (enum cdi_direction dir, basic_block bb)
    direction DIR) by some block between N_REGION ones stored in REGION,
    except for blocks in the REGION itself.  */
 
-vec<basic_block> 
+auto_vec<basic_block> 
 get_dominated_by_region (enum cdi_direction dir, basic_block *region,
 			 unsigned n_region)
 {
   unsigned i;
   basic_block dom;
-  vec<basic_block> doms = vNULL;
+  auto_vec<basic_block> doms;
 
   for (i = 0; i < n_region; i++)
     region[i]->flags |= BB_DUPLICATED;
diff --git a/gcc/dominance.h b/gcc/dominance.h
index 515a369aacf..c74ad297c6a 100644
--- a/gcc/dominance.h
+++ b/gcc/dominance.h
@@ -47,7 +47,7 @@ extern basic_block get_immediate_dominator (enum cdi_direction, basic_block);
 extern void set_immediate_dominator (enum cdi_direction, basic_block,
 				     basic_block);
 extern auto_vec<basic_block> get_dominated_by (enum cdi_direction, basic_block);
-extern vec<basic_block> get_dominated_by_region (enum cdi_direction,
+extern auto_vec<basic_block> get_dominated_by_region (enum cdi_direction,
 							 basic_block *,
 							 unsigned);
 extern vec<basic_block> get_dominated_to_depth (enum cdi_direction,
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 6bdd1a561fd..c9403deed19 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -6495,7 +6495,6 @@ gimple_duplicate_sese_region (edge entry, edge exit,
   bool free_region_copy = false, copying_header = false;
   class loop *loop = entry->dest->loop_father;
   edge exit_copy;
-  vec<basic_block> doms = vNULL;
   edge redirected;
   profile_count total_count = profile_count::uninitialized ();
   profile_count entry_count = profile_count::uninitialized ();
@@ -6549,9 +6548,9 @@ gimple_duplicate_sese_region (edge entry, edge exit,
 
   /* Record blocks outside the region that are dominated by something
      inside.  */
+  auto_vec<basic_block> doms;
   if (update_dominance)
     {
-      doms.create (0);
       doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region);
     }
 
@@ -6596,7 +6595,6 @@ gimple_duplicate_sese_region (edge entry, edge exit,
       set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
       doms.safe_push (get_bb_original (entry->dest));
       iterate_fix_dominators (CDI_DOMINATORS, doms, false);
-      doms.release ();
     }
 
   /* Add the other PHI node arguments.  */
@@ -6662,7 +6660,6 @@ gimple_duplicate_sese_tail (edge entry, edge exit,
   class loop *loop = exit->dest->loop_father;
   class loop *orig_loop = entry->dest->loop_father;
   basic_block switch_bb, entry_bb, nentry_bb;
-  vec<basic_block> doms;
   profile_count total_count = profile_count::uninitialized (),
 		exit_count = profile_count::uninitialized ();
   edge exits[2], nexits[2], e;
@@ -6705,7 +6702,8 @@ gimple_duplicate_sese_tail (edge entry, edge exit,
 
   /* Record blocks outside the region that are dominated by something
      inside.  */
-  doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region);
+  auto_vec<basic_block> doms = get_dominated_by_region (CDI_DOMINATORS, region,
+							n_region);
 
   total_count = exit->src->count;
   exit_count = exit->count ();
@@ -6785,7 +6783,6 @@ gimple_duplicate_sese_tail (edge entry, edge exit,
   /* Anything that is outside of the region, but was dominated by something
      inside needs to update dominance info.  */
   iterate_fix_dominators (CDI_DOMINATORS, doms, false);
-  doms.release ();
   /* Update the SSA web.  */
   update_ssa (TODO_update_ssa);
 
@@ -7567,7 +7564,7 @@ basic_block
 move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
 		        basic_block exit_bb, tree orig_block)
 {
-  vec<basic_block> bbs, dom_bbs;
+  vec<basic_block> bbs;
   basic_block dom_entry = get_immediate_dominator (CDI_DOMINATORS, entry_bb);
   basic_block after, bb, *entry_pred, *exit_succ, abb;
   struct function *saved_cfun = cfun;
@@ -7599,9 +7596,9 @@ move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
 
   /* The blocks that used to be dominated by something in BBS will now be
      dominated by the new block.  */
-  dom_bbs = get_dominated_by_region (CDI_DOMINATORS,
-				     bbs.address (),
-				     bbs.length ());
+  auto_vec<basic_block> dom_bbs = get_dominated_by_region (CDI_DOMINATORS,
+							   bbs.address (),
+							   bbs.length ());
 
   /* Detach ENTRY_BB and EXIT_BB from CFUN->CFG.  We need to remember
      the predecessor edges to ENTRY_BB and the successor edges to
@@ -7937,7 +7934,6 @@ move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
   set_immediate_dominator (CDI_DOMINATORS, bb, dom_entry);
   FOR_EACH_VEC_ELT (dom_bbs, i, abb)
     set_immediate_dominator (CDI_DOMINATORS, abb, bb);
-  dom_bbs.release ();
 
   if (exit_bb)
     {
