return auto_vec from cgraph_node::collect_callers

This ensures the callers of collect_callers () take ownership of the vector and
free it when appropriate.

Signed-off-by: Trevor Saunders <tbsaunde@tbsaunde.org>

gcc/ChangeLog:

	* cgraph.c (cgraph_node::collect_callers): Return
	auto_vec<cgraph_edge *>.
	* cgraph.h (cgraph_node::collect_callers): Likewise.
	* ipa-cp.c (create_specialized_node): Adjust.
	(decide_about_value): Likewise.
	(decide_whether_version_node): Likewise.
	* ipa-sra.c (process_isra_node_results): Likewise.
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index d7c78d5..abe4e3e 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -3074,10 +3074,10 @@
 /* Collect all callers of cgraph_node and its aliases that are known to lead to
    cgraph_node (i.e. are not overwritable).  */
 
-vec<cgraph_edge *>
+auto_vec<cgraph_edge *>
 cgraph_node::collect_callers (void)
 {
-  vec<cgraph_edge *> redirect_callers = vNULL;
+  auto_vec<cgraph_edge *> redirect_callers;
   call_for_symbol_thunks_and_aliases (collect_callers_of_node_1,
 				    &redirect_callers, false);
   return redirect_callers;
diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index 4a1f899..9f4338f 100644
--- a/gcc/cgraph.h
+++ b/gcc/cgraph.h
@@ -1139,7 +1139,7 @@
 
   /* Collect all callers of cgraph_node and its aliases that are known to lead
      to NODE (i.e. are not overwritable) and that are not thunks.  */
-  vec<cgraph_edge *> collect_callers (void);
+  auto_vec<cgraph_edge *> collect_callers (void);
 
   /* Remove all callers from the node.  */
   void remove_callers (void);
diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c
index 2cae69e..57c18af 100644
--- a/gcc/ipa-cp.c
+++ b/gcc/ipa-cp.c
@@ -4527,7 +4527,7 @@
 			 vec<tree> known_csts,
 			 vec<ipa_polymorphic_call_context> known_contexts,
 			 struct ipa_agg_replacement_value *aggvals,
-			 vec<cgraph_edge *> callers)
+			 vec<cgraph_edge *> &callers)
 {
   ipa_node_params *new_info, *info = ipa_node_params_sum->get (node);
   vec<ipa_replace_map *, va_gc> *replace_trees = NULL;
@@ -4672,7 +4672,6 @@
 
   ipcp_discover_new_direct_edges (new_node, known_csts, known_contexts, aggvals);
 
-  callers.release ();
   return new_node;
 }
 
@@ -5562,6 +5561,7 @@
 						      offset, val->value));
   val->spec_node = create_specialized_node (node, known_csts, known_contexts,
 					    aggvals, callers);
+  callers.release ();
   overall_size += val->local_size_cost;
   if (dump_file && (dump_flags & TDF_DETAILS))
     fprintf (dump_file, "     overall size reached %li\n",
@@ -5638,7 +5638,7 @@
 	}
 
       struct cgraph_node *clone;
-      vec<cgraph_edge *> callers = node->collect_callers ();
+      auto_vec<cgraph_edge *> callers = node->collect_callers ();
 
       for (int i = callers.length () - 1; i >= 0; i--)
 	{
@@ -5654,7 +5654,6 @@
 	  /* If node is not called by anyone, or all its caller edges are
 	     self-recursive, the node is not really in use, no need to do
 	     cloning.  */
-	  callers.release ();
 	  info->do_clone_for_all_contexts = false;
 	  return ret;
 	}
diff --git a/gcc/ipa-sra.c b/gcc/ipa-sra.c
index 3f90d4d..3272daf 100644
--- a/gcc/ipa-sra.c
+++ b/gcc/ipa-sra.c
@@ -3755,7 +3755,7 @@
   unsigned &suffix_counter = clone_num_suffixes->get_or_insert (
 			       IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (
 				 node->decl)));
-  vec<cgraph_edge *> callers = node->collect_callers ();
+  auto_vec<cgraph_edge *> callers = node->collect_callers ();
   cgraph_node *new_node
     = node->create_virtual_clone (callers, NULL, new_adjustments, "isra",
 				  suffix_counter);