re PR bootstrap/87134 (SEGV in cc1 caused by r263875)

2018-09-05  Richard Biener  <rguenther@suse.de>

	PR bootstrap/87134
	* tree-ssa-sccvn.c (rpo_elim::eliminate_push_avail): Make sure
	to zero-init the emplaced vec.

From-SVN: r264125

gcc/ChangeLog

+2018-09-05  Richard Biener  <rguenther@suse.de>
+
+	PR bootstrap/87134
+	* tree-ssa-sccvn.c (rpo_elim::eliminate_push_avail): Make sure
+	to zero-init the emplaced vec.
+
 2018-09-05  Martin Liska  <mliska@suse.cz>
 
 	PR tree-optimization/87205

gcc/tree-ssa-sccvn.c

@@ -5799,6 +5799,7 @@ rpo_elim::eliminate_push_avail (basic_block bb, tree leader)
   if (!existed)
     {
       new (&av) vec<std::pair<int, int> >;
+      av = vNULL;
       av.reserve_exact (2);
     }
   av.safe_push (std::make_pair (bb->index, SSA_NAME_VERSION (leader)));