8238811: C2: assert(i >= req() || i == 0 || is_Region() || is_Phi()) …

…with -XX:+VerifyGraphEdges

Fix -XX:+VerifyGraphEdges by additionally handling ArrayCopyNodes and UnlockNodes and add some basic flag testing.

Reviewed-by: roland, neliasso

src/hotspot/share/opto/node.cpp

@@ -2123,7 +2123,8 @@ void Node::verify_edges(Unique_Node_List &visited) {
       }
       assert( cnt == 0,"Mismatched edge count.");
     } else if (n == NULL) {
-      assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
+      assert(i >= req() || i == 0 || is_Region() || is_Phi() || is_ArrayCopy()
+              || (is_Unlock() && i == req()-1), "only region, phi, arraycopy or unlock nodes have null data edges");
     } else {
       assert(n->is_top(), "sanity");
       // Nothing to check.
@@ -2137,9 +2138,6 @@ void Node::verify_edges(Unique_Node_List &visited) {
   }
 }
 
-//------------------------------verify_recur-----------------------------------
-static const Node *unique_top = NULL;
-
 void Node::verify_recur(const Node *n, int verify_depth,
                         VectorSet &old_space, VectorSet &new_space) {
   if ( verify_depth == 0 )  return;

test/hotspot/jtreg/compiler/c2/TestVerifyGraphEdges.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8238811
+ * @requires vm.debug == true & vm.flavor == "server"
+ * @summary Run with -Xcomp to test -XX:+VerifyGraphEdges in debug builds.
+ *
+ * @run main/othervm -Xbatch -Xcomp -XX:+VerifyGraphEdges compiler.c2.TestVerifyGraphEdges
+ */
+package compiler.c2;
+
+public class TestVerifyGraphEdges {
+    public static void main(String[] args) {
+    }
+}