8258243: C2: assert failed ("Bad derived pointer") with -XX:+VerifyRegisterAllocator

Reviewed-by: kvn, thartmann

Author: chhagedorn

src/hotspot/share/opto/chaitin.cpp

@@ -2406,9 +2406,9 @@ void PhaseChaitin::verify_base_ptrs(ResourceArea* a) const {
                     worklist.push(check->in(m));
                   }
                 } else if (check->is_Con()) {
-                  if (is_derived) {
-                    // Derived is NULL+offset
-                    assert(!is_derived || check->bottom_type()->is_ptr()->ptr() == TypePtr::Null, "Bad derived pointer");
+                  if (is_derived && check->bottom_type()->is_ptr()->_offset != 0) {
+                    // Derived is NULL+non-zero offset, base must be NULL.
+                    assert(check->bottom_type()->is_ptr()->ptr() == TypePtr::Null, "Bad derived pointer");
                   } else {
                     assert(check->bottom_type()->is_ptr()->_offset == 0, "Bad base pointer");
                     // Base either ConP(NULL) or loadConP

test/hotspot/jtreg/compiler/regalloc/TestVerifyRegisterAllocator.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2021, 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 8258243
+ * @requires vm.debug == true & vm.compiler2.enabled
+ * @summary Sanity check the -XX:+VerifyRegisterAllocator flag in a hello world program.
+ *
+ * @run main/othervm -Xcomp -XX:-TieredCompilation -XX:+VerifyRegisterAllocator
+ *                   compiler.regalloc.TestVerifyRegisterAllocator
+ */
+package compiler.regalloc;
+
+public class TestVerifyRegisterAllocator {
+    public static void main(String[] strArr) {
+        System.out.println("Hello world!");
+    }
+}
+