8239569: PublicMethodsTest.java failed due to NPE in java.base/java.nio.file.FileSystems.getFileSystem(FileSystems.java:230)

Reviewed-by: thartmann, kvn

src/hotspot/share/opto/cfgnode.cpp

@@ -2073,7 +2073,7 @@ Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
         }
         // Accumulate type for resulting Phi
         base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
-        address_type = address_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
+        address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
       }
       if (doit && base == NULL) {
         // Check for neighboring AddP nodes in a tree.

test/hotspot/jtreg/compiler/loopopts/TestWrongOffsetConstantArrayConstant.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2020, Red Hat, Inc. 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 8239569
+ * @summary Phi of AddP transformation can cause offset in constant array to be dropped
+ *
+ * @run main/othervm -XX:-BackgroundCompilation TestWrongOffsetConstantArrayConstant
+ */
+
+public class TestWrongOffsetConstantArrayConstant {
+    private static volatile char volatileField;
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 20_000; i++) {
+            if (test('o') != 'o') {
+                throw new RuntimeException("bad result");
+            }
+        }
+    }
+
+
+    static final byte[] str = {'f', 'o'};
+
+    private static char test(char b1) {
+        // Trigger extra rounds of loop opts
+        for (int i = 0; i < 3; i++) {
+            for (int k = 0; k < 3; k++) {
+                for (int l = 0; l < 3; l++) {
+
+                }
+            }
+        }
+        // Will fully unroll
+        int i = 0;
+        for (; i < str.length; i++) {
+            final byte b = str[i]; // LoadB
+            if (b == b1) {
+                break;
+            }
+        }
+        // LoadUB that shares address with LoadB above
+        // Will split thru phi
+        final char c = (char) (str[i] & 0xff);
+        volatileField = c;
+        // LoadUB that shares address with LoadB and LoadUB above
+        final char c2 = (char) (str[i] & 0xff);
+        return c2;
+    }
+}