8175887: C1 value numbering handling of Unsafe.get*Volatile is incorrect

Reviewed-by: vlivanov

src/share/vm/c1/c1_ValueMap.hpp

@@ -158,6 +158,12 @@ class ValueNumberingVisitor: public InstructionVisitor {
   void do_UnsafePutRaw   (UnsafePutRaw*    x) { kill_memory(); }
   void do_UnsafePutObject(UnsafePutObject* x) { kill_memory(); }
   void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) { kill_memory(); }
+  void do_UnsafeGetRaw   (UnsafeGetRaw*    x) { /* nothing to do */ }
+  void do_UnsafeGetObject(UnsafeGetObject* x) {
+    if (x->is_volatile()) { // the JMM requires this
+      kill_memory();
+    }
+  }
   void do_Intrinsic      (Intrinsic*       x) { if (!x->preserves_state()) kill_memory(); }
 
   void do_Phi            (Phi*             x) { /* nothing to do */ }
@@ -198,8 +204,6 @@ class ValueNumberingVisitor: public InstructionVisitor {
   void do_OsrEntry       (OsrEntry*        x) { /* nothing to do */ }
   void do_ExceptionObject(ExceptionObject* x) { /* nothing to do */ }
   void do_RoundFP        (RoundFP*         x) { /* nothing to do */ }
-  void do_UnsafeGetRaw   (UnsafeGetRaw*    x) { /* nothing to do */ }
-  void do_UnsafeGetObject(UnsafeGetObject* x) { /* nothing to do */ }
   void do_UnsafePrefetchRead (UnsafePrefetchRead*  x) { /* nothing to do */ }
   void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) { /* nothing to do */ }
   void do_ProfileCall    (ProfileCall*     x) { /* nothing to do */ }

test/compiler/c1/UnsafeVolatileGuardTest.java

+/*
+ * Copyright (c) 2017, 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.
+ */
+
+import java.lang.reflect.Field;
+
+/**
+ * @test
+ * @bug 8175887
+ * @summary C1 value numbering handling of Unsafe.get*Volatile is incorrect
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:TieredStopAtLevel=1 UnsafeVolatileGuardTest
+ */
+public class UnsafeVolatileGuardTest {
+    volatile static private int a;
+    static private int b;
+
+    static final sun.misc.Unsafe UNSAFE;
+
+    static final Object BASE;
+    static final long OFFSET;
+
+    static {
+        try {
+            Field uf = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
+            uf.setAccessible(true);
+            UNSAFE = (sun.misc.Unsafe)uf.get(null);
+
+            Field f = UnsafeVolatileGuardTest.class.getDeclaredField("a");
+            BASE = UNSAFE.staticFieldBase(f);
+            OFFSET = UNSAFE.staticFieldOffset(f);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static void test() {
+        int tt = b; // makes the JVM CSE the value of b
+
+        while (UNSAFE.getIntVolatile(BASE, OFFSET) == 0) {} // burn
+        if (b == 0) {
+            System.err.println("wrong value of b");
+            System.exit(1); // fail hard to report the error
+        }
+    }
+
+    public static void main(String [] args) throws Exception {
+        for (int i = 0; i < 10; i++) {
+            new Thread(UnsafeVolatileGuardTest::test).start();
+        }
+        b = 1;
+        a = 1;
+    }
+}

test/compiler/c1/VolatileGuardTest.java

+/*
+ * Copyright (c) 2017, 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 8175887
+ * @summary C1 doesn't respect the JMM with volatile field loads
+ *
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:TieredStopAtLevel=1 VolatileGuardTest
+ */
+public class VolatileGuardTest {
+    volatile static private int a;
+    static private int b;
+
+    static void test() {
+        int tt = b; // makes the JVM CSE the value of b
+
+        while (a == 0) {} // burn
+        if (b == 0) {
+            System.err.println("wrong value of b");
+            System.exit(1); // fail hard to report the error
+        }
+    }
+
+    public static void main(String [] args) throws Exception {
+        for (int i = 0; i < 10; i++) {
+            new Thread(VolatileGuardTest::test).start();
+        }
+        b = 1;
+        a = 1;
+    }
+}