8307508: IndirectVarHandle.isAccessModeSupported throws NPE

Reviewed-by: mchung
Backport-of: 75dcc4ef94d90e4aa7f8ca5eccc97c91492d6eed

Author: liach

src/java.base/share/classes/java/lang/invoke/IndirectVarHandle.java

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ *  Copyright (c) 2020, 2023, 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
@@ -27,9 +27,7 @@
 package java.lang.invoke;
 
 import jdk.internal.vm.annotation.ForceInline;
-import jdk.internal.vm.annotation.Stable;
 
-import java.util.List;
 import java.util.function.BiFunction;
 
 /**
@@ -44,8 +42,6 @@
  */
 /* package */ final class IndirectVarHandle extends VarHandle {
 
-    @Stable
-    private final MethodHandle[] handleMap = new MethodHandle[AccessMode.COUNT];
     private final VarHandle directTarget; // cache, for performance reasons
     private final VarHandle target;
     private final BiFunction<AccessMode, MethodHandle, MethodHandle> handleFactory;
@@ -66,16 +62,6 @@ private IndirectVarHandle(VarHandle target, Class<?> value, Class<?>[] coordinat
         this.coordinates = coordinates;
     }
 
-    @Override
-    public Class<?> varType() {
-        return value;
-    }
-
-    @Override
-    public List<Class<?>> coordinateTypes() {
-        return List.of(coordinates);
-    }
-
     @Override
     MethodType accessModeTypeUncached(AccessType at) {
         return at.accessModeType(null, value, coordinates);
@@ -86,17 +72,20 @@ VarHandle asDirect() {
         return directTarget;
     }
 
-    VarHandle target() {
-        return target;
-    }
-
     @Override
     public VarHandle withInvokeExactBehavior() {
         return hasInvokeExactBehavior()
             ? this
             : new IndirectVarHandle(target, value, coordinates, handleFactory, vform, true);
     }
 
+    @Override
+    public VarHandle withInvokeBehavior() {
+        return !hasInvokeExactBehavior()
+                ? this
+                : new IndirectVarHandle(target, value, coordinates, handleFactory, vform, false);
+    }
+
     @ForceInline
     boolean checkAccessModeThenIsDirect(VarHandle.AccessDescriptor ad) {
         super.checkAccessModeThenIsDirect(ad);
@@ -105,21 +94,14 @@ boolean checkAccessModeThenIsDirect(VarHandle.AccessDescriptor ad) {
     }
 
     @Override
-    public VarHandle withInvokeBehavior() {
-        return !hasInvokeExactBehavior()
-            ? this
-            : new IndirectVarHandle(target, value, coordinates, handleFactory, vform, false);
+    public boolean isAccessModeSupported(AccessMode accessMode) {
+        return directTarget.isAccessModeSupported(accessMode);
     }
 
     @Override
-    @ForceInline
-    MethodHandle getMethodHandle(int mode) {
-        MethodHandle handle = handleMap[mode];
-        if (handle == null) {
-            MethodHandle targetHandle = target.getMethodHandle(mode); // might throw UOE of access mode is not supported, which is ok
-            handle = handleMap[mode] = handleFactory.apply(AccessMode.values()[mode], targetHandle);
-        }
-        return handle;
+    MethodHandle getMethodHandleUncached(int mode) {
+        MethodHandle targetHandle = target.getMethodHandle(mode); // might throw UOE of access mode is not supported, which is ok
+        return handleFactory.apply(AccessMode.values()[mode], targetHandle);
     }
 
     @Override

src/java.base/share/classes/java/lang/invoke/VarHandle.java

@@ -526,8 +526,6 @@ VarHandle asDirect() {
         return this;
     }
 
-    VarHandle target() { return null; }
-
     /**
      * Returns {@code true} if this VarHandle has <a href="#invoke-exact-behavior"><em>invoke-exact behavior</em></a>.
      *
@@ -2120,7 +2118,7 @@ final MethodType accessModeTypeUncached(int accessTypeOrdinal) {
      * @return {@code true} if the given access mode is supported, otherwise
      * {@code false}.
      */
-    public final boolean isAccessModeSupported(AccessMode accessMode) {
+    public boolean isAccessModeSupported(AccessMode accessMode) {
         return vform.getMemberNameOrNull(accessMode.ordinal()) != null;
     }
 
@@ -2176,7 +2174,7 @@ public Optional<VarHandleDesc> describeConstable() {
     MethodHandle[] methodHandleTable;
 
     @ForceInline
-    MethodHandle getMethodHandle(int mode) {
+    final MethodHandle getMethodHandle(int mode) {
         MethodHandle[] mhTable = methodHandleTable;
         if (mhTable == null) {
             mhTable = methodHandleTable = new MethodHandle[AccessMode.COUNT];
@@ -2188,7 +2186,7 @@ MethodHandle getMethodHandle(int mode) {
         return mh;
     }
 
-    private final MethodHandle getMethodHandleUncached(int mode) {
+    MethodHandle getMethodHandleUncached(int mode) {
         MethodType mt = accessModeType(AccessMode.values()[mode]).
                 insertParameterTypes(0, VarHandle.class);
         MemberName mn = vform.getMemberName(mode);

test/jdk/java/lang/invoke/VarHandles/IndirectVarHandleTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2023, 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 8307508
+ * @enablePreview
+ * @run junit IndirectVarHandleTest
+ * @summary Test VarHandle::isAccessModeSupported on indirect VarHandle
+ *          produced by MethodHandles.filterCoordinates
+ */
+import org.junit.jupiter.api.Test;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.invoke.VarHandle;
+import java.util.function.IntUnaryOperator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class IndirectVarHandleTest {
+    @Test
+    public void testIsAccessModeTypeSupported() throws Throwable {
+        var lookup = MethodHandles.lookup();
+        var intArrayVh = MethodHandles.arrayElementVarHandle(int[].class);
+        var addOne = lookup.bind((IntUnaryOperator) a -> a + 1, "applyAsInt",
+                MethodType.methodType(int.class, int.class));
+        var offsetIntArrayVh = MethodHandles.filterCoordinates(intArrayVh, 1, addOne);
+
+        for (var mode : VarHandle.AccessMode.values()) {
+            assertEquals(intArrayVh.isAccessModeSupported(mode),
+                    offsetIntArrayVh.isAccessModeSupported(mode), mode.toString());
+        }
+
+        var stringArrayVh = MethodHandles.arrayElementVarHandle(String[].class);
+        var offsetStringArrayVh = MethodHandles.filterCoordinates(stringArrayVh, 1, addOne);
+
+        for (var mode : VarHandle.AccessMode.values()) {
+            assertEquals(stringArrayVh.isAccessModeSupported(mode),
+                    offsetStringArrayVh.isAccessModeSupported(mode), mode.toString());
+        }
+    }
+}