8238549: Add explicit cast to correct implementation type in VarHandle implementation methods

Reviewed-by: jvernee

Author: mcimadamore

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

@@ -247,7 +247,7 @@ void addAccessModeTypeMethod(BinderClassWriter cw) {
     void addAccessModeMethodIfNeeded(VarHandle.AccessMode mode, BinderClassWriter cw) {
         String methName = mode.methodName();
         MethodType methType = form.getMethodType(mode.at.ordinal())
-                .insertParameterTypes(0, BASE_CLASS);
+                .insertParameterTypes(0, VarHandle.class);
 
         try {
             MethodType helperType = methType.insertParameterTypes(2, long.class);
@@ -272,6 +272,7 @@ void addAccessModeMethodIfNeeded(VarHandle.AccessMode mode, BinderClassWriter cw
             // offset calculation
             int slot = 2;
             mv.visitVarInsn(ALOAD, 0); // load recv
+            mv.visitTypeInsn(CHECKCAST, Type.getInternalName(BASE_CLASS));
             mv.visitFieldInsn(GETFIELD, Type.getInternalName(BASE_CLASS), "offset", "J");
             for (int i = 0 ; i < dimensions ; i++) {
                 // load ADD MH

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

@@ -29,6 +29,7 @@
 import jdk.internal.vm.annotation.ForceInline;
 import jdk.internal.vm.annotation.Stable;
 
+import java.util.List;
 import java.util.function.BiFunction;
 
 /**
@@ -48,17 +49,31 @@
     private final VarHandle directTarget; // cache, for performance reasons
     private final VarHandle target;
     private final BiFunction<AccessMode, MethodHandle, MethodHandle> handleFactory;
+    private final Class<?> value;
+    private final Class<?>[] coordinates;
 
     IndirectVarHandle(VarHandle target, Class<?> value, Class<?>[] coordinates, BiFunction<AccessMode, MethodHandle, MethodHandle> handleFactory) {
         super(new VarForm(value, coordinates));
         this.handleFactory = handleFactory;
         this.target = target;
         this.directTarget = target.asDirect();
+        this.value = value;
+        this.coordinates = coordinates;
+    }
+
+    @Override
+    public Class<?> varType() {
+        return value;
+    }
+
+    @Override
+    public List<Class<?>> coordinateTypes() {
+        return List.of(coordinates);
     }
 
     @Override
     MethodType accessModeTypeUncached(AccessMode accessMode) {
-        return getMethodHandle(accessMode.ordinal()).type().dropParameterTypes(0, 1);
+        return accessMode.at.accessModeType(directTarget.getClass(), value, coordinates);
     }
 
     @Override
@@ -84,6 +99,6 @@ MethodHandle getMethodHandle(int mode) {
 
     @Override
     public MethodHandle toMethodHandle(AccessMode accessMode) {
-        return getMethodHandle(accessMode.ordinal()).bindTo(this.directTarget);
+        return getMethodHandle(accessMode.ordinal()).bindTo(directTarget);
     }
 }

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

@@ -415,6 +415,7 @@ private static LambdaForm varHandleMethodInvokerHandleForm(VarHandle.AccessMode
         final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
         int nameCursor = ARG_LIMIT;
         final int VAD_ARG      = nameCursor++;
+        final int UNBOUND_VH   = nameCursor++;
         final int CHECK_TYPE   = nameCursor++;
         final int LINKER_CALL  = nameCursor++;
 
@@ -431,14 +432,17 @@ private static LambdaForm varHandleMethodInvokerHandleForm(VarHandle.AccessMode
         NamedFunction getter = speciesData.getterFunction(0);
         names[VAD_ARG] = new Name(getter, names[THIS_MH]);
 
+        names[UNBOUND_VH] = new Name(getFunction(NF_directVarHandleTarget), names[CALL_VH]);
+
         if (isExact) {
             names[CHECK_TYPE] = new Name(getFunction(NF_checkVarHandleExactType), names[CALL_VH], names[VAD_ARG]);
         } else {
             names[CHECK_TYPE] = new Name(getFunction(NF_checkVarHandleGenericType), names[CALL_VH], names[VAD_ARG]);
         }
         Object[] outArgs = new Object[ARG_LIMIT];
         outArgs[0] = names[CHECK_TYPE];
-        for (int i = 1; i < ARG_LIMIT; i++) {
+        outArgs[1] = names[UNBOUND_VH];
+        for (int i = 2; i < ARG_LIMIT; i++) {
             outArgs[i] = names[i];
         }
 

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

@@ -1890,7 +1890,7 @@ public final String toString() {
      *
      * @return the variable type of variables referenced by this VarHandle
      */
-    public final Class<?> varType() {
+    public Class<?> varType() {
         MethodType typeSet = accessModeType(AccessMode.SET);
         return typeSet.parameterType(typeSet.parameterCount() - 1);
     }
@@ -1901,7 +1901,7 @@ public final Class<?> varType() {
      * @return the coordinate types for this VarHandle. The returned
      * list is unmodifiable
      */
-    public final List<Class<?>> coordinateTypes() {
+    public List<Class<?>> coordinateTypes() {
         MethodType typeGet = accessModeType(AccessMode.GET);
         return typeGet.parameterList();
     }

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

@@ -334,7 +334,7 @@ private static VarHandle maybeAdapt(VarHandle target) {
         if (!VAR_HANDLE_IDENTITY_ADAPT) return target;
         target = MethodHandles.filterValue(target,
                         MethodHandles.identity(target.varType()), MethodHandles.identity(target.varType()));
-        MethodType mtype = target.accessModeType(VarHandle.AccessMode.GET);
+        MethodType mtype = target.accessModeType(VarHandle.AccessMode.GET).dropParameterTypes(0, 1);
         for (int i = 0 ; i < mtype.parameterCount() ; i++) {
             target = MethodHandles.filterCoordinates(target, i, MethodHandles.identity(mtype.parameterType(i)));
         }