/*

 * Copyright (c) 2011, 2018, 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.

 */

package org.graalvm.compiler.nodes.java;

import org.graalvm.compiler.core.common.type.Stamp;

import org.graalvm.compiler.core.common.type.StampFactory;

import org.graalvm.compiler.core.common.type.StampPair;

import org.graalvm.compiler.core.common.type.TypeReference;

import org.graalvm.compiler.graph.IterableNodeType;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.spi.Simplifiable;

import org.graalvm.compiler.graph.spi.SimplifierTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodeinfo.Verbosity;

import org.graalvm.compiler.nodes.CallTargetNode;

import org.graalvm.compiler.nodes.FixedGuardNode;

import org.graalvm.compiler.nodes.Invoke;

import org.graalvm.compiler.nodes.LogicNode;

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.PiNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.extended.ValueAnchorNode;

import org.graalvm.compiler.nodes.spi.UncheckedInterfaceProvider;

import org.graalvm.compiler.nodes.type.StampTool;

import jdk.vm.ci.code.BytecodeFrame;

import jdk.vm.ci.meta.Assumptions;

import jdk.vm.ci.meta.Assumptions.AssumptionResult;

import jdk.vm.ci.meta.DeoptimizationAction;

import jdk.vm.ci.meta.DeoptimizationReason;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.JavaTypeProfile;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.ResolvedJavaType;

@NodeInfo

public class MethodCallTargetNode extends CallTargetNode implements IterableNodeType, Simplifiable {

    public static final NodeClass<MethodCallTargetNode> TYPE = NodeClass.create(MethodCallTargetNode.class);

    protected JavaTypeProfile profile;

    public MethodCallTargetNode(InvokeKind invokeKind, ResolvedJavaMethod targetMethod, ValueNode[] arguments, StampPair returnStamp, JavaTypeProfile profile) {

        this(TYPE, invokeKind, targetMethod, arguments, returnStamp, profile);

    }

    protected MethodCallTargetNode(NodeClass<? extends MethodCallTargetNode> c, InvokeKind invokeKind, ResolvedJavaMethod targetMethod, ValueNode[] arguments, StampPair returnStamp,

                    JavaTypeProfile profile) {

        super(c, arguments, targetMethod, invokeKind, returnStamp);

        this.profile = profile;

    }

    /**

     * Gets the instruction that produces the receiver object for this invocation, if any.

     *

     * @return the instruction that produces the receiver object for this invocation if any,

     *         {@code null} if this invocation does not take a receiver object

     */

    public ValueNode receiver() {

        return isStatic() ? null : arguments().get(0);

    }

    /**

     * Checks whether this is an invocation of a static method.

     *

     * @return {@code true} if the invocation is a static invocation

     */

    public boolean isStatic() {

        return invokeKind() == InvokeKind.Static;

    }

    public JavaKind returnKind() {

        return targetMethod().getSignature().getReturnKind();

    }

    @Override

    public boolean verify() {

        assert getUsageCount() <= 1 : "call target may only be used by a single invoke";

        for (Node n : usages()) {

            assertTrue(n instanceof Invoke, "call target can only be used from an invoke (%s)", n);

        }

        if (invokeKind().isDirect()) {

            assertTrue(targetMethod().isConcrete(), "special calls or static calls are only allowed for concrete methods (%s)", targetMethod());

        }

        if (invokeKind() == InvokeKind.Static) {

            assertTrue(targetMethod().isStatic(), "static calls are only allowed for static methods (%s)", targetMethod());

        } else {

            assertFalse(targetMethod().isStatic(), "static calls are only allowed for non-static methods (%s)", targetMethod());

        }

        return super.verify();

    }

    @Override

    public String toString(Verbosity verbosity) {

        if (verbosity == Verbosity.Long) {

            return super.toString(Verbosity.Short) + "(" + targetMethod() + ")";

        } else {

            return super.toString(verbosity);

        }

    }

    public static ResolvedJavaMethod findSpecialCallTarget(InvokeKind invokeKind, ValueNode receiver, ResolvedJavaMethod targetMethod, ResolvedJavaType contextType) {

        if (invokeKind.isDirect()) {

            return null;

        }

        // check for trivial cases (e.g. final methods, nonvirtual methods)

        if (targetMethod.canBeStaticallyBound()) {

            return targetMethod;

        }

        return devirtualizeCall(invokeKind, targetMethod, contextType, receiver.graph().getAssumptions(), receiver.stamp(NodeView.DEFAULT));

    }

    public static ResolvedJavaMethod devirtualizeCall(InvokeKind invokeKind, ResolvedJavaMethod targetMethod, ResolvedJavaType contextType, Assumptions assumptions, Stamp receiverStamp) {

        TypeReference type = StampTool.typeReferenceOrNull(receiverStamp);

        if (type == null && invokeKind == InvokeKind.Virtual) {

            // For virtual calls, we are guaranteed to receive a correct receiver type.

            type = TypeReference.createTrusted(assumptions, targetMethod.getDeclaringClass());

        }

        if (type != null) {

            /*

             * either the holder class is exact, or the receiver object has an exact type, or it's

             * an array type

             */

            ResolvedJavaMethod resolvedMethod = type.getType().resolveConcreteMethod(targetMethod, contextType);

            if (resolvedMethod != null && (resolvedMethod.canBeStaticallyBound() || type.isExact() || type.getType().isArray())) {

                return resolvedMethod;

            }

            AssumptionResult<ResolvedJavaMethod> uniqueConcreteMethod = type.getType().findUniqueConcreteMethod(targetMethod);

            if (uniqueConcreteMethod != null && uniqueConcreteMethod.canRecordTo(assumptions)) {

                uniqueConcreteMethod.recordTo(assumptions);

                return uniqueConcreteMethod.getResult();

            }

        }

        return null;

    }

    @Override

    public void simplify(SimplifierTool tool) {

        // attempt to devirtualize the call

        if (invoke().getContextMethod() == null) {

            // avoid invokes that have placeholder bcis: they do not have a valid contextType

            assert (invoke().stateAfter() != null && BytecodeFrame.isPlaceholderBci(invoke().stateAfter().bci)) || BytecodeFrame.isPlaceholderBci(invoke().stateDuring().bci);

            return;

        }

        ResolvedJavaType contextType = (invoke().stateAfter() == null && invoke().stateDuring() == null) ? null : invoke().getContextType();

        ResolvedJavaMethod specialCallTarget = findSpecialCallTarget(invokeKind, receiver(), targetMethod, contextType);

        if (specialCallTarget != null) {

            this.setTargetMethod(specialCallTarget);

            setInvokeKind(InvokeKind.Special);

            return;

        }

        Assumptions assumptions = graph().getAssumptions();

        /*

         * Even though we are not registering an assumption (see comment below), the optimization is

         * only valid when speculative optimizations are enabled.

         */

        if (invokeKind().isIndirect() && invokeKind().isInterface() && assumptions != null) {

            // check if the type of the receiver can narrow the result

            ValueNode receiver = receiver();

            // try to turn a interface call into a virtual call

            ResolvedJavaType declaredReceiverType = targetMethod().getDeclaringClass();

            /*

             * We need to check the invoke kind to avoid recursive simplification for virtual

             * interface methods calls.

             */

            if (declaredReceiverType.isInterface()) {

                ResolvedJavaType singleImplementor = declaredReceiverType.getSingleImplementor();

                if (singleImplementor != null && !singleImplementor.equals(declaredReceiverType)) {

                    TypeReference speculatedType = TypeReference.createTrusted(assumptions, singleImplementor);

                    if (tryCheckCastSingleImplementor(receiver, speculatedType)) {

                        return;

                    }

                }

            }

            if (receiver instanceof UncheckedInterfaceProvider) {

                UncheckedInterfaceProvider uncheckedInterfaceProvider = (UncheckedInterfaceProvider) receiver;

                Stamp uncheckedStamp = uncheckedInterfaceProvider.uncheckedStamp();

                if (uncheckedStamp != null) {

                    TypeReference speculatedType = StampTool.typeReferenceOrNull(uncheckedStamp);

                    if (speculatedType != null) {

                        tryCheckCastSingleImplementor(receiver, speculatedType);

                    }

                }

            }

        }

    }

    private boolean tryCheckCastSingleImplementor(ValueNode receiver, TypeReference speculatedType) {

        ResolvedJavaType singleImplementor = speculatedType.getType();

        if (singleImplementor != null) {

            ResolvedJavaMethod singleImplementorMethod = singleImplementor.resolveConcreteMethod(targetMethod(), invoke().getContextType());

            if (singleImplementorMethod != null) {

                /**

                 * We have an invoke on an interface with a single implementor. We can replace this

                 * with an invoke virtual.

                 *

                 * To do so we need to ensure two properties: 1) the receiver must implement the

                 * interface (declaredReceiverType). The verifier does not prove this so we need a

                 * dynamic check. 2) we need to ensure that there is still only one implementor of

                 * this interface, i.e. that we are calling the right method. We could do this with

                 * an assumption but as we need an instanceof check anyway we can verify both

                 * properties by checking of the receiver is an instance of the single implementor.

                 */

                ValueAnchorNode anchor = new ValueAnchorNode(null);

                if (anchor != null) {

                    graph().add(anchor);

                    graph().addBeforeFixed(invoke().asNode(), anchor);

                }

                LogicNode condition = graph().addOrUniqueWithInputs(InstanceOfNode.create(speculatedType, receiver, getProfile(), anchor));

                FixedGuardNode guard = graph().add(new FixedGuardNode(condition, DeoptimizationReason.OptimizedTypeCheckViolated, DeoptimizationAction.InvalidateRecompile, false));

                graph().addBeforeFixed(invoke().asNode(), guard);

                ValueNode valueNode = graph().addOrUnique(new PiNode(receiver, StampFactory.objectNonNull(speculatedType), guard));

                arguments().set(0, valueNode);

                if (speculatedType.isExact()) {

                    setInvokeKind(InvokeKind.Special);

                } else {

                    setInvokeKind(InvokeKind.Virtual);

                }

                setTargetMethod(singleImplementorMethod);

                return true;

            }

        }

        return false;

    }

    public JavaTypeProfile getProfile() {

        return profile;

    }

    @Override

    public String targetName() {

        if (targetMethod() == null) {

            return "??Invalid!";

        }

        return targetMethod().format("%h.%n");

    }

    public static MethodCallTargetNode find(StructuredGraph graph, ResolvedJavaMethod method) {

        for (MethodCallTargetNode target : graph.getNodes(MethodCallTargetNode.TYPE)) {

            if (target.targetMethod().equals(method)) {

                return target;

            }

        }

        return null;

    }

}