/*

 * Copyright (c) 2011, 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.hotspot.phases;

import static jdk.vm.ci.meta.SpeculationLog.SpeculationReason;

import static org.graalvm.compiler.phases.common.DeadCodeEliminationPhase.Optionality.Required;

import org.graalvm.compiler.core.common.PermanentBailoutException;

import org.graalvm.compiler.core.common.cfg.Loop;

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

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

import org.graalvm.compiler.debug.CounterKey;

import org.graalvm.compiler.debug.DebugCloseable;

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.iterators.NodeIterable;

import org.graalvm.compiler.loop.LoopsData;

import org.graalvm.compiler.loop.phases.LoopTransformations;

import org.graalvm.compiler.nodeinfo.InputType;

import org.graalvm.compiler.nodeinfo.Verbosity;

import org.graalvm.compiler.nodes.AbstractBeginNode;

import org.graalvm.compiler.nodes.EntryMarkerNode;

import org.graalvm.compiler.nodes.EntryProxyNode;

import org.graalvm.compiler.nodes.FixedGuardNode;

import org.graalvm.compiler.nodes.FixedNode;

import org.graalvm.compiler.nodes.FrameState;

import org.graalvm.compiler.nodes.LogicNode;

import org.graalvm.compiler.nodes.LoopBeginNode;

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.ParameterNode;

import org.graalvm.compiler.nodes.PiNode;

import org.graalvm.compiler.nodes.StartNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.cfg.Block;

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

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

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

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

import org.graalvm.compiler.nodes.java.AccessMonitorNode;

import org.graalvm.compiler.nodes.java.InstanceOfNode;

import org.graalvm.compiler.nodes.java.MonitorEnterNode;

import org.graalvm.compiler.nodes.java.MonitorExitNode;

import org.graalvm.compiler.nodes.java.MonitorIdNode;

import org.graalvm.compiler.nodes.util.GraphUtil;

import org.graalvm.compiler.options.Option;

import org.graalvm.compiler.options.OptionKey;

import org.graalvm.compiler.options.OptionType;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.phases.Phase;

import org.graalvm.compiler.phases.common.DeadCodeEliminationPhase;

import jdk.vm.ci.meta.DeoptimizationAction;

import jdk.vm.ci.meta.DeoptimizationReason;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.runtime.JVMCICompiler;

public class OnStackReplacementPhase extends Phase {

    public static class Options {

        // @formatter:off

        @Option(help = "Deoptimize OSR compiled code when the OSR entry loop is finished " +

                       "if there is no mature profile available for the rest of the method.", type = OptionType.Debug)

        public static final OptionKey<Boolean> DeoptAfterOSR = new OptionKey<>(true);

        @Option(help = "Support OSR compilations with locks. If DeoptAfterOSR is true we can per definition not have " +

                       "unbalaced enter/extis mappings. If DeoptAfterOSR is false insert artificial monitor enters after " +

                       "the OSRStart to have balanced enter/exits in the graph.", type = OptionType.Debug)

        public static final OptionKey<Boolean> SupportOSRWithLocks = new OptionKey<>(true);

        // @formatter:on

    }

    private static final CounterKey OsrWithLocksCount = DebugContext.counter("OSRWithLocks");

    private static boolean supportOSRWithLocks(OptionValues options) {

        return Options.SupportOSRWithLocks.getValue(options);

    }

    @Override

    @SuppressWarnings("try")

    protected void run(StructuredGraph graph) {

        DebugContext debug = graph.getDebug();

        if (graph.getEntryBCI() == JVMCICompiler.INVOCATION_ENTRY_BCI) {

            // This happens during inlining in a OSR method, because the same phase plan will be

            // used.

            assert graph.getNodes(EntryMarkerNode.TYPE).isEmpty();

            return;

        }

        debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement initial at bci %d", graph.getEntryBCI());

        EntryMarkerNode osr;

        int maxIterations = -1;

        int iterations = 0;

        final EntryMarkerNode originalOSRNode = getEntryMarker(graph);

        final LoopBeginNode originalOSRLoop = osrLoop(originalOSRNode);

        final boolean currentOSRWithLocks = osrWithLocks(originalOSRNode);

        if (originalOSRLoop == null) {

            /*

             * OSR with Locks: We do not have an OSR loop for the original OSR bci. Therefore we

             * cannot decide where to deopt and which framestate will be used. In the worst case the

             * framestate of the OSR entry would be used.

             */

            throw new PermanentBailoutException("OSR compilation without OSR entry loop.");

        }

        if (!supportOSRWithLocks(graph.getOptions()) && currentOSRWithLocks) {

            throw new PermanentBailoutException("OSR with locks disabled.");

        }

        do {

            osr = getEntryMarker(graph);

            LoopsData loops = new LoopsData(graph);

            // Find the loop that contains the EntryMarker

            Loop<Block> l = loops.getCFG().getNodeToBlock().get(osr).getLoop();

            if (l == null) {

                break;

            }

            iterations++;

            if (maxIterations == -1) {

                maxIterations = l.getDepth();

            } else if (iterations > maxIterations) {

                throw GraalError.shouldNotReachHere();

            }

            // Peel the outermost loop first

            while (l.getParent() != null) {

                l = l.getParent();

            }

            LoopTransformations.peel(loops.loop(l));

            osr.replaceAtUsages(InputType.Guard, AbstractBeginNode.prevBegin((FixedNode) osr.predecessor()));

            for (Node usage : osr.usages().snapshot()) {

                EntryProxyNode proxy = (EntryProxyNode) usage;

                proxy.replaceAndDelete(proxy.value());

            }

            GraphUtil.removeFixedWithUnusedInputs(osr);

            debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement loop peeling result");

        } while (true);

        StartNode start = graph.start();

        FrameState osrState = osr.stateAfter();

        OSRStartNode osrStart;

        try (DebugCloseable context = osr.withNodeSourcePosition()) {

            osr.setStateAfter(null);

            osrStart = graph.add(new OSRStartNode());

            FixedNode next = osr.next();

            osr.setNext(null);

            osrStart.setNext(next);

            graph.setStart(osrStart);

            osrStart.setStateAfter(osrState);

            debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement after setting OSR start");

            final int localsSize = osrState.localsSize();

            final int locksSize = osrState.locksSize();

            for (int i = 0; i < localsSize + locksSize; i++) {

                ValueNode value = null;

                if (i >= localsSize) {

                    value = osrState.lockAt(i - localsSize);

                } else {

                    value = osrState.localAt(i);

                }

                if (value instanceof EntryProxyNode) {

                    EntryProxyNode proxy = (EntryProxyNode) value;

                    /*

                     * We need to drop the stamp since the types we see during OSR may be too

                     * precise (if a branch was not parsed for example). In cases when this is

                     * possible, we insert a guard and narrow the OSRLocal stamp at its usages.

                     */

                    Stamp narrowedStamp = proxy.value().stamp(NodeView.DEFAULT);

                    Stamp unrestrictedStamp = proxy.stamp(NodeView.DEFAULT).unrestricted();

                    ValueNode osrLocal;

                    if (i >= localsSize) {

                        osrLocal = graph.addOrUnique(new OSRLockNode(i - localsSize, unrestrictedStamp));

                    } else {

                        osrLocal = graph.addOrUnique(new OSRLocalNode(i, unrestrictedStamp));

                    }

                    // Speculate on the OSRLocal stamps that could be more precise.

                    OSRLocalSpeculationReason reason = new OSRLocalSpeculationReason(osrState.bci, narrowedStamp, i);

                    if (graph.getSpeculationLog().maySpeculate(reason) && osrLocal instanceof OSRLocalNode && value.getStackKind().equals(JavaKind.Object) && !narrowedStamp.isUnrestricted()) {

                        // Add guard.

                        LogicNode check = graph.addOrUniqueWithInputs(InstanceOfNode.createHelper((ObjectStamp) narrowedStamp, osrLocal, null, null));

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

                        graph.addAfterFixed(osrStart, guard);

                        // Replace with a more specific type at usages.

                        // We know that we are at the root,

                        // so we need to replace the proxy in the state.

                        proxy.replaceAtMatchingUsages(osrLocal, n -> n == osrState);

                        osrLocal = graph.addOrUnique(new PiNode(osrLocal, narrowedStamp, guard));

                    }

                    proxy.replaceAndDelete(osrLocal);

                } else {

                    assert value == null || value instanceof OSRLocalNode;

                }

            }

            osr.replaceAtUsages(InputType.Guard, osrStart);

        }

        debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement after replacing entry proxies");

        GraphUtil.killCFG(start);

        debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement result");

        new DeadCodeEliminationPhase(Required).apply(graph);

        if (currentOSRWithLocks) {

            OsrWithLocksCount.increment(debug);

            try (DebugCloseable context = osrStart.withNodeSourcePosition()) {

                for (int i = osrState.monitorIdCount() - 1; i >= 0; --i) {

                    MonitorIdNode id = osrState.monitorIdAt(i);

                    ValueNode lockedObject = osrState.lockAt(i);

                    OSRMonitorEnterNode osrMonitorEnter = graph.add(new OSRMonitorEnterNode(lockedObject, id));

                    for (Node usage : id.usages()) {

                        if (usage instanceof AccessMonitorNode) {

                            AccessMonitorNode access = (AccessMonitorNode) usage;

                            access.setObject(lockedObject);

                        }

                    }

                    FixedNode oldNext = osrStart.next();

                    oldNext.replaceAtPredecessor(null);

                    osrMonitorEnter.setNext(oldNext);

                    osrStart.setNext(osrMonitorEnter);

                }

            }

            debug.dump(DebugContext.DETAILED_LEVEL, graph, "After inserting OSR monitor enters");

            /*

             * Ensure balanced monitorenter - monitorexit

             *

             * Ensure that there is no monitor exit without a monitor enter in the graph. If there

             * is one this can only be done by bytecode as we have the monitor enter before the OSR

             * loop but the exit in a path of the loop that must be under a condition, else it will

             * throw an IllegalStateException anyway in the 2.iteration

             */

            for (MonitorExitNode exit : graph.getNodes(MonitorExitNode.TYPE)) {

                MonitorIdNode id = exit.getMonitorId();

                if (id.usages().filter(MonitorEnterNode.class).count() != 1) {

                    throw new PermanentBailoutException("Unbalanced monitor enter-exit in OSR compilation with locks. Object is locked before the loop but released inside the loop.");

                }

            }

        }

        debug.dump(DebugContext.DETAILED_LEVEL, graph, "OnStackReplacement result");

        new DeadCodeEliminationPhase(Required).apply(graph);

        /*

         * There must not be any parameter nodes left after OSR compilation.

         */

        assert graph.getNodes(ParameterNode.TYPE).count() == 0 : "OSR Compilation contains references to parameters.";

    }

    private static EntryMarkerNode getEntryMarker(StructuredGraph graph) {

        NodeIterable<EntryMarkerNode> osrNodes = graph.getNodes(EntryMarkerNode.TYPE);

        EntryMarkerNode osr = osrNodes.first();

        if (osr == null) {

            throw new PermanentBailoutException("No OnStackReplacementNode generated");

        }

        if (osrNodes.count() > 1) {

            throw new GraalError("Multiple OnStackReplacementNodes generated");

        }

        if (osr.stateAfter().stackSize() != 0) {

            throw new PermanentBailoutException("OSR with stack entries not supported: %s", osr.stateAfter().toString(Verbosity.Debugger));

        }

        return osr;

    }

    private static LoopBeginNode osrLoop(EntryMarkerNode osr) {

        // Check that there is an OSR loop for the OSR begin

        LoopsData loops = new LoopsData(osr.graph());

        Loop<Block> l = loops.getCFG().getNodeToBlock().get(osr).getLoop();

        if (l == null) {

            return null;

        }

        return (LoopBeginNode) l.getHeader().getBeginNode();

    }

    private static boolean osrWithLocks(EntryMarkerNode osr) {

        return osr.stateAfter().locksSize() != 0;

    }

    @Override

    public float codeSizeIncrease() {

        return 5.0f;

    }

    private static class OSRLocalSpeculationReason implements SpeculationReason {

        private int bci;

        private Stamp speculatedStamp;

        private int localIndex;

        OSRLocalSpeculationReason(int bci, Stamp speculatedStamp, int localIndex) {

            this.bci = bci;

            this.speculatedStamp = speculatedStamp;

            this.localIndex = localIndex;

        }

        @Override

        public boolean equals(Object obj) {

            if (obj instanceof OSRLocalSpeculationReason) {

                OSRLocalSpeculationReason that = (OSRLocalSpeculationReason) obj;

                return this.bci == that.bci && this.speculatedStamp.equals(that.speculatedStamp) && this.localIndex == that.localIndex;

            }

            return false;

        }

        @Override

        public int hashCode() {

            return (bci << 16) ^ speculatedStamp.hashCode() ^ localIndex;

        }

    }

}