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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * 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.
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package org.graalvm.compiler.hotspot.phases;

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.meta.SpeculationLog;
import jdk.vm.ci.meta.SpeculationLog.SpeculationReason;
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));
                        SpeculationLog.Speculation constant = graph.getSpeculationLog().speculate(reason);
                        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;
        }
    }
}