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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
 * 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.
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package org.graalvm.compiler.phases.graph;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.nodes.AbstractBeginNode;
import org.graalvm.compiler.nodes.AbstractEndNode;
import org.graalvm.compiler.nodes.AbstractMergeNode;
import org.graalvm.compiler.nodes.EndNode;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.FixedWithNextNode;
import org.graalvm.compiler.nodes.LoopBeginNode;
import org.graalvm.compiler.nodes.LoopEndNode;
import org.graalvm.compiler.nodes.LoopExitNode;

public final class ReentrantNodeIterator {

    public static class LoopInfo<StateT> {

        public final Map<LoopEndNode, StateT> endStates;
        public final Map<LoopExitNode, StateT> exitStates;

        public LoopInfo(int endCount, int exitCount) {
            endStates = Node.newIdentityMap(endCount);
            exitStates = Node.newIdentityMap(exitCount);
        }
    }

    public abstract static class NodeIteratorClosure<StateT> {

        protected abstract StateT processNode(FixedNode node, StateT currentState);

        protected abstract StateT merge(AbstractMergeNode merge, List<StateT> states);

        protected abstract StateT afterSplit(AbstractBeginNode node, StateT oldState);

        protected abstract Map<LoopExitNode, StateT> processLoop(LoopBeginNode loop, StateT initialState);

        
Determine whether iteration should continue in the current state.
Params:
  • currentState –
/** * Determine whether iteration should continue in the current state. * * @param currentState */
protected boolean continueIteration(StateT currentState) { return true; } } private ReentrantNodeIterator() { // no instances allowed } public static <StateT> LoopInfo<StateT> processLoop(NodeIteratorClosure<StateT> closure, LoopBeginNode loop, StateT initialState) { Map<FixedNode, StateT> blockEndStates = apply(closure, loop, initialState, loop); LoopInfo<StateT> info = new LoopInfo<>(loop.loopEnds().count(), loop.loopExits().count()); for (LoopEndNode end : loop.loopEnds()) { if (blockEndStates.containsKey(end)) { info.endStates.put(end, blockEndStates.get(end)); } } for (LoopExitNode exit : loop.loopExits()) { if (blockEndStates.containsKey(exit)) { info.exitStates.put(exit, blockEndStates.get(exit)); } } return info; } public static <StateT> void apply(NodeIteratorClosure<StateT> closure, FixedNode start, StateT initialState) { apply(closure, start, initialState, null); } private static <StateT> Map<FixedNode, StateT> apply(NodeIteratorClosure<StateT> closure, FixedNode start, StateT initialState, LoopBeginNode boundary) { assert start != null; Deque<AbstractBeginNode> nodeQueue = new ArrayDeque<>(); Map<FixedNode, StateT> blockEndStates = Node.newIdentityMap(); StateT state = initialState; FixedNode current = start; do { while (current instanceof FixedWithNextNode) { if (boundary != null && current instanceof LoopExitNode && ((LoopExitNode) current).loopBegin() == boundary) { blockEndStates.put(current, state); current = null; } else { FixedNode next = ((FixedWithNextNode) current).next(); state = closure.processNode(current, state); current = closure.continueIteration(state) ? next : null; } } if (current != null) { state = closure.processNode(current, state); if (closure.continueIteration(state)) { Iterator<Node> successors = current.successors().iterator(); if (!successors.hasNext()) { if (current instanceof LoopEndNode) { blockEndStates.put(current, state); } else if (current instanceof EndNode) { // add the end node and see if the merge is ready for processing AbstractMergeNode merge = ((EndNode) current).merge(); if (merge instanceof LoopBeginNode) { Map<LoopExitNode, StateT> loopExitState = closure.processLoop((LoopBeginNode) merge, state); for (Map.Entry<LoopExitNode, StateT> entry : loopExitState.entrySet()) { blockEndStates.put(entry.getKey(), entry.getValue()); nodeQueue.add(entry.getKey()); } } else { boolean endsVisited = true; for (AbstractEndNode forwardEnd : merge.forwardEnds()) { if (forwardEnd != current && !blockEndStates.containsKey(forwardEnd)) { endsVisited = false; break; } } if (endsVisited) { ArrayList<StateT> states = new ArrayList<>(merge.forwardEndCount()); for (int i = 0; i < merge.forwardEndCount(); i++) { AbstractEndNode forwardEnd = merge.forwardEndAt(i); assert forwardEnd == current || blockEndStates.containsKey(forwardEnd); StateT other = forwardEnd == current ? state : blockEndStates.remove(forwardEnd); states.add(other); } state = closure.merge(merge, states); current = closure.continueIteration(state) ? merge : null; continue; } else { assert !blockEndStates.containsKey(current); blockEndStates.put(current, state); } } } } else { FixedNode firstSuccessor = (FixedNode) successors.next(); if (!successors.hasNext()) { current = firstSuccessor; continue; } else { do { AbstractBeginNode successor = (AbstractBeginNode) successors.next(); StateT successorState = closure.afterSplit(successor, state); if (closure.continueIteration(successorState)) { blockEndStates.put(successor, successorState); nodeQueue.add(successor); } } while (successors.hasNext()); state = closure.afterSplit((AbstractBeginNode) firstSuccessor, state); current = closure.continueIteration(state) ? firstSuccessor : null; continue; } } } } // get next queued block if (nodeQueue.isEmpty()) { return blockEndStates; } else { current = nodeQueue.removeFirst(); assert blockEndStates.containsKey(current); state = blockEndStates.remove(current); assert !(current instanceof AbstractMergeNode) && current instanceof AbstractBeginNode; } } while (true); } }