hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.phases.common/src/org/graalvm/compiler/phases/common/NewConditionalEliminationPhase.java
changeset 46459 7d4e637d3f21
parent 46458 3c12af929e7d
child 46460 d25a320cd821
--- a/hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.phases.common/src/org/graalvm/compiler/phases/common/NewConditionalEliminationPhase.java	Fri May 12 13:14:25 2017 -0700
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1035 +0,0 @@
-/*
- * Copyright (c) 2015, 2017, 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.phases.common;
-
-import java.util.ArrayDeque;
-import java.util.Deque;
-import java.util.List;
-
-import org.graalvm.compiler.core.common.cfg.BlockMap;
-import org.graalvm.compiler.core.common.type.ArithmeticOpTable;
-import org.graalvm.compiler.core.common.type.ArithmeticOpTable.BinaryOp;
-import org.graalvm.compiler.core.common.type.ArithmeticOpTable.BinaryOp.And;
-import org.graalvm.compiler.core.common.type.ArithmeticOpTable.BinaryOp.Or;
-import org.graalvm.compiler.core.common.type.IntegerStamp;
-import org.graalvm.compiler.core.common.type.ObjectStamp;
-import org.graalvm.compiler.core.common.type.Stamp;
-import org.graalvm.compiler.core.common.type.StampFactory;
-import org.graalvm.compiler.debug.Debug;
-import org.graalvm.compiler.debug.DebugCloseable;
-import org.graalvm.compiler.debug.DebugCounter;
-import org.graalvm.compiler.graph.Node;
-import org.graalvm.compiler.graph.NodeMap;
-import org.graalvm.compiler.graph.NodeStack;
-import org.graalvm.compiler.graph.spi.CanonicalizerTool;
-import org.graalvm.compiler.nodeinfo.InputType;
-import org.graalvm.compiler.nodes.AbstractBeginNode;
-import org.graalvm.compiler.nodes.AbstractMergeNode;
-import org.graalvm.compiler.nodes.BinaryOpLogicNode;
-import org.graalvm.compiler.nodes.ConditionAnchorNode;
-import org.graalvm.compiler.nodes.DeoptimizeNode;
-import org.graalvm.compiler.nodes.DeoptimizingGuard;
-import org.graalvm.compiler.nodes.EndNode;
-import org.graalvm.compiler.nodes.FixedGuardNode;
-import org.graalvm.compiler.nodes.FixedNode;
-import org.graalvm.compiler.nodes.FixedWithNextNode;
-import org.graalvm.compiler.nodes.GuardNode;
-import org.graalvm.compiler.nodes.IfNode;
-import org.graalvm.compiler.nodes.LogicNode;
-import org.graalvm.compiler.nodes.LoopExitNode;
-import org.graalvm.compiler.nodes.MergeNode;
-import org.graalvm.compiler.nodes.ParameterNode;
-import org.graalvm.compiler.nodes.PiNode;
-import org.graalvm.compiler.nodes.ProxyNode;
-import org.graalvm.compiler.nodes.ShortCircuitOrNode;
-import org.graalvm.compiler.nodes.StructuredGraph;
-import org.graalvm.compiler.nodes.UnaryOpLogicNode;
-import org.graalvm.compiler.nodes.ValueNode;
-import org.graalvm.compiler.nodes.ValuePhiNode;
-import org.graalvm.compiler.nodes.calc.AndNode;
-import org.graalvm.compiler.nodes.calc.BinaryArithmeticNode;
-import org.graalvm.compiler.nodes.calc.BinaryNode;
-import org.graalvm.compiler.nodes.calc.IntegerEqualsNode;
-import org.graalvm.compiler.nodes.calc.UnaryNode;
-import org.graalvm.compiler.nodes.cfg.Block;
-import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
-import org.graalvm.compiler.nodes.extended.GuardingNode;
-import org.graalvm.compiler.nodes.extended.IntegerSwitchNode;
-import org.graalvm.compiler.nodes.extended.LoadHubNode;
-import org.graalvm.compiler.nodes.extended.ValueAnchorNode;
-import org.graalvm.compiler.nodes.java.TypeSwitchNode;
-import org.graalvm.compiler.nodes.spi.NodeWithState;
-import org.graalvm.compiler.nodes.spi.StampInverter;
-import org.graalvm.compiler.nodes.util.GraphUtil;
-import org.graalvm.compiler.phases.BasePhase;
-import org.graalvm.compiler.phases.schedule.SchedulePhase;
-import org.graalvm.compiler.phases.tiers.PhaseContext;
-import org.graalvm.util.EconomicMap;
-import org.graalvm.util.Equivalence;
-import org.graalvm.util.MapCursor;
-import org.graalvm.util.Pair;
-
-import jdk.vm.ci.meta.JavaConstant;
-import jdk.vm.ci.meta.TriState;
-
-public class NewConditionalEliminationPhase extends BasePhase<PhaseContext> {
-
-    private static final DebugCounter counterStampsRegistered = Debug.counter("StampsRegistered");
-    private static final DebugCounter counterStampsFound = Debug.counter("StampsFound");
-    private static final DebugCounter counterIfsKilled = Debug.counter("CE_KilledIfs");
-    private static final DebugCounter counterPhiStampsImproved = Debug.counter("CE_ImprovedPhis");
-    private final boolean fullSchedule;
-
-    public NewConditionalEliminationPhase(boolean fullSchedule) {
-        this.fullSchedule = fullSchedule;
-    }
-
-    @Override
-    @SuppressWarnings("try")
-    protected void run(StructuredGraph graph, PhaseContext context) {
-        try (Debug.Scope s = Debug.scope("DominatorConditionalElimination")) {
-            BlockMap<List<Node>> blockToNodes = null;
-            ControlFlowGraph cfg = ControlFlowGraph.compute(graph, true, true, true, true);
-            if (fullSchedule) {
-                cfg.visitDominatorTree(new MoveGuardsUpwards(), graph.hasValueProxies());
-                SchedulePhase.run(graph, SchedulePhase.SchedulingStrategy.EARLIEST, cfg);
-                blockToNodes = graph.getLastSchedule().getBlockToNodesMap();
-            }
-
-            Instance visitor = new Instance(graph, blockToNodes, context);
-            cfg.visitDominatorTree(visitor, graph.hasValueProxies());
-        }
-    }
-
-    public static class MoveGuardsUpwards implements ControlFlowGraph.RecursiveVisitor<Block> {
-
-        Block anchorBlock;
-
-        @Override
-        @SuppressWarnings("try")
-        public Block enter(Block b) {
-            Block oldAnchorBlock = anchorBlock;
-            if (b.getDominator() == null || b.getDominator().getPostdominator() != b) {
-                // New anchor.
-                anchorBlock = b;
-            }
-
-            AbstractBeginNode beginNode = b.getBeginNode();
-            if (beginNode instanceof AbstractMergeNode && anchorBlock != b) {
-                AbstractMergeNode mergeNode = (AbstractMergeNode) beginNode;
-                for (GuardNode guard : mergeNode.guards().snapshot()) {
-                    try (DebugCloseable closeable = guard.withNodeSourcePosition()) {
-                        GuardNode newlyCreatedGuard = new GuardNode(guard.getCondition(), anchorBlock.getBeginNode(), guard.getReason(), guard.getAction(), guard.isNegated(), guard.getSpeculation());
-                        GuardNode newGuard = mergeNode.graph().unique(newlyCreatedGuard);
-                        guard.replaceAndDelete(newGuard);
-                    }
-                }
-            }
-
-            FixedNode endNode = b.getEndNode();
-            if (endNode instanceof IfNode) {
-                IfNode node = (IfNode) endNode;
-
-                // Check if we can move guards upwards.
-                AbstractBeginNode trueSuccessor = node.trueSuccessor();
-                EconomicMap<LogicNode, GuardNode> trueGuards = EconomicMap.create(Equivalence.IDENTITY);
-                for (GuardNode guard : trueSuccessor.guards()) {
-                    LogicNode condition = guard.getCondition();
-                    if (condition.hasMoreThanOneUsage()) {
-                        trueGuards.put(condition, guard);
-                    }
-                }
-
-                if (!trueGuards.isEmpty()) {
-                    for (GuardNode guard : node.falseSuccessor().guards().snapshot()) {
-                        GuardNode otherGuard = trueGuards.get(guard.getCondition());
-                        if (otherGuard != null && guard.isNegated() == otherGuard.isNegated()) {
-                            JavaConstant speculation = otherGuard.getSpeculation();
-                            if (speculation == null) {
-                                speculation = guard.getSpeculation();
-                            } else if (guard.getSpeculation() != null && guard.getSpeculation() != speculation) {
-                                // Cannot optimize due to different speculations.
-                                continue;
-                            }
-                            try (DebugCloseable closeable = guard.withNodeSourcePosition()) {
-                                GuardNode newlyCreatedGuard = new GuardNode(guard.getCondition(), anchorBlock.getBeginNode(), guard.getReason(), guard.getAction(), guard.isNegated(), speculation);
-                                GuardNode newGuard = node.graph().unique(newlyCreatedGuard);
-                                if (otherGuard.isAlive()) {
-                                    otherGuard.replaceAndDelete(newGuard);
-                                }
-                                guard.replaceAndDelete(newGuard);
-                            }
-                        }
-                    }
-                }
-            }
-            return oldAnchorBlock;
-        }
-
-        @Override
-        public void exit(Block b, Block value) {
-            anchorBlock = value;
-        }
-
-    }
-
-    private static final class PhiInfoElement {
-
-        private EconomicMap<EndNode, InfoElement> infoElements;
-
-        public void set(EndNode end, InfoElement infoElement) {
-            if (infoElements == null) {
-                infoElements = EconomicMap.create(Equivalence.IDENTITY);
-            }
-            infoElements.put(end, infoElement);
-        }
-
-        public InfoElement get(EndNode end) {
-            if (infoElements == null) {
-                return null;
-            }
-            return infoElements.get(end);
-        }
-    }
-
-    public static class Instance implements ControlFlowGraph.RecursiveVisitor<Integer> {
-        protected final NodeMap<InfoElement> map;
-        protected final BlockMap<List<Node>> blockToNodes;
-        protected final CanonicalizerTool tool;
-        protected final NodeStack undoOperations;
-        protected final StructuredGraph graph;
-        protected final EconomicMap<MergeNode, EconomicMap<ValuePhiNode, PhiInfoElement>> mergeMaps;
-
-        /**
-         * Tests which may be eliminated because post dominating tests to prove a broader condition.
-         */
-        private Deque<PendingTest> pendingTests;
-
-        public Instance(StructuredGraph graph, BlockMap<List<Node>> blockToNodes, PhaseContext context) {
-            this.graph = graph;
-            this.blockToNodes = blockToNodes;
-            this.undoOperations = new NodeStack();
-            this.map = graph.createNodeMap();
-            pendingTests = new ArrayDeque<>();
-            tool = GraphUtil.getDefaultSimplifier(context.getMetaAccess(), context.getConstantReflection(), context.getConstantFieldProvider(), false, graph.getAssumptions(), graph.getOptions(),
-                            context.getLowerer());
-            mergeMaps = EconomicMap.create();
-        }
-
-        protected void processConditionAnchor(ConditionAnchorNode node) {
-            tryProveCondition(node.condition(), (guard, result, guardedValueStamp, newInput) -> {
-                if (result != node.isNegated()) {
-                    node.replaceAtUsages(guard.asNode());
-                    GraphUtil.unlinkFixedNode(node);
-                    GraphUtil.killWithUnusedFloatingInputs(node);
-                } else {
-                    ValueAnchorNode valueAnchor = node.graph().add(new ValueAnchorNode(null));
-                    node.replaceAtUsages(valueAnchor);
-                    node.graph().replaceFixedWithFixed(node, valueAnchor);
-                }
-                return true;
-            });
-        }
-
-        protected void processGuard(GuardNode node) {
-            if (!tryProveGuardCondition(node, node.getCondition(), (guard, result, guardedValueStamp, newInput) -> {
-                if (result != node.isNegated()) {
-                    node.replaceAndDelete(guard.asNode());
-                } else {
-                    DeoptimizeNode deopt = node.graph().add(new DeoptimizeNode(node.getAction(), node.getReason(), node.getSpeculation()));
-                    AbstractBeginNode beginNode = (AbstractBeginNode) node.getAnchor();
-                    FixedNode next = beginNode.next();
-                    beginNode.setNext(deopt);
-                    GraphUtil.killCFG(next);
-                }
-                return true;
-            })) {
-                registerNewCondition(node.getCondition(), node.isNegated(), node);
-            }
-        }
-
-        protected void processFixedGuard(FixedGuardNode node) {
-            if (!tryProveGuardCondition(node, node.condition(), (guard, result, guardedValueStamp, newInput) -> {
-                if (result != node.isNegated()) {
-                    node.replaceAtUsages(guard.asNode());
-                    GraphUtil.unlinkFixedNode(node);
-                    GraphUtil.killWithUnusedFloatingInputs(node);
-                } else {
-                    DeoptimizeNode deopt = node.graph().add(new DeoptimizeNode(node.getAction(), node.getReason(), node.getSpeculation()));
-                    deopt.setStateBefore(node.stateBefore());
-                    node.replaceAtPredecessor(deopt);
-                    GraphUtil.killCFG(node);
-                }
-                Debug.log("Kill fixed guard guard");
-                return true;
-            })) {
-                registerNewCondition(node.condition(), node.isNegated(), node);
-            }
-        }
-
-        protected void processIf(IfNode node) {
-            tryProveCondition(node.condition(), (guard, result, guardedValueStamp, newInput) -> {
-                AbstractBeginNode survivingSuccessor = node.getSuccessor(result);
-                survivingSuccessor.replaceAtUsages(InputType.Guard, guard.asNode());
-                survivingSuccessor.replaceAtPredecessor(null);
-                node.replaceAtPredecessor(survivingSuccessor);
-                GraphUtil.killCFG(node);
-                counterIfsKilled.increment();
-                return true;
-            });
-        }
-
-        @Override
-        public Integer enter(Block block) {
-            int mark = undoOperations.size();
-            Debug.log("[Pre Processing block %s]", block);
-            // For now conservatively collect guards only within the same block.
-            pendingTests.clear();
-            if (blockToNodes != null) {
-                for (Node n : blockToNodes.get(block)) {
-                    if (n.isAlive()) {
-                        processNode(n);
-                    }
-                }
-            } else {
-                processBlock(block);
-            }
-            return mark;
-        }
-
-        private void processBlock(Block block) {
-            FixedNode n = block.getBeginNode();
-            FixedNode endNode = block.getEndNode();
-            Debug.log("[Processing block %s]", block);
-            while (n != endNode) {
-                if (n.isDeleted() || endNode.isDeleted()) {
-                    // This branch was deleted!
-                    return;
-                }
-                FixedNode next = ((FixedWithNextNode) n).next();
-                processNode(n);
-                n = next;
-            }
-            if (endNode.isAlive()) {
-                processNode(endNode);
-            }
-        }
-
-        @SuppressWarnings("try")
-        protected void processNode(Node node) {
-            try (DebugCloseable closeable = node.withNodeSourcePosition()) {
-                if (node instanceof NodeWithState && !(node instanceof GuardingNode)) {
-                    pendingTests.clear();
-                }
-
-                if (node instanceof MergeNode) {
-                    introducePisForPhis((MergeNode) node);
-                }
-
-                if (node instanceof AbstractBeginNode) {
-                    if (node instanceof LoopExitNode && graph.hasValueProxies()) {
-                        // Condition must not be used down this path.
-                        return;
-                    }
-                    processAbstractBegin((AbstractBeginNode) node);
-                } else if (node instanceof FixedGuardNode) {
-                    processFixedGuard((FixedGuardNode) node);
-                } else if (node instanceof GuardNode) {
-                    processGuard((GuardNode) node);
-                } else if (node instanceof ConditionAnchorNode) {
-                    processConditionAnchor((ConditionAnchorNode) node);
-                } else if (node instanceof IfNode) {
-                    processIf((IfNode) node);
-                } else if (node instanceof EndNode) {
-                    processEnd((EndNode) node);
-                }
-            }
-        }
-
-        private void introducePisForPhis(MergeNode merge) {
-            EconomicMap<ValuePhiNode, PhiInfoElement> mergeMap = this.mergeMaps.get(merge);
-            if (mergeMap != null) {
-                MapCursor<ValuePhiNode, PhiInfoElement> entries = mergeMap.getEntries();
-                while (entries.advance()) {
-                    ValuePhiNode phi = entries.getKey();
-                    PhiInfoElement phiInfoElements = entries.getValue();
-                    Stamp bestPossibleStamp = null;
-                    for (int i = 0; i < phi.valueCount(); ++i) {
-                        ValueNode valueAt = phi.valueAt(i);
-                        Stamp curBestStamp = valueAt.stamp();
-                        InfoElement infoElement = phiInfoElements.get(merge.forwardEndAt(i));
-                        if (infoElement != null) {
-                            curBestStamp = curBestStamp.join(infoElement.getStamp());
-                        }
-
-                        if (bestPossibleStamp == null) {
-                            bestPossibleStamp = curBestStamp;
-                        } else {
-                            bestPossibleStamp = bestPossibleStamp.meet(curBestStamp);
-                        }
-                    }
-
-                    Stamp oldStamp = phi.stamp();
-                    if (oldStamp.tryImproveWith(bestPossibleStamp) != null) {
-
-                        // Need to be careful to not run into stamp update cycles with the iterative
-                        // canonicalization.
-                        boolean allow = false;
-                        if (bestPossibleStamp instanceof ObjectStamp) {
-                            // Always allow object stamps.
-                            allow = true;
-                        } else if (bestPossibleStamp instanceof IntegerStamp) {
-                            IntegerStamp integerStamp = (IntegerStamp) bestPossibleStamp;
-                            IntegerStamp oldIntegerStamp = (IntegerStamp) oldStamp;
-                            if (integerStamp.isPositive() != oldIntegerStamp.isPositive()) {
-                                allow = true;
-                            } else if (integerStamp.isNegative() != oldIntegerStamp.isNegative()) {
-                                allow = true;
-                            } else if (integerStamp.isStrictlyPositive() != oldIntegerStamp.isStrictlyPositive()) {
-                                allow = true;
-                            } else if (integerStamp.isStrictlyNegative() != oldIntegerStamp.isStrictlyNegative()) {
-                                allow = true;
-                            } else if (integerStamp.asConstant() != null) {
-                                allow = true;
-                            } else if (oldStamp.isUnrestricted()) {
-                                allow = true;
-                            }
-                        } else {
-                            allow = (bestPossibleStamp.asConstant() != null);
-                        }
-
-                        if (allow) {
-                            ValuePhiNode newPhi = graph.addWithoutUnique(new ValuePhiNode(bestPossibleStamp, merge));
-                            for (int i = 0; i < phi.valueCount(); ++i) {
-                                ValueNode valueAt = phi.valueAt(i);
-                                if (bestPossibleStamp.meet(valueAt.stamp()).equals(bestPossibleStamp)) {
-                                    // Pi not required here.
-                                } else {
-                                    InfoElement infoElement = phiInfoElements.get(merge.forwardEndAt(i));
-                                    assert infoElement != null;
-                                    Stamp curBestStamp = infoElement.getStamp();
-                                    ValueNode input = infoElement.getProxifiedInput();
-                                    if (input == null) {
-                                        input = valueAt;
-                                    }
-                                    ValueNode valueNode = graph.maybeAddOrUnique(PiNode.create(input, curBestStamp, (ValueNode) infoElement.guard));
-                                    valueAt = valueNode;
-                                }
-                                newPhi.addInput(valueAt);
-                            }
-                            counterPhiStampsImproved.increment();
-                            phi.replaceAtUsagesAndDelete(newPhi);
-                        }
-                    }
-                }
-            }
-        }
-
-        private void processEnd(EndNode end) {
-            AbstractMergeNode abstractMerge = end.merge();
-            if (abstractMerge instanceof MergeNode) {
-                MergeNode merge = (MergeNode) abstractMerge;
-
-                EconomicMap<ValuePhiNode, PhiInfoElement> mergeMap = this.mergeMaps.get(merge);
-                for (ValuePhiNode phi : merge.valuePhis()) {
-                    ValueNode valueAt = phi.valueAt(end);
-                    InfoElement infoElement = this.getInfoElements(valueAt);
-                    while (infoElement != null) {
-                        Stamp newStamp = infoElement.getStamp();
-                        if (phi.stamp().tryImproveWith(newStamp) != null) {
-                            if (mergeMap == null) {
-                                mergeMap = EconomicMap.create();
-                                mergeMaps.put(merge, mergeMap);
-                            }
-
-                            PhiInfoElement phiInfoElement = mergeMap.get(phi);
-                            if (phiInfoElement == null) {
-                                phiInfoElement = new PhiInfoElement();
-                                mergeMap.put(phi, phiInfoElement);
-                            }
-
-                            phiInfoElement.set(end, infoElement);
-                            break;
-                        }
-                        infoElement = nextElement(infoElement);
-                    }
-                }
-            }
-        }
-
-        protected void registerNewCondition(LogicNode condition, boolean negated, GuardingNode guard) {
-            if (condition instanceof UnaryOpLogicNode) {
-                UnaryOpLogicNode unaryLogicNode = (UnaryOpLogicNode) condition;
-                ValueNode value = unaryLogicNode.getValue();
-                if (maybeMultipleUsages(value)) {
-                    Stamp newStamp = unaryLogicNode.getSucceedingStampForValue(negated);
-                    registerNewStamp(value, newStamp, guard);
-                }
-            } else if (condition instanceof BinaryOpLogicNode) {
-                BinaryOpLogicNode binaryOpLogicNode = (BinaryOpLogicNode) condition;
-                ValueNode x = binaryOpLogicNode.getX();
-                ValueNode y = binaryOpLogicNode.getY();
-                if (!x.isConstant() && maybeMultipleUsages(x)) {
-                    Stamp newStampX = binaryOpLogicNode.getSucceedingStampForX(negated, getSafeStamp(x), getOtherSafeStamp(y));
-                    registerNewStamp(x, newStampX, guard);
-                }
-
-                if (!y.isConstant() && maybeMultipleUsages(y)) {
-                    Stamp newStampY = binaryOpLogicNode.getSucceedingStampForY(negated, getOtherSafeStamp(x), getSafeStamp(y));
-                    registerNewStamp(y, newStampY, guard);
-                }
-
-                if (condition instanceof IntegerEqualsNode && guard instanceof DeoptimizingGuard && !negated) {
-                    if (y.isConstant() && x instanceof AndNode) {
-                        AndNode and = (AndNode) x;
-                        ValueNode andX = and.getX();
-                        if (and.getY() == y && maybeMultipleUsages(andX)) {
-                            /*
-                             * This 'and' proves something about some of the bits in and.getX().
-                             * It's equivalent to or'ing in the mask value since those values are
-                             * known to be set.
-                             */
-                            BinaryOp<Or> op = ArithmeticOpTable.forStamp(x.stamp()).getOr();
-                            IntegerStamp newStampX = (IntegerStamp) op.foldStamp(getSafeStamp(andX), getOtherSafeStamp(y));
-                            registerNewStamp(andX, newStampX, guard);
-                        }
-                    }
-                }
-            }
-            if (guard instanceof DeoptimizingGuard) {
-                pendingTests.push(new PendingTest(condition, (DeoptimizingGuard) guard));
-            }
-            registerCondition(condition, negated, guard);
-        }
-
-        Pair<InfoElement, Stamp> recursiveFoldStamp(Node node) {
-            if (node instanceof UnaryNode) {
-                UnaryNode unary = (UnaryNode) node;
-                ValueNode value = unary.getValue();
-                InfoElement infoElement = getInfoElements(value);
-                while (infoElement != null) {
-                    Stamp result = unary.foldStamp(infoElement.getStamp());
-                    if (result != null) {
-                        return Pair.create(infoElement, result);
-                    }
-                    infoElement = nextElement(infoElement);
-                }
-            } else if (node instanceof BinaryNode) {
-                BinaryNode binary = (BinaryNode) node;
-                ValueNode y = binary.getY();
-                ValueNode x = binary.getX();
-                if (y.isConstant()) {
-                    InfoElement infoElement = getInfoElements(x);
-                    while (infoElement != null) {
-                        Stamp result = binary.foldStamp(infoElement.stamp, y.stamp());
-                        if (result != null) {
-                            return Pair.create(infoElement, result);
-                        }
-                        infoElement = nextElement(infoElement);
-                    }
-                }
-            }
-            return null;
-        }
-
-        /**
-         * Get the stamp that may be used for the value for which we are registering the condition.
-         * We may directly use the stamp here without restriction, because any later lookup of the
-         * registered info elements is in the same chain of pi nodes.
-         */
-        private static Stamp getSafeStamp(ValueNode x) {
-            return x.stamp();
-        }
-
-        /**
-         * We can only use the stamp of a second value involved in the condition if we are sure that
-         * we are not implicitly creating a dependency on a pi node that is responsible for that
-         * stamp. For now, we are conservatively only using the stamps of constants. Under certain
-         * circumstances, we may also be able to use the stamp of the value after skipping pi nodes
-         * (e.g., the stamp of a parameter after inlining, or the stamp of a fixed node that can
-         * never be replaced with a pi node via canonicalization).
-         */
-        private static Stamp getOtherSafeStamp(ValueNode x) {
-            if (x.isConstant()) {
-                return x.stamp();
-            }
-            return x.stamp().unrestricted();
-        }
-
-        /**
-         * Recursively try to fold stamps within this expression using information from
-         * {@link #getInfoElements(ValueNode)}. It's only safe to use constants and one
-         * {@link InfoElement} otherwise more than one guard would be required.
-         *
-         * @param node
-         * @return the pair of the @{link InfoElement} used and the stamp produced for the whole
-         *         expression
-         */
-        Pair<InfoElement, Stamp> recursiveFoldStampFromInfo(Node node) {
-            return recursiveFoldStamp(node);
-        }
-
-        protected boolean foldPendingTest(DeoptimizingGuard thisGuard, ValueNode original, Stamp newStamp, GuardRewirer rewireGuardFunction) {
-            for (PendingTest pending : pendingTests) {
-                TriState result = TriState.UNKNOWN;
-                if (pending.condition instanceof UnaryOpLogicNode) {
-                    UnaryOpLogicNode unaryLogicNode = (UnaryOpLogicNode) pending.condition;
-                    if (unaryLogicNode.getValue() == original) {
-                        result = unaryLogicNode.tryFold(newStamp);
-                    }
-                } else if (pending.condition instanceof BinaryOpLogicNode) {
-                    BinaryOpLogicNode binaryOpLogicNode = (BinaryOpLogicNode) pending.condition;
-                    ValueNode x = binaryOpLogicNode.getX();
-                    ValueNode y = binaryOpLogicNode.getY();
-                    if (x == original) {
-                        result = binaryOpLogicNode.tryFold(newStamp, getOtherSafeStamp(y));
-                    } else if (y == original) {
-                        result = binaryOpLogicNode.tryFold(getOtherSafeStamp(x), newStamp);
-                    } else if (binaryOpLogicNode instanceof IntegerEqualsNode && y.isConstant() && x instanceof AndNode) {
-                        AndNode and = (AndNode) x;
-                        if (and.getY() == y && and.getX() == original) {
-                            BinaryOp<And> andOp = ArithmeticOpTable.forStamp(newStamp).getAnd();
-                            result = binaryOpLogicNode.tryFold(andOp.foldStamp(newStamp, getOtherSafeStamp(y)), getOtherSafeStamp(y));
-                        }
-                    }
-                }
-                if (result.isKnown()) {
-                    /*
-                     * The test case be folded using the information available but the test can only
-                     * be moved up if we're sure there's no schedule dependence. For now limit it to
-                     * the original node and constants.
-                     */
-                    InputFilter v = new InputFilter(original);
-                    thisGuard.getCondition().applyInputs(v);
-                    if (v.ok && foldGuard(thisGuard, pending.guard, newStamp, rewireGuardFunction)) {
-                        return true;
-                    }
-                }
-            }
-            return false;
-        }
-
-        protected boolean foldGuard(DeoptimizingGuard thisGuard, DeoptimizingGuard otherGuard, Stamp guardedValueStamp, GuardRewirer rewireGuardFunction) {
-            if (otherGuard.getAction() == thisGuard.getAction() && otherGuard.getSpeculation() == thisGuard.getSpeculation()) {
-                LogicNode condition = (LogicNode) thisGuard.getCondition().copyWithInputs();
-                GuardRewirer rewirer = (guard, result, innerGuardedValueStamp, newInput) -> {
-                    if (rewireGuardFunction.rewire(guard, result, innerGuardedValueStamp, newInput)) {
-                        otherGuard.setCondition(condition, thisGuard.isNegated());
-                        return true;
-                    }
-                    condition.safeDelete();
-                    return false;
-                };
-                // Move the later test up
-                return rewireGuards(otherGuard, !thisGuard.isNegated(), null, guardedValueStamp, rewirer);
-            }
-            return false;
-        }
-
-        protected void registerCondition(LogicNode condition, boolean negated, GuardingNode guard) {
-            if (condition.getUsageCount() > 1) {
-                registerNewStamp(condition, negated ? StampFactory.contradiction() : StampFactory.tautology(), guard);
-            }
-        }
-
-        protected InfoElement getInfoElements(ValueNode proxiedValue) {
-            ValueNode value = GraphUtil.skipPi(proxiedValue);
-            if (value == null) {
-                return null;
-            }
-            return map.getAndGrow(value);
-        }
-
-        protected boolean rewireGuards(GuardingNode guard, boolean result, ValueNode proxifiedInput, Stamp guardedValueStamp, GuardRewirer rewireGuardFunction) {
-            counterStampsFound.increment();
-            return rewireGuardFunction.rewire(guard, result, guardedValueStamp, proxifiedInput);
-        }
-
-        protected boolean tryProveCondition(LogicNode node, GuardRewirer rewireGuardFunction) {
-            return tryProveGuardCondition(null, node, rewireGuardFunction);
-        }
-
-        private InfoElement nextElement(InfoElement current) {
-            InfoElement parent = current.getParent();
-            if (parent != null) {
-                return parent;
-            } else {
-                ValueNode proxifiedInput = current.getProxifiedInput();
-                if (proxifiedInput instanceof PiNode) {
-                    PiNode piNode = (PiNode) proxifiedInput;
-                    return getInfoElements(piNode.getOriginalNode());
-                }
-            }
-            return null;
-        }
-
-        protected boolean tryProveGuardCondition(DeoptimizingGuard thisGuard, LogicNode node, GuardRewirer rewireGuardFunction) {
-            InfoElement infoElement = getInfoElements(node);
-            if (infoElement != null) {
-                assert infoElement.getStamp() == StampFactory.tautology() || infoElement.getStamp() == StampFactory.contradiction();
-                // No proxified input and stamp required.
-                return rewireGuards(infoElement.getGuard(), infoElement.getStamp() == StampFactory.tautology(), null, null, rewireGuardFunction);
-            }
-            if (node instanceof UnaryOpLogicNode) {
-                UnaryOpLogicNode unaryLogicNode = (UnaryOpLogicNode) node;
-                ValueNode value = unaryLogicNode.getValue();
-                infoElement = getInfoElements(value);
-                while (infoElement != null) {
-                    Stamp stamp = infoElement.getStamp();
-                    TriState result = unaryLogicNode.tryFold(stamp);
-                    if (result.isKnown()) {
-                        return rewireGuards(infoElement.getGuard(), result.toBoolean(), infoElement.getProxifiedInput(), infoElement.getStamp(), rewireGuardFunction);
-                    }
-                    infoElement = nextElement(infoElement);
-                }
-                Pair<InfoElement, Stamp> foldResult = recursiveFoldStampFromInfo(value);
-                if (foldResult != null) {
-                    TriState result = unaryLogicNode.tryFold(foldResult.getRight());
-                    if (result.isKnown()) {
-                        return rewireGuards(foldResult.getLeft().getGuard(), result.toBoolean(), foldResult.getLeft().getProxifiedInput(), foldResult.getRight(), rewireGuardFunction);
-                    }
-                }
-                if (thisGuard != null) {
-                    Stamp newStamp = unaryLogicNode.getSucceedingStampForValue(thisGuard.isNegated());
-                    if (newStamp != null && foldPendingTest(thisGuard, value, newStamp, rewireGuardFunction)) {
-                        return true;
-                    }
-
-                }
-            } else if (node instanceof BinaryOpLogicNode) {
-                BinaryOpLogicNode binaryOpLogicNode = (BinaryOpLogicNode) node;
-                infoElement = getInfoElements(binaryOpLogicNode);
-                while (infoElement != null) {
-                    if (infoElement.getStamp().equals(StampFactory.contradiction())) {
-                        return rewireGuards(infoElement.getGuard(), false, infoElement.getProxifiedInput(), null, rewireGuardFunction);
-                    } else if (infoElement.getStamp().equals(StampFactory.tautology())) {
-                        return rewireGuards(infoElement.getGuard(), true, infoElement.getProxifiedInput(), null, rewireGuardFunction);
-                    }
-                    infoElement = nextElement(infoElement);
-                }
-
-                ValueNode x = binaryOpLogicNode.getX();
-                ValueNode y = binaryOpLogicNode.getY();
-                infoElement = getInfoElements(x);
-                while (infoElement != null) {
-                    TriState result = binaryOpLogicNode.tryFold(infoElement.getStamp(), y.stamp());
-                    if (result.isKnown()) {
-                        return rewireGuards(infoElement.getGuard(), result.toBoolean(), infoElement.getProxifiedInput(), infoElement.getStamp(), rewireGuardFunction);
-                    }
-                    infoElement = nextElement(infoElement);
-                }
-
-                if (y.isConstant()) {
-                    Pair<InfoElement, Stamp> foldResult = recursiveFoldStampFromInfo(x);
-                    if (foldResult != null) {
-                        TriState result = binaryOpLogicNode.tryFold(foldResult.getRight(), y.stamp());
-                        if (result.isKnown()) {
-                            return rewireGuards(foldResult.getLeft().getGuard(), result.toBoolean(), foldResult.getLeft().getProxifiedInput(), foldResult.getRight(), rewireGuardFunction);
-                        }
-                    }
-                } else {
-                    infoElement = getInfoElements(y);
-                    while (infoElement != null) {
-                        TriState result = binaryOpLogicNode.tryFold(x.stamp(), infoElement.getStamp());
-                        if (result.isKnown()) {
-                            return rewireGuards(infoElement.getGuard(), result.toBoolean(), infoElement.getProxifiedInput(), infoElement.getStamp(), rewireGuardFunction);
-                        }
-                        infoElement = nextElement(infoElement);
-                    }
-                }
-
-                /*
-                 * For complex expressions involving constants, see if it's possible to fold the
-                 * tests by using stamps one level up in the expression. For instance, (x + n < y)
-                 * might fold if something is known about x and all other values are constants. The
-                 * reason for the constant restriction is that if more than 1 real value is involved
-                 * the code might need to adopt multiple guards to have proper dependences.
-                 */
-                if (x instanceof BinaryArithmeticNode<?> && y.isConstant()) {
-                    BinaryArithmeticNode<?> binary = (BinaryArithmeticNode<?>) x;
-                    if (binary.getY().isConstant()) {
-                        infoElement = getInfoElements(binary.getX());
-                        while (infoElement != null) {
-                            Stamp newStampX = binary.foldStamp(infoElement.getStamp(), binary.getY().stamp());
-                            TriState result = binaryOpLogicNode.tryFold(newStampX, y.stamp());
-                            if (result.isKnown()) {
-                                return rewireGuards(infoElement.getGuard(), result.toBoolean(), infoElement.getProxifiedInput(), newStampX, rewireGuardFunction);
-                            }
-                            infoElement = nextElement(infoElement);
-                        }
-                    }
-                }
-
-                if (thisGuard != null && binaryOpLogicNode instanceof IntegerEqualsNode && !thisGuard.isNegated()) {
-                    if (y.isConstant() && x instanceof AndNode) {
-                        AndNode and = (AndNode) x;
-                        if (and.getY() == y) {
-                            /*
-                             * This 'and' proves something about some of the bits in and.getX().
-                             * It's equivalent to or'ing in the mask value since those values are
-                             * known to be set.
-                             */
-                            BinaryOp<Or> op = ArithmeticOpTable.forStamp(x.stamp()).getOr();
-                            IntegerStamp newStampX = (IntegerStamp) op.foldStamp(getSafeStamp(and.getX()), getOtherSafeStamp(y));
-                            if (foldPendingTest(thisGuard, and.getX(), newStampX, rewireGuardFunction)) {
-                                return true;
-                            }
-                        }
-                    }
-                }
-
-                if (thisGuard != null) {
-                    if (!x.isConstant()) {
-                        Stamp newStampX = binaryOpLogicNode.getSucceedingStampForX(thisGuard.isNegated(), getSafeStamp(x), getOtherSafeStamp(y));
-                        if (newStampX != null && foldPendingTest(thisGuard, x, newStampX, rewireGuardFunction)) {
-                            return true;
-                        }
-                    }
-                    if (!y.isConstant()) {
-                        Stamp newStampY = binaryOpLogicNode.getSucceedingStampForY(thisGuard.isNegated(), getOtherSafeStamp(x), getSafeStamp(y));
-                        if (newStampY != null && foldPendingTest(thisGuard, y, newStampY, rewireGuardFunction)) {
-                            return true;
-                        }
-                    }
-                }
-            } else if (node instanceof ShortCircuitOrNode) {
-                final ShortCircuitOrNode shortCircuitOrNode = (ShortCircuitOrNode) node;
-                return tryProveCondition(shortCircuitOrNode.getX(), (guard, result, guardedValueStamp, newInput) -> {
-                    if (result == !shortCircuitOrNode.isXNegated()) {
-                        return rewireGuards(guard, true, newInput, guardedValueStamp, rewireGuardFunction);
-                    } else {
-                        return tryProveCondition(shortCircuitOrNode.getY(), (innerGuard, innerResult, innerGuardedValueStamp, innerNewInput) -> {
-                            ValueNode proxifiedInput = newInput;
-                            if (proxifiedInput == null) {
-                                proxifiedInput = innerNewInput;
-                            } else if (innerNewInput != null) {
-                                if (innerNewInput != newInput) {
-                                    // Cannot canonicalize due to different proxied inputs.
-                                    return false;
-                                }
-                            }
-                            // Can only canonicalize if the guards are equal.
-                            if (innerGuard == guard) {
-                                return rewireGuards(guard, innerResult ^ shortCircuitOrNode.isYNegated(), proxifiedInput, guardedValueStamp, rewireGuardFunction);
-                            }
-                            return false;
-                        });
-                    }
-                });
-            }
-
-            return false;
-        }
-
-        protected void registerNewStamp(ValueNode maybeProxiedValue, Stamp newStamp, GuardingNode guard) {
-            assert maybeProxiedValue != null;
-            assert guard != null;
-            if (newStamp != null) {
-                ValueNode value = maybeProxiedValue;
-                Stamp stamp = newStamp;
-                ValueNode proxiedValue = null;
-                if (value instanceof PiNode) {
-                    proxiedValue = value;
-                }
-                do {
-                    counterStampsRegistered.increment();
-                    Debug.log("\t Saving stamp for node %s stamp %s guarded by %s", value, stamp, guard);
-                    assert value instanceof LogicNode || stamp.isCompatible(value.stamp()) : stamp + " vs. " + value.stamp() + " (" + value + ")";
-                    map.setAndGrow(value, new InfoElement(stamp, guard, proxiedValue, map.getAndGrow(value)));
-                    undoOperations.push(value);
-                    if (value instanceof StampInverter) {
-                        StampInverter stampInverter = (StampInverter) value;
-                        value = stampInverter.getValue();
-                        stamp = stampInverter.invertStamp(stamp);
-                    } else {
-                        value = null;
-                        stamp = null;
-                    }
-                } while (value != null && stamp != null);
-            }
-        }
-
-        protected void processAbstractBegin(AbstractBeginNode beginNode) {
-            Node predecessor = beginNode.predecessor();
-            if (predecessor instanceof IfNode) {
-                IfNode ifNode = (IfNode) predecessor;
-                boolean negated = (ifNode.falseSuccessor() == beginNode);
-                LogicNode condition = ifNode.condition();
-                registerNewCondition(condition, negated, beginNode);
-            } else if (predecessor instanceof TypeSwitchNode) {
-                TypeSwitchNode typeSwitch = (TypeSwitchNode) predecessor;
-                processTypeSwitch(beginNode, typeSwitch);
-            } else if (predecessor instanceof IntegerSwitchNode) {
-                IntegerSwitchNode integerSwitchNode = (IntegerSwitchNode) predecessor;
-                processIntegerSwitch(beginNode, integerSwitchNode);
-            }
-        }
-
-        private static boolean maybeMultipleUsages(ValueNode value) {
-            if (value.hasMoreThanOneUsage()) {
-                return true;
-            } else {
-                return value instanceof ProxyNode;
-            }
-        }
-
-        protected void processIntegerSwitch(AbstractBeginNode beginNode, IntegerSwitchNode integerSwitchNode) {
-            ValueNode value = integerSwitchNode.value();
-            if (maybeMultipleUsages(value)) {
-                Stamp stamp = integerSwitchNode.getValueStampForSuccessor(beginNode);
-                if (stamp != null) {
-                    registerNewStamp(value, stamp, beginNode);
-                }
-            }
-        }
-
-        protected void processTypeSwitch(AbstractBeginNode beginNode, TypeSwitchNode typeSwitch) {
-            ValueNode hub = typeSwitch.value();
-            if (hub instanceof LoadHubNode) {
-                LoadHubNode loadHub = (LoadHubNode) hub;
-                ValueNode value = loadHub.getValue();
-                if (maybeMultipleUsages(value)) {
-                    Stamp stamp = typeSwitch.getValueStampForSuccessor(beginNode);
-                    if (stamp != null) {
-                        registerNewStamp(value, stamp, beginNode);
-                    }
-                }
-            }
-        }
-
-        @Override
-        public void exit(Block b, Integer state) {
-            int mark = state;
-            while (undoOperations.size() > mark) {
-                Node node = undoOperations.pop();
-                if (node.isAlive()) {
-                    map.set(node, map.get(node).getParent());
-                }
-            }
-        }
-    }
-
-    @FunctionalInterface
-    protected interface InfoElementProvider {
-        Iterable<InfoElement> getInfoElements(ValueNode value);
-    }
-
-    /**
-     * Checks for safe nodes when moving pending tests up.
-     */
-    static class InputFilter extends Node.EdgeVisitor {
-        boolean ok;
-        private ValueNode value;
-
-        InputFilter(ValueNode value) {
-            this.value = value;
-            this.ok = true;
-        }
-
-        @Override
-        public Node apply(Node node, Node curNode) {
-            if (!ok) {
-                // Abort the recursion
-                return curNode;
-            }
-            if (!(curNode instanceof ValueNode)) {
-                ok = false;
-                return curNode;
-            }
-            ValueNode curValue = (ValueNode) curNode;
-            if (curValue.isConstant() || curValue == value || curValue instanceof ParameterNode) {
-                return curNode;
-            }
-            if (curValue instanceof BinaryNode || curValue instanceof UnaryNode) {
-                curValue.applyInputs(this);
-            } else {
-                ok = false;
-            }
-            return curNode;
-        }
-    }
-
-    @FunctionalInterface
-    protected interface GuardRewirer {
-        /**
-         * Called if the condition could be proven to have a constant value ({@code result}) under
-         * {@code guard}.
-         *
-         * @param guard the guard whose result is proven
-         * @param result the known result of the guard
-         * @param newInput new input to pi nodes depending on the new guard
-         * @return whether the transformation could be applied
-         */
-        boolean rewire(GuardingNode guard, boolean result, Stamp guardedValueStamp, ValueNode newInput);
-    }
-
-    protected static class PendingTest {
-        private final LogicNode condition;
-        private final DeoptimizingGuard guard;
-
-        public PendingTest(LogicNode condition, DeoptimizingGuard guard) {
-            this.condition = condition;
-            this.guard = guard;
-        }
-    }
-
-    protected static final class InfoElement {
-        private final Stamp stamp;
-        private final GuardingNode guard;
-        private final ValueNode proxifiedInput;
-        private final InfoElement parent;
-
-        public InfoElement(Stamp stamp, GuardingNode guard, ValueNode proxifiedInput, InfoElement parent) {
-            this.stamp = stamp;
-            this.guard = guard;
-            this.proxifiedInput = proxifiedInput;
-            this.parent = parent;
-        }
-
-        public InfoElement getParent() {
-            return parent;
-        }
-
-        public Stamp getStamp() {
-            return stamp;
-        }
-
-        public GuardingNode getGuard() {
-            return guard;
-        }
-
-        public ValueNode getProxifiedInput() {
-            return proxifiedInput;
-        }
-
-        @Override
-        public String toString() {
-            return stamp + " -> " + guard;
-        }
-    }
-
-    @Override
-    public float codeSizeIncrease() {
-        return 1.5f;
-    }
-}