[GR-49568] Improve performance of GraphUtil#killWithFloatingInputs

PullRequest: graal/15844

compiler/src/jdk.graal.compiler.microbenchmarks/src/jdk/graal/compiler/microbenchmarks/graal/KillWithUnusedFloatingInputsBenchmark.java

@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2023, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 jdk.graal.compiler.microbenchmarks.graal;
+
+import org.openjdk.jmh.annotations.Benchmark;
+
+import jdk.graal.compiler.java.FrameStateBuilder;
+import jdk.graal.compiler.microbenchmarks.graal.util.GraalState;
+import jdk.graal.compiler.microbenchmarks.graal.util.GraphState;
+import jdk.graal.compiler.microbenchmarks.graal.util.MethodSpec;
+import jdk.graal.compiler.nodes.FrameState;
+import jdk.graal.compiler.nodes.ReturnNode;
+import jdk.graal.compiler.nodes.StructuredGraph;
+import jdk.graal.compiler.nodes.ValueNode;
+import jdk.graal.compiler.nodes.util.GraphUtil;
+import jdk.graal.compiler.phases.OptimisticOptimizations;
+import jdk.graal.compiler.phases.PhaseSuite;
+import jdk.graal.compiler.phases.tiers.HighTierContext;
+import jdk.vm.ci.meta.JavaKind;
+
+public class KillWithUnusedFloatingInputsBenchmark extends GraalBenchmark {
+
+    @Benchmark
+    public void killWithUnusedFloatingInputsTinyBenchmark(TinyGraph s) {
+        s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
+    }
+
+    @Benchmark
+    public void killAllWithUnusedFloatingInputsTinyBenchmark(TinyGraph s) {
+        GraphUtil.killAllWithUnusedFloatingInputs(s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()), false);
+    }
+
+    @Benchmark
+    public void killWithUnusedFloatingInputsSmallBenchmark(SmallGraph s) {
+        s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
+    }
+
+    @Benchmark
+    public void killAllWithUnusedFloatingInputsSmallBenchmark(SmallGraph s) {
+        GraphUtil.killAllWithUnusedFloatingInputs(s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()), false);
+    }
+
+    @Benchmark
+    public void killWithUnusedFloatingInputsMediumBenchmark(MediumGraph s) {
+        s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
+    }
+
+    @Benchmark
+    public void killAllWithUnusedFloatingInputsMediumBenchmark(MediumGraph s) {
+        GraphUtil.killAllWithUnusedFloatingInputs(s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()), false);
+    }
+
+    // too long running
+    public void killWithUnusedFloatingInputsLargeBenchmark(LargeGraph s) {
+        s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
+    }
+
+    // too long running
+    public void killAllWithUnusedFloatingInputsLargeBenchmark(LargeGraph s) {
+        GraphUtil.killAllWithUnusedFloatingInputs(s.graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()), false);
+    }
+
+    public static int snippet(int base, int mul) {
+        // the base graph which is later enlarged
+        return base * mul;
+    }
+
+    @MethodSpec(declaringClass = KillWithUnusedFloatingInputsBenchmark.class, name = "snippet")
+    public static class TinyGraph extends EnlargedGraph {
+        public TinyGraph() {
+            super(1);
+        }
+    }
+
+    @MethodSpec(declaringClass = KillWithUnusedFloatingInputsBenchmark.class, name = "snippet")
+    public static class SmallGraph extends EnlargedGraph {
+        public SmallGraph() {
+            super(10);
+        }
+    }
+
+    @MethodSpec(declaringClass = KillWithUnusedFloatingInputsBenchmark.class, name = "snippet")
+    public static class MediumGraph extends EnlargedGraph {
+        public MediumGraph() {
+            super(100);
+        }
+    }
+
+    @MethodSpec(declaringClass = KillWithUnusedFloatingInputsBenchmark.class, name = "snippet")
+    public static class LargeGraph extends EnlargedGraph {
+        public LargeGraph() {
+            super(1000);
+        }
+    }
+
+    public static class EnlargedGraph extends GraphState {
+        private final int sizeParam;
+
+        public EnlargedGraph(int sizeParam) {
+            this.sizeParam = sizeParam;
+            modifyGraph(originalGraph);
+        }
+
+        @Override
+        protected StructuredGraph preprocessOriginal(StructuredGraph structuredGraph) {
+            compileUntilModification(structuredGraph);
+            return structuredGraph;
+        }
+
+        private static void compileUntilModification(StructuredGraph g) {
+            GraalState graal = new GraalState();
+            PhaseSuite<HighTierContext> highTier = graal.backend.getSuites().getDefaultSuites(graal.options, graal.backend.getTarget().arch).getHighTier();
+            highTier.apply(g, new HighTierContext(graal.providers, graal.backend.getSuites().getDefaultGraphBuilderSuite(), OptimisticOptimizations.ALL));
+        }
+
+        private void modifyGraph(StructuredGraph g) {
+            ReturnNode ret = g.getNodes(ReturnNode.TYPE).first();
+            ValueNode val = ret.result();
+
+            /*
+             * Creates "sizeParam" FrameStates without usages. Each of the these FrameStates has
+             * "sizeParam" inputs.
+             */
+            FrameStateBuilder fb = new FrameStateBuilder(null, g.method(), g);
+            ValueNode[] vals = new ValueNode[sizeParam];
+            JavaKind[] kinds = new JavaKind[sizeParam];
+            for (int i = 0; i < sizeParam; i++) {
+                vals[i] = val;
+                kinds[i] = JavaKind.Int;
+            }
+
+            for (int j = 0; j < sizeParam; j++) {
+                FrameState fs = fb.create(1, null, false, kinds, vals);
+                g.addOrUnique(fs);
+            }
+        }
+    }
+}

compiler/src/jdk.graal.compiler.microbenchmarks/src/jdk/graal/compiler/microbenchmarks/graal/util/GraphState.java

@@ -68,7 +68,7 @@ protected StructuredGraph preprocessOriginal(StructuredGraph structuredGraph) {
     /**
      * Original graph from which the per-benchmark invocation {@link #graph} is cloned.
      */
-    private final StructuredGraph originalGraph;
+    protected final StructuredGraph originalGraph;
 
     /**
      * The graph processed by the benchmark.

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/graph/Node.java

@@ -41,6 +41,8 @@
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
+import org.graalvm.collections.EconomicSet;
+
 import jdk.graal.compiler.core.common.Fields;
 import jdk.graal.compiler.core.common.type.AbstractPointerStamp;
 import jdk.graal.compiler.core.common.type.Stamp;
@@ -418,7 +420,7 @@ public Iterable<Position> successorPositions() {
     }
 
     /**
-     * Gets the maximum number of usages {@code this} has had at any point in time.
+     * Gets the current number of usages {@code this} node has.
      */
     public int getUsageCount() {
         if (usage0 == null) {
@@ -558,31 +560,83 @@ private void movUsageFromEndToIndexOne() {
      * Removes one occurrence of a given node from this node's {@linkplain #usages() usages}.
      *
      * @param node the node to remove
-     * @return whether or not {@code usage} was in the usage list
      */
     public boolean removeUsage(Node node) {
         assert node != null;
         // For large graphs, usage removal is performance critical.
         // Furthermore, it is critical that this method maintains the invariant that the usage list
         // has no null element preceding a non-null element.
-        incUsageModCount();
         if (usage0 == node) {
             movUsageFromEndToIndexZero();
+            incUsageModCount();
             return true;
         }
         if (usage1 == node) {
             movUsageFromEndToIndexOne();
+            incUsageModCount();
             return true;
         }
         for (int i = this.extraUsagesCount - 1; i >= 0; i--) {
             if (extraUsages[i] == node) {
                 movUsageFromEndToExtraUsages(i);
+                incUsageModCount();
                 return true;
             }
         }
         return false;
     }
 
+    /**
+     * Removes all nodes in the provided set from {@code this} node's usages. This is significantly
+     * faster than repeated execution of {@link Node#removeUsage}.
+     */
+    public void removeUsages(EconomicSet<Node> toDelete) {
+        if (toDelete.size() == 0) {
+            return;
+        } else if (toDelete.size() == 1) {
+            removeUsage(toDelete.iterator().next());
+            return;
+        }
+
+        // requires iteration from back to front to check nodes prior to being moved to the front
+        for (int i = extraUsagesCount - 1; i >= 0; i--) {
+            if (toDelete.contains(extraUsages[i])) {
+                movUsageFromEndToExtraUsages(i);
+                incUsageModCount();
+            }
+        }
+        if (usage1 != null && toDelete.contains(usage1)) {
+            movUsageFromEndToIndexOne();
+            incUsageModCount();
+        }
+        if (usage0 != null && toDelete.contains(usage0)) {
+            movUsageFromEndToIndexZero();
+            incUsageModCount();
+        }
+    }
+
+    /**
+     * Removes all dead nodes from {@code this} node's usages. This is significantly faster than
+     * repeated execution of {@link Node#removeUsage}.
+     */
+    public void removeDeadUsages() {
+        // requires iteration from back to front to check nodes prior to being moved to the front
+        for (int i = extraUsagesCount - 1; i >= 0; i--) {
+            if (!extraUsages[i].isAlive()) {
+                movUsageFromEndToExtraUsages(i);
+                incUsageModCount();
+            }
+        }
+        if (usage1 != null && !usage1.isAlive()) {
+            movUsageFromEndToIndexOne();
+            incUsageModCount();
+        }
+        if (usage0 != null && !usage0.isAlive()) {
+            movUsageFromEndToIndexZero();
+            incUsageModCount();
+        }
+    }
+
     public final Node predecessor() {
         return predecessor;
     }

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/nodes/util/GraphUtil.java

@@ -410,6 +410,89 @@ public static void killWithUnusedFloatingInputs(Node node, boolean mayKillGuard)
                         // input is found
     }
 
+    /**
+     * Deletes the specified nodes in the graph and all nodes transitively, which are left without
+     * usages (except {@link GuardNode}s). This implementation is more efficient than repeated
+     * invocations of {@link GraphUtil#killWithUnusedFloatingInputs(Node, boolean)}.
+     */
+    public static void killAllWithUnusedFloatingInputs(NodeIterable<? extends Node> toKill, boolean mayKillGuard) {
+        /*
+         * Removing single nodes from a node's usage list is expensive (especially for complex
+         * graphs). This implementation works in the following:
+         *
+         * 1) If node x uses node y and y is deleted, the deletion of y from x's usages is deferred
+         * until it is known that x is not deleted as well. Thus, if both x any y are deleted, the
+         * usage is not deleted.
+         *
+         * 2) Nodes which were not deleted during the transitive deletion have their dead usages
+         * removed all at once, which yields linear complexity for removing multiple usages for one
+         * node.
+         */
+
+        // tracks the usage counts for each node instead of actually deleting usages for now
+        EconomicMap<Node, Integer> usageMap = EconomicMap.create();
+
+        EconomicSet<Node> maybeKill = EconomicSet.create();
+
+        // delete the initial set of nodes to be killed
+        for (Node n : toKill) {
+            assert checkKill(n, mayKillGuard);
+            n.markDeleted();
+            for (Node in : n.inputs()) {
+                Integer usages = usageMap.get(in);
+                if (usages == null) {
+                    usages = in.getUsageCount();
+                }
+                usageMap.put(in, usages - 1);
+                maybeKill.add(in);
+            }
+        }
+
+        // fixed point algorithm for transitive deletion of nodes which have no more usages
+        EconomicSet<Node> newMaybeKill;
+        do {
+            newMaybeKill = EconomicSet.create();
+
+            for (Node n : maybeKill) {
+                if (n.isAlive()) {
+                    if (usageMap.get(n) == 0) {
+                        n.maybeNotifyZeroUsages(n);
+                        if (!isFloatingNode(n)) {
+                            continue;
+                        }
+                        if (n instanceof GuardNode) {
+                            // Guard nodes are only killed if their anchor dies.
+                            continue;
+                        }
+                    } else if (n instanceof PhiNode phi && phi.isDegenerated()) {
+                        n.replaceAtUsages(null);
+                        n.maybeNotifyZeroUsages(n);
+                    } else {
+                        continue;
+                    }
+                    // no "checkKill" because usages were not actually removed
+                    n.markDeleted();
+                    for (Node in : n.inputs()) {
+                        Integer usages = usageMap.get(in);
+                        if (usages == null) {
+                            usages = in.usages().count();
+                        }
+                        usageMap.put(in, usages - 1);
+                        newMaybeKill.add(in);
+                    }
+                }
+            }
+            maybeKill = newMaybeKill;
+        } while (!newMaybeKill.isEmpty());
+
+        // actual removal of deleted usages for each node which is still alive
+        for (Node n : usageMap.getKeys()) {
+            if (n.isAlive() && (n.getUsageCount() != usageMap.get(n))) {
+                n.removeDeadUsages();
+            }
+        }
+    }
+
     public static void removeFixedWithUnusedInputs(FixedWithNextNode fixed) {
         if (fixed instanceof StateSplit) {
             FrameState stateAfter = ((StateSplit) fixed).stateAfter();

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/phases/common/FrameStateAssignmentPhase.java

@@ -145,7 +145,7 @@ public Optional<NotApplicable> notApplicableTo(GraphState graphState) {
     protected void run(StructuredGraph graph) {
         assert !hasFloatingDeopts(graph);
         ReentrantNodeIterator.apply(new FrameStateAssignmentClosure(), graph.start(), null);
-        graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
+        GraphUtil.killAllWithUnusedFloatingInputs(graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()), false);
     }
 
     @Override