1 /*
   2  * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 
  25 package org.graalvm.compiler.nodes.extended;
  26 
  27 import static org.graalvm.compiler.nodeinfo.InputType.Guard;
  28 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
  29 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;
  30 
  31 import org.graalvm.compiler.core.common.type.StampFactory;
  32 import org.graalvm.compiler.graph.Node;
  33 import org.graalvm.compiler.graph.NodeClass;
  34 import org.graalvm.compiler.graph.NodeInputList;
  35 import org.graalvm.compiler.graph.spi.Canonicalizable;
  36 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
  37 import org.graalvm.compiler.graph.spi.Simplifiable;
  38 import org.graalvm.compiler.graph.spi.SimplifierTool;
  39 import org.graalvm.compiler.nodeinfo.NodeInfo;
  40 import org.graalvm.compiler.nodes.StructuredGraph;
  41 import org.graalvm.compiler.nodes.ValueNode;
  42 import org.graalvm.compiler.nodes.calc.FloatingNode;
  43 import org.graalvm.compiler.nodes.spi.LIRLowerable;
  44 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
  45 import org.graalvm.compiler.nodes.util.GraphUtil;
  46 
  47 @NodeInfo(allowedUsageTypes = Guard, cycles = CYCLES_0, size = SIZE_0)
  48 public final class MultiGuardNode extends FloatingNode implements GuardingNode, LIRLowerable, Simplifiable, Canonicalizable, Node.ValueNumberable {
  49     public static final NodeClass<MultiGuardNode> TYPE = NodeClass.create(MultiGuardNode.class);
  50 
  51     @OptionalInput(Guard) NodeInputList<ValueNode> guards;
  52 
  53     public MultiGuardNode(ValueNode... guards) {
  54         super(TYPE, StampFactory.forVoid());
  55         this.guards = new NodeInputList<>(this, guards);
  56     }
  57 
  58     @Override
  59     public void generate(NodeLIRBuilderTool generator) {
  60     }
  61 
  62     @Override
  63     public Node canonical(CanonicalizerTool tool) {
  64         // Make sure there are no nulls remaining in the set of guards references.
  65         guards.trim();
  66         if (guards.size() == 0) {
  67             // No guards left => can delete the multi-guard.
  68             return null;
  69         } else if (guards.size() == 1) {
  70             // Only a single guard left => replace multi-guard with that single guard.
  71             return guards.get(0);
  72         }
  73         return this;
  74     }
  75 
  76     @Override
  77     public void simplify(SimplifierTool tool) {
  78         if (usages().filter(node -> node instanceof ValueAnchorNode).isNotEmpty()) {
  79             /*
  80              * For ValueAnchorNode usages, we can optimize MultiGuardNodes away if they depend on
  81              * zero or one floating nodes (as opposed to fixed nodes).
  82              */
  83             Node singleFloatingGuard = null;
  84             for (ValueNode guard : guards) {
  85                 if (GraphUtil.isFloatingNode(guard)) {
  86                     if (singleFloatingGuard == null) {
  87                         singleFloatingGuard = guard;
  88                     } else if (singleFloatingGuard != guard) {
  89                         return;
  90                     }
  91                 }
  92             }
  93             for (Node usage : usages().snapshot()) {
  94                 if (usage instanceof ValueAnchorNode) {
  95                     usage.replaceFirstInput(this, singleFloatingGuard);
  96                     tool.addToWorkList(usage);
  97                 }
  98             }
  99             if (usages().isEmpty()) {
 100                 GraphUtil.killWithUnusedFloatingInputs(this);
 101             }
 102         }
 103     }
 104 
 105     public void addGuard(GuardingNode g) {
 106         this.guards.add(g.asNode());
 107     }
 108 
 109     public static GuardingNode combine(GuardingNode first, GuardingNode second) {
 110         if (first == null) {
 111             return second;
 112         } else if (second == null) {
 113             return first;
 114         } else {
 115             StructuredGraph graph = first.asNode().graph();
 116             return graph.unique(new MultiGuardNode(first.asNode(), second.asNode()));
 117         }
 118     }
 119 
 120     public static GuardingNode addGuard(GuardingNode first, GuardingNode second) {
 121         if (first instanceof MultiGuardNode && second != null) {
 122             MultiGuardNode multi = (MultiGuardNode) first;
 123             multi.addGuard(second);
 124             return multi;
 125         } else {
 126             return combine(first, second);
 127         }
 128     }
 129 }