1 /* 2 * Copyright (c) 2009, 2015, 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 package org.graalvm.compiler.nodes.calc; 24 25 import org.graalvm.compiler.core.common.type.AbstractPointerStamp; 26 import org.graalvm.compiler.core.common.type.ObjectStamp; 27 import org.graalvm.compiler.core.common.type.Stamp; 28 import org.graalvm.compiler.core.common.type.StampFactory; 29 import org.graalvm.compiler.graph.NodeClass; 30 import org.graalvm.compiler.graph.spi.CanonicalizerTool; 31 import org.graalvm.compiler.nodeinfo.NodeCycles; 32 import org.graalvm.compiler.nodeinfo.NodeInfo; 33 import org.graalvm.compiler.nodes.LogicConstantNode; 34 import org.graalvm.compiler.nodes.LogicNode; 35 import org.graalvm.compiler.nodes.PiNode; 36 import org.graalvm.compiler.nodes.UnaryOpLogicNode; 37 import org.graalvm.compiler.nodes.ValueNode; 38 import org.graalvm.compiler.nodes.spi.LIRLowerable; 39 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool; 40 import org.graalvm.compiler.nodes.spi.PiPushable; 41 import org.graalvm.compiler.nodes.spi.Virtualizable; 42 import org.graalvm.compiler.nodes.spi.VirtualizerTool; 43 import org.graalvm.compiler.nodes.type.StampTool; 44 45 import jdk.vm.ci.meta.TriState; 46 47 /** 48 * An IsNullNode will be true if the supplied value is null, and false if it is non-null. 49 */ 50 @NodeInfo(cycles = NodeCycles.CYCLES_2) 51 public final class IsNullNode extends UnaryOpLogicNode implements LIRLowerable, Virtualizable, PiPushable { 52 53 public static final NodeClass<IsNullNode> TYPE = NodeClass.create(IsNullNode.class); 54 55 public IsNullNode(ValueNode object) { 56 super(TYPE, object); 57 assert object != null; 58 } 59 60 public static LogicNode create(ValueNode forValue) { 61 LogicNode result = tryCanonicalize(forValue); 62 return result == null ? new IsNullNode(forValue) : result; 63 } 64 65 public static LogicNode tryCanonicalize(ValueNode forValue) { 66 if (StampTool.isPointerAlwaysNull(forValue)) { 67 return LogicConstantNode.tautology(); 68 } else if (StampTool.isPointerNonNull(forValue)) { 69 return LogicConstantNode.contradiction(); 70 } 71 return null; 72 } 73 74 @Override 75 public void generate(NodeLIRBuilderTool gen) { 76 // Nothing to do. 77 } 78 79 @Override 80 public boolean verify() { 81 assertTrue(getValue() != null, "is null input must not be null"); 82 assertTrue(getValue().stamp() instanceof AbstractPointerStamp, "input must be a pointer not %s", getValue().stamp()); 83 return super.verify(); 84 } 85 86 @Override 87 public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { 88 LogicNode result = tryCanonicalize(forValue); 89 return result == null ? this : result; 90 } 91 92 @Override 93 public void virtualize(VirtualizerTool tool) { 94 ValueNode alias = tool.getAlias(getValue()); 95 TriState fold = tryFold(alias.stamp()); 96 if (fold != TriState.UNKNOWN) { 97 tool.replaceWithValue(LogicConstantNode.forBoolean(fold.isTrue(), graph())); 98 } 99 } 100 101 @Override 102 public boolean push(PiNode parent) { 103 if (parent.stamp() instanceof ObjectStamp && parent.object().stamp() instanceof ObjectStamp) { 104 ObjectStamp piStamp = (ObjectStamp) parent.stamp(); 105 ObjectStamp piValueStamp = (ObjectStamp) parent.object().stamp(); 106 if (piStamp.nonNull() == piValueStamp.nonNull() && piStamp.alwaysNull() == piValueStamp.alwaysNull()) { 107 replaceFirstInput(parent, parent.object()); 108 return true; 109 } 110 } 111 return false; 112 } 113 114 @NodeIntrinsic 115 public static native IsNullNode isNull(Object object); 116 117 @Override 118 public Stamp getSucceedingStampForValue(boolean negated) { 119 return negated ? getValue().stamp().join(StampFactory.objectNonNull()) : StampFactory.alwaysNull(); 120 } 121 122 @Override 123 public TriState tryFold(Stamp valueStamp) { 124 if (valueStamp instanceof ObjectStamp) { 125 ObjectStamp objectStamp = (ObjectStamp) valueStamp; 126 if (objectStamp.alwaysNull()) { 127 return TriState.TRUE; 128 } else if (objectStamp.nonNull()) { 129 return TriState.FALSE; 130 } 131 } 132 return TriState.UNKNOWN; 133 } 134 }