| /* |
| * Copyright (c) 2009, 2015, 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.nodes.calc; |
| |
| import org.graalvm.compiler.core.common.type.AbstractPointerStamp; |
| import org.graalvm.compiler.core.common.type.ObjectStamp; |
| import org.graalvm.compiler.core.common.type.Stamp; |
| import org.graalvm.compiler.graph.NodeClass; |
| import org.graalvm.compiler.graph.spi.CanonicalizerTool; |
| import org.graalvm.compiler.nodeinfo.NodeCycles; |
| import org.graalvm.compiler.nodeinfo.NodeInfo; |
| import org.graalvm.compiler.nodes.CompressionNode; |
| import org.graalvm.compiler.nodes.LogicConstantNode; |
| import org.graalvm.compiler.nodes.LogicNode; |
| import org.graalvm.compiler.nodes.NodeView; |
| import org.graalvm.compiler.nodes.PiNode; |
| import org.graalvm.compiler.nodes.UnaryOpLogicNode; |
| import org.graalvm.compiler.nodes.ValueNode; |
| import org.graalvm.compiler.nodes.spi.LIRLowerable; |
| import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool; |
| import org.graalvm.compiler.nodes.spi.Virtualizable; |
| import org.graalvm.compiler.nodes.spi.VirtualizerTool; |
| import org.graalvm.compiler.nodes.type.StampTool; |
| import org.graalvm.compiler.nodes.util.GraphUtil; |
| |
| import jdk.vm.ci.meta.JavaConstant; |
| import jdk.vm.ci.meta.TriState; |
| |
| /** |
| * An IsNullNode will be true if the supplied value is null, and false if it is non-null. |
| */ |
| @NodeInfo(cycles = NodeCycles.CYCLES_2) |
| public final class IsNullNode extends UnaryOpLogicNode implements LIRLowerable, Virtualizable { |
| |
| public static final NodeClass<IsNullNode> TYPE = NodeClass.create(IsNullNode.class); |
| |
| /* |
| * When linear pointer compression is enabled, compressed and uncompressed nulls differ. |
| */ |
| private final JavaConstant nullConstant; |
| |
| private IsNullNode(ValueNode object, JavaConstant nullConstant) { |
| super(TYPE, object); |
| this.nullConstant = nullConstant; |
| assert object != null; |
| } |
| |
| public IsNullNode(ValueNode object) { |
| this(object, JavaConstant.NULL_POINTER); |
| } |
| |
| public JavaConstant nullConstant() { |
| return nullConstant; |
| } |
| |
| public static LogicNode create(ValueNode forValue) { |
| return canonicalized(null, forValue, JavaConstant.NULL_POINTER); |
| } |
| |
| @Override |
| public void generate(NodeLIRBuilderTool gen) { |
| // Nothing to do. |
| } |
| |
| @Override |
| public boolean verify() { |
| assertTrue(getValue() != null, "is null input must not be null"); |
| assertTrue(getValue().stamp(NodeView.DEFAULT) instanceof AbstractPointerStamp, "input must be a pointer not %s", getValue().stamp(NodeView.DEFAULT)); |
| return super.verify(); |
| } |
| |
| @Override |
| public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { |
| return canonicalized(this, forValue, nullConstant); |
| } |
| |
| private static LogicNode canonicalized(IsNullNode node, ValueNode forValue, JavaConstant forNullConstant) { |
| JavaConstant nullConstant = forNullConstant; |
| ValueNode value = forValue; |
| while (true) { |
| if (StampTool.isPointerAlwaysNull(value)) { |
| return LogicConstantNode.tautology(); |
| } else if (StampTool.isPointerNonNull(value)) { |
| return LogicConstantNode.contradiction(); |
| } |
| |
| if (value instanceof PiNode) { |
| value = GraphUtil.skipPi(value); |
| continue; |
| } |
| |
| if (value instanceof ConvertNode) { |
| ConvertNode convertNode = (ConvertNode) value; |
| if (convertNode.mayNullCheckSkipConversion()) { |
| value = convertNode.getValue(); |
| continue; |
| } |
| /* |
| * CompressionNode.mayNullCheckSkipConversion returns false when linear pointer |
| * compression is enabled. |
| */ |
| if (value instanceof CompressionNode) { |
| CompressionNode compressionNode = (CompressionNode) value; |
| nullConstant = compressionNode.nullConstant(); |
| value = compressionNode.getValue(); |
| continue; |
| } |
| } |
| /* |
| * If we are at original node, just return it. Otherwise create a new node. |
| */ |
| return (node != null && value == forValue) ? node : new IsNullNode(value, nullConstant); |
| } |
| } |
| |
| @Override |
| public void virtualize(VirtualizerTool tool) { |
| ValueNode alias = tool.getAlias(getValue()); |
| TriState fold = tryFold(alias.stamp(NodeView.DEFAULT)); |
| if (fold != TriState.UNKNOWN) { |
| tool.replaceWithValue(LogicConstantNode.forBoolean(fold.isTrue(), graph())); |
| } |
| } |
| |
| @Override |
| public Stamp getSucceedingStampForValue(boolean negated) { |
| // Ignore any more precise input stamp since canonicalization will skip through PiNodes |
| AbstractPointerStamp pointerStamp = (AbstractPointerStamp) getValue().stamp(NodeView.DEFAULT).unrestricted(); |
| return negated ? pointerStamp.asNonNull() : pointerStamp.asAlwaysNull(); |
| } |
| |
| @Override |
| public TriState tryFold(Stamp valueStamp) { |
| if (valueStamp instanceof ObjectStamp) { |
| ObjectStamp objectStamp = (ObjectStamp) valueStamp; |
| if (objectStamp.alwaysNull()) { |
| return TriState.TRUE; |
| } else if (objectStamp.nonNull()) { |
| return TriState.FALSE; |
| } |
| } |
| return TriState.UNKNOWN; |
| } |
| } |