/*
 * Copyright (c) 2014, 2020, 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.hotspot.replacements;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;

import org.graalvm.compiler.core.common.calc.CanonicalCondition;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.Canonicalizable;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.hotspot.nodes.type.KlassPointerStamp;
import org.graalvm.compiler.hotspot.word.KlassPointer;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.PiNode;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.calc.ConvertNode;
import org.graalvm.compiler.nodes.calc.FloatingNode;
import org.graalvm.compiler.nodes.extended.GetClassNode;
import org.graalvm.compiler.nodes.extended.GuardingNode;
import org.graalvm.compiler.nodes.extended.LoadHubNode;
import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext;
import org.graalvm.compiler.nodes.memory.ReadNode;
import org.graalvm.compiler.nodes.memory.address.AddressNode;
import org.graalvm.compiler.nodes.spi.Lowerable;
import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.meta.Constant;
import jdk.vm.ci.meta.ConstantReflectionProvider;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.MetaAccessProvider;
import jdk.vm.ci.meta.ResolvedJavaMethod;
import jdk.vm.ci.meta.ResolvedJavaType;

Read Class::_klass to get the hub for a Class. This node mostly exists to replace _klass._java_mirror._klass with _klass. The constant folding could be handled by ReadNode.canonicalizeRead(ValueNode, AddressNode, LocationIdentity, CanonicalizerTool).
/** * Read {@code Class::_klass} to get the hub for a {@link java.lang.Class}. This node mostly exists * to replace {@code _klass._java_mirror._klass} with {@code _klass}. The constant folding could be * handled by * {@link ReadNode#canonicalizeRead(ValueNode, AddressNode, LocationIdentity, CanonicalizerTool)}. */
@NodeInfo(cycles = CYCLES_1, size = SIZE_1) public final class ClassGetHubNode extends FloatingNode implements Lowerable, Canonicalizable, ConvertNode { public static final NodeClass<ClassGetHubNode> TYPE = NodeClass.create(ClassGetHubNode.class); @Input protected ValueNode clazz; public ClassGetHubNode(ValueNode clazz) { super(TYPE, KlassPointerStamp.klass()); this.clazz = clazz; } public static ValueNode create(ValueNode clazz, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, boolean allUsagesAvailable) { return canonical(null, metaAccess, constantReflection, allUsagesAvailable, KlassPointerStamp.klass(), clazz); } @SuppressWarnings("unused") public static boolean intrinsify(GraphBuilderContext b, ResolvedJavaMethod method, ValueNode clazz) { ValueNode clazzValue = create(clazz, b.getMetaAccess(), b.getConstantReflection(), false); b.push(JavaKind.Object, b.append(clazzValue)); return true; } public static ValueNode canonical(ClassGetHubNode classGetHubNode, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, boolean allUsagesAvailable, Stamp stamp, ValueNode clazz) { ClassGetHubNode self = classGetHubNode; if (allUsagesAvailable && self != null && self.hasNoUsages()) { return null; } else { if (clazz.isConstant() && !clazz.isNullConstant()) { if (metaAccess != null) { ResolvedJavaType exactType = constantReflection.asJavaType(clazz.asJavaConstant()); if (exactType.isPrimitive()) { return ConstantNode.forConstant(stamp, JavaConstant.NULL_POINTER, metaAccess); } else { return ConstantNode.forConstant(stamp, constantReflection.asObjectHub(exactType), metaAccess); } } } if (clazz instanceof GetClassNode) { GetClassNode getClass = (GetClassNode) clazz; return new LoadHubNode(KlassPointerStamp.klassNonNull(), getClass.getObject()); } if (clazz instanceof HubGetClassNode) { // Replace: _klass._java_mirror._klass -> _klass return ((HubGetClassNode) clazz).getHub(); } if (self == null) { self = new ClassGetHubNode(clazz); } return self; } } @Override public Node canonical(CanonicalizerTool tool) { return canonical(this, tool.getMetaAccess(), tool.getConstantReflection(), tool.allUsagesAvailable(), stamp(NodeView.DEFAULT), clazz); } @NodeIntrinsic public static native KlassPointer readClass(Class<?> clazzNonNull); @NodeIntrinsic(PiNode.class) public static native KlassPointer piCastNonNull(Object object, GuardingNode anchor); @Override public ValueNode getValue() { return clazz; } @Override public Constant convert(Constant c, ConstantReflectionProvider constantReflection) { ResolvedJavaType exactType = constantReflection.asJavaType(c); if (exactType.isPrimitive()) { return JavaConstant.NULL_POINTER; } else { return constantReflection.asObjectHub(exactType); } } @Override public Constant reverse(Constant c, ConstantReflectionProvider constantReflection) { assert !c.equals(JavaConstant.NULL_POINTER); ResolvedJavaType objectType = constantReflection.asJavaType(c); return constantReflection.asJavaClass(objectType); } @Override public boolean isLossless() { return false; }
There is more than one Class value that has a NULL hub.
/** * There is more than one {@link java.lang.Class} value that has a NULL hub. */
@Override public boolean mayNullCheckSkipConversion() { return false; } @Override public boolean preservesOrder(CanonicalCondition op, Constant value, ConstantReflectionProvider constantReflection) { assert op == CanonicalCondition.EQ; ResolvedJavaType exactType = constantReflection.asJavaType(value); return !exactType.isPrimitive(); } }