/*
 * Copyright (c) 2013, 2018, 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.phases;

import static org.graalvm.compiler.nodes.ConstantNode.getConstantNodes;
import static org.graalvm.compiler.nodes.NamedLocationIdentity.FINAL_LOCATION;

import org.graalvm.compiler.core.common.CompressEncoding;
import org.graalvm.compiler.core.common.type.AbstractObjectStamp;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.core.common.type.TypeReference;
import org.graalvm.compiler.debug.GraalError;
import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;
import org.graalvm.compiler.hotspot.nodes.HotSpotCompressionNode;
import org.graalvm.compiler.hotspot.nodes.type.HotSpotNarrowOopStamp;
import org.graalvm.compiler.hotspot.nodes.type.KlassPointerStamp;
import org.graalvm.compiler.hotspot.replacements.HubGetClassNode;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.memory.FloatingReadNode;
import org.graalvm.compiler.nodes.memory.address.AddressNode;
import org.graalvm.compiler.nodes.memory.address.OffsetAddressNode;
import org.graalvm.compiler.phases.BasePhase;
import org.graalvm.compiler.phases.common.LoweringPhase;
import org.graalvm.compiler.phases.tiers.PhaseContext;

import jdk.vm.ci.hotspot.HotSpotObjectConstant;
import jdk.vm.ci.hotspot.HotSpotResolvedJavaField;
import jdk.vm.ci.hotspot.HotSpotResolvedObjectType;
import jdk.vm.ci.hotspot.HotSpotResolvedPrimitiveType;
import jdk.vm.ci.meta.ConstantReflectionProvider;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.MetaAccessProvider;
import jdk.vm.ci.meta.ResolvedJavaType;

For AOT compilation we aren't allowed to use a Class reference (javaMirror) directly. Instead the Class reference should be obtained from the Klass object. The reason for this is, that in Class Data Sharing (CDS) a Klass object is mapped to a fixed address in memory, but the javaMirror is not (which lives in the Java heap). Lowering can introduce new ConstantNodes containing a Class reference, thus this phase must be applied after LoweringPhase.
See Also:
/** * For AOT compilation we aren't allowed to use a {@link Class} reference ({@code javaMirror}) * directly. Instead the {@link Class} reference should be obtained from the {@code Klass} object. * The reason for this is, that in Class Data Sharing (CDS) a {@code Klass} object is mapped to a * fixed address in memory, but the {@code javaMirror} is not (which lives in the Java heap). * * Lowering can introduce new {@link ConstantNode}s containing a {@link Class} reference, thus this * phase must be applied after {@link LoweringPhase}. * * @see AheadOfTimeVerificationPhase */
public class LoadJavaMirrorWithKlassPhase extends BasePhase<PhaseContext> { private final CompressEncoding oopEncoding; public LoadJavaMirrorWithKlassPhase(GraalHotSpotVMConfig config) { this.oopEncoding = config.useCompressedOops ? config.getOopEncoding() : null; } private ValueNode getClassConstantReplacement(StructuredGraph graph, PhaseContext context, JavaConstant constant) { if (constant instanceof HotSpotObjectConstant) { ConstantReflectionProvider constantReflection = context.getConstantReflection(); ResolvedJavaType type = constantReflection.asJavaType(constant); if (type != null) { MetaAccessProvider metaAccess = context.getMetaAccess(); Stamp stamp = StampFactory.objectNonNull(TypeReference.createExactTrusted(metaAccess.lookupJavaType(Class.class))); if (type instanceof HotSpotResolvedObjectType) { ConstantNode klass = ConstantNode.forConstant(KlassPointerStamp.klassNonNull(), ((HotSpotResolvedObjectType) type).klass(), metaAccess, graph); ValueNode getClass = graph.unique(new HubGetClassNode(metaAccess, klass)); if (((HotSpotObjectConstant) constant).isCompressed()) { return HotSpotCompressionNode.compress(getClass, oopEncoding); } else { return getClass; } } else { /* * Primitive classes are more difficult since they don't have a corresponding * Klass* so get them from Class.TYPE for the java box type. */ HotSpotResolvedPrimitiveType primitive = (HotSpotResolvedPrimitiveType) type; ResolvedJavaType boxingClass = metaAccess.lookupJavaType(primitive.getJavaKind().toBoxedJavaClass()); ConstantNode clazz = ConstantNode.forConstant(context.getConstantReflection().asJavaClass(boxingClass), metaAccess, graph); HotSpotResolvedJavaField[] a = (HotSpotResolvedJavaField[]) boxingClass.getStaticFields(); HotSpotResolvedJavaField typeField = null; for (HotSpotResolvedJavaField f : a) { if (f.getName().equals("TYPE")) { typeField = f; break; } } if (typeField == null) { throw new GraalError("Can't find TYPE field in class"); } if (oopEncoding != null) { stamp = HotSpotNarrowOopStamp.compressed((AbstractObjectStamp) stamp, oopEncoding); } AddressNode address = graph.unique(new OffsetAddressNode(clazz, ConstantNode.forLong(typeField.getOffset(), graph))); ValueNode read = graph.unique(new FloatingReadNode(address, FINAL_LOCATION, null, stamp)); if (oopEncoding == null || ((HotSpotObjectConstant) constant).isCompressed()) { return read; } else { return HotSpotCompressionNode.uncompress(read, oopEncoding); } } } } return null; } @Override protected void run(StructuredGraph graph, PhaseContext context) { for (ConstantNode node : getConstantNodes(graph)) { JavaConstant constant = node.asJavaConstant(); ValueNode freadNode = getClassConstantReplacement(graph, context, constant); if (freadNode != null) { node.replace(graph, freadNode); } } } @Override public float codeSizeIncrease() { return 2.5f; } }