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 * Copyright (c) 2014, 2016, 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.
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package org.graalvm.compiler.nodes;

import static org.graalvm.compiler.core.common.GraalOptions.GeneratePIC;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_2;

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.debug.GraalError;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.lir.gen.LIRGeneratorTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.calc.ConvertNode;
import org.graalvm.compiler.nodes.calc.UnaryNode;
import org.graalvm.compiler.nodes.spi.LIRLowerable;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
import org.graalvm.compiler.nodes.type.StampTool;

import jdk.vm.ci.meta.Constant;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.ConstantReflectionProvider;
import jdk.vm.ci.meta.Value;

Compress or uncompress an oop or metaspace pointer.
/** * Compress or uncompress an oop or metaspace pointer. */
@NodeInfo(nameTemplate = "{p#op/s}", cycles = CYCLES_2, size = SIZE_2) public abstract class CompressionNode extends UnaryNode implements ConvertNode, LIRLowerable { public static final NodeClass<CompressionNode> TYPE = NodeClass.create(CompressionNode.class); public enum CompressionOp { Compress, Uncompress } protected final CompressionOp op; protected final CompressEncoding encoding; public CompressionNode(NodeClass<? extends UnaryNode> c, CompressionOp op, ValueNode input, Stamp stamp, CompressEncoding encoding) { super(c, stamp, input); this.op = op; this.encoding = encoding; } @Override public Stamp foldStamp(Stamp newStamp) { assert newStamp.isCompatible(getValue().stamp(NodeView.DEFAULT)); return mkStamp(newStamp); } protected abstract Constant compress(Constant c); protected abstract Constant uncompress(Constant c); public JavaConstant nullConstant() { return JavaConstant.NULL_POINTER; } @Override public Constant convert(Constant c, ConstantReflectionProvider constantReflection) { switch (op) { case Compress: return compress(c); case Uncompress: return uncompress(c); default: throw GraalError.shouldNotReachHere(); } } @Override public Constant reverse(Constant c, ConstantReflectionProvider constantReflection) { switch (op) { case Compress: return uncompress(c); case Uncompress: return compress(c); default: throw GraalError.shouldNotReachHere(); } } @Override public boolean isLossless() { return true; } protected abstract Stamp mkStamp(Stamp input); public CompressionOp getOp() { return op; } public CompressEncoding getEncoding() { return encoding; } @Override public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { if (forValue.isConstant()) { if (GeneratePIC.getValue(tool.getOptions())) { // We always want uncompressed constants return this; } ConstantNode constant = (ConstantNode) forValue; return ConstantNode.forConstant(stamp(NodeView.DEFAULT), convert(constant.getValue(), tool.getConstantReflection()), constant.getStableDimension(), constant.isDefaultStable(), tool.getMetaAccess()); } else if (forValue instanceof CompressionNode) { CompressionNode other = (CompressionNode) forValue; if (op != other.op && encoding.equals(other.encoding)) { return other.getValue(); } } return this; } @Override public void generate(NodeLIRBuilderTool gen) { boolean nonNull; if (value.stamp(NodeView.DEFAULT) instanceof AbstractObjectStamp) { nonNull = StampTool.isPointerNonNull(value.stamp(NodeView.DEFAULT)); } else { // metaspace pointers are never null nonNull = true; } LIRGeneratorTool tool = gen.getLIRGeneratorTool(); Value result; switch (op) { case Compress: result = tool.emitCompress(gen.operand(value), encoding, nonNull); break; case Uncompress: result = tool.emitUncompress(gen.operand(value), encoding, nonNull); break; default: throw GraalError.shouldNotReachHere(); } gen.setResult(this, result); } @Override public boolean mayNullCheckSkipConversion() { return true; } }