1 /*

     2  * Copyright (c) 2013, 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.word;

    24 

    25 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;

    26 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;

    27 

    28 import org.graalvm.compiler.core.common.LIRKind;

    29 import org.graalvm.compiler.core.common.type.AbstractPointerStamp;

    30 import org.graalvm.compiler.core.common.type.ObjectStamp;

    31 import org.graalvm.compiler.core.common.type.Stamp;

    32 import org.graalvm.compiler.core.common.type.StampFactory;

    33 import org.graalvm.compiler.graph.Node;

    34 import org.graalvm.compiler.graph.NodeClass;

    35 import org.graalvm.compiler.graph.spi.Canonicalizable;

    36 import org.graalvm.compiler.graph.spi.CanonicalizerTool;

    37 import org.graalvm.compiler.lir.ConstantValue;

    38 import org.graalvm.compiler.nodeinfo.NodeInfo;

    39 import org.graalvm.compiler.nodes.ConstantNode;

    40 import org.graalvm.compiler.nodes.FixedWithNextNode;

    41 import org.graalvm.compiler.nodes.ValueNode;

    42 import org.graalvm.compiler.nodes.spi.LIRLowerable;

    43 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

    44 

    45 import jdk.vm.ci.meta.AllocatableValue;

    46 import jdk.vm.ci.meta.JavaConstant;

    47 import jdk.vm.ci.meta.JavaKind;

    48 import jdk.vm.ci.meta.Value;

    49 import jdk.vm.ci.meta.ValueKind;

    50 

    51 /**

    52  * Casts between Word and Object exposed by the {@link Word#fromAddress},

    53  * {@link Word#objectToTrackedPointer}, {@link Word#objectToUntrackedPointer} and

    54  * {@link Word#toObject()} operations. It has an impact on the pointer maps for the GC, so it must

    55  * not be scheduled or optimized away.

    56  */

    57 @NodeInfo(cycles = CYCLES_1, size = SIZE_1)

    58 public final class WordCastNode extends FixedWithNextNode implements LIRLowerable, Canonicalizable {

    59 

    60     public static final NodeClass<WordCastNode> TYPE = NodeClass.create(WordCastNode.class);

    61 

    62     @Input ValueNode input;

    63     public final boolean trackedPointer;

    64 

    65     public static WordCastNode wordToObject(ValueNode input, JavaKind wordKind) {

    66         assert input.getStackKind() == wordKind;

    67         return new WordCastNode(StampFactory.object(), input);

    68     }

    69 

    70     public static WordCastNode wordToObjectNonNull(ValueNode input, JavaKind wordKind) {

    71         assert input.getStackKind() == wordKind;

    72         return new WordCastNode(StampFactory.objectNonNull(), input);

    73     }

    74 

    75     public static WordCastNode addressToWord(ValueNode input, JavaKind wordKind) {

    76         assert input.stamp() instanceof AbstractPointerStamp;

    77         return new WordCastNode(StampFactory.forKind(wordKind), input);

    78     }

    79 

    80     public static WordCastNode objectToTrackedPointer(ValueNode input, JavaKind wordKind) {

    81         assert input.stamp() instanceof ObjectStamp;

    82         return new WordCastNode(StampFactory.forKind(wordKind), input, true);

    83     }

    84 

    85     public static WordCastNode objectToUntrackedPointer(ValueNode input, JavaKind wordKind) {

    86         assert input.stamp() instanceof ObjectStamp;

    87         return new WordCastNode(StampFactory.forKind(wordKind), input, false);

    88     }

    89 

    90     protected WordCastNode(Stamp stamp, ValueNode input) {

    91         this(stamp, input, true);

    92     }

    93 

    94     protected WordCastNode(Stamp stamp, ValueNode input, boolean trackedPointer) {

    95         super(TYPE, stamp);

    96         this.input = input;

    97         this.trackedPointer = trackedPointer;

    98     }

    99 

   100     public ValueNode getInput() {

   101         return input;

   102     }

   103 

   104     @Override

   105     public Node canonical(CanonicalizerTool tool) {

   106         if (tool.allUsagesAvailable() && hasNoUsages()) {

   107             /* If the cast is unused, it can be eliminated. */

   108             return input;

   109         }

   110 

   111         assert !stamp().isCompatible(input.stamp());

   112         if (input.isConstant()) {

   113             /* Null pointers are uncritical for GC, so they can be constant folded. */

   114             if (input.asJavaConstant().isNull()) {

   115                 return ConstantNode.forIntegerStamp(stamp(), 0);

   116             } else if (input.asJavaConstant().getJavaKind().isNumericInteger() && input.asJavaConstant().asLong() == 0) {

   117                 return ConstantNode.forConstant(stamp(), JavaConstant.NULL_POINTER, tool.getMetaAccess());

   118             }

   119         }

   120 

   121         return this;

   122     }

   123 

   124     @Override

   125     public void generate(NodeLIRBuilderTool generator) {

   126         Value value = generator.operand(input);

   127         ValueKind<?> kind = generator.getLIRGeneratorTool().getLIRKind(stamp());

   128         assert kind.getPlatformKind().getSizeInBytes() == value.getPlatformKind().getSizeInBytes();

   129 

   130         if (trackedPointer && LIRKind.isValue(kind) && !LIRKind.isValue(value)) {

   131             // just change the PlatformKind, but don't drop reference information

   132             kind = value.getValueKind().changeType(kind.getPlatformKind());

   133         }

   134 

   135         if (kind.equals(value.getValueKind()) && !(value instanceof ConstantValue)) {

   136             generator.setResult(this, value);

   137         } else {

   138             AllocatableValue result = generator.getLIRGeneratorTool().newVariable(kind);

   139             generator.getLIRGeneratorTool().emitMove(result, value);

   140             generator.setResult(this, result);

   141         }

   142     }

   143 }