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.nodes;
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.nodeinfo.NodeInfo;
38 import org.graalvm.compiler.nodes.ConstantNode;
39 import org.graalvm.compiler.nodes.FixedWithNextNode;
40 import org.graalvm.compiler.nodes.ValueNode;
41 import org.graalvm.compiler.nodes.spi.LIRLowerable;
42 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
43 import org.graalvm.compiler.word.Word.Opcode;
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 Opcode#FROM_ADDRESS},
53 * {@link Opcode#OBJECT_TO_TRACKED}, {@link Opcode#OBJECT_TO_UNTRACKED} and {@link Opcode#TO_OBJECT}
54 * operations. It has an impact on the pointer maps for the GC, so it must not be scheduled or
55 * 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 addressToWord(ValueNode input, JavaKind wordKind) {
71 assert input.stamp() instanceof AbstractPointerStamp;
72 return new WordCastNode(StampFactory.forKind(wordKind), input);
73 }
74
75 public static WordCastNode objectToTrackedPointer(ValueNode input, JavaKind wordKind) {
76 assert input.stamp() instanceof ObjectStamp;
77 return new WordCastNode(StampFactory.forKind(wordKind), input, true);
78 }
79
80 public static WordCastNode objectToUntrackedPointer(ValueNode input, JavaKind wordKind) {
81 assert input.stamp() instanceof ObjectStamp;
82 return new WordCastNode(StampFactory.forKind(wordKind), input, false);
83 }
84
85 protected WordCastNode(Stamp stamp, ValueNode input) {
86 this(stamp, input, true);
87 }
88
89 protected WordCastNode(Stamp stamp, ValueNode input, boolean trackedPointer) {
90 super(TYPE, stamp);
91 this.input = input;
92 this.trackedPointer = trackedPointer;
93 }
94
95 public ValueNode getInput() {
96 return input;
97 }
98
99 @Override
100 public Node canonical(CanonicalizerTool tool) {
101 if (tool.allUsagesAvailable() && hasNoUsages()) {
102 /* If the cast is unused, it can be eliminated. */
103 return input;
104 }
105
106 assert !stamp().isCompatible(input.stamp());
107 if (input.isConstant()) {
108 /* Null pointers are uncritical for GC, so they can be constant folded. */
109 if (input.asJavaConstant().isNull()) {
110 return ConstantNode.forIntegerStamp(stamp(), 0);
111 } else if (input.asJavaConstant().getJavaKind().isNumericInteger() && input.asJavaConstant().asLong() == 0) {
112 return ConstantNode.forConstant(stamp(), JavaConstant.NULL_POINTER, tool.getMetaAccess());
113 }
114 }
115
116 return this;
117 }
118
119 @Override
120 public void generate(NodeLIRBuilderTool generator) {
121 Value value = generator.operand(input);
122 ValueKind<?> kind = generator.getLIRGeneratorTool().getLIRKind(stamp());
123 assert kind.getPlatformKind().getSizeInBytes() == value.getPlatformKind().getSizeInBytes();
124
125 if (trackedPointer && LIRKind.isValue(kind) && !LIRKind.isValue(value)) {
126 // just change the PlatformKind, but don't drop reference information
127 kind = value.getValueKind().changeType(kind.getPlatformKind());
128 }
129
130 if (kind.equals(value.getValueKind())) {
131 generator.setResult(this, value);
132 } else {
133 AllocatableValue result = generator.getLIRGeneratorTool().newVariable(kind);
134 generator.getLIRGeneratorTool().emitMove(result, value);
135 generator.setResult(this, result);
136 }
137 }
138 }