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
24
25 package org.graalvm.compiler.word;
26
27 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;
28 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;
29
30 import org.graalvm.compiler.core.common.LIRKind;
31 import org.graalvm.compiler.core.common.type.AbstractPointerStamp;
32 import org.graalvm.compiler.core.common.type.IntegerStamp;
33 import org.graalvm.compiler.core.common.type.ObjectStamp;
34 import org.graalvm.compiler.core.common.type.Stamp;
35 import org.graalvm.compiler.core.common.type.StampFactory;
36 import org.graalvm.compiler.graph.Node;
37 import org.graalvm.compiler.graph.NodeClass;
38 import org.graalvm.compiler.graph.spi.Canonicalizable;
39 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
40 import org.graalvm.compiler.lir.ConstantValue;
41 import org.graalvm.compiler.nodeinfo.NodeInfo;
42 import org.graalvm.compiler.nodes.ConstantNode;
43 import org.graalvm.compiler.nodes.FixedWithNextNode;
44 import org.graalvm.compiler.nodes.NodeView;
45 import org.graalvm.compiler.nodes.ValueNode;
46 import org.graalvm.compiler.nodes.spi.LIRLowerable;
47 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
48 import org.graalvm.compiler.nodes.type.NarrowOopStamp;
49
50 import jdk.vm.ci.meta.AllocatableValue;
51 import jdk.vm.ci.meta.JavaConstant;
52 import jdk.vm.ci.meta.JavaKind;
53 import jdk.vm.ci.meta.Value;
54 import jdk.vm.ci.meta.ValueKind;
55
56 /**
57 * Casts between Word and Object exposed by the {@link Word#fromAddress},
58 * {@link Word#objectToTrackedPointer}, {@link Word#objectToUntrackedPointer} and
59 * {@link Word#toObject()} operations. It has an impact on the pointer maps for the GC, so it must
60 * not be scheduled or optimized away.
61 */
62 @NodeInfo(cycles = CYCLES_1, size = SIZE_1)
63 public final class WordCastNode extends FixedWithNextNode implements LIRLowerable, Canonicalizable {
64
65 public static final NodeClass<WordCastNode> TYPE = NodeClass.create(WordCastNode.class);
66
67 @Input ValueNode input;
68 private final boolean trackedPointer;
69
70 public static WordCastNode wordToObject(ValueNode input, JavaKind wordKind) {
71 assert input.getStackKind() == wordKind;
72 return new WordCastNode(objectStampFor(input), input);
73 }
74
75 public static WordCastNode wordToObjectNonNull(ValueNode input, JavaKind wordKind) {
76 assert input.getStackKind() == wordKind;
77 return new WordCastNode(StampFactory.objectNonNull(), input);
78 }
79
80 public static WordCastNode wordToNarrowObject(ValueNode input, NarrowOopStamp stamp) {
81 return new WordCastNode(stamp, input);
82 }
83
84 public static WordCastNode addressToWord(ValueNode input, JavaKind wordKind) {
85 assert input.stamp(NodeView.DEFAULT) instanceof AbstractPointerStamp;
86 return new WordCastNode(StampFactory.forKind(wordKind), input);
87 }
88
89 public static WordCastNode objectToTrackedPointer(ValueNode input, JavaKind wordKind) {
90 assert input.stamp(NodeView.DEFAULT) instanceof ObjectStamp;
91 return new WordCastNode(StampFactory.forKind(wordKind), input);
92 }
93
94 public static WordCastNode objectToUntrackedPointer(ValueNode input, JavaKind wordKind) {
95 assert input.stamp(NodeView.DEFAULT) instanceof ObjectStamp;
96 return new WordCastNode(StampFactory.forKind(wordKind), input, false);
97 }
98
99 public static WordCastNode narrowOopToUntrackedWord(ValueNode input, JavaKind wordKind) {
100 assert input.stamp(NodeView.DEFAULT) instanceof NarrowOopStamp;
101 return new WordCastNode(StampFactory.forKind(wordKind), input, false);
102 }
103
104 private WordCastNode(Stamp stamp, ValueNode input) {
105 this(stamp, input, true);
106 }
107
108 protected WordCastNode(Stamp stamp, ValueNode input, boolean trackedPointer) {
109 super(TYPE, stamp);
110 this.input = input;
111 this.trackedPointer = trackedPointer;
112 }
113
114 public ValueNode getInput() {
115 return input;
116 }
117
118 private static boolean isZeroConstant(ValueNode value) {
119 JavaConstant constant = value.asJavaConstant();
120 return constant.getJavaKind().isNumericInteger() && constant.asLong() == 0;
121 }
122
123 private static Stamp objectStampFor(ValueNode input) {
124 Stamp inputStamp = input.stamp(NodeView.DEFAULT);
125 if (inputStamp instanceof AbstractPointerStamp) {
126 AbstractPointerStamp pointerStamp = (AbstractPointerStamp) inputStamp;
127 if (pointerStamp.alwaysNull()) {
128 return StampFactory.alwaysNull();
129 } else if (pointerStamp.nonNull()) {
130 return StampFactory.objectNonNull();
131 }
132 } else if (inputStamp instanceof IntegerStamp && !((IntegerStamp) inputStamp).contains(0)) {
133 return StampFactory.objectNonNull();
134 } else if (input.isConstant() && isZeroConstant(input)) {
135 return StampFactory.alwaysNull();
136 }
137 return StampFactory.object();
138 }
139
140 @Override
141 public boolean inferStamp() {
142 if (stamp instanceof AbstractPointerStamp) {
143 AbstractPointerStamp objectStamp = (AbstractPointerStamp) stamp;
144 if (!objectStamp.alwaysNull() && !objectStamp.nonNull()) {
145 Stamp newStamp = stamp;
146 Stamp inputStamp = input.stamp(NodeView.DEFAULT);
147 if (inputStamp instanceof AbstractPointerStamp) {
148 AbstractPointerStamp pointerStamp = (AbstractPointerStamp) inputStamp;
149 if (pointerStamp.alwaysNull()) {
150 newStamp = objectStamp.asAlwaysNull();
151 } else if (pointerStamp.nonNull()) {
152 newStamp = objectStamp.asNonNull();
153 }
154 } else if (inputStamp instanceof IntegerStamp && !((IntegerStamp) inputStamp).contains(0)) {
155 newStamp = objectStamp.asNonNull();
156 } else if (input.isConstant() && isZeroConstant(input)) {
157 newStamp = objectStamp.asAlwaysNull();
158 }
159 return updateStamp(newStamp);
160 }
161 }
162 return false;
163 }
164
165 @Override
166 public Node canonical(CanonicalizerTool tool) {
167 if (tool.allUsagesAvailable() && hasNoUsages()) {
168 /* If the cast is unused, it can be eliminated. */
169 return input;
170 }
171
172 assert !stamp.isCompatible(input.stamp(NodeView.DEFAULT));
173 if (input.isConstant()) {
174 /* Null pointers are uncritical for GC, so they can be constant folded. */
175 if (input.asJavaConstant().isNull()) {
176 return ConstantNode.forIntegerStamp(stamp, 0);
177 } else if (isZeroConstant(input)) {
178 return ConstantNode.forConstant(stamp, ((AbstractPointerStamp) stamp).nullConstant(), tool.getMetaAccess());
179 }
180 }
181
182 return this;
183 }
184
185 @Override
186 public void generate(NodeLIRBuilderTool generator) {
187 Value value = generator.operand(input);
188 ValueKind<?> kind = generator.getLIRGeneratorTool().getLIRKind(stamp(NodeView.DEFAULT));
189 assert kind.getPlatformKind().getSizeInBytes() == value.getPlatformKind().getSizeInBytes();
190
191 if (trackedPointer && LIRKind.isValue(kind) && !LIRKind.isValue(value)) {
192 // just change the PlatformKind, but don't drop reference information
193 kind = value.getValueKind().changeType(kind.getPlatformKind());
194 }
195
196 if (kind.equals(value.getValueKind()) && !(value instanceof ConstantValue)) {
197 generator.setResult(this, value);
198 } else {
199 AllocatableValue result = generator.getLIRGeneratorTool().newVariable(kind);
200 if (stamp.equals(StampFactory.object())) {
201 generator.getLIRGeneratorTool().emitConvertZeroToNull(result, value);
202 } else if (!trackedPointer && !((AbstractPointerStamp) input.stamp(NodeView.DEFAULT)).nonNull()) {
203 generator.getLIRGeneratorTool().emitConvertNullToZero(result, value);
204 } else {
205 generator.getLIRGeneratorTool().emitMove(result, value);
206 }
207 generator.setResult(this, result);
208 }
209 }
210 }