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