1 /*
2 * Copyright (c) 2012, 2016, 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.nodes.type;
24
25 import java.util.Iterator;
26
27 import org.graalvm.compiler.core.common.type.AbstractObjectStamp;
28 import org.graalvm.compiler.core.common.type.AbstractPointerStamp;
29 import org.graalvm.compiler.core.common.type.IntegerStamp;
30 import org.graalvm.compiler.core.common.type.Stamp;
31 import org.graalvm.compiler.core.common.type.StampFactory;
32 import org.graalvm.compiler.core.common.type.TypeReference;
33 import org.graalvm.compiler.nodes.ValueNode;
34
35 import jdk.vm.ci.code.CodeUtil;
36 import jdk.vm.ci.meta.JavaKind;
37 import jdk.vm.ci.meta.MetaAccessProvider;
38 import jdk.vm.ci.meta.ResolvedJavaType;
39
40 /**
41 * Helper class that is used to keep all stamp-related operations in one place.
42 */
43 public class StampTool {
44
45 public static Stamp meet(Iterable<? extends ValueNode> values) {
46 Stamp stamp = meetOrNull(values, null);
47 if (stamp == null) {
48 return StampFactory.forVoid();
49 }
50 return stamp;
51 }
52
53 /**
54 * Meet a collection of {@link ValueNode}s optionally excluding {@code selfValue}. If no values
55 * are encountered then return {@code null}.
56 */
57 public static Stamp meetOrNull(Iterable<? extends ValueNode> values, ValueNode selfValue) {
58 Iterator<? extends ValueNode> iterator = values.iterator();
59 Stamp stamp = null;
60 while (iterator.hasNext()) {
61 ValueNode nextValue = iterator.next();
62 if (nextValue != selfValue) {
63 if (stamp == null) {
64 stamp = nextValue.stamp();
65 } else {
66 stamp = stamp.meet(nextValue.stamp());
67 }
68 }
69 }
70 return stamp;
71 }
72
73 /**
74 * Compute the stamp resulting from the unsigned comparison being true.
75 *
76 * @return null if it's can't be true or it nothing useful can be encoded.
77 */
78 public static Stamp unsignedCompare(Stamp stamp, Stamp stamp2) {
79 IntegerStamp x = (IntegerStamp) stamp;
80 IntegerStamp y = (IntegerStamp) stamp2;
81 if (x == x.unrestricted() && y == y.unrestricted()) {
82 // Don't know anything.
83 return null;
84 }
85 // c <| n, where c is a constant and n is known to be positive.
86 if (x.lowerBound() == x.upperBound()) {
87 if (y.isPositive()) {
88 if (x.lowerBound() == (1 << x.getBits()) - 1) {
89 // Constant is MAX_VALUE which must fail.
90 return null;
91 }
92 if (x.lowerBound() <= y.lowerBound()) {
93 // Test will fail. Return illegalStamp instead?
94 return null;
95 }
96 // If the test succeeds then this proves that n is at greater than c so the bounds
97 // are [c+1..-n.upperBound)].
98 return StampFactory.forInteger(x.getBits(), x.lowerBound() + 1, y.upperBound());
99 }
100 return null;
101 }
102 // n <| c, where c is a strictly positive constant
103 if (y.lowerBound() == y.upperBound() && y.isStrictlyPositive()) {
104 // The test proves that n is positive and less than c, [0..c-1]
105 return StampFactory.forInteger(y.getBits(), 0, y.lowerBound() - 1);
106 }
107 return null;
108 }
109
110 public static Stamp stampForLeadingZeros(IntegerStamp valueStamp) {
111 long mask = CodeUtil.mask(valueStamp.getBits());
112 // Don't count zeros from the mask in the result.
113 int adjust = Long.numberOfLeadingZeros(mask);
114 assert adjust == 0 || adjust == 32;
115 int min = Long.numberOfLeadingZeros(valueStamp.upMask() & mask) - adjust;
116 int max = Long.numberOfLeadingZeros(valueStamp.downMask() & mask) - adjust;
117 return StampFactory.forInteger(JavaKind.Int, min, max);
118 }
119
120 public static Stamp stampForTrailingZeros(IntegerStamp valueStamp) {
121 long mask = CodeUtil.mask(valueStamp.getBits());
122 int min = Long.numberOfTrailingZeros(valueStamp.upMask() & mask);
123 int max = Long.numberOfTrailingZeros(valueStamp.downMask() & mask);
124 return StampFactory.forInteger(JavaKind.Int, min, max);
125 }
126
127 /**
128 * Checks whether this {@link ValueNode} represents a {@linkplain Stamp#hasValues() legal}
129 * pointer value which is known to be always null.
130 *
131 * @param node the node to check
132 * @return true if this node represents a legal object value which is known to be always null
133 */
134 public static boolean isPointerAlwaysNull(ValueNode node) {
135 return isPointerAlwaysNull(node.stamp());
136 }
137
138 /**
139 * Checks whether this {@link Stamp} represents a {@linkplain Stamp#hasValues() legal} pointer
140 * stamp whose values are known to be always null.
141 *
142 * @param stamp the stamp to check
143 * @return true if this stamp represents a legal object stamp whose values are known to be
144 * always null
145 */
146 public static boolean isPointerAlwaysNull(Stamp stamp) {
147 if (stamp instanceof AbstractPointerStamp && stamp.hasValues()) {
148 return ((AbstractPointerStamp) stamp).alwaysNull();
149 }
150 return false;
151 }
152
153 /**
154 * Checks whether this {@link ValueNode} represents a {@linkplain Stamp#hasValues() legal}
155 * pointer value which is known to never be null.
156 *
157 * @param node the node to check
158 * @return true if this node represents a legal object value which is known to never be null
159 */
160 public static boolean isPointerNonNull(ValueNode node) {
161 return isPointerNonNull(node.stamp());
162 }
163
164 /**
165 * Checks whether this {@link Stamp} represents a {@linkplain Stamp#hasValues() legal} pointer
166 * stamp whose values are known to never be null.
167 *
168 * @param stamp the stamp to check
169 * @return true if this stamp represents a legal object stamp whose values are known to be
170 * always null
171 */
172 public static boolean isPointerNonNull(Stamp stamp) {
173 if (stamp instanceof AbstractPointerStamp) {
174 return ((AbstractPointerStamp) stamp).nonNull();
175 }
176 return false;
177 }
178
179 /**
180 * Returns the {@linkplain ResolvedJavaType Java type} this {@linkplain ValueNode} has if it is
181 * a {@linkplain Stamp#hasValues() legal} Object value.
182 *
183 * @param node the node to check
184 * @return the Java type this value has if it is a legal Object type, null otherwise
185 */
186 public static TypeReference typeReferenceOrNull(ValueNode node) {
187 return typeReferenceOrNull(node.stamp());
188 }
189
190 public static ResolvedJavaType typeOrNull(ValueNode node) {
191 return typeOrNull(node.stamp());
192 }
193
194 public static ResolvedJavaType typeOrNull(Stamp stamp) {
195 TypeReference type = typeReferenceOrNull(stamp);
196 return type == null ? null : type.getType();
197 }
198
199 public static ResolvedJavaType typeOrNull(Stamp stamp, MetaAccessProvider metaAccess) {
200 if (stamp instanceof AbstractObjectStamp && stamp.hasValues()) {
201 AbstractObjectStamp abstractObjectStamp = (AbstractObjectStamp) stamp;
202 ResolvedJavaType type = abstractObjectStamp.type();
203 if (type == null) {
204 return metaAccess.lookupJavaType(Object.class);
205 } else {
206 return type;
207 }
208 }
209 return null;
210 }
211
212 public static ResolvedJavaType typeOrNull(ValueNode node, MetaAccessProvider metaAccess) {
213 return typeOrNull(node.stamp(), metaAccess);
214 }
215
216 /**
217 * Returns the {@linkplain ResolvedJavaType Java type} this {@linkplain Stamp} has if it is a
218 * {@linkplain Stamp#hasValues() legal} Object stamp.
219 *
220 * @param stamp the stamp to check
221 * @return the Java type this stamp has if it is a legal Object stamp, null otherwise
222 */
223 public static TypeReference typeReferenceOrNull(Stamp stamp) {
224 if (stamp instanceof AbstractObjectStamp && stamp.hasValues()) {
225 AbstractObjectStamp abstractObjectStamp = (AbstractObjectStamp) stamp;
226 if (abstractObjectStamp.isExactType()) {
227 return TypeReference.createExactTrusted(abstractObjectStamp.type());
228 } else {
229 return TypeReference.createTrustedWithoutAssumptions(abstractObjectStamp.type());
230 }
231 }
232 return null;
233 }
234
235 /**
236 * Checks whether this {@link ValueNode} represents a {@linkplain Stamp#hasValues() legal}
237 * Object value whose Java type is known exactly. If this method returns true then the
238 * {@linkplain ResolvedJavaType Java type} returned by {@link #typeReferenceOrNull(ValueNode)}
239 * is the concrete dynamic/runtime Java type of this value.
240 *
241 * @param node the node to check
242 * @return true if this node represents a legal object value whose Java type is known exactly
243 */
244 public static boolean isExactType(ValueNode node) {
245 return isExactType(node.stamp());
246 }
247
248 /**
249 * Checks whether this {@link Stamp} represents a {@linkplain Stamp#hasValues() legal} Object
250 * stamp whose {@linkplain ResolvedJavaType Java type} is known exactly. If this method returns
251 * true then the Java type returned by {@link #typeReferenceOrNull(Stamp)} is the only concrete
252 * dynamic/runtime Java type possible for values of this stamp.
253 *
254 * @param stamp the stamp to check
255 * @return true if this node represents a legal object stamp whose Java type is known exactly
256 */
257 public static boolean isExactType(Stamp stamp) {
258 if (stamp instanceof AbstractObjectStamp && stamp.hasValues()) {
259 return ((AbstractObjectStamp) stamp).isExactType();
260 }
261 return false;
262 }
263 }