1 /* 2 * Copyright (c) 2017, 2021, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang.runtime; 27 28 import java.lang.invoke.ConstantCallSite; 29 import java.lang.invoke.MethodHandle; 30 import java.lang.invoke.MethodHandles; 31 import java.lang.invoke.MethodType; 32 import java.lang.invoke.TypeDescriptor; 33 import java.security.AccessController; 34 import java.security.PrivilegedAction; 35 import java.util.Arrays; 36 import java.util.HashMap; 37 import java.util.List; 38 import java.util.Objects; 39 40 import static java.util.Objects.requireNonNull; 41 42 /** 43 * Bootstrap methods for state-driven implementations of core methods, 44 * including {@link Object#equals(Object)}, {@link Object#hashCode()}, and 45 * {@link Object#toString()}. These methods may be used, for example, by 46 * Java compiler implementations to implement the bodies of {@link Object} 47 * methods for record classes. 48 * 49 * @since 16 50 */ 51 public class ObjectMethods { 52 ObjectMethods()53 private ObjectMethods() { } 54 55 private static final MethodType DESCRIPTOR_MT = MethodType.methodType(MethodType.class); 56 private static final MethodType NAMES_MT = MethodType.methodType(List.class); 57 private static final MethodHandle FALSE = MethodHandles.constant(boolean.class, false); 58 private static final MethodHandle TRUE = MethodHandles.constant(boolean.class, true); 59 private static final MethodHandle ZERO = MethodHandles.constant(int.class, 0); 60 private static final MethodHandle CLASS_IS_INSTANCE; 61 private static final MethodHandle OBJECT_EQUALS; 62 private static final MethodHandle OBJECTS_EQUALS; 63 private static final MethodHandle OBJECTS_HASHCODE; 64 private static final MethodHandle OBJECTS_TOSTRING; 65 private static final MethodHandle OBJECT_EQ; 66 private static final MethodHandle OBJECT_HASHCODE; 67 private static final MethodHandle OBJECT_TO_STRING; 68 private static final MethodHandle STRING_FORMAT; 69 private static final MethodHandle HASH_COMBINER; 70 71 private static final HashMap<Class<?>, MethodHandle> primitiveEquals = new HashMap<>(); 72 private static final HashMap<Class<?>, MethodHandle> primitiveHashers = new HashMap<>(); 73 private static final HashMap<Class<?>, MethodHandle> primitiveToString = new HashMap<>(); 74 75 static { 76 try { 77 Class<ObjectMethods> OBJECT_METHODS_CLASS = ObjectMethods.class; 78 MethodHandles.Lookup publicLookup = MethodHandles.publicLookup(); 79 MethodHandles.Lookup lookup = MethodHandles.lookup(); 80 81 // Android-changed: Use the "normal" class loader 82 /* 83 @SuppressWarnings("removal") 84 ClassLoader loader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() { 85 @Override public ClassLoader run() { return ClassLoader.getPlatformClassLoader(); } 86 }); 87 */ 88 ClassLoader loader = ObjectMethods.class.getClassLoader(); 89 90 CLASS_IS_INSTANCE = publicLookup.findVirtual(Class.class, "isInstance", 91 MethodType.methodType(boolean.class, Object.class)); 92 OBJECT_EQUALS = publicLookup.findVirtual(Object.class, "equals", 93 MethodType.methodType(boolean.class, Object.class)); 94 OBJECT_HASHCODE = publicLookup.findVirtual(Object.class, "hashCode", 95 MethodType.fromMethodDescriptorString("()I", loader)); 96 OBJECT_TO_STRING = publicLookup.findVirtual(Object.class, "toString", 97 MethodType.methodType(String.class)); 98 STRING_FORMAT = publicLookup.findStatic(String.class, "format", 99 MethodType.methodType(String.class, String.class, Object[].class)); 100 OBJECTS_EQUALS = publicLookup.findStatic(Objects.class, "equals", 101 MethodType.methodType(boolean.class, Object.class, Object.class)); 102 OBJECTS_HASHCODE = publicLookup.findStatic(Objects.class, "hashCode", 103 MethodType.methodType(int.class, Object.class)); 104 OBJECTS_TOSTRING = publicLookup.findStatic(Objects.class, "toString", 105 MethodType.methodType(String.class, Object.class)); 106 107 OBJECT_EQ = lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 108 MethodType.methodType(boolean.class, Object.class, Object.class)); 109 HASH_COMBINER = lookup.findStatic(OBJECT_METHODS_CLASS, "hashCombiner", 110 MethodType.fromMethodDescriptorString("(II)I", loader)); 111 primitiveEquals.put(byte.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(BB)Z", loader)))112 primitiveEquals.put(byte.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 113 MethodType.fromMethodDescriptorString("(BB)Z", loader))); primitiveEquals.put(short.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(SS)Z", loader)))114 primitiveEquals.put(short.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 115 MethodType.fromMethodDescriptorString("(SS)Z", loader))); primitiveEquals.put(char.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(CC)Z", loader)))116 primitiveEquals.put(char.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 117 MethodType.fromMethodDescriptorString("(CC)Z", loader))); primitiveEquals.put(int.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(II)Z", loader)))118 primitiveEquals.put(int.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 119 MethodType.fromMethodDescriptorString("(II)Z", loader))); primitiveEquals.put(long.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(JJ)Z", loader)))120 primitiveEquals.put(long.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 121 MethodType.fromMethodDescriptorString("(JJ)Z", loader))); primitiveEquals.put(float.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(FF)Z", loader)))122 primitiveEquals.put(float.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 123 MethodType.fromMethodDescriptorString("(FF)Z", loader))); primitiveEquals.put(double.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(DD)Z", loader)))124 primitiveEquals.put(double.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 125 MethodType.fromMethodDescriptorString("(DD)Z", loader))); primitiveEquals.put(boolean.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", MethodType.fromMethodDescriptorString("(ZZ)Z", loader)))126 primitiveEquals.put(boolean.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 127 MethodType.fromMethodDescriptorString("(ZZ)Z", loader))); 128 primitiveHashers.put(byte.class, lookup.findStatic(Byte.class, "hashCode", MethodType.fromMethodDescriptorString("(B)I", loader)))129 primitiveHashers.put(byte.class, lookup.findStatic(Byte.class, "hashCode", 130 MethodType.fromMethodDescriptorString("(B)I", loader))); primitiveHashers.put(short.class, lookup.findStatic(Short.class, "hashCode", MethodType.fromMethodDescriptorString("(S)I", loader)))131 primitiveHashers.put(short.class, lookup.findStatic(Short.class, "hashCode", 132 MethodType.fromMethodDescriptorString("(S)I", loader))); primitiveHashers.put(char.class, lookup.findStatic(Character.class, "hashCode", MethodType.fromMethodDescriptorString("(C)I", loader)))133 primitiveHashers.put(char.class, lookup.findStatic(Character.class, "hashCode", 134 MethodType.fromMethodDescriptorString("(C)I", loader))); primitiveHashers.put(int.class, lookup.findStatic(Integer.class, "hashCode", MethodType.fromMethodDescriptorString("(I)I", loader)))135 primitiveHashers.put(int.class, lookup.findStatic(Integer.class, "hashCode", 136 MethodType.fromMethodDescriptorString("(I)I", loader))); primitiveHashers.put(long.class, lookup.findStatic(Long.class, "hashCode", MethodType.fromMethodDescriptorString("(J)I", loader)))137 primitiveHashers.put(long.class, lookup.findStatic(Long.class, "hashCode", 138 MethodType.fromMethodDescriptorString("(J)I", loader))); primitiveHashers.put(float.class, lookup.findStatic(Float.class, "hashCode", MethodType.fromMethodDescriptorString("(F)I", loader)))139 primitiveHashers.put(float.class, lookup.findStatic(Float.class, "hashCode", 140 MethodType.fromMethodDescriptorString("(F)I", loader))); primitiveHashers.put(double.class, lookup.findStatic(Double.class, "hashCode", MethodType.fromMethodDescriptorString("(D)I", loader)))141 primitiveHashers.put(double.class, lookup.findStatic(Double.class, "hashCode", 142 MethodType.fromMethodDescriptorString("(D)I", loader))); primitiveHashers.put(boolean.class, lookup.findStatic(Boolean.class, "hashCode", MethodType.fromMethodDescriptorString("(Z)I", loader)))143 primitiveHashers.put(boolean.class, lookup.findStatic(Boolean.class, "hashCode", 144 MethodType.fromMethodDescriptorString("(Z)I", loader))); 145 primitiveToString.put(byte.class, lookup.findStatic(Byte.class, "toString", MethodType.methodType(String.class, byte.class)))146 primitiveToString.put(byte.class, lookup.findStatic(Byte.class, "toString", 147 MethodType.methodType(String.class, byte.class))); primitiveToString.put(short.class, lookup.findStatic(Short.class, "toString", MethodType.methodType(String.class, short.class)))148 primitiveToString.put(short.class, lookup.findStatic(Short.class, "toString", 149 MethodType.methodType(String.class, short.class))); primitiveToString.put(char.class, lookup.findStatic(Character.class, "toString", MethodType.methodType(String.class, char.class)))150 primitiveToString.put(char.class, lookup.findStatic(Character.class, "toString", 151 MethodType.methodType(String.class, char.class))); primitiveToString.put(int.class, lookup.findStatic(Integer.class, "toString", MethodType.methodType(String.class, int.class)))152 primitiveToString.put(int.class, lookup.findStatic(Integer.class, "toString", 153 MethodType.methodType(String.class, int.class))); primitiveToString.put(long.class, lookup.findStatic(Long.class, "toString", MethodType.methodType(String.class, long.class)))154 primitiveToString.put(long.class, lookup.findStatic(Long.class, "toString", 155 MethodType.methodType(String.class, long.class))); primitiveToString.put(float.class, lookup.findStatic(Float.class, "toString", MethodType.methodType(String.class, float.class)))156 primitiveToString.put(float.class, lookup.findStatic(Float.class, "toString", 157 MethodType.methodType(String.class, float.class))); primitiveToString.put(double.class, lookup.findStatic(Double.class, "toString", MethodType.methodType(String.class, double.class)))158 primitiveToString.put(double.class, lookup.findStatic(Double.class, "toString", 159 MethodType.methodType(String.class, double.class))); primitiveToString.put(boolean.class, lookup.findStatic(Boolean.class, "toString", MethodType.methodType(String.class, boolean.class)))160 primitiveToString.put(boolean.class, lookup.findStatic(Boolean.class, "toString", 161 MethodType.methodType(String.class, boolean.class))); 162 } 163 catch (ReflectiveOperationException e) { 164 throw new RuntimeException(e); 165 } 166 } 167 hashCombiner(int x, int y)168 private static int hashCombiner(int x, int y) { 169 return x*31 + y; 170 } 171 eq(Object a, Object b)172 private static boolean eq(Object a, Object b) { return a == b; } eq(byte a, byte b)173 private static boolean eq(byte a, byte b) { return a == b; } eq(short a, short b)174 private static boolean eq(short a, short b) { return a == b; } eq(char a, char b)175 private static boolean eq(char a, char b) { return a == b; } eq(int a, int b)176 private static boolean eq(int a, int b) { return a == b; } eq(long a, long b)177 private static boolean eq(long a, long b) { return a == b; } eq(float a, float b)178 private static boolean eq(float a, float b) { return Float.compare(a, b) == 0; } eq(double a, double b)179 private static boolean eq(double a, double b) { return Double.compare(a, b) == 0; } eq(boolean a, boolean b)180 private static boolean eq(boolean a, boolean b) { return a == b; } 181 182 /** Get the method handle for combining two values of a given type */ equalator(Class<?> clazz)183 private static MethodHandle equalator(Class<?> clazz) { 184 return (clazz.isPrimitive() 185 ? primitiveEquals.get(clazz) 186 : OBJECTS_EQUALS.asType(MethodType.methodType(boolean.class, clazz, clazz))); 187 } 188 189 /** Get the hasher for a value of a given type */ hasher(Class<?> clazz)190 private static MethodHandle hasher(Class<?> clazz) { 191 return (clazz.isPrimitive() 192 ? primitiveHashers.get(clazz) 193 : OBJECTS_HASHCODE.asType(MethodType.methodType(int.class, clazz))); 194 } 195 196 /** Get the stringifier for a value of a given type */ stringifier(Class<?> clazz)197 private static MethodHandle stringifier(Class<?> clazz) { 198 return (clazz.isPrimitive() 199 ? primitiveToString.get(clazz) 200 : OBJECTS_TOSTRING.asType(MethodType.methodType(String.class, clazz))); 201 } 202 203 /** 204 * Generates a method handle for the {@code equals} method for a given data class 205 * @param receiverClass the data class 206 * @param getters the list of getters 207 * @return the method handle 208 */ makeEquals(Class<?> receiverClass, List<MethodHandle> getters)209 private static MethodHandle makeEquals(Class<?> receiverClass, 210 List<MethodHandle> getters) { 211 MethodType rr = MethodType.methodType(boolean.class, receiverClass, receiverClass); 212 MethodType ro = MethodType.methodType(boolean.class, receiverClass, Object.class); 213 MethodHandle instanceFalse = MethodHandles.dropArguments(FALSE, 0, receiverClass, Object.class); // (RO)Z 214 MethodHandle instanceTrue = MethodHandles.dropArguments(TRUE, 0, receiverClass, Object.class); // (RO)Z 215 MethodHandle isSameObject = OBJECT_EQ.asType(ro); // (RO)Z 216 MethodHandle isInstance = MethodHandles.dropArguments(CLASS_IS_INSTANCE.bindTo(receiverClass), 0, receiverClass); // (RO)Z 217 MethodHandle accumulator = MethodHandles.dropArguments(TRUE, 0, receiverClass, receiverClass); // (RR)Z 218 219 for (MethodHandle getter : getters) { 220 MethodHandle equalator = equalator(getter.type().returnType()); // (TT)Z 221 MethodHandle thisFieldEqual = MethodHandles.filterArguments(equalator, 0, getter, getter); // (RR)Z 222 accumulator = MethodHandles.guardWithTest(thisFieldEqual, accumulator, instanceFalse.asType(rr)); 223 } 224 225 return MethodHandles.guardWithTest(isSameObject, 226 instanceTrue, 227 MethodHandles.guardWithTest(isInstance, accumulator.asType(ro), instanceFalse)); 228 } 229 230 /** 231 * Generates a method handle for the {@code hashCode} method for a given data class 232 * @param receiverClass the data class 233 * @param getters the list of getters 234 * @return the method handle 235 */ makeHashCode(Class<?> receiverClass, List<MethodHandle> getters)236 private static MethodHandle makeHashCode(Class<?> receiverClass, 237 List<MethodHandle> getters) { 238 MethodHandle accumulator = MethodHandles.dropArguments(ZERO, 0, receiverClass); // (R)I 239 240 // @@@ Use loop combinator instead? 241 for (MethodHandle getter : getters) { 242 MethodHandle hasher = hasher(getter.type().returnType()); // (T)I 243 MethodHandle hashThisField = MethodHandles.filterArguments(hasher, 0, getter); // (R)I 244 MethodHandle combineHashes = MethodHandles.filterArguments(HASH_COMBINER, 0, accumulator, hashThisField); // (RR)I 245 accumulator = MethodHandles.permuteArguments(combineHashes, accumulator.type(), 0, 0); // adapt (R)I to (RR)I 246 } 247 248 return accumulator; 249 } 250 251 /** 252 * Generates a method handle for the {@code toString} method for a given data class 253 * @param receiverClass the data class 254 * @param getters the list of getters 255 * @param names the names 256 * @return the method handle 257 */ makeToString(Class<?> receiverClass, List<MethodHandle> getters, List<String> names)258 private static MethodHandle makeToString(Class<?> receiverClass, 259 List<MethodHandle> getters, 260 List<String> names) { 261 // This is a pretty lousy algorithm; we spread the receiver over N places, 262 // apply the N getters, apply N toString operations, and concat the result with String.format 263 // Better to use String.format directly, or delegate to StringConcatFactory 264 // Also probably want some quoting around String components 265 266 assert getters.size() == names.size(); 267 268 int[] invArgs = new int[getters.size()]; 269 Arrays.fill(invArgs, 0); 270 MethodHandle[] filters = new MethodHandle[getters.size()]; 271 StringBuilder sb = new StringBuilder(); 272 sb.append(receiverClass.getSimpleName()).append("["); 273 for (int i=0; i<getters.size(); i++) { 274 MethodHandle getter = getters.get(i); // (R)T 275 MethodHandle stringify = stringifier(getter.type().returnType()); // (T)String 276 MethodHandle stringifyThisField = MethodHandles.filterArguments(stringify, 0, getter); // (R)String 277 filters[i] = stringifyThisField; 278 sb.append(names.get(i)).append("=%s"); 279 if (i != getters.size() - 1) 280 sb.append(", "); 281 } 282 sb.append(']'); 283 String formatString = sb.toString(); 284 MethodHandle formatter = MethodHandles.insertArguments(STRING_FORMAT, 0, formatString) 285 .asCollector(String[].class, getters.size()); // (R*)String 286 if (getters.size() == 0) { 287 // Add back extra R 288 formatter = MethodHandles.dropArguments(formatter, 0, receiverClass); 289 } 290 else { 291 MethodHandle filtered = MethodHandles.filterArguments(formatter, 0, filters); 292 formatter = MethodHandles.permuteArguments(filtered, MethodType.methodType(String.class, receiverClass), invArgs); 293 } 294 295 return formatter; 296 } 297 298 /** 299 * Bootstrap method to generate the {@link Object#equals(Object)}, 300 * {@link Object#hashCode()}, and {@link Object#toString()} methods, based 301 * on a description of the component names and accessor methods, for either 302 * {@code invokedynamic} call sites or dynamic constant pool entries. 303 * 304 * For more detail on the semantics of the generated methods see the specification 305 * of {@link java.lang.Record#equals(Object)}, {@link java.lang.Record#hashCode()} and 306 * {@link java.lang.Record#toString()}. 307 * 308 * 309 * @param lookup Every bootstrap method is expected to have a {@code lookup} 310 * which usually represents a lookup context with the 311 * accessibility privileges of the caller. This is because 312 * {@code invokedynamic} call sites always provide a {@code lookup} 313 * to the corresponding bootstrap method, but this method just 314 * ignores the {@code lookup} parameter 315 * @param methodName the name of the method to generate, which must be one of 316 * {@code "equals"}, {@code "hashCode"}, or {@code "toString"} 317 * @param type a {@link MethodType} corresponding the descriptor type 318 * for the method, which must correspond to the descriptor 319 * for the corresponding {@link Object} method, if linking 320 * an {@code invokedynamic} call site, or the 321 * constant {@code MethodHandle.class}, if linking a 322 * dynamic constant 323 * @param recordClass the record class hosting the record components 324 * @param names the list of component names, joined into a string 325 * separated by ";", or the empty string if there are no 326 * components. Maybe be null, if the {@code methodName} 327 * is {@code "equals"} or {@code "hashCode"}. 328 * @param getters method handles for the accessor methods for the components 329 * @return a call site if invoked by indy, or a method handle 330 * if invoked by a condy 331 * @throws IllegalArgumentException if the bootstrap arguments are invalid 332 * or inconsistent 333 * @throws Throwable if any exception is thrown during call site construction 334 */ bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type, Class<?> recordClass, String names, MethodHandle... getters)335 public static Object bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type, 336 Class<?> recordClass, 337 String names, 338 MethodHandle... getters) throws Throwable { 339 // Android-changed: nullchecks are from Java 21. 340 requireNonNull(lookup); 341 requireNonNull(methodName); 342 requireNonNull(type); 343 requireNonNull(recordClass); 344 requireNonNull(names); 345 requireNonNull(getters); 346 MethodType methodType; 347 if (type instanceof MethodType) 348 methodType = (MethodType) type; 349 else { 350 methodType = null; 351 if (!MethodHandle.class.equals(type)) 352 throw new IllegalArgumentException(type.toString()); 353 } 354 List<MethodHandle> getterList = List.of(getters); 355 MethodHandle handle = switch (methodName) { 356 case "equals" -> { 357 if (methodType != null && !methodType.equals(MethodType.methodType(boolean.class, recordClass, Object.class))) 358 throw new IllegalArgumentException("Bad method type: " + methodType); 359 yield makeEquals(recordClass, getterList); 360 } 361 case "hashCode" -> { 362 if (methodType != null && !methodType.equals(MethodType.methodType(int.class, recordClass))) 363 throw new IllegalArgumentException("Bad method type: " + methodType); 364 yield makeHashCode(recordClass, getterList); 365 } 366 case "toString" -> { 367 if (methodType != null && !methodType.equals(MethodType.methodType(String.class, recordClass))) 368 throw new IllegalArgumentException("Bad method type: " + methodType); 369 List<String> nameList = "".equals(names) ? List.of() : List.of(names.split(";")); 370 if (nameList.size() != getterList.size()) 371 throw new IllegalArgumentException("Name list and accessor list do not match"); 372 yield makeToString(recordClass, getterList, nameList); 373 } 374 default -> throw new IllegalArgumentException(methodName); 375 }; 376 return methodType != null ? new ConstantCallSite(handle) : handle; 377 } 378 } 379