1 /* 2 * Copyright (c) 2017, 2020, 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 /** 41 * Bootstrap methods for state-driven implementations of core methods, 42 * including {@link Object#equals(Object)}, {@link Object#hashCode()}, and 43 * {@link Object#toString()}. These methods may be used, for example, by 44 * Java compiler implementations to implement the bodies of {@link Object} 45 * methods for record classes. 46 * 47 * @since 16 48 */ 49 public class ObjectMethods { 50 ObjectMethods()51 private ObjectMethods() { } 52 53 private static final MethodType DESCRIPTOR_MT = MethodType.methodType(MethodType.class); 54 private static final MethodType NAMES_MT = MethodType.methodType(List.class); 55 private static final MethodHandle FALSE = MethodHandles.constant(boolean.class, false); 56 private static final MethodHandle TRUE = MethodHandles.constant(boolean.class, true); 57 private static final MethodHandle ZERO = MethodHandles.constant(int.class, 0); 58 private static final MethodHandle CLASS_IS_INSTANCE; 59 private static final MethodHandle OBJECT_EQUALS; 60 private static final MethodHandle OBJECTS_EQUALS; 61 private static final MethodHandle OBJECTS_HASHCODE; 62 private static final MethodHandle OBJECTS_TOSTRING; 63 private static final MethodHandle OBJECT_EQ; 64 private static final MethodHandle OBJECT_HASHCODE; 65 private static final MethodHandle OBJECT_TO_STRING; 66 private static final MethodHandle STRING_FORMAT; 67 private static final MethodHandle HASH_COMBINER; 68 69 private static final HashMap<Class<?>, MethodHandle> primitiveEquals = new HashMap<>(); 70 private static final HashMap<Class<?>, MethodHandle> primitiveHashers = new HashMap<>(); 71 private static final HashMap<Class<?>, MethodHandle> primitiveToString = new HashMap<>(); 72 73 static { 74 try { 75 Class<ObjectMethods> OBJECT_METHODS_CLASS = ObjectMethods.class; 76 MethodHandles.Lookup publicLookup = MethodHandles.publicLookup(); 77 MethodHandles.Lookup lookup = MethodHandles.lookup(); 78 79 ClassLoader loader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() { 80 @Override public ClassLoader run() { return ClassLoader.getPlatformClassLoader(); } 81 }); 82 83 CLASS_IS_INSTANCE = publicLookup.findVirtual(Class.class, "isInstance", 84 MethodType.methodType(boolean.class, Object.class)); 85 OBJECT_EQUALS = publicLookup.findVirtual(Object.class, "equals", 86 MethodType.methodType(boolean.class, Object.class)); 87 OBJECT_HASHCODE = publicLookup.findVirtual(Object.class, "hashCode", 88 MethodType.fromMethodDescriptorString("()I", loader)); 89 OBJECT_TO_STRING = publicLookup.findVirtual(Object.class, "toString", 90 MethodType.methodType(String.class)); 91 STRING_FORMAT = publicLookup.findStatic(String.class, "format", 92 MethodType.methodType(String.class, String.class, Object[].class)); 93 OBJECTS_EQUALS = publicLookup.findStatic(Objects.class, "equals", 94 MethodType.methodType(boolean.class, Object.class, Object.class)); 95 OBJECTS_HASHCODE = publicLookup.findStatic(Objects.class, "hashCode", 96 MethodType.methodType(int.class, Object.class)); 97 OBJECTS_TOSTRING = publicLookup.findStatic(Objects.class, "toString", 98 MethodType.methodType(String.class, Object.class)); 99 100 OBJECT_EQ = lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 101 MethodType.methodType(boolean.class, Object.class, Object.class)); 102 HASH_COMBINER = lookup.findStatic(OBJECT_METHODS_CLASS, "hashCombiner", 103 MethodType.fromMethodDescriptorString("(II)I", loader)); 104 primitiveEquals.put(byte.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))105 primitiveEquals.put(byte.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 106 MethodType.fromMethodDescriptorString("(BB)Z", loader))); primitiveEquals.put(short.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))107 primitiveEquals.put(short.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 108 MethodType.fromMethodDescriptorString("(SS)Z", loader))); primitiveEquals.put(char.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))109 primitiveEquals.put(char.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 110 MethodType.fromMethodDescriptorString("(CC)Z", loader))); primitiveEquals.put(int.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))111 primitiveEquals.put(int.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 112 MethodType.fromMethodDescriptorString("(II)Z", loader))); primitiveEquals.put(long.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))113 primitiveEquals.put(long.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 114 MethodType.fromMethodDescriptorString("(JJ)Z", loader))); primitiveEquals.put(float.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))115 primitiveEquals.put(float.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 116 MethodType.fromMethodDescriptorString("(FF)Z", loader))); primitiveEquals.put(double.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))117 primitiveEquals.put(double.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 118 MethodType.fromMethodDescriptorString("(DD)Z", loader))); primitiveEquals.put(boolean.class, lookup.findStatic(OBJECT_METHODS_CLASS, R, MethodType.fromMethodDescriptorString(R, loader)))119 primitiveEquals.put(boolean.class, lookup.findStatic(OBJECT_METHODS_CLASS, "eq", 120 MethodType.fromMethodDescriptorString("(ZZ)Z", loader))); 121 primitiveHashers.put(byte.class, lookup.findStatic(Byte.class, R, MethodType.fromMethodDescriptorString(R, loader)))122 primitiveHashers.put(byte.class, lookup.findStatic(Byte.class, "hashCode", 123 MethodType.fromMethodDescriptorString("(B)I", loader))); primitiveHashers.put(short.class, lookup.findStatic(Short.class, R, MethodType.fromMethodDescriptorString(R, loader)))124 primitiveHashers.put(short.class, lookup.findStatic(Short.class, "hashCode", 125 MethodType.fromMethodDescriptorString("(S)I", loader))); primitiveHashers.put(char.class, lookup.findStatic(Character.class, R, MethodType.fromMethodDescriptorString(R, loader)))126 primitiveHashers.put(char.class, lookup.findStatic(Character.class, "hashCode", 127 MethodType.fromMethodDescriptorString("(C)I", loader))); primitiveHashers.put(int.class, lookup.findStatic(Integer.class, R, MethodType.fromMethodDescriptorString(R, loader)))128 primitiveHashers.put(int.class, lookup.findStatic(Integer.class, "hashCode", 129 MethodType.fromMethodDescriptorString("(I)I", loader))); primitiveHashers.put(long.class, lookup.findStatic(Long.class, R, MethodType.fromMethodDescriptorString(R, loader)))130 primitiveHashers.put(long.class, lookup.findStatic(Long.class, "hashCode", 131 MethodType.fromMethodDescriptorString("(J)I", loader))); primitiveHashers.put(float.class, lookup.findStatic(Float.class, R, MethodType.fromMethodDescriptorString(R, loader)))132 primitiveHashers.put(float.class, lookup.findStatic(Float.class, "hashCode", 133 MethodType.fromMethodDescriptorString("(F)I", loader))); primitiveHashers.put(double.class, lookup.findStatic(Double.class, R, MethodType.fromMethodDescriptorString(R, loader)))134 primitiveHashers.put(double.class, lookup.findStatic(Double.class, "hashCode", 135 MethodType.fromMethodDescriptorString("(D)I", loader))); primitiveHashers.put(boolean.class, lookup.findStatic(Boolean.class, R, MethodType.fromMethodDescriptorString(R, loader)))136 primitiveHashers.put(boolean.class, lookup.findStatic(Boolean.class, "hashCode", 137 MethodType.fromMethodDescriptorString("(Z)I", loader))); 138 primitiveToString.put(byte.class, lookup.findStatic(Byte.class, R, MethodType.methodType(String.class, byte.class)))139 primitiveToString.put(byte.class, lookup.findStatic(Byte.class, "toString", 140 MethodType.methodType(String.class, byte.class))); primitiveToString.put(short.class, lookup.findStatic(Short.class, R, MethodType.methodType(String.class, short.class)))141 primitiveToString.put(short.class, lookup.findStatic(Short.class, "toString", 142 MethodType.methodType(String.class, short.class))); primitiveToString.put(char.class, lookup.findStatic(Character.class, R, MethodType.methodType(String.class, char.class)))143 primitiveToString.put(char.class, lookup.findStatic(Character.class, "toString", 144 MethodType.methodType(String.class, char.class))); primitiveToString.put(int.class, lookup.findStatic(Integer.class, R, MethodType.methodType(String.class, int.class)))145 primitiveToString.put(int.class, lookup.findStatic(Integer.class, "toString", 146 MethodType.methodType(String.class, int.class))); primitiveToString.put(long.class, lookup.findStatic(Long.class, R, MethodType.methodType(String.class, long.class)))147 primitiveToString.put(long.class, lookup.findStatic(Long.class, "toString", 148 MethodType.methodType(String.class, long.class))); primitiveToString.put(float.class, lookup.findStatic(Float.class, R, MethodType.methodType(String.class, float.class)))149 primitiveToString.put(float.class, lookup.findStatic(Float.class, "toString", 150 MethodType.methodType(String.class, float.class))); primitiveToString.put(double.class, lookup.findStatic(Double.class, R, MethodType.methodType(String.class, double.class)))151 primitiveToString.put(double.class, lookup.findStatic(Double.class, "toString", 152 MethodType.methodType(String.class, double.class))); primitiveToString.put(boolean.class, lookup.findStatic(Boolean.class, R, MethodType.methodType(String.class, boolean.class)))153 primitiveToString.put(boolean.class, lookup.findStatic(Boolean.class, "toString", 154 MethodType.methodType(String.class, boolean.class))); 155 } 156 catch (ReflectiveOperationException e) { 157 throw new RuntimeException(e); 158 } 159 } 160 hashCombiner(int x, int y)161 private static int hashCombiner(int x, int y) { 162 return x*31 + y; 163 } 164 eq(Object a, Object b)165 private static boolean eq(Object a, Object b) { return a == b; } eq(byte a, byte b)166 private static boolean eq(byte a, byte b) { return a == b; } eq(short a, short b)167 private static boolean eq(short a, short b) { return a == b; } eq(char a, char b)168 private static boolean eq(char a, char b) { return a == b; } eq(int a, int b)169 private static boolean eq(int a, int b) { return a == b; } eq(long a, long b)170 private static boolean eq(long a, long b) { return a == b; } eq(float a, float b)171 private static boolean eq(float a, float b) { return Float.compare(a, b) == 0; } eq(double a, double b)172 private static boolean eq(double a, double b) { return Double.compare(a, b) == 0; } eq(boolean a, boolean b)173 private static boolean eq(boolean a, boolean b) { return a == b; } 174 175 /** Get the method handle for combining two values of a given type */ equalator(Class<?> clazz)176 private static MethodHandle equalator(Class<?> clazz) { 177 return (clazz.isPrimitive() 178 ? primitiveEquals.get(clazz) 179 : OBJECTS_EQUALS.asType(MethodType.methodType(boolean.class, clazz, clazz))); 180 } 181 182 /** Get the hasher for a value of a given type */ hasher(Class<?> clazz)183 private static MethodHandle hasher(Class<?> clazz) { 184 return (clazz.isPrimitive() 185 ? primitiveHashers.get(clazz) 186 : OBJECTS_HASHCODE.asType(MethodType.methodType(int.class, clazz))); 187 } 188 189 /** Get the stringifier for a value of a given type */ stringifier(Class<?> clazz)190 private static MethodHandle stringifier(Class<?> clazz) { 191 return (clazz.isPrimitive() 192 ? primitiveToString.get(clazz) 193 : OBJECTS_TOSTRING.asType(MethodType.methodType(String.class, clazz))); 194 } 195 196 /** 197 * Generates a method handle for the {@code equals} method for a given data class 198 * @param receiverClass the data class 199 * @param getters the list of getters 200 * @return the method handle 201 */ makeEquals(Class<?> receiverClass, List<MethodHandle> getters)202 private static MethodHandle makeEquals(Class<?> receiverClass, 203 List<MethodHandle> getters) { 204 MethodType rr = MethodType.methodType(boolean.class, receiverClass, receiverClass); 205 MethodType ro = MethodType.methodType(boolean.class, receiverClass, Object.class); 206 MethodHandle instanceFalse = MethodHandles.dropArguments(FALSE, 0, receiverClass, Object.class); // (RO)Z 207 MethodHandle instanceTrue = MethodHandles.dropArguments(TRUE, 0, receiverClass, Object.class); // (RO)Z 208 MethodHandle isSameObject = OBJECT_EQ.asType(ro); // (RO)Z 209 MethodHandle isInstance = MethodHandles.dropArguments(CLASS_IS_INSTANCE.bindTo(receiverClass), 0, receiverClass); // (RO)Z 210 MethodHandle accumulator = MethodHandles.dropArguments(TRUE, 0, receiverClass, receiverClass); // (RR)Z 211 212 for (MethodHandle getter : getters) { 213 MethodHandle equalator = equalator(getter.type().returnType()); // (TT)Z 214 MethodHandle thisFieldEqual = MethodHandles.filterArguments(equalator, 0, getter, getter); // (RR)Z 215 accumulator = MethodHandles.guardWithTest(thisFieldEqual, accumulator, instanceFalse.asType(rr)); 216 } 217 218 return MethodHandles.guardWithTest(isSameObject, 219 instanceTrue, 220 MethodHandles.guardWithTest(isInstance, accumulator.asType(ro), instanceFalse)); 221 } 222 223 /** 224 * Generates a method handle for the {@code hashCode} method for a given data class 225 * @param receiverClass the data class 226 * @param getters the list of getters 227 * @return the method handle 228 */ makeHashCode(Class<?> receiverClass, List<MethodHandle> getters)229 private static MethodHandle makeHashCode(Class<?> receiverClass, 230 List<MethodHandle> getters) { 231 MethodHandle accumulator = MethodHandles.dropArguments(ZERO, 0, receiverClass); // (R)I 232 233 // @@@ Use loop combinator instead? 234 for (MethodHandle getter : getters) { 235 MethodHandle hasher = hasher(getter.type().returnType()); // (T)I 236 MethodHandle hashThisField = MethodHandles.filterArguments(hasher, 0, getter); // (R)I 237 MethodHandle combineHashes = MethodHandles.filterArguments(HASH_COMBINER, 0, accumulator, hashThisField); // (RR)I 238 accumulator = MethodHandles.permuteArguments(combineHashes, accumulator.type(), 0, 0); // adapt (R)I to (RR)I 239 } 240 241 return accumulator; 242 } 243 244 /** 245 * Generates a method handle for the {@code toString} method for a given data class 246 * @param receiverClass the data class 247 * @param getters the list of getters 248 * @param names the names 249 * @return the method handle 250 */ makeToString(Class<?> receiverClass, List<MethodHandle> getters, List<String> names)251 private static MethodHandle makeToString(Class<?> receiverClass, 252 List<MethodHandle> getters, 253 List<String> names) { 254 // This is a pretty lousy algorithm; we spread the receiver over N places, 255 // apply the N getters, apply N toString operations, and concat the result with String.format 256 // Better to use String.format directly, or delegate to StringConcatFactory 257 // Also probably want some quoting around String components 258 259 assert getters.size() == names.size(); 260 261 int[] invArgs = new int[getters.size()]; 262 Arrays.fill(invArgs, 0); 263 MethodHandle[] filters = new MethodHandle[getters.size()]; 264 StringBuilder sb = new StringBuilder(); 265 sb.append(receiverClass.getSimpleName()).append("["); 266 for (int i=0; i<getters.size(); i++) { 267 MethodHandle getter = getters.get(i); // (R)T 268 MethodHandle stringify = stringifier(getter.type().returnType()); // (T)String 269 MethodHandle stringifyThisField = MethodHandles.filterArguments(stringify, 0, getter); // (R)String 270 filters[i] = stringifyThisField; 271 sb.append(names.get(i)).append("=%s"); 272 if (i != getters.size() - 1) 273 sb.append(", "); 274 } 275 sb.append(']'); 276 String formatString = sb.toString(); 277 MethodHandle formatter = MethodHandles.insertArguments(STRING_FORMAT, 0, formatString) 278 .asCollector(String[].class, getters.size()); // (R*)String 279 if (getters.size() == 0) { 280 // Add back extra R 281 formatter = MethodHandles.dropArguments(formatter, 0, receiverClass); 282 } 283 else { 284 MethodHandle filtered = MethodHandles.filterArguments(formatter, 0, filters); 285 formatter = MethodHandles.permuteArguments(filtered, MethodType.methodType(String.class, receiverClass), invArgs); 286 } 287 288 return formatter; 289 } 290 291 /** 292 * Bootstrap method to generate the {@link Object#equals(Object)}, 293 * {@link Object#hashCode()}, and {@link Object#toString()} methods, based 294 * on a description of the component names and accessor methods, for either 295 * {@code invokedynamic} call sites or dynamic constant pool entries. 296 * 297 * For more detail on the semantics of the generated methods see the specification 298 * of {@link java.lang.Record#equals(Object)}, {@link java.lang.Record#hashCode()} and 299 * {@link java.lang.Record#toString()}. 300 * 301 * 302 * @param lookup Every bootstrap method is expected to have a {@code lookup} 303 * which usually represents a lookup context with the 304 * accessibility privileges of the caller. This is because 305 * {@code invokedynamic} call sites always provide a {@code lookup} 306 * to the corresponding bootstrap method, but this method just 307 * ignores the {@code lookup} parameter 308 * @param methodName the name of the method to generate, which must be one of 309 * {@code "equals"}, {@code "hashCode"}, or {@code "toString"} 310 * @param type a {@link MethodType} corresponding the descriptor type 311 * for the method, which must correspond to the descriptor 312 * for the corresponding {@link Object} method, if linking 313 * an {@code invokedynamic} call site, or the 314 * constant {@code MethodHandle.class}, if linking a 315 * dynamic constant 316 * @param recordClass the record class hosting the record components 317 * @param names the list of component names, joined into a string 318 * separated by ";", or the empty string if there are no 319 * components. Maybe be null, if the {@code methodName} 320 * is {@code "equals"} or {@code "hashCode"}. 321 * @param getters method handles for the accessor methods for the components 322 * @return a call site if invoked by indy, or a method handle 323 * if invoked by a condy 324 * @throws IllegalArgumentException if the bootstrap arguments are invalid 325 * or inconsistent 326 * @throws Throwable if any exception is thrown during call site construction 327 */ bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type, Class<?> recordClass, String names, MethodHandle... getters)328 public static Object bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type, 329 Class<?> recordClass, 330 String names, 331 MethodHandle... getters) throws Throwable { 332 MethodType methodType; 333 if (type instanceof MethodType) 334 methodType = (MethodType) type; 335 else { 336 methodType = null; 337 if (!MethodHandle.class.equals(type)) 338 throw new IllegalArgumentException(type.toString()); 339 } 340 List<MethodHandle> getterList = List.of(getters); 341 MethodHandle handle; 342 switch (methodName) { 343 case "equals": 344 if (methodType != null && !methodType.equals(MethodType.methodType(boolean.class, recordClass, Object.class))) 345 throw new IllegalArgumentException("Bad method type: " + methodType); 346 handle = makeEquals(recordClass, getterList); 347 return methodType != null ? new ConstantCallSite(handle) : handle; 348 case "hashCode": 349 if (methodType != null && !methodType.equals(MethodType.methodType(int.class, recordClass))) 350 throw new IllegalArgumentException("Bad method type: " + methodType); 351 handle = makeHashCode(recordClass, getterList); 352 return methodType != null ? new ConstantCallSite(handle) : handle; 353 case "toString": 354 if (methodType != null && !methodType.equals(MethodType.methodType(String.class, recordClass))) 355 throw new IllegalArgumentException("Bad method type: " + methodType); 356 List<String> nameList = "".equals(names) ? List.of() : List.of(names.split(";")); 357 if (nameList.size() != getterList.size()) 358 throw new IllegalArgumentException("Name list and accessor list do not match"); 359 handle = makeToString(recordClass, getterList, nameList); 360 return methodType != null ? new ConstantCallSite(handle) : handle; 361 default: 362 throw new IllegalArgumentException(methodName); 363 } 364 } 365 } 366