1/* 2 * Copyright (c) 2014, 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. 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 26package java.lang.invoke; 27 28import static java.lang.invoke.MethodHandleStatics.UNSAFE; 29 30final class VarHandles { 31 32 static VarHandle makeFieldHandle(MemberName f, Class<?> refc, Class<?> type, boolean isWriteAllowedOnFinalFields) { 33 if (!f.isStatic()) { 34 long foffset = MethodHandleNatives.objectFieldOffset(f); 35 if (!type.isPrimitive()) { 36 return f.isFinal() && !isWriteAllowedOnFinalFields 37 ? new VarHandleObjects.FieldInstanceReadOnly(refc, foffset, type) 38 : new VarHandleObjects.FieldInstanceReadWrite(refc, foffset, type); 39 } 40 else if (type == boolean.class) { 41 return f.isFinal() && !isWriteAllowedOnFinalFields 42 ? new VarHandleBooleans.FieldInstanceReadOnly(refc, foffset) 43 : new VarHandleBooleans.FieldInstanceReadWrite(refc, foffset); 44 } 45 else if (type == byte.class) { 46 return f.isFinal() && !isWriteAllowedOnFinalFields 47 ? new VarHandleBytes.FieldInstanceReadOnly(refc, foffset) 48 : new VarHandleBytes.FieldInstanceReadWrite(refc, foffset); 49 } 50 else if (type == short.class) { 51 return f.isFinal() && !isWriteAllowedOnFinalFields 52 ? new VarHandleShorts.FieldInstanceReadOnly(refc, foffset) 53 : new VarHandleShorts.FieldInstanceReadWrite(refc, foffset); 54 } 55 else if (type == char.class) { 56 return f.isFinal() && !isWriteAllowedOnFinalFields 57 ? new VarHandleChars.FieldInstanceReadOnly(refc, foffset) 58 : new VarHandleChars.FieldInstanceReadWrite(refc, foffset); 59 } 60 else if (type == int.class) { 61 return f.isFinal() && !isWriteAllowedOnFinalFields 62 ? new VarHandleInts.FieldInstanceReadOnly(refc, foffset) 63 : new VarHandleInts.FieldInstanceReadWrite(refc, foffset); 64 } 65 else if (type == long.class) { 66 return f.isFinal() && !isWriteAllowedOnFinalFields 67 ? new VarHandleLongs.FieldInstanceReadOnly(refc, foffset) 68 : new VarHandleLongs.FieldInstanceReadWrite(refc, foffset); 69 } 70 else if (type == float.class) { 71 return f.isFinal() && !isWriteAllowedOnFinalFields 72 ? new VarHandleFloats.FieldInstanceReadOnly(refc, foffset) 73 : new VarHandleFloats.FieldInstanceReadWrite(refc, foffset); 74 } 75 else if (type == double.class) { 76 return f.isFinal() && !isWriteAllowedOnFinalFields 77 ? new VarHandleDoubles.FieldInstanceReadOnly(refc, foffset) 78 : new VarHandleDoubles.FieldInstanceReadWrite(refc, foffset); 79 } 80 else { 81 throw new UnsupportedOperationException(); 82 } 83 } 84 else { 85 // TODO This is not lazy on first invocation 86 // and might cause some circular initialization issues 87 88 // Replace with something similar to direct method handles 89 // where a barrier is used then elided after use 90 91 if (UNSAFE.shouldBeInitialized(refc)) 92 UNSAFE.ensureClassInitialized(refc); 93 94 Object base = MethodHandleNatives.staticFieldBase(f); 95 long foffset = MethodHandleNatives.staticFieldOffset(f); 96 if (!type.isPrimitive()) { 97 return f.isFinal() && !isWriteAllowedOnFinalFields 98 ? new VarHandleObjects.FieldStaticReadOnly(base, foffset, type) 99 : new VarHandleObjects.FieldStaticReadWrite(base, foffset, type); 100 } 101 else if (type == boolean.class) { 102 return f.isFinal() && !isWriteAllowedOnFinalFields 103 ? new VarHandleBooleans.FieldStaticReadOnly(base, foffset) 104 : new VarHandleBooleans.FieldStaticReadWrite(base, foffset); 105 } 106 else if (type == byte.class) { 107 return f.isFinal() && !isWriteAllowedOnFinalFields 108 ? new VarHandleBytes.FieldStaticReadOnly(base, foffset) 109 : new VarHandleBytes.FieldStaticReadWrite(base, foffset); 110 } 111 else if (type == short.class) { 112 return f.isFinal() && !isWriteAllowedOnFinalFields 113 ? new VarHandleShorts.FieldStaticReadOnly(base, foffset) 114 : new VarHandleShorts.FieldStaticReadWrite(base, foffset); 115 } 116 else if (type == char.class) { 117 return f.isFinal() && !isWriteAllowedOnFinalFields 118 ? new VarHandleChars.FieldStaticReadOnly(base, foffset) 119 : new VarHandleChars.FieldStaticReadWrite(base, foffset); 120 } 121 else if (type == int.class) { 122 return f.isFinal() && !isWriteAllowedOnFinalFields 123 ? new VarHandleInts.FieldStaticReadOnly(base, foffset) 124 : new VarHandleInts.FieldStaticReadWrite(base, foffset); 125 } 126 else if (type == long.class) { 127 return f.isFinal() && !isWriteAllowedOnFinalFields 128 ? new VarHandleLongs.FieldStaticReadOnly(base, foffset) 129 : new VarHandleLongs.FieldStaticReadWrite(base, foffset); 130 } 131 else if (type == float.class) { 132 return f.isFinal() && !isWriteAllowedOnFinalFields 133 ? new VarHandleFloats.FieldStaticReadOnly(base, foffset) 134 : new VarHandleFloats.FieldStaticReadWrite(base, foffset); 135 } 136 else if (type == double.class) { 137 return f.isFinal() && !isWriteAllowedOnFinalFields 138 ? new VarHandleDoubles.FieldStaticReadOnly(base, foffset) 139 : new VarHandleDoubles.FieldStaticReadWrite(base, foffset); 140 } 141 else { 142 throw new UnsupportedOperationException(); 143 } 144 } 145 } 146 147 static VarHandle makeArrayElementHandle(Class<?> arrayClass) { 148 if (!arrayClass.isArray()) 149 throw new IllegalArgumentException("not an array: " + arrayClass); 150 151 Class<?> componentType = arrayClass.getComponentType(); 152 153 int aoffset = UNSAFE.arrayBaseOffset(arrayClass); 154 int ascale = UNSAFE.arrayIndexScale(arrayClass); 155 int ashift = 31 - Integer.numberOfLeadingZeros(ascale); 156 157 if (!componentType.isPrimitive()) { 158 return new VarHandleObjects.Array(aoffset, ashift, arrayClass); 159 } 160 else if (componentType == boolean.class) { 161 return new VarHandleBooleans.Array(aoffset, ashift); 162 } 163 else if (componentType == byte.class) { 164 return new VarHandleBytes.Array(aoffset, ashift); 165 } 166 else if (componentType == short.class) { 167 return new VarHandleShorts.Array(aoffset, ashift); 168 } 169 else if (componentType == char.class) { 170 return new VarHandleChars.Array(aoffset, ashift); 171 } 172 else if (componentType == int.class) { 173 return new VarHandleInts.Array(aoffset, ashift); 174 } 175 else if (componentType == long.class) { 176 return new VarHandleLongs.Array(aoffset, ashift); 177 } 178 else if (componentType == float.class) { 179 return new VarHandleFloats.Array(aoffset, ashift); 180 } 181 else if (componentType == double.class) { 182 return new VarHandleDoubles.Array(aoffset, ashift); 183 } 184 else { 185 throw new UnsupportedOperationException(); 186 } 187 } 188 189 static VarHandle byteArrayViewHandle(Class<?> viewArrayClass, 190 boolean be) { 191 if (!viewArrayClass.isArray()) 192 throw new IllegalArgumentException("not an array: " + viewArrayClass); 193 194 Class<?> viewComponentType = viewArrayClass.getComponentType(); 195 196 if (viewComponentType == long.class) { 197 return new VarHandleByteArrayAsLongs.ArrayHandle(be); 198 } 199 else if (viewComponentType == int.class) { 200 return new VarHandleByteArrayAsInts.ArrayHandle(be); 201 } 202 else if (viewComponentType == short.class) { 203 return new VarHandleByteArrayAsShorts.ArrayHandle(be); 204 } 205 else if (viewComponentType == char.class) { 206 return new VarHandleByteArrayAsChars.ArrayHandle(be); 207 } 208 else if (viewComponentType == double.class) { 209 return new VarHandleByteArrayAsDoubles.ArrayHandle(be); 210 } 211 else if (viewComponentType == float.class) { 212 return new VarHandleByteArrayAsFloats.ArrayHandle(be); 213 } 214 215 throw new UnsupportedOperationException(); 216 } 217 218 static VarHandle makeByteBufferViewHandle(Class<?> viewArrayClass, 219 boolean be) { 220 if (!viewArrayClass.isArray()) 221 throw new IllegalArgumentException("not an array: " + viewArrayClass); 222 223 Class<?> viewComponentType = viewArrayClass.getComponentType(); 224 225 if (viewComponentType == long.class) { 226 return new VarHandleByteArrayAsLongs.ByteBufferHandle(be); 227 } 228 else if (viewComponentType == int.class) { 229 return new VarHandleByteArrayAsInts.ByteBufferHandle(be); 230 } 231 else if (viewComponentType == short.class) { 232 return new VarHandleByteArrayAsShorts.ByteBufferHandle(be); 233 } 234 else if (viewComponentType == char.class) { 235 return new VarHandleByteArrayAsChars.ByteBufferHandle(be); 236 } 237 else if (viewComponentType == double.class) { 238 return new VarHandleByteArrayAsDoubles.ByteBufferHandle(be); 239 } 240 else if (viewComponentType == float.class) { 241 return new VarHandleByteArrayAsFloats.ByteBufferHandle(be); 242 } 243 244 throw new UnsupportedOperationException(); 245 } 246 247// /** 248// * A helper program to generate the VarHandleGuards class with a set of 249// * static guard methods each of which corresponds to a particular shape and 250// * performs a type check of the symbolic type descriptor with the VarHandle 251// * type descriptor before linking/invoking to the underlying operation as 252// * characterized by the operation member name on the VarForm of the 253// * VarHandle. 254// * <p> 255// * The generated class essentially encapsulates pre-compiled LambdaForms, 256// * one for each method, for the most set of common method signatures. 257// * This reduces static initialization costs, footprint costs, and circular 258// * dependencies that may arise if a class is generated per LambdaForm. 259// * <p> 260// * A maximum of L*T*S methods will be generated where L is the number of 261// * access modes kinds (or unique operation signatures) and T is the number 262// * of variable types and S is the number of shapes (such as instance field, 263// * static field, or array access). 264// * If there are 4 unique operation signatures, 5 basic types (Object, int, 265// * long, float, double), and 3 shapes then a maximum of 60 methods will be 266// * generated. However, the number is likely to be less since there 267// * be duplicate signatures. 268// * <p> 269// * Each method is annotated with @LambdaForm.Compiled to inform the runtime 270// * that such methods should be treated as if a method of a class that is the 271// * result of compiling a LambdaForm. Annotation of such methods is 272// * important for correct evaluation of certain assertions and method return 273// * type profiling in HotSpot. 274// */ 275// public static class GuardMethodGenerator { 276// 277// static final String GUARD_METHOD_SIG_TEMPLATE = "<RETURN> <NAME>_<SIGNATURE>(<PARAMS>)"; 278// 279// static final String GUARD_METHOD_TEMPLATE = 280// "@ForceInline\n" + 281// "@LambdaForm.Compiled\n" + 282// "final static <METHOD> throws Throwable {\n" + 283// " if (handle.vform.methodType_table[ad.type] == ad.symbolicMethodType) {\n" + 284// " <RESULT_ERASED>MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);<RETURN_ERASED>\n" + 285// " }\n" + 286// " else {\n" + 287// " MethodHandle mh = handle.getMethodHandle(ad.mode);\n" + 288// " <RETURN>mh.asType(ad.symbolicMethodTypeInvoker).invokeBasic(<LINK_TO_INVOKER_ARGS>);\n" + 289// " }\n" + 290// "}"; 291// 292// static final String GUARD_METHOD_TEMPLATE_V = 293// "@ForceInline\n" + 294// "@LambdaForm.Compiled\n" + 295// "final static <METHOD> throws Throwable {\n" + 296// " if (handle.vform.methodType_table[ad.type] == ad.symbolicMethodType) {\n" + 297// " MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);\n" + 298// " }\n" + 299// " else if (handle.vform.getMethodType_V(ad.type) == ad.symbolicMethodType) {\n" + 300// " MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);\n" + 301// " }\n" + 302// " else {\n" + 303// " MethodHandle mh = handle.getMethodHandle(ad.mode);\n" + 304// " mh.asType(ad.symbolicMethodTypeInvoker).invokeBasic(<LINK_TO_INVOKER_ARGS>);\n" + 305// " }\n" + 306// "}"; 307// 308// // A template for deriving the operations 309// // could be supported by annotating VarHandle directly with the 310// // operation kind and shape 311// interface VarHandleTemplate { 312// Object get(); 313// 314// void set(Object value); 315// 316// boolean compareAndSwap(Object actualValue, Object expectedValue); 317// 318// Object compareAndExchange(Object actualValue, Object expectedValue); 319// 320// Object getAndUpdate(Object value); 321// } 322// 323// static class HandleType { 324// final Class<?> receiver; 325// final Class<?>[] intermediates; 326// final Class<?> value; 327// 328// HandleType(Class<?> receiver, Class<?> value, Class<?>... intermediates) { 329// this.receiver = receiver; 330// this.intermediates = intermediates; 331// this.value = value; 332// } 333// } 334// 335// /** 336// * @param args parameters 337// */ 338// public static void main(String[] args) { 339// System.out.println("package java.lang.invoke;"); 340// System.out.println(); 341// System.out.println("import jdk.internal.vm.annotation.ForceInline;"); 342// System.out.println(); 343// System.out.println("// This class is auto-generated by " + 344// GuardMethodGenerator.class.getName() + 345// ". Do not edit."); 346// System.out.println("final class VarHandleGuards {"); 347// 348// System.out.println(); 349// 350// // Declare the stream of shapes 351// Stream<HandleType> hts = Stream.of( 352// // Object->Object 353// new HandleType(Object.class, Object.class), 354// // Object->int 355// new HandleType(Object.class, int.class), 356// // Object->long 357// new HandleType(Object.class, long.class), 358// // Object->float 359// new HandleType(Object.class, float.class), 360// // Object->double 361// new HandleType(Object.class, double.class), 362// 363// // <static>->Object 364// new HandleType(null, Object.class), 365// // <static>->int 366// new HandleType(null, int.class), 367// // <static>->long 368// new HandleType(null, long.class), 369// // <static>->float 370// new HandleType(null, float.class), 371// // <static>->double 372// new HandleType(null, double.class), 373// 374// // Array[int]->Object 375// new HandleType(Object.class, Object.class, int.class), 376// // Array[int]->int 377// new HandleType(Object.class, int.class, int.class), 378// // Array[int]->long 379// new HandleType(Object.class, long.class, int.class), 380// // Array[int]->float 381// new HandleType(Object.class, float.class, int.class), 382// // Array[int]->double 383// new HandleType(Object.class, double.class, int.class), 384// 385// // Array[long]->int 386// new HandleType(Object.class, int.class, long.class), 387// // Array[long]->long 388// new HandleType(Object.class, long.class, long.class) 389// ); 390// 391// hts.flatMap(ht -> Stream.of(VarHandleTemplate.class.getMethods()). 392// map(m -> generateMethodType(m, ht.receiver, ht.value, ht.intermediates))). 393// distinct(). 394// map(mt -> generateMethod(mt)). 395// forEach(s -> { 396// System.out.println(s); 397// System.out.println(); 398// }); 399// 400// System.out.println("}"); 401// } 402// 403// static MethodType generateMethodType(Method m, Class<?> receiver, Class<?> value, Class<?>... intermediates) { 404// Class<?> returnType = m.getReturnType() == Object.class 405// ? value : m.getReturnType(); 406// 407// List<Class<?>> params = new ArrayList<>(); 408// if (receiver != null) 409// params.add(receiver); 410// for (int i = 0; i < intermediates.length; i++) { 411// params.add(intermediates[i]); 412// } 413// for (Parameter p : m.getParameters()) { 414// params.add(value); 415// } 416// return MethodType.methodType(returnType, params); 417// } 418// 419// static String generateMethod(MethodType mt) { 420// Class<?> returnType = mt.returnType(); 421// 422// LinkedHashMap<String, Class<?>> params = new LinkedHashMap<>(); 423// params.put("handle", VarHandle.class); 424// for (int i = 0; i < mt.parameterCount(); i++) { 425// params.put("arg" + i, mt.parameterType(i)); 426// } 427// params.put("ad", VarHandle.AccessDescriptor.class); 428// 429// // Generate method signature line 430// String RETURN = className(returnType); 431// String NAME = "guard"; 432// String SIGNATURE = getSignature(mt); 433// String PARAMS = params.entrySet().stream(). 434// map(e -> className(e.getValue()) + " " + e.getKey()). 435// collect(joining(", ")); 436// String METHOD = GUARD_METHOD_SIG_TEMPLATE. 437// replace("<RETURN>", RETURN). 438// replace("<NAME>", NAME). 439// replace("<SIGNATURE>", SIGNATURE). 440// replace("<PARAMS>", PARAMS); 441// 442// // Generate method 443// params.remove("ad"); 444// 445// List<String> LINK_TO_STATIC_ARGS = params.keySet().stream(). 446// collect(toList()); 447// LINK_TO_STATIC_ARGS.add("handle.vform.getMemberName(ad.mode)"); 448// List<String> LINK_TO_STATIC_ARGS_V = params.keySet().stream(). 449// collect(toList()); 450// LINK_TO_STATIC_ARGS_V.add("handle.vform.getMemberName_V(ad.mode)"); 451// 452// List<String> LINK_TO_INVOKER_ARGS = params.keySet().stream(). 453// collect(toList()); 454// 455// RETURN = returnType == void.class 456// ? "" 457// : returnType == Object.class 458// ? "return " 459// : "return (" + returnType.getName() + ") "; 460// 461// String RESULT_ERASED = returnType == void.class 462// ? "" 463// : returnType != Object.class 464// ? "return (" + returnType.getName() + ") " 465// : "Object r = "; 466// 467// String RETURN_ERASED = returnType != Object.class 468// ? "" 469// : " return ad.returnType.cast(r);"; 470// 471// String template = returnType == void.class 472// ? GUARD_METHOD_TEMPLATE_V 473// : GUARD_METHOD_TEMPLATE; 474// return template. 475// replace("<METHOD>", METHOD). 476// replace("<NAME>", NAME). 477// replaceAll("<RETURN>", RETURN). 478// replace("<RESULT_ERASED>", RESULT_ERASED). 479// replace("<RETURN_ERASED>", RETURN_ERASED). 480// replaceAll("<LINK_TO_STATIC_ARGS>", LINK_TO_STATIC_ARGS.stream(). 481// collect(joining(", "))). 482// replaceAll("<LINK_TO_STATIC_ARGS_V>", LINK_TO_STATIC_ARGS_V.stream(). 483// collect(joining(", "))). 484// replace("<LINK_TO_INVOKER_ARGS>", LINK_TO_INVOKER_ARGS.stream(). 485// collect(joining(", "))) 486// ; 487// } 488// 489// static String className(Class<?> c) { 490// String n = c.getName(); 491// if (n.startsWith("java.lang.")) { 492// n = n.replace("java.lang.", ""); 493// if (n.startsWith("invoke.")) { 494// n = n.replace("invoke.", ""); 495// } 496// } 497// return n.replace('$', '.'); 498// } 499// 500// static String getSignature(MethodType m) { 501// StringBuilder sb = new StringBuilder(m.parameterCount() + 1); 502// 503// for (int i = 0; i < m.parameterCount(); i++) { 504// Class<?> pt = m.parameterType(i); 505// sb.append(getCharType(pt)); 506// } 507// 508// sb.append('_').append(getCharType(m.returnType())); 509// 510// return sb.toString(); 511// } 512// 513// static char getCharType(Class<?> pt) { 514// if (pt == void.class) { 515// return 'V'; 516// } 517// else if (!pt.isPrimitive()) { 518// return 'L'; 519// } 520// else if (pt == boolean.class) { 521// return 'Z'; 522// } 523// else if (pt == int.class) { 524// return 'I'; 525// } 526// else if (pt == long.class) { 527// return 'J'; 528// } 529// else if (pt == float.class) { 530// return 'F'; 531// } 532// else if (pt == double.class) { 533// return 'D'; 534// } 535// else { 536// throw new IllegalStateException(pt.getName()); 537// } 538// } 539// } 540} 541