1 /* 2 * Copyright (c) 2008, 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.invoke; 27 28 import jdk.internal.misc.Unsafe; 29 import jdk.internal.vm.annotation.ForceInline; 30 import jdk.internal.vm.annotation.Stable; 31 import sun.invoke.util.ValueConversions; 32 import sun.invoke.util.VerifyAccess; 33 import sun.invoke.util.VerifyType; 34 import sun.invoke.util.Wrapper; 35 36 import java.lang.ref.WeakReference; 37 import java.util.Arrays; 38 import java.util.Objects; 39 import java.util.function.Function; 40 41 import static java.lang.invoke.LambdaForm.*; 42 import static java.lang.invoke.LambdaForm.Kind.*; 43 import static java.lang.invoke.MethodHandleNatives.Constants.*; 44 import static java.lang.invoke.MethodHandleStatics.UNSAFE; 45 import static java.lang.invoke.MethodHandleStatics.newInternalError; 46 import static java.lang.invoke.MethodTypeForm.*; 47 48 /** 49 * The flavor of method handle which implements a constant reference 50 * to a class member. 51 * @author jrose 52 */ 53 class DirectMethodHandle extends MethodHandle { 54 final MemberName member; 55 final boolean crackable; 56 57 // Constructors and factory methods in this class *must* be package scoped or private. DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member, boolean crackable)58 private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member, boolean crackable) { 59 super(mtype, form); 60 if (!member.isResolved()) throw new InternalError(); 61 62 if (member.getDeclaringClass().isInterface() && 63 member.getReferenceKind() == REF_invokeInterface && 64 member.isMethod() && !member.isAbstract()) { 65 // Check for corner case: invokeinterface of Object method 66 MemberName m = new MemberName(Object.class, member.getName(), member.getMethodType(), member.getReferenceKind()); 67 m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null, LM_TRUSTED); 68 if (m != null && m.isPublic()) { 69 assert(member.getReferenceKind() == m.getReferenceKind()); // else this.form is wrong 70 member = m; 71 } 72 } 73 74 this.member = member; 75 this.crackable = crackable; 76 } 77 78 // Factory methods: make(byte refKind, Class<?> refc, MemberName member, Class<?> callerClass)79 static DirectMethodHandle make(byte refKind, Class<?> refc, MemberName member, Class<?> callerClass) { 80 MethodType mtype = member.getMethodOrFieldType(); 81 if (!member.isStatic()) { 82 if (!member.getDeclaringClass().isAssignableFrom(refc) || member.isConstructor()) 83 throw new InternalError(member.toString()); 84 mtype = mtype.insertParameterTypes(0, refc); 85 } 86 if (!member.isField()) { 87 // refKind reflects the original type of lookup via findSpecial or 88 // findVirtual etc. 89 return switch (refKind) { 90 case REF_invokeSpecial -> { 91 member = member.asSpecial(); 92 // if caller is an interface we need to adapt to get the 93 // receiver check inserted 94 if (callerClass == null) { 95 throw new InternalError("callerClass must not be null for REF_invokeSpecial"); 96 } 97 LambdaForm lform = preparedLambdaForm(member, callerClass.isInterface()); 98 yield new Special(mtype, lform, member, true, callerClass); 99 } 100 case REF_invokeInterface -> { 101 // for interfaces we always need the receiver typecheck, 102 // so we always pass 'true' to ensure we adapt if needed 103 // to include the REF_invokeSpecial case 104 LambdaForm lform = preparedLambdaForm(member, true); 105 yield new Interface(mtype, lform, member, true, refc); 106 } 107 default -> { 108 LambdaForm lform = preparedLambdaForm(member); 109 yield new DirectMethodHandle(mtype, lform, member, true); 110 } 111 }; 112 } else { 113 LambdaForm lform = preparedFieldLambdaForm(member); 114 if (member.isStatic()) { 115 long offset = MethodHandleNatives.staticFieldOffset(member); 116 Object base = MethodHandleNatives.staticFieldBase(member); 117 return new StaticAccessor(mtype, lform, member, true, base, offset); 118 } else { 119 long offset = MethodHandleNatives.objectFieldOffset(member); 120 assert(offset == (int)offset); 121 return new Accessor(mtype, lform, member, true, (int)offset); 122 } 123 } 124 } 125 static DirectMethodHandle make(Class<?> refc, MemberName member) { 126 byte refKind = member.getReferenceKind(); 127 if (refKind == REF_invokeSpecial) 128 refKind = REF_invokeVirtual; 129 return make(refKind, refc, member, null /* no callerClass context */); 130 } 131 static DirectMethodHandle make(MemberName member) { 132 if (member.isConstructor()) 133 return makeAllocator(member); 134 return make(member.getDeclaringClass(), member); 135 } 136 private static DirectMethodHandle makeAllocator(MemberName ctor) { 137 assert(ctor.isConstructor() && ctor.getName().equals("<init>")); 138 Class<?> instanceClass = ctor.getDeclaringClass(); 139 ctor = ctor.asConstructor(); 140 assert(ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor; 141 MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass); 142 LambdaForm lform = preparedLambdaForm(ctor); 143 MemberName init = ctor.asSpecial(); 144 assert(init.getMethodType().returnType() == void.class); 145 return new Constructor(mtype, lform, ctor, true, init, instanceClass); 146 } 147 148 @Override 149 BoundMethodHandle rebind() { 150 return BoundMethodHandle.makeReinvoker(this); 151 } 152 153 @Override 154 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 155 assert(this.getClass() == DirectMethodHandle.class); // must override in subclasses 156 return new DirectMethodHandle(mt, lf, member, crackable); 157 } 158 159 @Override 160 MethodHandle viewAsType(MethodType newType, boolean strict) { 161 // No actual conversions, just a new view of the same method. 162 // However, we must not expose a DMH that is crackable into a 163 // MethodHandleInfo, so we return a cloned, uncrackable DMH 164 assert(viewAsTypeChecks(newType, strict)); 165 assert(this.getClass() == DirectMethodHandle.class); // must override in subclasses 166 return new DirectMethodHandle(newType, form, member, false); 167 } 168 169 @Override 170 boolean isCrackable() { 171 return crackable; 172 } 173 174 @Override 175 String internalProperties() { 176 return "\n& DMH.MN="+internalMemberName(); 177 } 178 179 //// Implementation methods. 180 @Override 181 @ForceInline 182 MemberName internalMemberName() { 183 return member; 184 } 185 186 private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory(); 187 188 /** 189 * Create a LF which can invoke the given method. 190 * Cache and share this structure among all methods with 191 * the same basicType and refKind. 192 */ 193 private static LambdaForm preparedLambdaForm(MemberName m, boolean adaptToSpecialIfc) { 194 assert(m.isInvocable()) : m; // call preparedFieldLambdaForm instead 195 MethodType mtype = m.getInvocationType().basicType(); 196 assert(!m.isMethodHandleInvoke()) : m; 197 // MemberName.getReferenceKind represents the JVM optimized form of the call 198 // as distinct from the "kind" passed to DMH.make which represents the original 199 // bytecode-equivalent request. Specifically private/final methods that use a direct 200 // call have getReferenceKind adapted to REF_invokeSpecial, even though the actual 201 // invocation mode may be invokevirtual or invokeinterface. 202 int which = switch (m.getReferenceKind()) { 203 case REF_invokeVirtual -> LF_INVVIRTUAL; 204 case REF_invokeStatic -> LF_INVSTATIC; 205 case REF_invokeSpecial -> LF_INVSPECIAL; 206 case REF_invokeInterface -> LF_INVINTERFACE; 207 case REF_newInvokeSpecial -> LF_NEWINVSPECIAL; 208 default -> throw new InternalError(m.toString()); 209 }; 210 if (which == LF_INVSTATIC && shouldBeInitialized(m)) { 211 // precompute the barrier-free version: 212 preparedLambdaForm(mtype, which); 213 which = LF_INVSTATIC_INIT; 214 } 215 if (which == LF_INVSPECIAL && adaptToSpecialIfc) { 216 which = LF_INVSPECIAL_IFC; 217 } 218 LambdaForm lform = preparedLambdaForm(mtype, which); 219 maybeCompile(lform, m); 220 assert(lform.methodType().dropParameterTypes(0, 1) 221 .equals(m.getInvocationType().basicType())) 222 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType()); 223 return lform; 224 } 225 226 private static LambdaForm preparedLambdaForm(MemberName m) { 227 return preparedLambdaForm(m, false); 228 } 229 230 private static LambdaForm preparedLambdaForm(MethodType mtype, int which) { 231 LambdaForm lform = mtype.form().cachedLambdaForm(which); 232 if (lform != null) return lform; 233 lform = makePreparedLambdaForm(mtype, which); 234 return mtype.form().setCachedLambdaForm(which, lform); 235 } 236 237 static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) { 238 boolean needsInit = (which == LF_INVSTATIC_INIT); 239 boolean doesAlloc = (which == LF_NEWINVSPECIAL); 240 boolean needsReceiverCheck = (which == LF_INVINTERFACE || 241 which == LF_INVSPECIAL_IFC); 242 243 String linkerName; 244 LambdaForm.Kind kind; 245 switch (which) { 246 case LF_INVVIRTUAL: linkerName = "linkToVirtual"; kind = DIRECT_INVOKE_VIRTUAL; break; 247 case LF_INVSTATIC: linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC; break; 248 case LF_INVSTATIC_INIT:linkerName = "linkToStatic"; kind = DIRECT_INVOKE_STATIC_INIT; break; 249 case LF_INVSPECIAL_IFC:linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL_IFC; break; 250 case LF_INVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_INVOKE_SPECIAL; break; 251 case LF_INVINTERFACE: linkerName = "linkToInterface"; kind = DIRECT_INVOKE_INTERFACE; break; 252 case LF_NEWINVSPECIAL: linkerName = "linkToSpecial"; kind = DIRECT_NEW_INVOKE_SPECIAL; break; 253 default: throw new InternalError("which="+which); 254 } 255 256 MethodType mtypeWithArg = mtype.appendParameterTypes(MemberName.class); 257 if (doesAlloc) 258 mtypeWithArg = mtypeWithArg 259 .insertParameterTypes(0, Object.class) // insert newly allocated obj 260 .changeReturnType(void.class); // <init> returns void 261 MemberName linker = new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic); 262 try { 263 linker = IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, LM_TRUSTED, 264 NoSuchMethodException.class); 265 } catch (ReflectiveOperationException ex) { 266 throw newInternalError(ex); 267 } 268 final int DMH_THIS = 0; 269 final int ARG_BASE = 1; 270 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount(); 271 int nameCursor = ARG_LIMIT; 272 final int NEW_OBJ = (doesAlloc ? nameCursor++ : -1); 273 final int GET_MEMBER = nameCursor++; 274 final int CHECK_RECEIVER = (needsReceiverCheck ? nameCursor++ : -1); 275 final int LINKER_CALL = nameCursor++; 276 Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType()); 277 assert(names.length == nameCursor); 278 if (doesAlloc) { 279 // names = { argx,y,z,... new C, init method } 280 names[NEW_OBJ] = new Name(getFunction(NF_allocateInstance), names[DMH_THIS]); 281 names[GET_MEMBER] = new Name(getFunction(NF_constructorMethod), names[DMH_THIS]); 282 } else if (needsInit) { 283 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberNameEnsureInit), names[DMH_THIS]); 284 } else { 285 names[GET_MEMBER] = new Name(getFunction(NF_internalMemberName), names[DMH_THIS]); 286 } 287 assert(findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]); 288 Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER+1, Object[].class); 289 if (needsReceiverCheck) { 290 names[CHECK_RECEIVER] = new Name(getFunction(NF_checkReceiver), names[DMH_THIS], names[ARG_BASE]); 291 outArgs[0] = names[CHECK_RECEIVER]; 292 } 293 assert(outArgs[outArgs.length-1] == names[GET_MEMBER]); // look, shifted args! 294 int result = LAST_RESULT; 295 if (doesAlloc) { 296 assert(outArgs[outArgs.length-2] == names[NEW_OBJ]); // got to move this one 297 System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length-2); 298 outArgs[0] = names[NEW_OBJ]; 299 result = NEW_OBJ; 300 } 301 names[LINKER_CALL] = new Name(linker, outArgs); 302 LambdaForm lform = new LambdaForm(ARG_LIMIT, names, result, kind); 303 304 // This is a tricky bit of code. Don't send it through the LF interpreter. 305 lform.compileToBytecode(); 306 return lform; 307 } 308 309 /* assert */ static Object findDirectMethodHandle(Name name) { 310 if (name.function.equals(getFunction(NF_internalMemberName)) || 311 name.function.equals(getFunction(NF_internalMemberNameEnsureInit)) || 312 name.function.equals(getFunction(NF_constructorMethod))) { 313 assert(name.arguments.length == 1); 314 return name.arguments[0]; 315 } 316 return null; 317 } 318 319 private static void maybeCompile(LambdaForm lform, MemberName m) { 320 if (lform.vmentry == null && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class)) 321 // Help along bootstrapping... 322 lform.compileToBytecode(); 323 } 324 325 /** Static wrapper for DirectMethodHandle.internalMemberName. */ 326 @ForceInline 327 /*non-public*/ 328 static Object internalMemberName(Object mh) { 329 return ((DirectMethodHandle)mh).member; 330 } 331 332 /** Static wrapper for DirectMethodHandle.internalMemberName. 333 * This one also forces initialization. 334 */ 335 /*non-public*/ 336 static Object internalMemberNameEnsureInit(Object mh) { 337 DirectMethodHandle dmh = (DirectMethodHandle)mh; 338 dmh.ensureInitialized(); 339 return dmh.member; 340 } 341 342 /*non-public*/ 343 static boolean shouldBeInitialized(MemberName member) { 344 switch (member.getReferenceKind()) { 345 case REF_invokeStatic: 346 case REF_getStatic: 347 case REF_putStatic: 348 case REF_newInvokeSpecial: 349 break; 350 default: 351 // No need to initialize the class on this kind of member. 352 return false; 353 } 354 Class<?> cls = member.getDeclaringClass(); 355 if (cls == ValueConversions.class || 356 cls == MethodHandleImpl.class || 357 cls == Invokers.class) { 358 // These guys have lots of <clinit> DMH creation but we know 359 // the MHs will not be used until the system is booted. 360 return false; 361 } 362 if (VerifyAccess.isSamePackage(MethodHandle.class, cls) || 363 VerifyAccess.isSamePackage(ValueConversions.class, cls)) { 364 // It is a system class. It is probably in the process of 365 // being initialized, but we will help it along just to be safe. 366 if (UNSAFE.shouldBeInitialized(cls)) { 367 UNSAFE.ensureClassInitialized(cls); 368 } 369 return false; 370 } 371 return UNSAFE.shouldBeInitialized(cls); 372 } 373 374 private static class EnsureInitialized extends ClassValue<WeakReference<Thread>> { 375 @Override 376 protected WeakReference<Thread> computeValue(Class<?> type) { 377 UNSAFE.ensureClassInitialized(type); 378 if (UNSAFE.shouldBeInitialized(type)) 379 // If the previous call didn't block, this can happen. 380 // We are executing inside <clinit>. 381 return new WeakReference<>(Thread.currentThread()); 382 return null; 383 } 384 static final EnsureInitialized INSTANCE = new EnsureInitialized(); 385 } 386 387 private void ensureInitialized() { 388 if (checkInitialized(member)) { 389 // The coast is clear. Delete the <clinit> barrier. 390 updateForm(new Function<>() { 391 public LambdaForm apply(LambdaForm oldForm) { 392 return (member.isField() ? preparedFieldLambdaForm(member) 393 : preparedLambdaForm(member)); 394 } 395 }); 396 } 397 } 398 private static boolean checkInitialized(MemberName member) { 399 Class<?> defc = member.getDeclaringClass(); 400 WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc); 401 if (ref == null) { 402 return true; // the final state 403 } 404 // Somebody may still be running defc.<clinit>. 405 if (ref.refersTo(Thread.currentThread())) { 406 // If anybody is running defc.<clinit>, it is this thread. 407 if (UNSAFE.shouldBeInitialized(defc)) 408 // Yes, we are running it; keep the barrier for now. 409 return false; 410 } else { 411 // We are in a random thread. Block. 412 UNSAFE.ensureClassInitialized(defc); 413 } 414 assert(!UNSAFE.shouldBeInitialized(defc)); 415 // put it into the final state 416 EnsureInitialized.INSTANCE.remove(defc); 417 return true; 418 } 419 420 /*non-public*/ 421 static void ensureInitialized(Object mh) { 422 ((DirectMethodHandle)mh).ensureInitialized(); 423 } 424 425 /** This subclass represents invokespecial instructions. */ 426 static class Special extends DirectMethodHandle { 427 private final Class<?> caller; 428 private Special(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> caller) { 429 super(mtype, form, member, crackable); 430 this.caller = caller; 431 } 432 @Override 433 boolean isInvokeSpecial() { 434 return true; 435 } 436 @Override 437 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 438 return new Special(mt, lf, member, crackable, caller); 439 } 440 @Override 441 MethodHandle viewAsType(MethodType newType, boolean strict) { 442 assert(viewAsTypeChecks(newType, strict)); 443 return new Special(newType, form, member, false, caller); 444 } 445 Object checkReceiver(Object recv) { 446 if (!caller.isInstance(recv)) { 447 String msg = String.format("Receiver class %s is not a subclass of caller class %s", 448 recv.getClass().getName(), caller.getName()); 449 throw new IncompatibleClassChangeError(msg); 450 } 451 return recv; 452 } 453 } 454 455 /** This subclass represents invokeinterface instructions. */ 456 static class Interface extends DirectMethodHandle { 457 private final Class<?> refc; 458 private Interface(MethodType mtype, LambdaForm form, MemberName member, boolean crackable, Class<?> refc) { 459 super(mtype, form, member, crackable); 460 assert(refc.isInterface()) : refc; 461 this.refc = refc; 462 } 463 @Override 464 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 465 return new Interface(mt, lf, member, crackable, refc); 466 } 467 @Override 468 MethodHandle viewAsType(MethodType newType, boolean strict) { 469 assert(viewAsTypeChecks(newType, strict)); 470 return new Interface(newType, form, member, false, refc); 471 } 472 @Override 473 Object checkReceiver(Object recv) { 474 if (!refc.isInstance(recv)) { 475 String msg = String.format("Receiver class %s does not implement the requested interface %s", 476 recv.getClass().getName(), refc.getName()); 477 throw new IncompatibleClassChangeError(msg); 478 } 479 return recv; 480 } 481 } 482 483 /** Used for interface receiver type checks, by Interface and Special modes. */ 484 Object checkReceiver(Object recv) { 485 throw new InternalError("Should only be invoked on a subclass"); 486 } 487 488 /** This subclass handles constructor references. */ 489 static class Constructor extends DirectMethodHandle { 490 final MemberName initMethod; 491 final Class<?> instanceClass; 492 493 private Constructor(MethodType mtype, LambdaForm form, MemberName constructor, 494 boolean crackable, MemberName initMethod, Class<?> instanceClass) { 495 super(mtype, form, constructor, crackable); 496 this.initMethod = initMethod; 497 this.instanceClass = instanceClass; 498 assert(initMethod.isResolved()); 499 } 500 @Override 501 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 502 return new Constructor(mt, lf, member, crackable, initMethod, instanceClass); 503 } 504 @Override 505 MethodHandle viewAsType(MethodType newType, boolean strict) { 506 assert(viewAsTypeChecks(newType, strict)); 507 return new Constructor(newType, form, member, false, initMethod, instanceClass); 508 } 509 } 510 511 /*non-public*/ 512 static Object constructorMethod(Object mh) { 513 Constructor dmh = (Constructor)mh; 514 return dmh.initMethod; 515 } 516 517 /*non-public*/ 518 static Object allocateInstance(Object mh) throws InstantiationException { 519 Constructor dmh = (Constructor)mh; 520 return UNSAFE.allocateInstance(dmh.instanceClass); 521 } 522 523 /** This subclass handles non-static field references. */ 524 static class Accessor extends DirectMethodHandle { 525 final Class<?> fieldType; 526 final int fieldOffset; 527 private Accessor(MethodType mtype, LambdaForm form, MemberName member, 528 boolean crackable, int fieldOffset) { 529 super(mtype, form, member, crackable); 530 this.fieldType = member.getFieldType(); 531 this.fieldOffset = fieldOffset; 532 } 533 534 @Override Object checkCast(Object obj) { 535 return fieldType.cast(obj); 536 } 537 @Override 538 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 539 return new Accessor(mt, lf, member, crackable, fieldOffset); 540 } 541 @Override 542 MethodHandle viewAsType(MethodType newType, boolean strict) { 543 assert(viewAsTypeChecks(newType, strict)); 544 return new Accessor(newType, form, member, false, fieldOffset); 545 } 546 } 547 548 @ForceInline 549 /*non-public*/ 550 static long fieldOffset(Object accessorObj) { 551 // Note: We return a long because that is what Unsafe.getObject likes. 552 // We store a plain int because it is more compact. 553 return ((Accessor)accessorObj).fieldOffset; 554 } 555 556 @ForceInline 557 /*non-public*/ 558 static Object checkBase(Object obj) { 559 // Note that the object's class has already been verified, 560 // since the parameter type of the Accessor method handle 561 // is either member.getDeclaringClass or a subclass. 562 // This was verified in DirectMethodHandle.make. 563 // Therefore, the only remaining check is for null. 564 // Since this check is *not* guaranteed by Unsafe.getInt 565 // and its siblings, we need to make an explicit one here. 566 return Objects.requireNonNull(obj); 567 } 568 569 /** This subclass handles static field references. */ 570 static class StaticAccessor extends DirectMethodHandle { 571 private final Class<?> fieldType; 572 private final Object staticBase; 573 private final long staticOffset; 574 575 private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member, 576 boolean crackable, Object staticBase, long staticOffset) { 577 super(mtype, form, member, crackable); 578 this.fieldType = member.getFieldType(); 579 this.staticBase = staticBase; 580 this.staticOffset = staticOffset; 581 } 582 583 @Override Object checkCast(Object obj) { 584 return fieldType.cast(obj); 585 } 586 @Override 587 MethodHandle copyWith(MethodType mt, LambdaForm lf) { 588 return new StaticAccessor(mt, lf, member, crackable, staticBase, staticOffset); 589 } 590 @Override 591 MethodHandle viewAsType(MethodType newType, boolean strict) { 592 assert(viewAsTypeChecks(newType, strict)); 593 return new StaticAccessor(newType, form, member, false, staticBase, staticOffset); 594 } 595 } 596 597 @ForceInline 598 /*non-public*/ 599 static Object nullCheck(Object obj) { 600 return Objects.requireNonNull(obj); 601 } 602 603 @ForceInline 604 /*non-public*/ 605 static Object staticBase(Object accessorObj) { 606 return ((StaticAccessor)accessorObj).staticBase; 607 } 608 609 @ForceInline 610 /*non-public*/ 611 static long staticOffset(Object accessorObj) { 612 return ((StaticAccessor)accessorObj).staticOffset; 613 } 614 615 @ForceInline 616 /*non-public*/ 617 static Object checkCast(Object mh, Object obj) { 618 return ((DirectMethodHandle) mh).checkCast(obj); 619 } 620 621 Object checkCast(Object obj) { 622 return member.getReturnType().cast(obj); 623 } 624 625 // Caching machinery for field accessors: 626 static final byte 627 AF_GETFIELD = 0, 628 AF_PUTFIELD = 1, 629 AF_GETSTATIC = 2, 630 AF_PUTSTATIC = 3, 631 AF_GETSTATIC_INIT = 4, 632 AF_PUTSTATIC_INIT = 5, 633 AF_LIMIT = 6; 634 // Enumerate the different field kinds using Wrapper, 635 // with an extra case added for checked references. 636 static final int 637 FT_LAST_WRAPPER = Wrapper.COUNT-1, 638 FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(), 639 FT_CHECKED_REF = FT_LAST_WRAPPER+1, 640 FT_LIMIT = FT_LAST_WRAPPER+2; 641 private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) { 642 return ((formOp * FT_LIMIT * 2) 643 + (isVolatile ? FT_LIMIT : 0) 644 + ftypeKind); 645 } 646 @Stable 647 private static final LambdaForm[] ACCESSOR_FORMS 648 = new LambdaForm[afIndex(AF_LIMIT, false, 0)]; 649 static int ftypeKind(Class<?> ftype) { 650 if (ftype.isPrimitive()) 651 return Wrapper.forPrimitiveType(ftype).ordinal(); 652 else if (VerifyType.isNullReferenceConversion(Object.class, ftype)) 653 return FT_UNCHECKED_REF; 654 else 655 return FT_CHECKED_REF; 656 } 657 658 /** 659 * Create a LF which can access the given field. 660 * Cache and share this structure among all fields with 661 * the same basicType and refKind. 662 */ 663 private static LambdaForm preparedFieldLambdaForm(MemberName m) { 664 Class<?> ftype = m.getFieldType(); 665 boolean isVolatile = m.isVolatile(); 666 byte formOp = switch (m.getReferenceKind()) { 667 case REF_getField -> AF_GETFIELD; 668 case REF_putField -> AF_PUTFIELD; 669 case REF_getStatic -> AF_GETSTATIC; 670 case REF_putStatic -> AF_PUTSTATIC; 671 default -> throw new InternalError(m.toString()); 672 }; 673 if (shouldBeInitialized(m)) { 674 // precompute the barrier-free version: 675 preparedFieldLambdaForm(formOp, isVolatile, ftype); 676 assert((AF_GETSTATIC_INIT - AF_GETSTATIC) == 677 (AF_PUTSTATIC_INIT - AF_PUTSTATIC)); 678 formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC); 679 } 680 LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype); 681 maybeCompile(lform, m); 682 assert(lform.methodType().dropParameterTypes(0, 1) 683 .equals(m.getInvocationType().basicType())) 684 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType()); 685 return lform; 686 } 687 private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype) { 688 int ftypeKind = ftypeKind(ftype); 689 int afIndex = afIndex(formOp, isVolatile, ftypeKind); 690 LambdaForm lform = ACCESSOR_FORMS[afIndex]; 691 if (lform != null) return lform; 692 lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind); 693 ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS 694 return lform; 695 } 696 697 private static final Wrapper[] ALL_WRAPPERS = Wrapper.values(); 698 699 private static Kind getFieldKind(boolean isGetter, boolean isVolatile, Wrapper wrapper) { 700 if (isGetter) { 701 if (isVolatile) { 702 switch (wrapper) { 703 case BOOLEAN: return GET_BOOLEAN_VOLATILE; 704 case BYTE: return GET_BYTE_VOLATILE; 705 case SHORT: return GET_SHORT_VOLATILE; 706 case CHAR: return GET_CHAR_VOLATILE; 707 case INT: return GET_INT_VOLATILE; 708 case LONG: return GET_LONG_VOLATILE; 709 case FLOAT: return GET_FLOAT_VOLATILE; 710 case DOUBLE: return GET_DOUBLE_VOLATILE; 711 case OBJECT: return GET_REFERENCE_VOLATILE; 712 } 713 } else { 714 switch (wrapper) { 715 case BOOLEAN: return GET_BOOLEAN; 716 case BYTE: return GET_BYTE; 717 case SHORT: return GET_SHORT; 718 case CHAR: return GET_CHAR; 719 case INT: return GET_INT; 720 case LONG: return GET_LONG; 721 case FLOAT: return GET_FLOAT; 722 case DOUBLE: return GET_DOUBLE; 723 case OBJECT: return GET_REFERENCE; 724 } 725 } 726 } else { 727 if (isVolatile) { 728 switch (wrapper) { 729 case BOOLEAN: return PUT_BOOLEAN_VOLATILE; 730 case BYTE: return PUT_BYTE_VOLATILE; 731 case SHORT: return PUT_SHORT_VOLATILE; 732 case CHAR: return PUT_CHAR_VOLATILE; 733 case INT: return PUT_INT_VOLATILE; 734 case LONG: return PUT_LONG_VOLATILE; 735 case FLOAT: return PUT_FLOAT_VOLATILE; 736 case DOUBLE: return PUT_DOUBLE_VOLATILE; 737 case OBJECT: return PUT_REFERENCE_VOLATILE; 738 } 739 } else { 740 switch (wrapper) { 741 case BOOLEAN: return PUT_BOOLEAN; 742 case BYTE: return PUT_BYTE; 743 case SHORT: return PUT_SHORT; 744 case CHAR: return PUT_CHAR; 745 case INT: return PUT_INT; 746 case LONG: return PUT_LONG; 747 case FLOAT: return PUT_FLOAT; 748 case DOUBLE: return PUT_DOUBLE; 749 case OBJECT: return PUT_REFERENCE; 750 } 751 } 752 } 753 throw new AssertionError("Invalid arguments"); 754 } 755 756 static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) { 757 boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1); 758 boolean isStatic = (formOp >= AF_GETSTATIC); 759 boolean needsInit = (formOp >= AF_GETSTATIC_INIT); 760 boolean needsCast = (ftypeKind == FT_CHECKED_REF); 761 Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]); 762 Class<?> ft = fw.primitiveType(); 763 assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind); 764 765 // getObject, putIntVolatile, etc. 766 Kind kind = getFieldKind(isGetter, isVolatile, fw); 767 768 MethodType linkerType; 769 if (isGetter) 770 linkerType = MethodType.methodType(ft, Object.class, long.class); 771 else 772 linkerType = MethodType.methodType(void.class, Object.class, long.class, ft); 773 MemberName linker = new MemberName(Unsafe.class, kind.methodName, linkerType, REF_invokeVirtual); 774 try { 775 linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, LM_TRUSTED, 776 NoSuchMethodException.class); 777 } catch (ReflectiveOperationException ex) { 778 throw newInternalError(ex); 779 } 780 781 // What is the external type of the lambda form? 782 MethodType mtype; 783 if (isGetter) 784 mtype = MethodType.methodType(ft); 785 else 786 mtype = MethodType.methodType(void.class, ft); 787 mtype = mtype.basicType(); // erase short to int, etc. 788 if (!isStatic) 789 mtype = mtype.insertParameterTypes(0, Object.class); 790 final int DMH_THIS = 0; 791 final int ARG_BASE = 1; 792 final int ARG_LIMIT = ARG_BASE + mtype.parameterCount(); 793 // if this is for non-static access, the base pointer is stored at this index: 794 final int OBJ_BASE = isStatic ? -1 : ARG_BASE; 795 // if this is for write access, the value to be written is stored at this index: 796 final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1; 797 int nameCursor = ARG_LIMIT; 798 final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any 799 final int F_OFFSET = nameCursor++; // Either static offset or field offset. 800 final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1); 801 final int U_HOLDER = nameCursor++; // UNSAFE holder 802 final int INIT_BAR = (needsInit ? nameCursor++ : -1); 803 final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1); 804 final int LINKER_CALL = nameCursor++; 805 final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1); 806 final int RESULT = nameCursor-1; // either the call or the cast 807 Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType()); 808 if (needsInit) 809 names[INIT_BAR] = new Name(getFunction(NF_ensureInitialized), names[DMH_THIS]); 810 if (needsCast && !isGetter) 811 names[PRE_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[SET_VALUE]); 812 Object[] outArgs = new Object[1 + linkerType.parameterCount()]; 813 assert(outArgs.length == (isGetter ? 3 : 4)); 814 outArgs[0] = names[U_HOLDER] = new Name(getFunction(NF_UNSAFE)); 815 if (isStatic) { 816 outArgs[1] = names[F_HOLDER] = new Name(getFunction(NF_staticBase), names[DMH_THIS]); 817 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_staticOffset), names[DMH_THIS]); 818 } else { 819 outArgs[1] = names[OBJ_CHECK] = new Name(getFunction(NF_checkBase), names[OBJ_BASE]); 820 outArgs[2] = names[F_OFFSET] = new Name(getFunction(NF_fieldOffset), names[DMH_THIS]); 821 } 822 if (!isGetter) { 823 outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]); 824 } 825 for (Object a : outArgs) assert(a != null); 826 names[LINKER_CALL] = new Name(linker, outArgs); 827 if (needsCast && isGetter) 828 names[POST_CAST] = new Name(getFunction(NF_checkCast), names[DMH_THIS], names[LINKER_CALL]); 829 for (Name n : names) assert(n != null); 830 831 LambdaForm form; 832 if (needsCast || needsInit) { 833 // can't use the pre-generated form when casting and/or initializing 834 form = new LambdaForm(ARG_LIMIT, names, RESULT); 835 } else { 836 form = new LambdaForm(ARG_LIMIT, names, RESULT, kind); 837 } 838 839 if (LambdaForm.debugNames()) { 840 // add some detail to the lambdaForm debugname, 841 // significant only for debugging 842 StringBuilder nameBuilder = new StringBuilder(kind.methodName); 843 if (isStatic) { 844 nameBuilder.append("Static"); 845 } else { 846 nameBuilder.append("Field"); 847 } 848 if (needsCast) { 849 nameBuilder.append("Cast"); 850 } 851 if (needsInit) { 852 nameBuilder.append("Init"); 853 } 854 LambdaForm.associateWithDebugName(form, nameBuilder.toString()); 855 } 856 return form; 857 } 858 859 /** 860 * Pre-initialized NamedFunctions for bootstrapping purposes. 861 */ 862 static final byte NF_internalMemberName = 0, 863 NF_internalMemberNameEnsureInit = 1, 864 NF_ensureInitialized = 2, 865 NF_fieldOffset = 3, 866 NF_checkBase = 4, 867 NF_staticBase = 5, 868 NF_staticOffset = 6, 869 NF_checkCast = 7, 870 NF_allocateInstance = 8, 871 NF_constructorMethod = 9, 872 NF_UNSAFE = 10, 873 NF_checkReceiver = 11, 874 NF_LIMIT = 12; 875 876 private static final @Stable NamedFunction[] NFS = new NamedFunction[NF_LIMIT]; 877 878 private static NamedFunction getFunction(byte func) { 879 NamedFunction nf = NFS[func]; 880 if (nf != null) { 881 return nf; 882 } 883 // Each nf must be statically invocable or we get tied up in our bootstraps. 884 nf = NFS[func] = createFunction(func); 885 assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf)); 886 return nf; 887 } 888 889 private static final MethodType OBJ_OBJ_TYPE = MethodType.methodType(Object.class, Object.class); 890 891 private static final MethodType LONG_OBJ_TYPE = MethodType.methodType(long.class, Object.class); 892 893 private static NamedFunction createFunction(byte func) { 894 try { 895 switch (func) { 896 case NF_internalMemberName: 897 return getNamedFunction("internalMemberName", OBJ_OBJ_TYPE); 898 case NF_internalMemberNameEnsureInit: 899 return getNamedFunction("internalMemberNameEnsureInit", OBJ_OBJ_TYPE); 900 case NF_ensureInitialized: 901 return getNamedFunction("ensureInitialized", MethodType.methodType(void.class, Object.class)); 902 case NF_fieldOffset: 903 return getNamedFunction("fieldOffset", LONG_OBJ_TYPE); 904 case NF_checkBase: 905 return getNamedFunction("checkBase", OBJ_OBJ_TYPE); 906 case NF_staticBase: 907 return getNamedFunction("staticBase", OBJ_OBJ_TYPE); 908 case NF_staticOffset: 909 return getNamedFunction("staticOffset", LONG_OBJ_TYPE); 910 case NF_checkCast: 911 return getNamedFunction("checkCast", MethodType.methodType(Object.class, Object.class, Object.class)); 912 case NF_allocateInstance: 913 return getNamedFunction("allocateInstance", OBJ_OBJ_TYPE); 914 case NF_constructorMethod: 915 return getNamedFunction("constructorMethod", OBJ_OBJ_TYPE); 916 case NF_UNSAFE: 917 MemberName member = new MemberName(MethodHandleStatics.class, "UNSAFE", Unsafe.class, REF_getField); 918 return new NamedFunction( 919 MemberName.getFactory().resolveOrFail(REF_getField, member, 920 DirectMethodHandle.class, LM_TRUSTED, 921 NoSuchMethodException.class)); 922 case NF_checkReceiver: 923 member = new MemberName(DirectMethodHandle.class, "checkReceiver", OBJ_OBJ_TYPE, REF_invokeVirtual); 924 return new NamedFunction( 925 MemberName.getFactory().resolveOrFail(REF_invokeVirtual, member, 926 DirectMethodHandle.class, LM_TRUSTED, 927 NoSuchMethodException.class)); 928 default: 929 throw newInternalError("Unknown function: " + func); 930 } 931 } catch (ReflectiveOperationException ex) { 932 throw newInternalError(ex); 933 } 934 } 935 936 private static NamedFunction getNamedFunction(String name, MethodType type) 937 throws ReflectiveOperationException 938 { 939 MemberName member = new MemberName(DirectMethodHandle.class, name, type, REF_invokeStatic); 940 return new NamedFunction( 941 MemberName.getFactory().resolveOrFail(REF_invokeStatic, member, 942 DirectMethodHandle.class, LM_TRUSTED, 943 NoSuchMethodException.class)); 944 } 945 946 static { 947 // The Holder class will contain pre-generated DirectMethodHandles resolved 948 // speculatively using MemberName.getFactory().resolveOrNull. However, that 949 // doesn't initialize the class, which subtly breaks inlining etc. By forcing 950 // initialization of the Holder class we avoid these issues. 951 UNSAFE.ensureClassInitialized(Holder.class); 952 } 953 954 /* Placeholder class for DirectMethodHandles generated ahead of time */ 955 final class Holder {} 956 } 957