MethodHandleNatives.java revision 12745:f068a4ffddd2
1/* 2 * Copyright (c) 2008, 2015, 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 java.lang.invoke.MethodHandles.Lookup; 29import java.lang.reflect.Field; 30import static java.lang.invoke.MethodHandleNatives.Constants.*; 31import static java.lang.invoke.MethodHandleStatics.*; 32import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; 33import sun.misc.Cleaner; 34 35/** 36 * The JVM interface for the method handles package is all here. 37 * This is an interface internal and private to an implementation of JSR 292. 38 * <em>This class is not part of the JSR 292 standard.</em> 39 * @author jrose 40 */ 41class MethodHandleNatives { 42 43 private MethodHandleNatives() { } // static only 44 45 /// MemberName support 46 47 static native void init(MemberName self, Object ref); 48 static native void expand(MemberName self); 49 static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError; 50 static native int getMembers(Class<?> defc, String matchName, String matchSig, 51 int matchFlags, Class<?> caller, int skip, MemberName[] results); 52 53 /// Field layout queries parallel to sun.misc.Unsafe: 54 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex 55 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex 56 static native Object staticFieldBase(MemberName self); // e.g., returns clazz 57 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget} 58 59 /// CallSite support 60 61 /** Tell the JVM that we need to change the target of a CallSite. */ 62 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target); 63 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target); 64 65 /** Represents a context to track nmethod dependencies on CallSite instance target. */ 66 static class CallSiteContext implements Runnable { 67 //@Injected JVM_nmethodBucket* vmdependencies; 68 69 static CallSiteContext make(CallSite cs) { 70 final CallSiteContext newContext = new CallSiteContext(); 71 // Cleaner is attached to CallSite instance and it clears native structures allocated for CallSite context. 72 // Though the CallSite can become unreachable, its Context is retained by the Cleaner instance (which is 73 // referenced from Cleaner class) until cleanup is performed. 74 Cleaner.create(cs, newContext); 75 return newContext; 76 } 77 78 @Override 79 public void run() { 80 MethodHandleNatives.clearCallSiteContext(this); 81 } 82 } 83 84 /** Invalidate all recorded nmethods. */ 85 private static native void clearCallSiteContext(CallSiteContext context); 86 87 private static native void registerNatives(); 88 static { 89 registerNatives(); 90 91 // The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed: 92 MethodHandleImpl.initStatics(); 93 } 94 95 /** 96 * Compile-time constants go here. This collection exists not only for 97 * reference from clients, but also for ensuring the VM and JDK agree on the 98 * values of these constants (see {@link #verifyConstants()}). 99 */ 100 static class Constants { 101 Constants() { } // static only 102 103 static final int 104 MN_IS_METHOD = 0x00010000, // method (not constructor) 105 MN_IS_CONSTRUCTOR = 0x00020000, // constructor 106 MN_IS_FIELD = 0x00040000, // field 107 MN_IS_TYPE = 0x00080000, // nested type 108 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected 109 MN_REFERENCE_KIND_SHIFT = 24, // refKind 110 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT, 111 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers: 112 MN_SEARCH_SUPERCLASSES = 0x00100000, 113 MN_SEARCH_INTERFACES = 0x00200000; 114 115 /** 116 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries. 117 */ 118 static final byte 119 REF_NONE = 0, // null value 120 REF_getField = 1, 121 REF_getStatic = 2, 122 REF_putField = 3, 123 REF_putStatic = 4, 124 REF_invokeVirtual = 5, 125 REF_invokeStatic = 6, 126 REF_invokeSpecial = 7, 127 REF_newInvokeSpecial = 8, 128 REF_invokeInterface = 9, 129 REF_LIMIT = 10; 130 } 131 132 static boolean refKindIsValid(int refKind) { 133 return (refKind > REF_NONE && refKind < REF_LIMIT); 134 } 135 static boolean refKindIsField(byte refKind) { 136 assert(refKindIsValid(refKind)); 137 return (refKind <= REF_putStatic); 138 } 139 static boolean refKindIsGetter(byte refKind) { 140 assert(refKindIsValid(refKind)); 141 return (refKind <= REF_getStatic); 142 } 143 static boolean refKindIsSetter(byte refKind) { 144 return refKindIsField(refKind) && !refKindIsGetter(refKind); 145 } 146 static boolean refKindIsMethod(byte refKind) { 147 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial); 148 } 149 static boolean refKindIsConstructor(byte refKind) { 150 return (refKind == REF_newInvokeSpecial); 151 } 152 static boolean refKindHasReceiver(byte refKind) { 153 assert(refKindIsValid(refKind)); 154 return (refKind & 1) != 0; 155 } 156 static boolean refKindIsStatic(byte refKind) { 157 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial); 158 } 159 static boolean refKindDoesDispatch(byte refKind) { 160 assert(refKindIsValid(refKind)); 161 return (refKind == REF_invokeVirtual || 162 refKind == REF_invokeInterface); 163 } 164 static { 165 final int HR_MASK = ((1 << REF_getField) | 166 (1 << REF_putField) | 167 (1 << REF_invokeVirtual) | 168 (1 << REF_invokeSpecial) | 169 (1 << REF_invokeInterface) 170 ); 171 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) { 172 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind; 173 } 174 } 175 static String refKindName(byte refKind) { 176 assert(refKindIsValid(refKind)); 177 switch (refKind) { 178 case REF_getField: return "getField"; 179 case REF_getStatic: return "getStatic"; 180 case REF_putField: return "putField"; 181 case REF_putStatic: return "putStatic"; 182 case REF_invokeVirtual: return "invokeVirtual"; 183 case REF_invokeStatic: return "invokeStatic"; 184 case REF_invokeSpecial: return "invokeSpecial"; 185 case REF_newInvokeSpecial: return "newInvokeSpecial"; 186 case REF_invokeInterface: return "invokeInterface"; 187 default: return "REF_???"; 188 } 189 } 190 191 private static native int getNamedCon(int which, Object[] name); 192 static boolean verifyConstants() { 193 Object[] box = { null }; 194 for (int i = 0; ; i++) { 195 box[0] = null; 196 int vmval = getNamedCon(i, box); 197 if (box[0] == null) break; 198 String name = (String) box[0]; 199 try { 200 Field con = Constants.class.getDeclaredField(name); 201 int jval = con.getInt(null); 202 if (jval == vmval) continue; 203 String err = (name+": JVM has "+vmval+" while Java has "+jval); 204 if (name.equals("CONV_OP_LIMIT")) { 205 System.err.println("warning: "+err); 206 continue; 207 } 208 throw new InternalError(err); 209 } catch (NoSuchFieldException | IllegalAccessException ex) { 210 String err = (name+": JVM has "+vmval+" which Java does not define"); 211 // ignore exotic ops the JVM cares about; we just wont issue them 212 //System.err.println("warning: "+err); 213 continue; 214 } 215 } 216 return true; 217 } 218 static { 219 assert(verifyConstants()); 220 } 221 222 // Up-calls from the JVM. 223 // These must NOT be public. 224 225 /** 226 * The JVM is linking an invokedynamic instruction. Create a reified call site for it. 227 */ 228 static MemberName linkCallSite(Object callerObj, 229 Object bootstrapMethodObj, 230 Object nameObj, Object typeObj, 231 Object staticArguments, 232 Object[] appendixResult) { 233 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 234 Class<?> caller = (Class<?>)callerObj; 235 String name = nameObj.toString().intern(); 236 MethodType type = (MethodType)typeObj; 237 if (!TRACE_METHOD_LINKAGE) 238 return linkCallSiteImpl(caller, bootstrapMethod, name, type, 239 staticArguments, appendixResult); 240 return linkCallSiteTracing(caller, bootstrapMethod, name, type, 241 staticArguments, appendixResult); 242 } 243 static MemberName linkCallSiteImpl(Class<?> caller, 244 MethodHandle bootstrapMethod, 245 String name, MethodType type, 246 Object staticArguments, 247 Object[] appendixResult) { 248 CallSite callSite = CallSite.makeSite(bootstrapMethod, 249 name, 250 type, 251 staticArguments, 252 caller); 253 if (callSite instanceof ConstantCallSite) { 254 appendixResult[0] = callSite.dynamicInvoker(); 255 return Invokers.linkToTargetMethod(type); 256 } else { 257 appendixResult[0] = callSite; 258 return Invokers.linkToCallSiteMethod(type); 259 } 260 } 261 // Tracing logic: 262 static MemberName linkCallSiteTracing(Class<?> caller, 263 MethodHandle bootstrapMethod, 264 String name, MethodType type, 265 Object staticArguments, 266 Object[] appendixResult) { 267 Object bsmReference = bootstrapMethod.internalMemberName(); 268 if (bsmReference == null) bsmReference = bootstrapMethod; 269 Object staticArglist = (staticArguments instanceof Object[] ? 270 java.util.Arrays.asList((Object[]) staticArguments) : 271 staticArguments); 272 System.out.println("linkCallSite "+caller.getName()+" "+ 273 bsmReference+" "+ 274 name+type+"/"+staticArglist); 275 try { 276 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type, 277 staticArguments, appendixResult); 278 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]); 279 return res; 280 } catch (Throwable ex) { 281 System.out.println("linkCallSite => throw "+ex); 282 throw ex; 283 } 284 } 285 286 /** 287 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one. 288 */ 289 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) { 290 return MethodType.makeImpl(rtype, ptypes, true); 291 } 292 293 /** 294 * The JVM wants to link a call site that requires a dynamic type check. 295 * Name is a type-checking invoker, invokeExact or invoke. 296 * Return a JVM method (MemberName) to handle the invoking. 297 * The method assumes the following arguments on the stack: 298 * 0: the method handle being invoked 299 * 1-N: the arguments to the method handle invocation 300 * N+1: an optional, implicitly added argument (typically the given MethodType) 301 * <p> 302 * The nominal method at such a call site is an instance of 303 * a signature-polymorphic method (see @PolymorphicSignature). 304 * Such method instances are user-visible entities which are 305 * "split" from the generic placeholder method in {@code MethodHandle}. 306 * (Note that the placeholder method is not identical with any of 307 * its instances. If invoked reflectively, is guaranteed to throw an 308 * {@code UnsupportedOperationException}.) 309 * If the signature-polymorphic method instance is ever reified, 310 * it appears as a "copy" of the original placeholder 311 * (a native final member of {@code MethodHandle}) except 312 * that its type descriptor has shape required by the instance, 313 * and the method instance is <em>not</em> varargs. 314 * The method instance is also marked synthetic, since the 315 * method (by definition) does not appear in Java source code. 316 * <p> 317 * The JVM is allowed to reify this method as instance metadata. 318 * For example, {@code invokeBasic} is always reified. 319 * But the JVM may instead call {@code linkMethod}. 320 * If the result is an * ordered pair of a {@code (method, appendix)}, 321 * the method gets all the arguments (0..N inclusive) 322 * plus the appendix (N+1), and uses the appendix to complete the call. 323 * In this way, one reusable method (called a "linker method") 324 * can perform the function of any number of polymorphic instance 325 * methods. 326 * <p> 327 * Linker methods are allowed to be weakly typed, with any or 328 * all references rewritten to {@code Object} and any primitives 329 * (except {@code long}/{@code float}/{@code double}) 330 * rewritten to {@code int}. 331 * A linker method is trusted to return a strongly typed result, 332 * according to the specific method type descriptor of the 333 * signature-polymorphic instance it is emulating. 334 * This can involve (as necessary) a dynamic check using 335 * data extracted from the appendix argument. 336 * <p> 337 * The JVM does not inspect the appendix, other than to pass 338 * it verbatim to the linker method at every call. 339 * This means that the JDK runtime has wide latitude 340 * for choosing the shape of each linker method and its 341 * corresponding appendix. 342 * Linker methods should be generated from {@code LambdaForm}s 343 * so that they do not become visible on stack traces. 344 * <p> 345 * The {@code linkMethod} call is free to omit the appendix 346 * (returning null) and instead emulate the required function 347 * completely in the linker method. 348 * As a corner case, if N==255, no appendix is possible. 349 * In this case, the method returned must be custom-generated to 350 * to perform any needed type checking. 351 * <p> 352 * If the JVM does not reify a method at a call site, but instead 353 * calls {@code linkMethod}, the corresponding call represented 354 * in the bytecodes may mention a valid method which is not 355 * representable with a {@code MemberName}. 356 * Therefore, use cases for {@code linkMethod} tend to correspond to 357 * special cases in reflective code such as {@code findVirtual} 358 * or {@code revealDirect}. 359 */ 360 static MemberName linkMethod(Class<?> callerClass, int refKind, 361 Class<?> defc, String name, Object type, 362 Object[] appendixResult) { 363 if (!TRACE_METHOD_LINKAGE) 364 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 365 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult); 366 } 367 static MemberName linkMethodImpl(Class<?> callerClass, int refKind, 368 Class<?> defc, String name, Object type, 369 Object[] appendixResult) { 370 try { 371 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) { 372 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult); 373 } 374 } catch (Throwable ex) { 375 if (ex instanceof LinkageError) 376 throw (LinkageError) ex; 377 else 378 throw new LinkageError(ex.getMessage(), ex); 379 } 380 throw new LinkageError("no such method "+defc.getName()+"."+name+type); 381 } 382 private static MethodType fixMethodType(Class<?> callerClass, Object type) { 383 if (type instanceof MethodType) 384 return (MethodType) type; 385 else 386 return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader()); 387 } 388 // Tracing logic: 389 static MemberName linkMethodTracing(Class<?> callerClass, int refKind, 390 Class<?> defc, String name, Object type, 391 Object[] appendixResult) { 392 System.out.println("linkMethod "+defc.getName()+"."+ 393 name+type+"/"+Integer.toHexString(refKind)); 394 try { 395 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 396 System.out.println("linkMethod => "+res+" + "+appendixResult[0]); 397 return res; 398 } catch (Throwable ex) { 399 System.out.println("linkMethod => throw "+ex); 400 throw ex; 401 } 402 } 403 404 405 /** 406 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help. 407 * It will make an up-call to this method. (Do not change the name or signature.) 408 * The type argument is a Class for field requests and a MethodType for non-fields. 409 * <p> 410 * Recent versions of the JVM may also pass a resolved MemberName for the type. 411 * In that case, the name is ignored and may be null. 412 */ 413 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind, 414 Class<?> defc, String name, Object type) { 415 try { 416 Lookup lookup = IMPL_LOOKUP.in(callerClass); 417 assert(refKindIsValid(refKind)); 418 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type); 419 } catch (IllegalAccessException ex) { 420 Throwable cause = ex.getCause(); 421 if (cause instanceof AbstractMethodError) { 422 throw (AbstractMethodError) cause; 423 } else { 424 Error err = new IllegalAccessError(ex.getMessage()); 425 throw initCauseFrom(err, ex); 426 } 427 } catch (NoSuchMethodException ex) { 428 Error err = new NoSuchMethodError(ex.getMessage()); 429 throw initCauseFrom(err, ex); 430 } catch (NoSuchFieldException ex) { 431 Error err = new NoSuchFieldError(ex.getMessage()); 432 throw initCauseFrom(err, ex); 433 } catch (ReflectiveOperationException ex) { 434 Error err = new IncompatibleClassChangeError(); 435 throw initCauseFrom(err, ex); 436 } 437 } 438 439 /** 440 * Use best possible cause for err.initCause(), substituting the 441 * cause for err itself if the cause has the same (or better) type. 442 */ 443 private static Error initCauseFrom(Error err, Exception ex) { 444 Throwable th = ex.getCause(); 445 if (err.getClass().isInstance(th)) 446 return (Error) th; 447 err.initCause(th == null ? ex : th); 448 return err; 449 } 450 451 /** 452 * Is this method a caller-sensitive method? 453 * I.e., does it call Reflection.getCallerClass or a similar method 454 * to ask about the identity of its caller? 455 */ 456 static boolean isCallerSensitive(MemberName mem) { 457 if (!mem.isInvocable()) return false; // fields are not caller sensitive 458 459 return mem.isCallerSensitive() || canBeCalledVirtual(mem); 460 } 461 462 static boolean canBeCalledVirtual(MemberName mem) { 463 assert(mem.isInvocable()); 464 Class<?> defc = mem.getDeclaringClass(); 465 switch (mem.getName()) { 466 case "checkMemberAccess": 467 return canBeCalledVirtual(mem, java.lang.SecurityManager.class); 468 case "getContextClassLoader": 469 return canBeCalledVirtual(mem, java.lang.Thread.class); 470 } 471 return false; 472 } 473 474 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) { 475 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass(); 476 if (symbolicRefClass == definingClass) return true; 477 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false; 478 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef 479 symbolicRefClass.isInterface()); // Mdef implements Msym 480 } 481} 482