1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/rt/emul/compact/src/main/java/java/lang/invoke/MethodHandleNatives.java Sat Aug 09 11:11:13 2014 +0200
1.3 @@ -0,0 +1,505 @@
1.4 +/*
1.5 + * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package java.lang.invoke;
1.30 +
1.31 +import java.lang.invoke.MethodHandles.Lookup;
1.32 +import java.lang.reflect.Field;
1.33 +import static java.lang.invoke.MethodHandleNatives.Constants.*;
1.34 +import static java.lang.invoke.MethodHandleStatics.*;
1.35 +import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
1.36 +
1.37 +/**
1.38 + * The JVM interface for the method handles package is all here.
1.39 + * This is an interface internal and private to an implementation of JSR 292.
1.40 + * <em>This class is not part of the JSR 292 standard.</em>
1.41 + * @author jrose
1.42 + */
1.43 +class MethodHandleNatives {
1.44 +
1.45 + private MethodHandleNatives() { } // static only
1.46 +
1.47 + /// MemberName support
1.48 +
1.49 + static native void init(MemberName self, Object ref);
1.50 + static native void expand(MemberName self);
1.51 + static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError;
1.52 + static native int getMembers(Class<?> defc, String matchName, String matchSig,
1.53 + int matchFlags, Class<?> caller, int skip, MemberName[] results);
1.54 +
1.55 + /// Field layout queries parallel to sun.misc.Unsafe:
1.56 + static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
1.57 + static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
1.58 + static native Object staticFieldBase(MemberName self); // e.g., returns clazz
1.59 + static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}
1.60 +
1.61 + /// MethodHandle support
1.62 +
1.63 + /** Fetch MH-related JVM parameter.
1.64 + * which=0 retrieves MethodHandlePushLimit
1.65 + * which=1 retrieves stack slot push size (in address units)
1.66 + */
1.67 + static native int getConstant(int which);
1.68 +
1.69 + static final boolean COUNT_GWT;
1.70 +
1.71 + /// CallSite support
1.72 +
1.73 + /** Tell the JVM that we need to change the target of a CallSite. */
1.74 + static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
1.75 + static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
1.76 +
1.77 + private static native void registerNatives();
1.78 + static {
1.79 + registerNatives();
1.80 + COUNT_GWT = getConstant(Constants.GC_COUNT_GWT) != 0;
1.81 +
1.82 + // The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed:
1.83 + MethodHandleImpl.initStatics();
1.84 +}
1.85 +
1.86 + // All compile-time constants go here.
1.87 + // There is an opportunity to check them against the JVM's idea of them.
1.88 + static class Constants {
1.89 + Constants() { } // static only
1.90 + // MethodHandleImpl
1.91 + static final int // for getConstant
1.92 + GC_COUNT_GWT = 4,
1.93 + GC_LAMBDA_SUPPORT = 5;
1.94 +
1.95 + // MemberName
1.96 + // The JVM uses values of -2 and above for vtable indexes.
1.97 + // Field values are simple positive offsets.
1.98 + // Ref: src/share/vm/oops/methodOop.hpp
1.99 + // This value is negative enough to avoid such numbers,
1.100 + // but not too negative.
1.101 + static final int
1.102 + MN_IS_METHOD = 0x00010000, // method (not constructor)
1.103 + MN_IS_CONSTRUCTOR = 0x00020000, // constructor
1.104 + MN_IS_FIELD = 0x00040000, // field
1.105 + MN_IS_TYPE = 0x00080000, // nested type
1.106 + MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
1.107 + MN_REFERENCE_KIND_SHIFT = 24, // refKind
1.108 + MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
1.109 + // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
1.110 + MN_SEARCH_SUPERCLASSES = 0x00100000,
1.111 + MN_SEARCH_INTERFACES = 0x00200000;
1.112 +
1.113 + /**
1.114 + * Basic types as encoded in the JVM. These code values are not
1.115 + * intended for use outside this class. They are used as part of
1.116 + * a private interface between the JVM and this class.
1.117 + */
1.118 + static final int
1.119 + T_BOOLEAN = 4,
1.120 + T_CHAR = 5,
1.121 + T_FLOAT = 6,
1.122 + T_DOUBLE = 7,
1.123 + T_BYTE = 8,
1.124 + T_SHORT = 9,
1.125 + T_INT = 10,
1.126 + T_LONG = 11,
1.127 + T_OBJECT = 12,
1.128 + //T_ARRAY = 13
1.129 + T_VOID = 14,
1.130 + //T_ADDRESS = 15
1.131 + T_ILLEGAL = 99;
1.132 +
1.133 + /**
1.134 + * Constant pool entry types.
1.135 + */
1.136 + static final byte
1.137 + CONSTANT_Utf8 = 1,
1.138 + CONSTANT_Integer = 3,
1.139 + CONSTANT_Float = 4,
1.140 + CONSTANT_Long = 5,
1.141 + CONSTANT_Double = 6,
1.142 + CONSTANT_Class = 7,
1.143 + CONSTANT_String = 8,
1.144 + CONSTANT_Fieldref = 9,
1.145 + CONSTANT_Methodref = 10,
1.146 + CONSTANT_InterfaceMethodref = 11,
1.147 + CONSTANT_NameAndType = 12,
1.148 + CONSTANT_MethodHandle = 15, // JSR 292
1.149 + CONSTANT_MethodType = 16, // JSR 292
1.150 + CONSTANT_InvokeDynamic = 18,
1.151 + CONSTANT_LIMIT = 19; // Limit to tags found in classfiles
1.152 +
1.153 + /**
1.154 + * Access modifier flags.
1.155 + */
1.156 + static final char
1.157 + ACC_PUBLIC = 0x0001,
1.158 + ACC_PRIVATE = 0x0002,
1.159 + ACC_PROTECTED = 0x0004,
1.160 + ACC_STATIC = 0x0008,
1.161 + ACC_FINAL = 0x0010,
1.162 + ACC_SYNCHRONIZED = 0x0020,
1.163 + ACC_VOLATILE = 0x0040,
1.164 + ACC_TRANSIENT = 0x0080,
1.165 + ACC_NATIVE = 0x0100,
1.166 + ACC_INTERFACE = 0x0200,
1.167 + ACC_ABSTRACT = 0x0400,
1.168 + ACC_STRICT = 0x0800,
1.169 + ACC_SYNTHETIC = 0x1000,
1.170 + ACC_ANNOTATION = 0x2000,
1.171 + ACC_ENUM = 0x4000,
1.172 + // aliases:
1.173 + ACC_SUPER = ACC_SYNCHRONIZED,
1.174 + ACC_BRIDGE = ACC_VOLATILE,
1.175 + ACC_VARARGS = ACC_TRANSIENT;
1.176 +
1.177 + /**
1.178 + * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
1.179 + */
1.180 + static final byte
1.181 + REF_NONE = 0, // null value
1.182 + REF_getField = 1,
1.183 + REF_getStatic = 2,
1.184 + REF_putField = 3,
1.185 + REF_putStatic = 4,
1.186 + REF_invokeVirtual = 5,
1.187 + REF_invokeStatic = 6,
1.188 + REF_invokeSpecial = 7,
1.189 + REF_newInvokeSpecial = 8,
1.190 + REF_invokeInterface = 9,
1.191 + REF_LIMIT = 10;
1.192 + }
1.193 +
1.194 + static boolean refKindIsValid(int refKind) {
1.195 + return (refKind > REF_NONE && refKind < REF_LIMIT);
1.196 + }
1.197 + static boolean refKindIsField(byte refKind) {
1.198 + assert(refKindIsValid(refKind));
1.199 + return (refKind <= REF_putStatic);
1.200 + }
1.201 + static boolean refKindIsGetter(byte refKind) {
1.202 + assert(refKindIsValid(refKind));
1.203 + return (refKind <= REF_getStatic);
1.204 + }
1.205 + static boolean refKindIsSetter(byte refKind) {
1.206 + return refKindIsField(refKind) && !refKindIsGetter(refKind);
1.207 + }
1.208 + static boolean refKindIsMethod(byte refKind) {
1.209 + return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
1.210 + }
1.211 + static boolean refKindIsConstructor(byte refKind) {
1.212 + return (refKind == REF_newInvokeSpecial);
1.213 + }
1.214 + static boolean refKindHasReceiver(byte refKind) {
1.215 + assert(refKindIsValid(refKind));
1.216 + return (refKind & 1) != 0;
1.217 + }
1.218 + static boolean refKindIsStatic(byte refKind) {
1.219 + return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
1.220 + }
1.221 + static boolean refKindDoesDispatch(byte refKind) {
1.222 + assert(refKindIsValid(refKind));
1.223 + return (refKind == REF_invokeVirtual ||
1.224 + refKind == REF_invokeInterface);
1.225 + }
1.226 + static {
1.227 + final int HR_MASK = ((1 << REF_getField) |
1.228 + (1 << REF_putField) |
1.229 + (1 << REF_invokeVirtual) |
1.230 + (1 << REF_invokeSpecial) |
1.231 + (1 << REF_invokeInterface)
1.232 + );
1.233 + for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
1.234 + assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
1.235 + }
1.236 + }
1.237 + static String refKindName(byte refKind) {
1.238 + assert(refKindIsValid(refKind));
1.239 + switch (refKind) {
1.240 + case REF_getField: return "getField";
1.241 + case REF_getStatic: return "getStatic";
1.242 + case REF_putField: return "putField";
1.243 + case REF_putStatic: return "putStatic";
1.244 + case REF_invokeVirtual: return "invokeVirtual";
1.245 + case REF_invokeStatic: return "invokeStatic";
1.246 + case REF_invokeSpecial: return "invokeSpecial";
1.247 + case REF_newInvokeSpecial: return "newInvokeSpecial";
1.248 + case REF_invokeInterface: return "invokeInterface";
1.249 + default: return "REF_???";
1.250 + }
1.251 + }
1.252 +
1.253 + private static native int getNamedCon(int which, Object[] name);
1.254 + static boolean verifyConstants() {
1.255 + Object[] box = { null };
1.256 + for (int i = 0; ; i++) {
1.257 + box[0] = null;
1.258 + int vmval = getNamedCon(i, box);
1.259 + if (box[0] == null) break;
1.260 + String name = (String) box[0];
1.261 + try {
1.262 + Field con = Constants.class.getDeclaredField(name);
1.263 + int jval = con.getInt(null);
1.264 + if (jval == vmval) continue;
1.265 + String err = (name+": JVM has "+vmval+" while Java has "+jval);
1.266 + if (name.equals("CONV_OP_LIMIT")) {
1.267 + System.err.println("warning: "+err);
1.268 + continue;
1.269 + }
1.270 + throw new InternalError(err);
1.271 + } catch (NoSuchFieldException | IllegalAccessException ex) {
1.272 + String err = (name+": JVM has "+vmval+" which Java does not define");
1.273 + // ignore exotic ops the JVM cares about; we just wont issue them
1.274 + //System.err.println("warning: "+err);
1.275 + continue;
1.276 + }
1.277 + }
1.278 + return true;
1.279 + }
1.280 + static {
1.281 + assert(verifyConstants());
1.282 + }
1.283 +
1.284 + // Up-calls from the JVM.
1.285 + // These must NOT be public.
1.286 +
1.287 + /**
1.288 + * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
1.289 + */
1.290 + static MemberName linkCallSite(Object callerObj,
1.291 + Object bootstrapMethodObj,
1.292 + Object nameObj, Object typeObj,
1.293 + Object staticArguments,
1.294 + Object[] appendixResult) {
1.295 + MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
1.296 + Class<?> caller = (Class<?>)callerObj;
1.297 + String name = nameObj.toString().intern();
1.298 + MethodType type = (MethodType)typeObj;
1.299 + CallSite callSite = CallSite.makeSite(bootstrapMethod,
1.300 + name,
1.301 + type,
1.302 + staticArguments,
1.303 + caller);
1.304 + if (callSite instanceof ConstantCallSite) {
1.305 + appendixResult[0] = callSite.dynamicInvoker();
1.306 + return Invokers.linkToTargetMethod(type);
1.307 + } else {
1.308 + appendixResult[0] = callSite;
1.309 + return Invokers.linkToCallSiteMethod(type);
1.310 + }
1.311 + }
1.312 +
1.313 + /**
1.314 + * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
1.315 + */
1.316 + static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
1.317 + return MethodType.makeImpl(rtype, ptypes, true);
1.318 + }
1.319 +
1.320 + /**
1.321 + * The JVM wants to link a call site that requires a dynamic type check.
1.322 + * Name is a type-checking invoker, invokeExact or invoke.
1.323 + * Return a JVM method (MemberName) to handle the invoking.
1.324 + * The method assumes the following arguments on the stack:
1.325 + * 0: the method handle being invoked
1.326 + * 1-N: the arguments to the method handle invocation
1.327 + * N+1: an optional, implicitly added argument (typically the given MethodType)
1.328 + * <p>
1.329 + * The nominal method at such a call site is an instance of
1.330 + * a signature-polymorphic method (see @PolymorphicSignature).
1.331 + * Such method instances are user-visible entities which are
1.332 + * "split" from the generic placeholder method in {@code MethodHandle}.
1.333 + * (Note that the placeholder method is not identical with any of
1.334 + * its instances. If invoked reflectively, is guaranteed to throw an
1.335 + * {@code UnsupportedOperationException}.)
1.336 + * If the signature-polymorphic method instance is ever reified,
1.337 + * it appears as a "copy" of the original placeholder
1.338 + * (a native final member of {@code MethodHandle}) except
1.339 + * that its type descriptor has shape required by the instance,
1.340 + * and the method instance is <em>not</em> varargs.
1.341 + * The method instance is also marked synthetic, since the
1.342 + * method (by definition) does not appear in Java source code.
1.343 + * <p>
1.344 + * The JVM is allowed to reify this method as instance metadata.
1.345 + * For example, {@code invokeBasic} is always reified.
1.346 + * But the JVM may instead call {@code linkMethod}.
1.347 + * If the result is an * ordered pair of a {@code (method, appendix)},
1.348 + * the method gets all the arguments (0..N inclusive)
1.349 + * plus the appendix (N+1), and uses the appendix to complete the call.
1.350 + * In this way, one reusable method (called a "linker method")
1.351 + * can perform the function of any number of polymorphic instance
1.352 + * methods.
1.353 + * <p>
1.354 + * Linker methods are allowed to be weakly typed, with any or
1.355 + * all references rewritten to {@code Object} and any primitives
1.356 + * (except {@code long}/{@code float}/{@code double})
1.357 + * rewritten to {@code int}.
1.358 + * A linker method is trusted to return a strongly typed result,
1.359 + * according to the specific method type descriptor of the
1.360 + * signature-polymorphic instance it is emulating.
1.361 + * This can involve (as necessary) a dynamic check using
1.362 + * data extracted from the appendix argument.
1.363 + * <p>
1.364 + * The JVM does not inspect the appendix, other than to pass
1.365 + * it verbatim to the linker method at every call.
1.366 + * This means that the JDK runtime has wide latitude
1.367 + * for choosing the shape of each linker method and its
1.368 + * corresponding appendix.
1.369 + * Linker methods should be generated from {@code LambdaForm}s
1.370 + * so that they do not become visible on stack traces.
1.371 + * <p>
1.372 + * The {@code linkMethod} call is free to omit the appendix
1.373 + * (returning null) and instead emulate the required function
1.374 + * completely in the linker method.
1.375 + * As a corner case, if N==255, no appendix is possible.
1.376 + * In this case, the method returned must be custom-generated to
1.377 + * to perform any needed type checking.
1.378 + * <p>
1.379 + * If the JVM does not reify a method at a call site, but instead
1.380 + * calls {@code linkMethod}, the corresponding call represented
1.381 + * in the bytecodes may mention a valid method which is not
1.382 + * representable with a {@code MemberName}.
1.383 + * Therefore, use cases for {@code linkMethod} tend to correspond to
1.384 + * special cases in reflective code such as {@code findVirtual}
1.385 + * or {@code revealDirect}.
1.386 + */
1.387 + static MemberName linkMethod(Class<?> callerClass, int refKind,
1.388 + Class<?> defc, String name, Object type,
1.389 + Object[] appendixResult) {
1.390 + if (!TRACE_METHOD_LINKAGE)
1.391 + return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
1.392 + return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
1.393 + }
1.394 + static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
1.395 + Class<?> defc, String name, Object type,
1.396 + Object[] appendixResult) {
1.397 + try {
1.398 + if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
1.399 + return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
1.400 + }
1.401 + } catch (Throwable ex) {
1.402 + if (ex instanceof LinkageError)
1.403 + throw (LinkageError) ex;
1.404 + else
1.405 + throw new LinkageError(ex.getMessage(), ex);
1.406 + }
1.407 + throw new LinkageError("no such method "+defc.getName()+"."+name+type);
1.408 + }
1.409 + private static MethodType fixMethodType(Class<?> callerClass, Object type) {
1.410 + if (type instanceof MethodType)
1.411 + return (MethodType) type;
1.412 + else
1.413 + return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
1.414 + }
1.415 + // Tracing logic:
1.416 + static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
1.417 + Class<?> defc, String name, Object type,
1.418 + Object[] appendixResult) {
1.419 + System.out.println("linkMethod "+defc.getName()+"."+
1.420 + name+type+"/"+Integer.toHexString(refKind));
1.421 + try {
1.422 + MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
1.423 + System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
1.424 + return res;
1.425 + } catch (Throwable ex) {
1.426 + System.out.println("linkMethod => throw "+ex);
1.427 + throw ex;
1.428 + }
1.429 + }
1.430 +
1.431 +
1.432 + /**
1.433 + * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
1.434 + * It will make an up-call to this method. (Do not change the name or signature.)
1.435 + * The type argument is a Class for field requests and a MethodType for non-fields.
1.436 + * <p>
1.437 + * Recent versions of the JVM may also pass a resolved MemberName for the type.
1.438 + * In that case, the name is ignored and may be null.
1.439 + */
1.440 + static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
1.441 + Class<?> defc, String name, Object type) {
1.442 + try {
1.443 + Lookup lookup = IMPL_LOOKUP.in(callerClass);
1.444 + assert(refKindIsValid(refKind));
1.445 + return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
1.446 + } catch (IllegalAccessException ex) {
1.447 + Throwable cause = ex.getCause();
1.448 + if (cause instanceof AbstractMethodError) {
1.449 + throw (AbstractMethodError) cause;
1.450 + } else {
1.451 + Error err = new IllegalAccessError(ex.getMessage());
1.452 + throw initCauseFrom(err, ex);
1.453 + }
1.454 + } catch (NoSuchMethodException ex) {
1.455 + Error err = new NoSuchMethodError(ex.getMessage());
1.456 + throw initCauseFrom(err, ex);
1.457 + } catch (NoSuchFieldException ex) {
1.458 + Error err = new NoSuchFieldError(ex.getMessage());
1.459 + throw initCauseFrom(err, ex);
1.460 + } catch (ReflectiveOperationException ex) {
1.461 + Error err = new IncompatibleClassChangeError();
1.462 + throw initCauseFrom(err, ex);
1.463 + }
1.464 + }
1.465 +
1.466 + /**
1.467 + * Use best possible cause for err.initCause(), substituting the
1.468 + * cause for err itself if the cause has the same (or better) type.
1.469 + */
1.470 + static private Error initCauseFrom(Error err, Exception ex) {
1.471 + Throwable th = ex.getCause();
1.472 + if (err.getClass().isInstance(th))
1.473 + return (Error) th;
1.474 + err.initCause(th == null ? ex : th);
1.475 + return err;
1.476 + }
1.477 +
1.478 + /**
1.479 + * Is this method a caller-sensitive method?
1.480 + * I.e., does it call Reflection.getCallerClass or a similer method
1.481 + * to ask about the identity of its caller?
1.482 + */
1.483 + static boolean isCallerSensitive(MemberName mem) {
1.484 + if (!mem.isInvocable()) return false; // fields are not caller sensitive
1.485 +
1.486 + return mem.isCallerSensitive() || canBeCalledVirtual(mem);
1.487 + }
1.488 +
1.489 + static boolean canBeCalledVirtual(MemberName mem) {
1.490 + assert(mem.isInvocable());
1.491 + Class<?> defc = mem.getDeclaringClass();
1.492 + switch (mem.getName()) {
1.493 + case "checkMemberAccess":
1.494 + return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
1.495 + case "getContextClassLoader":
1.496 + return canBeCalledVirtual(mem, java.lang.Thread.class);
1.497 + }
1.498 + return false;
1.499 + }
1.500 +
1.501 + static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
1.502 + Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
1.503 + if (symbolicRefClass == definingClass) return true;
1.504 + if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
1.505 + return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
1.506 + symbolicRefClass.isInterface()); // Mdef implements Msym
1.507 + }
1.508 +}