示例#1
0
 /*non-public*/ static boolean shouldBeInitialized(MemberName member) {
   switch (member.getReferenceKind()) {
     case REF_invokeStatic:
     case REF_getStatic:
     case REF_putStatic:
     case REF_newInvokeSpecial:
       break;
     default:
       // No need to initialize the class on this kind of member.
       return false;
   }
   Class<?> cls = member.getDeclaringClass();
   if (cls == ValueConversions.class || cls == MethodHandleImpl.class || cls == Invokers.class) {
     // These guys have lots of <clinit> DMH creation but we know
     // the MHs will not be used until the system is booted.
     return false;
   }
   if (VerifyAccess.isSamePackage(MethodHandle.class, cls)
       || VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
     // It is a system class.  It is probably in the process of
     // being initialized, but we will help it along just to be safe.
     if (UNSAFE.shouldBeInitialized(cls)) {
       UNSAFE.ensureClassInitialized(cls);
     }
     return false;
   }
   return UNSAFE.shouldBeInitialized(cls);
 }
示例#2
0
 private static DirectMethodHandle makeAllocator(MemberName ctor) {
   assert (ctor.isConstructor() && ctor.getName().equals("<init>"));
   Class<?> instanceClass = ctor.getDeclaringClass();
   ctor = ctor.asConstructor();
   assert (ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;
   MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);
   LambdaForm lform = preparedLambdaForm(ctor);
   MemberName init = ctor.asSpecial();
   assert (init.getMethodType().returnType() == void.class);
   return new Constructor(mtype, lform, ctor, init, instanceClass);
 }
示例#3
0
 /// Queries
 List<MemberName> getMembers(
     Class<?> defc, String matchName, Object matchType, int matchFlags, Class<?> lookupClass) {
   matchFlags &= ALLOWED_FLAGS;
   String matchSig = null;
   if (matchType != null) {
     matchSig = BytecodeDescriptor.unparse(matchType);
     if (matchSig.startsWith("(")) matchFlags &= ~(ALL_KINDS & ~IS_INVOCABLE);
     else matchFlags &= ~(ALL_KINDS & ~IS_FIELD);
   }
   final int BUF_MAX = 0x2000;
   int len1 = matchName == null ? 10 : matchType == null ? 4 : 1;
   MemberName[] buf = newMemberBuffer(len1);
   int totalCount = 0;
   ArrayList<MemberName[]> bufs = null;
   int bufCount = 0;
   for (; ; ) {
     bufCount =
         MethodHandleNatives.getMembers(
             defc, matchName, matchSig, matchFlags, lookupClass, totalCount, buf);
     if (bufCount <= buf.length) {
       if (bufCount < 0) bufCount = 0;
       totalCount += bufCount;
       break;
     }
     // JVM returned to us with an intentional overflow!
     totalCount += buf.length;
     int excess = bufCount - buf.length;
     if (bufs == null) bufs = new ArrayList<MemberName[]>(1);
     bufs.add(buf);
     int len2 = buf.length;
     len2 = Math.max(len2, excess);
     len2 = Math.max(len2, totalCount / 4);
     buf = newMemberBuffer(Math.min(BUF_MAX, len2));
   }
   ArrayList<MemberName> result = new ArrayList<MemberName>(totalCount);
   if (bufs != null) {
     for (MemberName[] buf0 : bufs) {
       Collections.addAll(result, buf0);
     }
   }
   result.addAll(Arrays.asList(buf).subList(0, bufCount));
   // Signature matching is not the same as type matching, since
   // one signature might correspond to several types.
   // So if matchType is a Class or MethodType, refilter the results.
   if (matchType != null && matchType != matchSig) {
     for (Iterator<MemberName> it = result.iterator(); it.hasNext(); ) {
       MemberName m = it.next();
       if (!matchType.equals(m.getType())) it.remove();
     }
   }
   return result;
 }
示例#4
0
 // Factory methods:
 static DirectMethodHandle make(byte refKind, Class<?> receiver, MemberName member) {
   MethodType mtype = member.getMethodOrFieldType();
   if (!member.isStatic()) {
     if (!member.getDeclaringClass().isAssignableFrom(receiver) || member.isConstructor())
       throw new InternalError(member.toString());
     mtype = mtype.insertParameterTypes(0, receiver);
   }
   if (!member.isField()) {
     if (refKind == REF_invokeSpecial) {
       member = member.asSpecial();
       LambdaForm lform = preparedLambdaForm(member);
       return new Special(mtype, lform, member);
     } else {
       LambdaForm lform = preparedLambdaForm(member);
       return new DirectMethodHandle(mtype, lform, member);
     }
   } else {
     LambdaForm lform = preparedFieldLambdaForm(member);
     if (member.isStatic()) {
       long offset = MethodHandleNatives.staticFieldOffset(member);
       Object base = MethodHandleNatives.staticFieldBase(member);
       return new StaticAccessor(mtype, lform, member, base, offset);
     } else {
       long offset = MethodHandleNatives.objectFieldOffset(member);
       assert (offset == (int) offset);
       return new Accessor(mtype, lform, member, (int) offset);
     }
   }
 }
示例#5
0
 private void ensureInitialized() {
   if (checkInitialized(member)) {
     // The coast is clear.  Delete the <clinit> barrier.
     if (member.isField()) updateForm(preparedFieldLambdaForm(member));
     else updateForm(preparedLambdaForm(member));
   }
 }
示例#6
0
 /**
  * Create a LF which can invoke the given method. Cache and share this structure among all methods
  * with the same basicType and refKind.
  */
 private static LambdaForm preparedLambdaForm(MemberName m) {
   assert (m.isInvocable()) : m; // call preparedFieldLambdaForm instead
   MethodType mtype = m.getInvocationType().basicType();
   assert (!m.isMethodHandleInvoke()) : m;
   int which;
   switch (m.getReferenceKind()) {
     case REF_invokeVirtual:
       which = LF_INVVIRTUAL;
       break;
     case REF_invokeStatic:
       which = LF_INVSTATIC;
       break;
     case REF_invokeSpecial:
       which = LF_INVSPECIAL;
       break;
     case REF_invokeInterface:
       which = LF_INVINTERFACE;
       break;
     case REF_newInvokeSpecial:
       which = LF_NEWINVSPECIAL;
       break;
     default:
       throw new InternalError(m.toString());
   }
   if (which == LF_INVSTATIC && shouldBeInitialized(m)) {
     // precompute the barrier-free version:
     preparedLambdaForm(mtype, which);
     which = LF_INVSTATIC_INIT;
   }
   LambdaForm lform = preparedLambdaForm(mtype, which);
   maybeCompile(lform, m);
   assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
       : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
   return lform;
 }
示例#7
0
 private Constructor(
     MethodType mtype,
     LambdaForm form,
     MemberName constructor,
     MemberName initMethod,
     Class<?> instanceClass) {
   super(mtype, form, constructor);
   this.initMethod = initMethod;
   this.instanceClass = instanceClass;
   assert (initMethod.isResolved());
 }
示例#8
0
 private StaticAccessor(
     MethodType mtype,
     LambdaForm form,
     MemberName member,
     Object staticBase,
     long staticOffset) {
   super(mtype, form, member);
   this.fieldType = member.getFieldType();
   this.staticBase = staticBase;
   this.staticOffset = staticOffset;
 }
示例#9
0
 /**
  * Produce a resolved version of the given member. Super types are searched (for inherited
  * members) if {@code searchSupers} is true. Access checking is performed on behalf of the given
  * {@code lookupClass}. If lookup fails or access is not permitted, a {@linkplain
  * ReflectiveOperationException} is thrown. Otherwise a fresh copy of the given member is
  * returned, with modifier bits filled in.
  */
 public <NoSuchMemberException extends ReflectiveOperationException> MemberName resolveOrFail(
     MemberName m,
     boolean searchSupers,
     Class<?> lookupClass,
     Class<NoSuchMemberException> nsmClass)
     throws IllegalAccessException, NoSuchMemberException {
   MemberName result = resolveOrNull(m, searchSupers, lookupClass);
   if (result != null) return result;
   ReflectiveOperationException ex = m.makeAccessException("no access");
   if (ex instanceof IllegalAccessException) throw (IllegalAccessException) ex;
   throw nsmClass.cast(ex);
 }
示例#10
0
 /**
  * Create a LF which can access the given field. Cache and share this structure among all fields
  * with the same basicType and refKind.
  */
 private static LambdaForm preparedFieldLambdaForm(MemberName m) {
   Class<?> ftype = m.getFieldType();
   boolean isVolatile = m.isVolatile();
   byte formOp;
   switch (m.getReferenceKind()) {
     case REF_getField:
       formOp = AF_GETFIELD;
       break;
     case REF_putField:
       formOp = AF_PUTFIELD;
       break;
     case REF_getStatic:
       formOp = AF_GETSTATIC;
       break;
     case REF_putStatic:
       formOp = AF_PUTSTATIC;
       break;
     default:
       throw new InternalError(m.toString());
   }
   if (shouldBeInitialized(m)) {
     // precompute the barrier-free version:
     preparedFieldLambdaForm(formOp, isVolatile, ftype);
     assert ((AF_GETSTATIC_INIT - AF_GETSTATIC) == (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
     formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
   }
   LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
   maybeCompile(lform, m);
   assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
       : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
   return lform;
 }
示例#11
0
 private static boolean checkInitialized(MemberName member) {
   Class<?> defc = member.getDeclaringClass();
   WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc);
   if (ref == null) {
     return true; // the final state
   }
   Thread clinitThread = ref.get();
   // Somebody may still be running defc.<clinit>.
   if (clinitThread == Thread.currentThread()) {
     // If anybody is running defc.<clinit>, it is this thread.
     if (UNSAFE.shouldBeInitialized(defc))
       // Yes, we are running it; keep the barrier for now.
       return false;
   } else {
     // We are in a random thread.  Block.
     UNSAFE.ensureClassInitialized(defc);
   }
   assert (!UNSAFE.shouldBeInitialized(defc));
   // put it into the final state
   EnsureInitialized.INSTANCE.remove(defc);
   return true;
 }
示例#12
0
 static DirectMethodHandle make(Class<?> receiver, MemberName member) {
   byte refKind = member.getReferenceKind();
   if (refKind == REF_invokeSpecial) refKind = REF_invokeVirtual;
   return make(refKind, receiver, member);
 }
示例#13
0
 /**
  * Produce a resolved version of the given member. Super types are searched (for inherited
  * members) if {@code searchSupers} is true. Access checking is performed on behalf of the given
  * {@code lookupClass}. If lookup fails or access is not permitted, null is returned. Otherwise
  * a fresh copy of the given member is returned, with modifier bits filled in.
  */
 public MemberName resolveOrNull(MemberName m, boolean searchSupers, Class<?> lookupClass) {
   MemberName result = m.clone();
   if (resolveInPlace(result, searchSupers, lookupClass)) return result;
   return null;
 }
示例#14
0
 boolean resolveInPlace(MemberName m, boolean searchSupers, Class<?> lookupClass) {
   if (m.name == null || m.type == null) { // find unique non-overloaded name
     Class<?> defc = m.getDeclaringClass();
     List<MemberName> choices = null;
     if (m.isMethod())
       choices = getMethods(defc, searchSupers, m.name, (MethodType) m.type, lookupClass);
     else if (m.isConstructor()) choices = getConstructors(defc, lookupClass);
     else if (m.isField())
       choices = getFields(defc, searchSupers, m.name, (Class<?>) m.type, lookupClass);
     // System.out.println("resolving "+m+" to "+choices);
     if (choices == null || choices.size() != 1) return false;
     if (m.name == null) m.name = choices.get(0).name;
     if (m.type == null) m.type = choices.get(0).type;
   }
   MethodHandleNatives.resolve(m, lookupClass);
   if (m.isResolved()) return true;
   int matchFlags = m.flags | (searchSupers ? SEARCH_ALL_SUPERS : 0);
   String matchSig = m.getSignature();
   MemberName[] buf = {m};
   int n =
       MethodHandleNatives.getMembers(
           m.getDeclaringClass(), m.getName(), matchSig, matchFlags, lookupClass, 0, buf);
   if (n != 1) return false;
   return m.isResolved();
 }
示例#15
0
 private static void maybeCompile(LambdaForm lform, MemberName m) {
   if (lform.vmentry == null
       && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
     // Help along bootstrapping...
     lform.compileToBytecode();
 }
示例#16
0
  // Constructors and factory methods in this class *must* be package scoped or private.
  private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member) {
    super(mtype, form);
    if (!member.isResolved()) throw new InternalError();

    if (member.getDeclaringClass().isInterface() && member.isMethod() && !member.isAbstract()) {
      // Check for corner case: invokeinterface of Object method
      MemberName m =
          new MemberName(
              Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());
      m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null);
      if (m != null && m.isPublic()) {
        assert (member.getReferenceKind() == m.getReferenceKind()); // else this.form is wrong
        member = m;
      }
    }

    this.member = member;
  }
示例#17
0
 Object checkCast(Object obj) {
   return member.getReturnType().cast(obj);
 }
示例#18
0
/**
 * The flavor of method handle which implements a constant reference to a class member.
 *
 * @author jrose
 */
class DirectMethodHandle extends MethodHandle {
  final MemberName member;

  // Constructors and factory methods in this class *must* be package scoped or private.
  private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member) {
    super(mtype, form);
    if (!member.isResolved()) throw new InternalError();

    if (member.getDeclaringClass().isInterface() && member.isMethod() && !member.isAbstract()) {
      // Check for corner case: invokeinterface of Object method
      MemberName m =
          new MemberName(
              Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());
      m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null);
      if (m != null && m.isPublic()) {
        assert (member.getReferenceKind() == m.getReferenceKind()); // else this.form is wrong
        member = m;
      }
    }

    this.member = member;
  }

  // Factory methods:
  static DirectMethodHandle make(byte refKind, Class<?> receiver, MemberName member) {
    MethodType mtype = member.getMethodOrFieldType();
    if (!member.isStatic()) {
      if (!member.getDeclaringClass().isAssignableFrom(receiver) || member.isConstructor())
        throw new InternalError(member.toString());
      mtype = mtype.insertParameterTypes(0, receiver);
    }
    if (!member.isField()) {
      if (refKind == REF_invokeSpecial) {
        member = member.asSpecial();
        LambdaForm lform = preparedLambdaForm(member);
        return new Special(mtype, lform, member);
      } else {
        LambdaForm lform = preparedLambdaForm(member);
        return new DirectMethodHandle(mtype, lform, member);
      }
    } else {
      LambdaForm lform = preparedFieldLambdaForm(member);
      if (member.isStatic()) {
        long offset = MethodHandleNatives.staticFieldOffset(member);
        Object base = MethodHandleNatives.staticFieldBase(member);
        return new StaticAccessor(mtype, lform, member, base, offset);
      } else {
        long offset = MethodHandleNatives.objectFieldOffset(member);
        assert (offset == (int) offset);
        return new Accessor(mtype, lform, member, (int) offset);
      }
    }
  }

  static DirectMethodHandle make(Class<?> receiver, MemberName member) {
    byte refKind = member.getReferenceKind();
    if (refKind == REF_invokeSpecial) refKind = REF_invokeVirtual;
    return make(refKind, receiver, member);
  }

  static DirectMethodHandle make(MemberName member) {
    if (member.isConstructor()) return makeAllocator(member);
    return make(member.getDeclaringClass(), member);
  }

  private static DirectMethodHandle makeAllocator(MemberName ctor) {
    assert (ctor.isConstructor() && ctor.getName().equals("<init>"));
    Class<?> instanceClass = ctor.getDeclaringClass();
    ctor = ctor.asConstructor();
    assert (ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;
    MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);
    LambdaForm lform = preparedLambdaForm(ctor);
    MemberName init = ctor.asSpecial();
    assert (init.getMethodType().returnType() == void.class);
    return new Constructor(mtype, lform, ctor, init, instanceClass);
  }

  @Override
  BoundMethodHandle rebind() {
    return BoundMethodHandle.makeReinvoker(this);
  }

  @Override
  MethodHandle copyWith(MethodType mt, LambdaForm lf) {
    assert (this.getClass() == DirectMethodHandle.class); // must override in subclasses
    return new DirectMethodHandle(mt, lf, member);
  }

  @Override
  String internalProperties() {
    return "\n& DMH.MN=" + internalMemberName();
  }

  //// Implementation methods.
  @Override
  @ForceInline
  MemberName internalMemberName() {
    return member;
  }

  private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();

  /**
   * Create a LF which can invoke the given method. Cache and share this structure among all methods
   * with the same basicType and refKind.
   */
  private static LambdaForm preparedLambdaForm(MemberName m) {
    assert (m.isInvocable()) : m; // call preparedFieldLambdaForm instead
    MethodType mtype = m.getInvocationType().basicType();
    assert (!m.isMethodHandleInvoke()) : m;
    int which;
    switch (m.getReferenceKind()) {
      case REF_invokeVirtual:
        which = LF_INVVIRTUAL;
        break;
      case REF_invokeStatic:
        which = LF_INVSTATIC;
        break;
      case REF_invokeSpecial:
        which = LF_INVSPECIAL;
        break;
      case REF_invokeInterface:
        which = LF_INVINTERFACE;
        break;
      case REF_newInvokeSpecial:
        which = LF_NEWINVSPECIAL;
        break;
      default:
        throw new InternalError(m.toString());
    }
    if (which == LF_INVSTATIC && shouldBeInitialized(m)) {
      // precompute the barrier-free version:
      preparedLambdaForm(mtype, which);
      which = LF_INVSTATIC_INIT;
    }
    LambdaForm lform = preparedLambdaForm(mtype, which);
    maybeCompile(lform, m);
    assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
        : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
    return lform;
  }

  private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {
    LambdaForm lform = mtype.form().cachedLambdaForm(which);
    if (lform != null) return lform;
    lform = makePreparedLambdaForm(mtype, which);
    return mtype.form().setCachedLambdaForm(which, lform);
  }

  static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {
    boolean needsInit = (which == LF_INVSTATIC_INIT);
    boolean doesAlloc = (which == LF_NEWINVSPECIAL);
    String linkerName;
    LambdaForm.Kind kind;
    switch (which) {
      case LF_INVVIRTUAL:
        linkerName = "linkToVirtual";
        kind = DIRECT_INVOKE_VIRTUAL;
        break;
      case LF_INVSTATIC:
        linkerName = "linkToStatic";
        kind = DIRECT_INVOKE_STATIC;
        break;
      case LF_INVSTATIC_INIT:
        linkerName = "linkToStatic";
        kind = DIRECT_INVOKE_STATIC_INIT;
        break;
      case LF_INVSPECIAL:
        linkerName = "linkToSpecial";
        kind = DIRECT_INVOKE_SPECIAL;
        break;
      case LF_INVINTERFACE:
        linkerName = "linkToInterface";
        kind = DIRECT_INVOKE_INTERFACE;
        break;
      case LF_NEWINVSPECIAL:
        linkerName = "linkToSpecial";
        kind = DIRECT_NEW_INVOKE_SPECIAL;
        break;
      default:
        throw new InternalError("which=" + which);
    }

    MethodType mtypeWithArg = mtype.appendParameterTypes(MemberName.class);
    if (doesAlloc)
      mtypeWithArg =
          mtypeWithArg
              .insertParameterTypes(0, Object.class) // insert newly allocated obj
              .changeReturnType(void.class); // <init> returns void
    MemberName linker =
        new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);
    try {
      linker =
          IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, NoSuchMethodException.class);
    } catch (ReflectiveOperationException ex) {
      throw newInternalError(ex);
    }
    final int DMH_THIS = 0;
    final int ARG_BASE = 1;
    final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
    int nameCursor = ARG_LIMIT;
    final int NEW_OBJ = (doesAlloc ? nameCursor++ : -1);
    final int GET_MEMBER = nameCursor++;
    final int LINKER_CALL = nameCursor++;
    Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
    assert (names.length == nameCursor);
    if (doesAlloc) {
      // names = { argx,y,z,... new C, init method }
      names[NEW_OBJ] = new Name(NF_allocateInstance, names[DMH_THIS]);
      names[GET_MEMBER] = new Name(NF_constructorMethod, names[DMH_THIS]);
    } else if (needsInit) {
      names[GET_MEMBER] = new Name(NF_internalMemberNameEnsureInit, names[DMH_THIS]);
    } else {
      names[GET_MEMBER] = new Name(NF_internalMemberName, names[DMH_THIS]);
    }
    assert (findDirectMethodHandle(names[GET_MEMBER]) == names[DMH_THIS]);
    Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER + 1, Object[].class);
    assert (outArgs[outArgs.length - 1] == names[GET_MEMBER]); // look, shifted args!
    int result = LAST_RESULT;
    if (doesAlloc) {
      assert (outArgs[outArgs.length - 2] == names[NEW_OBJ]); // got to move this one
      System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length - 2);
      outArgs[0] = names[NEW_OBJ];
      result = NEW_OBJ;
    }
    names[LINKER_CALL] = new Name(linker, outArgs);
    String lambdaName = kind.defaultLambdaName + "_" + shortenSignature(basicTypeSignature(mtype));
    LambdaForm lform = new LambdaForm(lambdaName, ARG_LIMIT, names, result, kind);

    // This is a tricky bit of code.  Don't send it through the LF interpreter.
    lform.compileToBytecode();
    return lform;
  }

  static Object findDirectMethodHandle(Name name) {
    if (name.function == NF_internalMemberName
        || name.function == NF_internalMemberNameEnsureInit
        || name.function == NF_constructorMethod) {
      assert (name.arguments.length == 1);
      return name.arguments[0];
    }
    return null;
  }

  private static void maybeCompile(LambdaForm lform, MemberName m) {
    if (lform.vmentry == null
        && VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))
      // Help along bootstrapping...
      lform.compileToBytecode();
  }

  /** Static wrapper for DirectMethodHandle.internalMemberName. */
  @ForceInline
  /*non-public*/ static Object internalMemberName(Object mh) {
    return ((DirectMethodHandle) mh).member;
  }

  /**
   * Static wrapper for DirectMethodHandle.internalMemberName. This one also forces initialization.
   */
  /*non-public*/ static Object internalMemberNameEnsureInit(Object mh) {
    DirectMethodHandle dmh = (DirectMethodHandle) mh;
    dmh.ensureInitialized();
    return dmh.member;
  }

  /*non-public*/ static boolean shouldBeInitialized(MemberName member) {
    switch (member.getReferenceKind()) {
      case REF_invokeStatic:
      case REF_getStatic:
      case REF_putStatic:
      case REF_newInvokeSpecial:
        break;
      default:
        // No need to initialize the class on this kind of member.
        return false;
    }
    Class<?> cls = member.getDeclaringClass();
    if (cls == ValueConversions.class || cls == MethodHandleImpl.class || cls == Invokers.class) {
      // These guys have lots of <clinit> DMH creation but we know
      // the MHs will not be used until the system is booted.
      return false;
    }
    if (VerifyAccess.isSamePackage(MethodHandle.class, cls)
        || VerifyAccess.isSamePackage(ValueConversions.class, cls)) {
      // It is a system class.  It is probably in the process of
      // being initialized, but we will help it along just to be safe.
      if (UNSAFE.shouldBeInitialized(cls)) {
        UNSAFE.ensureClassInitialized(cls);
      }
      return false;
    }
    return UNSAFE.shouldBeInitialized(cls);
  }

  private static class EnsureInitialized extends ClassValue<WeakReference<Thread>> {
    @Override
    protected WeakReference<Thread> computeValue(Class<?> type) {
      UNSAFE.ensureClassInitialized(type);
      if (UNSAFE.shouldBeInitialized(type))
        // If the previous call didn't block, this can happen.
        // We are executing inside <clinit>.
        return new WeakReference<>(Thread.currentThread());
      return null;
    }

    static final EnsureInitialized INSTANCE = new EnsureInitialized();
  }

  private void ensureInitialized() {
    if (checkInitialized(member)) {
      // The coast is clear.  Delete the <clinit> barrier.
      if (member.isField()) updateForm(preparedFieldLambdaForm(member));
      else updateForm(preparedLambdaForm(member));
    }
  }

  private static boolean checkInitialized(MemberName member) {
    Class<?> defc = member.getDeclaringClass();
    WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc);
    if (ref == null) {
      return true; // the final state
    }
    Thread clinitThread = ref.get();
    // Somebody may still be running defc.<clinit>.
    if (clinitThread == Thread.currentThread()) {
      // If anybody is running defc.<clinit>, it is this thread.
      if (UNSAFE.shouldBeInitialized(defc))
        // Yes, we are running it; keep the barrier for now.
        return false;
    } else {
      // We are in a random thread.  Block.
      UNSAFE.ensureClassInitialized(defc);
    }
    assert (!UNSAFE.shouldBeInitialized(defc));
    // put it into the final state
    EnsureInitialized.INSTANCE.remove(defc);
    return true;
  }

  /*non-public*/ static void ensureInitialized(Object mh) {
    ((DirectMethodHandle) mh).ensureInitialized();
  }

  /** This subclass represents invokespecial instructions. */
  static class Special extends DirectMethodHandle {
    private Special(MethodType mtype, LambdaForm form, MemberName member) {
      super(mtype, form, member);
    }

    @Override
    boolean isInvokeSpecial() {
      return true;
    }

    @Override
    MethodHandle copyWith(MethodType mt, LambdaForm lf) {
      return new Special(mt, lf, member);
    }
  }

  /** This subclass handles constructor references. */
  static class Constructor extends DirectMethodHandle {
    final MemberName initMethod;
    final Class<?> instanceClass;

    private Constructor(
        MethodType mtype,
        LambdaForm form,
        MemberName constructor,
        MemberName initMethod,
        Class<?> instanceClass) {
      super(mtype, form, constructor);
      this.initMethod = initMethod;
      this.instanceClass = instanceClass;
      assert (initMethod.isResolved());
    }

    @Override
    MethodHandle copyWith(MethodType mt, LambdaForm lf) {
      return new Constructor(mt, lf, member, initMethod, instanceClass);
    }
  }

  /*non-public*/ static Object constructorMethod(Object mh) {
    Constructor dmh = (Constructor) mh;
    return dmh.initMethod;
  }

  /*non-public*/ static Object allocateInstance(Object mh) throws InstantiationException {
    Constructor dmh = (Constructor) mh;
    return UNSAFE.allocateInstance(dmh.instanceClass);
  }

  /** This subclass handles non-static field references. */
  static class Accessor extends DirectMethodHandle {
    final Class<?> fieldType;
    final int fieldOffset;

    private Accessor(MethodType mtype, LambdaForm form, MemberName member, int fieldOffset) {
      super(mtype, form, member);
      this.fieldType = member.getFieldType();
      this.fieldOffset = fieldOffset;
    }

    @Override
    Object checkCast(Object obj) {
      return fieldType.cast(obj);
    }

    @Override
    MethodHandle copyWith(MethodType mt, LambdaForm lf) {
      return new Accessor(mt, lf, member, fieldOffset);
    }
  }

  @ForceInline
  /*non-public*/ static long fieldOffset(Object accessorObj) {
    // Note: We return a long because that is what Unsafe.getObject likes.
    // We store a plain int because it is more compact.
    return ((Accessor) accessorObj).fieldOffset;
  }

  @ForceInline
  /*non-public*/ static Object checkBase(Object obj) {
    // Note that the object's class has already been verified,
    // since the parameter type of the Accessor method handle
    // is either member.getDeclaringClass or a subclass.
    // This was verified in DirectMethodHandle.make.
    // Therefore, the only remaining check is for null.
    // Since this check is *not* guaranteed by Unsafe.getInt
    // and its siblings, we need to make an explicit one here.
    return Objects.requireNonNull(obj);
  }

  /** This subclass handles static field references. */
  static class StaticAccessor extends DirectMethodHandle {
    private final Class<?> fieldType;
    private final Object staticBase;
    private final long staticOffset;

    private StaticAccessor(
        MethodType mtype,
        LambdaForm form,
        MemberName member,
        Object staticBase,
        long staticOffset) {
      super(mtype, form, member);
      this.fieldType = member.getFieldType();
      this.staticBase = staticBase;
      this.staticOffset = staticOffset;
    }

    @Override
    Object checkCast(Object obj) {
      return fieldType.cast(obj);
    }

    @Override
    MethodHandle copyWith(MethodType mt, LambdaForm lf) {
      return new StaticAccessor(mt, lf, member, staticBase, staticOffset);
    }
  }

  @ForceInline
  /*non-public*/ static Object nullCheck(Object obj) {
    return Objects.requireNonNull(obj);
  }

  @ForceInline
  /*non-public*/ static Object staticBase(Object accessorObj) {
    return ((StaticAccessor) accessorObj).staticBase;
  }

  @ForceInline
  /*non-public*/ static long staticOffset(Object accessorObj) {
    return ((StaticAccessor) accessorObj).staticOffset;
  }

  @ForceInline
  /*non-public*/ static Object checkCast(Object mh, Object obj) {
    return ((DirectMethodHandle) mh).checkCast(obj);
  }

  Object checkCast(Object obj) {
    return member.getReturnType().cast(obj);
  }

  // Caching machinery for field accessors:
  private static final byte AF_GETFIELD = 0,
      AF_PUTFIELD = 1,
      AF_GETSTATIC = 2,
      AF_PUTSTATIC = 3,
      AF_GETSTATIC_INIT = 4,
      AF_PUTSTATIC_INIT = 5,
      AF_LIMIT = 6;
  // Enumerate the different field kinds using Wrapper,
  // with an extra case added for checked references.
  private static final int FT_LAST_WRAPPER = Wrapper.COUNT - 1,
      FT_UNCHECKED_REF = Wrapper.OBJECT.ordinal(),
      FT_CHECKED_REF = FT_LAST_WRAPPER + 1,
      FT_LIMIT = FT_LAST_WRAPPER + 2;

  private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {
    return ((formOp * FT_LIMIT * 2) + (isVolatile ? FT_LIMIT : 0) + ftypeKind);
  }

  @Stable
  private static final LambdaForm[] ACCESSOR_FORMS = new LambdaForm[afIndex(AF_LIMIT, false, 0)];

  private static int ftypeKind(Class<?> ftype) {
    if (ftype.isPrimitive()) return Wrapper.forPrimitiveType(ftype).ordinal();
    else if (VerifyType.isNullReferenceConversion(Object.class, ftype)) return FT_UNCHECKED_REF;
    else return FT_CHECKED_REF;
  }

  /**
   * Create a LF which can access the given field. Cache and share this structure among all fields
   * with the same basicType and refKind.
   */
  private static LambdaForm preparedFieldLambdaForm(MemberName m) {
    Class<?> ftype = m.getFieldType();
    boolean isVolatile = m.isVolatile();
    byte formOp;
    switch (m.getReferenceKind()) {
      case REF_getField:
        formOp = AF_GETFIELD;
        break;
      case REF_putField:
        formOp = AF_PUTFIELD;
        break;
      case REF_getStatic:
        formOp = AF_GETSTATIC;
        break;
      case REF_putStatic:
        formOp = AF_PUTSTATIC;
        break;
      default:
        throw new InternalError(m.toString());
    }
    if (shouldBeInitialized(m)) {
      // precompute the barrier-free version:
      preparedFieldLambdaForm(formOp, isVolatile, ftype);
      assert ((AF_GETSTATIC_INIT - AF_GETSTATIC) == (AF_PUTSTATIC_INIT - AF_PUTSTATIC));
      formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);
    }
    LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);
    maybeCompile(lform, m);
    assert (lform.methodType().dropParameterTypes(0, 1).equals(m.getInvocationType().basicType()))
        : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());
    return lform;
  }

  private static LambdaForm preparedFieldLambdaForm(
      byte formOp, boolean isVolatile, Class<?> ftype) {
    int ftypeKind = ftypeKind(ftype);
    int afIndex = afIndex(formOp, isVolatile, ftypeKind);
    LambdaForm lform = ACCESSOR_FORMS[afIndex];
    if (lform != null) return lform;
    lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind);
    ACCESSOR_FORMS[afIndex] = lform; // don't bother with a CAS
    return lform;
  }

  private static final Wrapper[] ALL_WRAPPERS = Wrapper.values();

  private static LambdaForm makePreparedFieldLambdaForm(
      byte formOp, boolean isVolatile, int ftypeKind) {
    boolean isGetter = (formOp & 1) == (AF_GETFIELD & 1);
    boolean isStatic = (formOp >= AF_GETSTATIC);
    boolean needsInit = (formOp >= AF_GETSTATIC_INIT);
    boolean needsCast = (ftypeKind == FT_CHECKED_REF);
    Wrapper fw = (needsCast ? Wrapper.OBJECT : ALL_WRAPPERS[ftypeKind]);
    Class<?> ft = fw.primitiveType();
    assert (ftypeKind(needsCast ? String.class : ft) == ftypeKind);

    // getObject, putIntVolatile, etc.
    StringBuilder nameBuilder = new StringBuilder();
    if (isGetter) {
      nameBuilder.append("get");
    } else {
      nameBuilder.append("put");
    }
    nameBuilder.append(fw.primitiveSimpleName());
    nameBuilder.setCharAt(3, Character.toUpperCase(nameBuilder.charAt(3)));
    if (isVolatile) {
      nameBuilder.append("Volatile");
    }

    MethodType linkerType;
    if (isGetter) linkerType = MethodType.methodType(ft, Object.class, long.class);
    else linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);
    MemberName linker =
        new MemberName(Unsafe.class, nameBuilder.toString(), linkerType, REF_invokeVirtual);
    try {
      linker =
          IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);
    } catch (ReflectiveOperationException ex) {
      throw newInternalError(ex);
    }

    // What is the external type of the lambda form?
    MethodType mtype;
    if (isGetter) mtype = MethodType.methodType(ft);
    else mtype = MethodType.methodType(void.class, ft);
    mtype = mtype.basicType(); // erase short to int, etc.
    if (!isStatic) mtype = mtype.insertParameterTypes(0, Object.class);
    final int DMH_THIS = 0;
    final int ARG_BASE = 1;
    final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();
    // if this is for non-static access, the base pointer is stored at this index:
    final int OBJ_BASE = isStatic ? -1 : ARG_BASE;
    // if this is for write access, the value to be written is stored at this index:
    final int SET_VALUE = isGetter ? -1 : ARG_LIMIT - 1;
    int nameCursor = ARG_LIMIT;
    final int F_HOLDER = (isStatic ? nameCursor++ : -1); // static base if any
    final int F_OFFSET = nameCursor++; // Either static offset or field offset.
    final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);
    final int INIT_BAR = (needsInit ? nameCursor++ : -1);
    final int PRE_CAST = (needsCast && !isGetter ? nameCursor++ : -1);
    final int LINKER_CALL = nameCursor++;
    final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);
    final int RESULT = nameCursor - 1; // either the call or the cast
    Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());
    if (needsInit) names[INIT_BAR] = new Name(NF_ensureInitialized, names[DMH_THIS]);
    if (needsCast && !isGetter)
      names[PRE_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[SET_VALUE]);
    Object[] outArgs = new Object[1 + linkerType.parameterCount()];
    assert (outArgs.length == (isGetter ? 3 : 4));
    outArgs[0] = UNSAFE;
    if (isStatic) {
      outArgs[1] = names[F_HOLDER] = new Name(NF_staticBase, names[DMH_THIS]);
      outArgs[2] = names[F_OFFSET] = new Name(NF_staticOffset, names[DMH_THIS]);
    } else {
      outArgs[1] = names[OBJ_CHECK] = new Name(NF_checkBase, names[OBJ_BASE]);
      outArgs[2] = names[F_OFFSET] = new Name(NF_fieldOffset, names[DMH_THIS]);
    }
    if (!isGetter) {
      outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);
    }
    for (Object a : outArgs) assert (a != null);
    names[LINKER_CALL] = new Name(linker, outArgs);
    if (needsCast && isGetter)
      names[POST_CAST] = new Name(NF_checkCast, names[DMH_THIS], names[LINKER_CALL]);
    for (Name n : names) assert (n != null);
    // add some detail to the lambdaForm debugname,
    // significant only for debugging
    if (isStatic) {
      nameBuilder.append("Static");
    } else {
      nameBuilder.append("Field");
    }
    if (needsCast) nameBuilder.append("Cast");
    if (needsInit) nameBuilder.append("Init");
    return new LambdaForm(nameBuilder.toString(), ARG_LIMIT, names, RESULT);
  }

  /**
   * Pre-initialized NamedFunctions for bootstrapping purposes. Factored in an inner class to delay
   * initialization until first usage.
   */
  static final NamedFunction NF_internalMemberName,
      NF_internalMemberNameEnsureInit,
      NF_ensureInitialized,
      NF_fieldOffset,
      NF_checkBase,
      NF_staticBase,
      NF_staticOffset,
      NF_checkCast,
      NF_allocateInstance,
      NF_constructorMethod;

  static {
    try {
      NamedFunction nfs[] = {
        NF_internalMemberName =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("internalMemberName", Object.class)),
        NF_internalMemberNameEnsureInit =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod(
                    "internalMemberNameEnsureInit", Object.class)),
        NF_ensureInitialized =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("ensureInitialized", Object.class)),
        NF_fieldOffset =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("fieldOffset", Object.class)),
        NF_checkBase =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("checkBase", Object.class)),
        NF_staticBase =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("staticBase", Object.class)),
        NF_staticOffset =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("staticOffset", Object.class)),
        NF_checkCast =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod(
                    "checkCast", Object.class, Object.class)),
        NF_allocateInstance =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("allocateInstance", Object.class)),
        NF_constructorMethod =
            new NamedFunction(
                DirectMethodHandle.class.getDeclaredMethod("constructorMethod", Object.class))
      };
      // Each nf must be statically invocable or we get tied up in our bootstraps.
      assert (InvokerBytecodeGenerator.isStaticallyInvocable(nfs));
    } catch (ReflectiveOperationException ex) {
      throw newInternalError(ex);
    }
  }

  static {
    // The Holder class will contain pre-generated DirectMethodHandles resolved
    // speculatively using MemberName.getFactory().resolveOrNull. However, that
    // doesn't initialize the class, which subtly breaks inlining etc. By forcing
    // initialization of the Holder class we avoid these issues.
    UNSAFE.ensureClassInitialized(Holder.class);
  }

  /* Placeholder class for DirectMethodHandles generated ahead of time */
  final class Holder {}
}
示例#19
0
 static DirectMethodHandle make(MemberName member) {
   if (member.isConstructor()) return makeAllocator(member);
   return make(member.getDeclaringClass(), member);
 }
示例#20
0
 private Accessor(MethodType mtype, LambdaForm form, MemberName member, int fieldOffset) {
   super(mtype, form, member);
   this.fieldType = member.getFieldType();
   this.fieldOffset = fieldOffset;
 }