C++ methodHandle::result_type方法代码示例

void ConstantPoolCacheEntry::set_interface_call(methodHandle method, int index) {
  klassOop interf = method->method_holder();
  assert(instanceKlass::cast(interf)->is_interface(), "must be an interface");
  set_f1(interf);
  set_f2(index);
  set_flags(as_flags(as_TosState(method->result_type()), method->is_final_method(), false, false, false, true) | method()->size_of_parameters());
  set_bytecode_1(Bytecodes::_invokeinterface);  
}

void ConstantPoolCacheEntry::set_interface_call(methodHandle method, int index) {
  assert(!is_secondary_entry(), "");
  klassOop interf = method->method_holder();
  assert(instanceKlass::cast(interf)->is_interface(), "must be an interface");
  assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
  set_f1(interf);
  set_f2(index);
  set_method_flags(as_TosState(method->result_type()),
                   0,  // no option bits
                   method()->size_of_parameters());
  set_bytecode_1(Bytecodes::_invokeinterface);
}

  uint64_t fingerprint() {
    // See if we fingerprinted this method already
    if (mh->constMethod()->fingerprint() != CONST64(0)) {
      return mh->constMethod()->fingerprint();
    }

    if (mh->size_of_parameters() > max_size_of_parameters ) {
      _fingerprint = UCONST64(-1);
      mh->constMethod()->set_fingerprint(_fingerprint);
      return _fingerprint;
    }

    assert( (int)mh->result_type() <= (int)result_feature_mask, "bad result type");
    _fingerprint = mh->result_type();
    _fingerprint <<= static_feature_size;
    if (mh->is_static())  _fingerprint |= 1;
    _shift_count = result_feature_size + static_feature_size;
    iterate_parameters();
    _fingerprint |= ((uint64_t)done_parm) << _shift_count;// mark end of sig
    mh->constMethod()->set_fingerprint(_fingerprint);
    return _fingerprint;
  }

void ConstantPoolCacheEntry::set_itable_call(Bytecodes::Code invoke_code, methodHandle method, int index) {
  assert(method->method_holder()->verify_itable_index(index), "");
  assert(invoke_code == Bytecodes::_invokeinterface, "");
  InstanceKlass* interf = method->method_holder();
  assert(interf->is_interface(), "must be an interface");
  assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
  set_f1(interf);
  set_f2(index);
  set_method_flags(as_TosState(method->result_type()),
                   0,  // no option bits
                   method()->size_of_parameters());
  set_bytecode_1(Bytecodes::_invokeinterface);
}

void ConstantPoolCacheEntry::set_method(Bytecodes::Code invoke_code,
                                        methodHandle method,
                                        int vtable_index) {

  assert(method->interpreter_entry() != NULL, "should have been set at this point");
  assert(!method->is_old_version(),  "attempt to write old method to cpCache");
  bool change_to_virtual = (invoke_code == Bytecodes::_invokeinterface);

  int byte_no = -1;
  bool needs_vfinal_flag = false;
  switch (invoke_code) {
    case Bytecodes::_invokevirtual:
    case Bytecodes::_invokeinterface: {
        if (Klass::can_be_statically_bound(method())) {
          set_f2((intptr_t)method());
	  needs_vfinal_flag = true;
        } else {
          set_f2(vtable_index);
        }
        byte_no = 2;
        break;
    }
    case Bytecodes::_invokespecial:
      // Preserve the value of the vfinal flag on invokevirtual bytecode
      // which may be shared with this constant pool cache entry.
      needs_vfinal_flag = is_resolved(Bytecodes::_invokevirtual) && is_vfinal();
      // fall through
    case Bytecodes::_invokestatic:
      set_f1(method());
      byte_no = 1;
      break;
    default:
      ShouldNotReachHere();
      break;
  }

  set_flags(as_flags(as_TosState(method->result_type()),
                     method->is_final_method(), 
                     needs_vfinal_flag, 
                     false, 
                     change_to_virtual,
                     true)|
            method()->size_of_parameters());

  // Note:  byte_no also appears in TemplateTable::resolve.
  if (byte_no == 1) {
    set_bytecode_1(invoke_code);
  } else if (byte_no == 2)  {
    if (change_to_virtual) {
      // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
      //
      // Workaround for the case where we encounter an invokeinterface, but we
      // should really have an _invokevirtual since the resolved method is a 
      // virtual method in java.lang.Object. This is a corner case in the spec
      // but is presumably legal. javac does not generate this code.
      //
      // We set bytecode_1() to _invokeinterface, because that is the
      // bytecode # used by the interpreter to see if it is resolved.
      // We set bytecode_2() to _invokevirtual.
      // See also interpreterRuntime.cpp. (8/25/2000)
      set_bytecode_1(invoke_code);
      set_bytecode_2(Bytecodes::_invokevirtual);
    } else {
      set_bytecode_2(invoke_code);
    }
  } else {
    ShouldNotReachHere();
  }
  verify(tty);
}

void ConstantPoolCacheEntry::set_method_handle_common(constantPoolHandle cpool,
                                                      Bytecodes::Code invoke_code,
                                                      const CallInfo &call_info) {
  // NOTE: This CPCE can be the subject of data races.
  // There are three words to update: flags, refs[f2], f1 (in that order).
  // Writers must store all other values before f1.
  // Readers must test f1 first for non-null before reading other fields.
  // Competing writers must acquire exclusive access via a lock.
  // A losing writer waits on the lock until the winner writes f1 and leaves
  // the lock, so that when the losing writer returns, he can use the linked
  // cache entry.

  MonitorLockerEx ml(cpool->lock());
  if (!is_f1_null()) {
    return;
  }

  const methodHandle adapter = call_info.resolved_method();
  const Handle appendix      = call_info.resolved_appendix();
  const Handle method_type   = call_info.resolved_method_type();
  const bool has_appendix    = appendix.not_null();
  const bool has_method_type = method_type.not_null();

  // Write the flags.
  set_method_flags(as_TosState(adapter->result_type()),
                   ((has_appendix    ? 1 : 0) << has_appendix_shift   ) |
                   ((has_method_type ? 1 : 0) << has_method_type_shift) |
                   (                   1      << is_final_shift       ),
                   adapter->size_of_parameters());

  if (TraceInvokeDynamic) {
    tty->print_cr("set_method_handle bc=%d appendix="PTR_FORMAT"%s method_type="PTR_FORMAT"%s method="PTR_FORMAT" ",
                  invoke_code,
                  (void *)appendix(),    (has_appendix    ? "" : " (unused)"),
                  (void *)method_type(), (has_method_type ? "" : " (unused)"),
                  (intptr_t)adapter());
    adapter->print();
    if (has_appendix)  appendix()->print();
  }

  // Method handle invokes and invokedynamic sites use both cp cache words.
  // refs[f2], if not null, contains a value passed as a trailing argument to the adapter.
  // In the general case, this could be the call site's MethodType,
  // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
  // f1 contains the adapter method which manages the actual call.
  // In the general case, this is a compiled LambdaForm.
  // (The Java code is free to optimize these calls by binding other
  // sorts of methods and appendices to call sites.)
  // JVM-level linking is via f1, as if for invokespecial, and signatures are erased.
  // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
  // Even with the appendix, the method will never take more than 255 parameter slots.
  //
  // This means that given a call site like (List)mh.invoke("foo"),
  // the f1 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
  // not '(Ljava/lang/String;)Ljava/util/List;'.
  // The fact that String and List are involved is encoded in the MethodType in refs[f2].
  // This allows us to create fewer method oops, while keeping type safety.
  //

  objArrayHandle resolved_references = cpool->resolved_references();
  // Store appendix, if any.
  if (has_appendix) {
    const int appendix_index = f2_as_index() + _indy_resolved_references_appendix_offset;
    assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
    assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
    resolved_references->obj_at_put(appendix_index, appendix());
  }

  // Store MethodType, if any.
  if (has_method_type) {
    const int method_type_index = f2_as_index() + _indy_resolved_references_method_type_offset;
    assert(method_type_index >= 0 && method_type_index < resolved_references->length(), "oob");
    assert(resolved_references->obj_at(method_type_index) == NULL, "init just once");
    resolved_references->obj_at_put(method_type_index, method_type());
  }

  release_set_f1(adapter());  // This must be the last one to set (see NOTE above)!

  // The interpreter assembly code does not check byte_2,
  // but it is used by is_resolved, method_if_resolved, etc.
  set_bytecode_1(invoke_code);
  NOT_PRODUCT(verify(tty));
  if (TraceInvokeDynamic) {
    this->print(tty, 0);
  }
}

void ConstantPoolCacheEntry::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
                                                       methodHandle method,
                                                       int vtable_index) {
  bool is_vtable_call = (vtable_index >= 0);  // FIXME: split this method on this boolean
  assert(method->interpreter_entry() != NULL, "should have been set at this point");
  assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");

  int byte_no = -1;
  bool change_to_virtual = false;

  switch (invoke_code) {
    case Bytecodes::_invokeinterface:
      // We get here from InterpreterRuntime::resolve_invoke when an invokeinterface
      // instruction somehow links to a non-interface method (in Object).
      // In that case, the method has no itable index and must be invoked as a virtual.
      // Set a flag to keep track of this corner case.
      change_to_virtual = true;

      // ...and fall through as if we were handling invokevirtual:
    case Bytecodes::_invokevirtual:
      {
        if (!is_vtable_call) {
          assert(method->can_be_statically_bound(), "");
          // set_f2_as_vfinal_method checks if is_vfinal flag is true.
          set_method_flags(as_TosState(method->result_type()),
                           (                             1      << is_vfinal_shift) |
                           ((method->is_final_method() ? 1 : 0) << is_final_shift)  |
                           ((change_to_virtual         ? 1 : 0) << is_forced_virtual_shift),
                           method()->size_of_parameters());
          set_f2_as_vfinal_method(method());
        } else {
          assert(!method->can_be_statically_bound(), "");
          assert(vtable_index >= 0, "valid index");
          assert(!method->is_final_method(), "sanity");
          set_method_flags(as_TosState(method->result_type()),
                           ((change_to_virtual ? 1 : 0) << is_forced_virtual_shift),
                           method()->size_of_parameters());
          set_f2(vtable_index);
        }
        byte_no = 2;
        break;
      }

    case Bytecodes::_invokespecial:
    case Bytecodes::_invokestatic:
      assert(!is_vtable_call, "");
      // Note:  Read and preserve the value of the is_vfinal flag on any
      // invokevirtual bytecode shared with this constant pool cache entry.
      // It is cheap and safe to consult is_vfinal() at all times.
      // Once is_vfinal is set, it must stay that way, lest we get a dangling oop.
      set_method_flags(as_TosState(method->result_type()),
                       ((is_vfinal()               ? 1 : 0) << is_vfinal_shift) |
                       ((method->is_final_method() ? 1 : 0) << is_final_shift),
                       method()->size_of_parameters());
      set_f1(method());
      byte_no = 1;
      break;
    default:
      ShouldNotReachHere();
      break;
  }

  // Note:  byte_no also appears in TemplateTable::resolve.
  if (byte_no == 1) {
    assert(invoke_code != Bytecodes::_invokevirtual &&
           invoke_code != Bytecodes::_invokeinterface, "");
    set_bytecode_1(invoke_code);
  } else if (byte_no == 2)  {
    if (change_to_virtual) {
      assert(invoke_code == Bytecodes::_invokeinterface, "");
      // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
      //
      // Workaround for the case where we encounter an invokeinterface, but we
      // should really have an _invokevirtual since the resolved method is a
      // virtual method in java.lang.Object. This is a corner case in the spec
      // but is presumably legal. javac does not generate this code.
      //
      // We set bytecode_1() to _invokeinterface, because that is the
      // bytecode # used by the interpreter to see if it is resolved.
      // We set bytecode_2() to _invokevirtual.
      // See also interpreterRuntime.cpp. (8/25/2000)
      // Only set resolved for the invokeinterface case if method is public.
      // Otherwise, the method needs to be reresolved with caller for each
      // interface call.
      if (method->is_public()) set_bytecode_1(invoke_code);
    } else {
      assert(invoke_code == Bytecodes::_invokevirtual, "");
    }
    // set up for invokevirtual, even if linking for invokeinterface also:
    set_bytecode_2(Bytecodes::_invokevirtual);
  } else {
    ShouldNotReachHere();
  }
  NOT_PRODUCT(verify(tty));
}

void ConstantPoolCacheEntry::set_method_handle_common(constantPoolHandle cpool,
                                                      Bytecodes::Code invoke_code,
                                                      methodHandle adapter,
                                                      Handle appendix, Handle method_type) {
  // NOTE: This CPCE can be the subject of data races.
  // There are three words to update: flags, f2, f1 (in that order).
  // Writers must store all other values before f1.
  // Readers must test f1 first for non-null before reading other fields.
  // Competing writers must acquire exclusive access via a lock.
  // A losing writer waits on the lock until the winner writes f1 and leaves
  // the lock, so that when the losing writer returns, he can use the linked
  // cache entry.

  Thread* THREAD = Thread::current();
  ObjectLocker ol(cpool, THREAD);
  if (!is_f1_null()) {
    return;
  }

  const bool has_appendix    = appendix.not_null();
  const bool has_method_type = method_type.not_null();

  if (!has_appendix) {
    // The extra argument is not used, but we need a non-null value to signify linkage state.
    // Set it to something benign that will never leak memory.
    appendix = Universe::void_mirror();
  }

  // Write the flags.
  set_method_flags(as_TosState(adapter->result_type()),
                   ((has_appendix    ? 1 : 0) << has_appendix_shift)    |
                   ((has_method_type ? 1 : 0) << has_method_type_shift) |
                   (                   1      << is_vfinal_shift)       |
                   (                   1      << is_final_shift),
                   adapter->size_of_parameters());

  if (TraceInvokeDynamic) {
    tty->print_cr("set_method_handle bc=%d appendix="PTR_FORMAT"%s method_type="PTR_FORMAT"%s method="PTR_FORMAT" ",
                  invoke_code,
                  (intptr_t)appendix(),    (has_appendix    ? "" : " (unused)"),
                  (intptr_t)method_type(), (has_method_type ? "" : " (unused)"),
                  (intptr_t)adapter());
    adapter->print();
    if (has_appendix)  appendix()->print();
  }

  // Method handle invokes and invokedynamic sites use both cp cache words.
  // f1, if not null, contains a value passed as a trailing argument to the adapter.
  // In the general case, this could be the call site's MethodType,
  // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
  // f2 contains the adapter method which manages the actual call.
  // In the general case, this is a compiled LambdaForm.
  // (The Java code is free to optimize these calls by binding other
  // sorts of methods and appendices to call sites.)
  // JVM-level linking is via f2, as if for invokevfinal, and signatures are erased.
  // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
  // In principle this means that the method (with appendix) could take up to 256 parameter slots.
  //
  // This means that given a call site like (List)mh.invoke("foo"),
  // the f2 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
  // not '(Ljava/lang/String;)Ljava/util/List;'.
  // The fact that String and List are involved is encoded in the MethodType in f1.
  // This allows us to create fewer method oops, while keeping type safety.
  //

  set_f2_as_vfinal_method(adapter());

  // Store MethodType, if any.
  if (has_method_type) {
    ConstantPoolCacheEntry* e2 = cpool->cache()->find_secondary_entry_for(this);

    // Write the flags.
    e2->set_method_flags(as_TosState(adapter->result_type()),
                     ((has_method_type ? 1 : 0) << has_method_type_shift) |
                     (                   1      << is_vfinal_shift)       |
                     (                   1      << is_final_shift),
                     adapter->size_of_parameters());
    e2->release_set_f1(method_type());
  }

  assert(appendix.not_null(), "needed for linkage state");
  release_set_f1(appendix());  // This must be the last one to set (see NOTE above)!

  if (!is_secondary_entry()) {
    // The interpreter assembly code does not check byte_2,
    // but it is used by is_resolved, method_if_resolved, etc.
    set_bytecode_2(invoke_code);
  }

  NOT_PRODUCT(verify(tty));
  if (TraceInvokeDynamic) {
    this->print(tty, 0);
  }
}