C++ Klass类代码示例

void InstanceMirrorKlass::oop_pc_follow_contents(oop obj, ParCompactionManager* cm) {
  InstanceKlass::oop_pc_follow_contents(obj, cm);

  // Follow the klass field in the mirror.
  Klass* klass = java_lang_Class::as_Klass(obj);
  if (klass != NULL) {
    // An anonymous class doesn't have its own class loader, so the call
    // to follow_klass will mark and push its java mirror instead of the
    // class loader. When handling the java mirror for an anonymous class
    // we need to make sure its class loader data is claimed, this is done
    // by calling follow_class_loader explicitly. For non-anonymous classes
    // the call to follow_class_loader is made when the class loader itself
    // is handled.
    if (klass->is_instance_klass() && InstanceKlass::cast(klass)->is_anonymous()) {
      cm->follow_class_loader(klass->class_loader_data());
    } else {
      cm->follow_klass(klass);
    }
  } else {
    // If klass is NULL then this a mirror for a primitive type.
    // We don't have to follow them, since they are handled as strong
    // roots in Universe::oops_do.
    assert(java_lang_Class::is_primitive(obj), "Sanity check");
  }

  ParCompactionManager::MarkAndPushClosure cl(cm);
  oop_oop_iterate_statics<true>(obj, &cl);
}

void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
  // Lock-free access requires load_ptr_acquire
  for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
    klass_closure->do_klass(k);
    assert(k != k->next_link(), "no loops!");
  }
}

void javaVFrame::print() {
  ResourceMark rm;
  vframe::print();
  tty->print("\t");
  method()->print_value();
  tty->cr();
  tty->print_cr("\tbci:    %d", bci());

  print_stack_values("locals",      locals());
  print_stack_values("expressions", expressions());

  GrowableArray<MonitorInfo*>* list = monitors();
  if (list->is_empty()) return;
  tty->print_cr("\tmonitor list:");
  for (int index = (list->length()-1); index >= 0; index--) {
    MonitorInfo* monitor = list->at(index);
    tty->print("\t  obj\t");
    if (monitor->owner_is_scalar_replaced()) {
      Klass* k = java_lang_Class::as_Klass(monitor->owner_klass());
      tty->print("( is scalar replaced %s)", k->external_name());
    } else if (monitor->owner() == NULL) {
      tty->print("( null )");
    } else {
      monitor->owner()->print_value();
      tty->print("(" INTPTR_FORMAT ")", (address)monitor->owner());
    }
    if (monitor->eliminated() && is_compiled_frame())
      tty->print(" ( lock is eliminated )");
    tty->cr();
    tty->print("\t  ");
    monitor->lock()->print_on(tty);
    tty->cr();
  }
}

void Dictionary::print() {
  ResourceMark rm;
  HandleMark   hm;

  tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
                 table_size(), number_of_entries());
  tty->print_cr("^ indicates that initiating loader is different from "
                "defining loader");

  for (int index = 0; index < table_size(); index++) {
    for (DictionaryEntry* probe = bucket(index);
                          probe != NULL;
                          probe = probe->next()) {
      if (Verbose) tty->print("%4d: ", index);
      Klass* e = probe->klass();
      ClassLoaderData* loader_data =  probe->loader_data();
      bool is_defining_class =
         (loader_data == InstanceKlass::cast(e)->class_loader_data());
      tty->print("%s%s", is_defining_class ? " " : "^",
                   e->external_name());

        tty->print(", loader ");
      loader_data->print_value();
      tty->cr();
    }
  }
  tty->cr();
  _pd_cache_table->print();
  tty->cr();
}

} UNSAFE_END

UNSAFE_ENTRY(jclass, Unsafe_GetJavaMirror(JNIEnv *env, jobject unsafe, jlong metaspace_klass)) {
  Klass* klass = (Klass*) (address) metaspace_klass;

  return (jclass) JNIHandles::make_local(klass->java_mirror());
} UNSAFE_END

void Dictionary::verify() {
  guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");

  int element_count = 0;
  for (int index = 0; index < table_size(); index++) {
    for (DictionaryEntry* probe = bucket(index);
                          probe != NULL;
                          probe = probe->next()) {
      Klass* e = probe->klass();
      ClassLoaderData* loader_data = probe->loader_data();
      guarantee(e->oop_is_instance(),
                              "Verify of system dictionary failed");
      // class loader must be present;  a null class loader is the
      // boostrap loader
      guarantee(loader_data != NULL || DumpSharedSpaces ||
                loader_data->class_loader() == NULL ||
                loader_data->class_loader()->is_instance(),
                "checking type of class_loader");
      e->verify();
      probe->verify_protection_domain_set();
      element_count++;
    }
  }
  guarantee(number_of_entries() == element_count,
            "Verify of system dictionary failed");
  debug_only(verify_lookup_length((double)number_of_entries() / table_size()));

  _pd_cache_table->verify();
}

oop AOTCompiledMethod::oop_at(int index) const {
  if (index == 0) { // 0 is reserved
    return NULL;
  }
  Metadata** entry = _metadata_got + (index - 1);
  intptr_t meta = (intptr_t)*entry;
  if ((meta & 1) == 1) {
    // already resolved
    Klass* k = (Klass*)(meta & ~1);
    return k->java_mirror();
  }
  // The entry is string which we need to resolve.
  const char* meta_name = _heap->get_name_at((int)meta);
  int klass_len = build_u2_from((address)meta_name);
  const char* klass_name = meta_name + 2;
  // Quick check the current method's holder.
  Klass* k = _method->method_holder();

  ResourceMark rm; // for signature_name()
  if (strncmp(k->signature_name(), klass_name, klass_len) != 0) { // Does not match?
    // Search klass in got cells in DSO which have this compiled method.
    k = _heap->get_klass_from_got(klass_name, klass_len, _method);
  }
  int method_name_len = build_u2_from((address)klass_name + klass_len);
  guarantee(method_name_len == 0, "only klass is expected here");
  meta = ((intptr_t)k) | 1;
  *entry = (Metadata*)meta; // Should be atomic on x64
  return k->java_mirror();
}

 // increment the count for the given basic type array class (and any
 // multi-dimensional arrays). For example, for [B we check for
 // [[B, [[[B, .. and the count is incremented for each one that exists.
 static void increment_for_basic_type_arrays(Klass* k) {
   JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
   assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
   for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
     that->set_count(that->get_count() + 1);
   }
 }

// ------------------------------------------------------------------
// ciObjectFactory::create_new_object
//
// Create a new ciObject from a Metadata*.
//
// Implementation note: this functionality could be virtual behavior
// of the oop itself.  For now, we explicitly marshal the object.
ciMetadata* ciObjectFactory::create_new_object(Metadata* o) {
  EXCEPTION_CONTEXT;

  if (o->is_klass()) {
    KlassHandle h_k(THREAD, (Klass*)o);
    Klass* k = (Klass*)o;
    if (k->oop_is_instance()) {
      return new (arena()) ciInstanceKlass(h_k);
    } else if (k->oop_is_objArray()) {
      return new (arena()) ciObjArrayKlass(h_k);
    } else if (k->oop_is_typeArray()) {
      return new (arena()) ciTypeArrayKlass(h_k);
    }
  } else if (o->is_method()) {
    methodHandle h_m(THREAD, (Method*)o);
    return new (arena()) ciMethod(h_m);
  } else if (o->is_methodData()) {
    // Hold methodHandle alive - might not be necessary ???
    methodHandle h_m(THREAD, ((MethodData*)o)->method());
    return new (arena()) ciMethodData((MethodData*)o);
  }

  // The oop is of some type not supported by the compiler interface.
  ShouldNotReachHere();
  return NULL;
}

Expr* PrimInliner::obj_new() {
  // replace generic allocation primitive by size-specific primitive, if possible
  Expr* rcvr = parameter(0);
  if (!rcvr->isConstantExpr() || !rcvr->constant()->is_klass()) return NULL;
  Klass* klass = klassOop(rcvr->constant())->klass_part();	// class being instantiated
  if (klass->oop_is_indexable()) return NULL;			// would fail (extremely unlikely)
  int size = klass->non_indexable_size();			// size in words

  if (klass->can_inline_allocation()) {
    // These special compiler primitives only work for memOop klasses
    int number_of_instance_variables = size - memOopDesc::header_size();
    switch (number_of_instance_variables) {
      case 0: _pdesc = primitives::new0(); break;
      case 1: _pdesc = primitives::new1(); break;
      case 2: _pdesc = primitives::new2(); break;
      case 3: _pdesc = primitives::new3(); break;
      case 4: _pdesc = primitives::new4(); break;
      case 5: _pdesc = primitives::new5(); break;
      case 6: _pdesc = primitives::new6(); break;
      case 7: _pdesc = primitives::new7(); break;
      case 8: _pdesc = primitives::new8(); break;
      case 9: _pdesc = primitives::new9(); break;
      default:  ; // use generic primitives
    }
  }
  Expr* u = genCall(true);
  return new KlassExpr(klass->as_klassOop(), u->preg(), u->node());
}

 void do_object(oop obj) {
   if (obj->is_klass()) {
     Klass* k = Klass::cast(klassOop(obj));
     k->set_alloc_count(0);
     k->set_alloc_size(0);
   }
 }

// Sets the do_print flag for every superclass and subclass of the specified class.
void KlassHierarchy::set_do_print_for_class_hierarchy(KlassInfoEntry* cie, KlassInfoTable* cit,
                                                      bool print_subclasses) {
  // Set do_print for all superclasses of this class.
  Klass* super = ((InstanceKlass*)cie->klass())->java_super();
  while (super != NULL) {
    KlassInfoEntry* super_cie = cit->lookup(super);
    super_cie->set_do_print(true);
    super = super->super();
  }

  // Set do_print for this class and all of its subclasses.
  Stack <KlassInfoEntry*, mtClass> class_stack;
  class_stack.push(cie);
  while (!class_stack.is_empty()) {
    KlassInfoEntry* curr_cie = class_stack.pop();
    curr_cie->set_do_print(true);
    if (print_subclasses && curr_cie->subclasses() != NULL) {
      // Current class has subclasses, so push all of them onto the stack.
      for (int i = 0; i < curr_cie->subclasses()->length(); i++) {
        KlassInfoEntry* cie = curr_cie->subclasses()->at(i);
        class_stack.push(cie);
      }
    }
  }
}

// ------------------------------------------------------------------
// ciKlass::least_common_ancestor
//
// Get the shared parent of two klasses.
//
// Implementation note: this method currently goes "over the wall"
// and does all of the work on the VM side.  It could be rewritten
// to use the super() method and do all of the work (aside from the
// lazy computation of super()) in native mode.  This may be
// worthwhile if the compiler is repeatedly requesting the same lca
// computation or possibly if most of the superklasses have already
// been created as ciObjects anyway.  Something to think about...
ciKlass*
ciKlass::least_common_ancestor(ciKlass* that) {
    assert(is_loaded() && that->is_loaded(), "must be loaded");
    assert(is_java_klass() && that->is_java_klass(), "must be java klasses");
    // Check to see if the klasses are identical.
    if (this == that) {
        return this;
    }

    VM_ENTRY_MARK;
    Klass* this_klass = get_Klass();
    Klass* that_klass = that->get_Klass();
    Klass* lca        = this_klass->LCA(that_klass);

    // Many times the LCA will be either this_klass or that_klass.
    // Treat these as special cases.
    if (lca == that_klass) {
        return that;
    }
    if (this_klass == lca) {
        return this;
    }

    // Create the ciInstanceKlass for the lca.
    ciKlass* result =
        CURRENT_THREAD_ENV->get_object(lca->as_klassOop())->as_klass();

    return result;
}

int InstanceMirrorKlass::compute_static_oop_field_count(oop obj) {
  Klass* k = java_lang_Class::as_Klass(obj);
  if (k != NULL && k->is_instance_klass()) {
    return InstanceKlass::cast(k)->static_oop_field_count();
  }
  return 0;
}

void ClassLoaderData::methods_do(void f(Method*)) {
  for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
    if (k->is_instance_klass()) {
      InstanceKlass::cast(k)->methods_do(f);
    }
  }
}