/*

 * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// ciObject

//

// This class represents an oop in the HotSpot virtual machine.

// Its subclasses are structured in a hierarchy which mirrors

// an aggregate of the VM's oop and klass hierarchies (see

// oopHierarchy.hpp).  Each instance of ciObject holds a handle

// to a corresponding oop on the VM side and provides routines

// for accessing the information in its oop.  By using the ciObject

// hierarchy for accessing oops in the VM, the compiler ensures

// that it is safe with respect to garbage collection; that is,

// GC and compilation can proceed independently without

// interference.

//

// Within the VM, the oop and klass hierarchies are separate.

// The compiler interface does not preserve this separation --

// the distinction between `klassOop' and `Klass' are not

// reflected in the interface and instead the Klass hierarchy

// is directly modeled as the subclasses of ciKlass.

class ciObject : public ResourceObj {

  CI_PACKAGE_ACCESS

  friend class ciEnv;

private:

  // A JNI handle referring to an oop in the VM.  This

  // handle may, in a small set of cases, correctly be NULL.

  jobject  _handle;

  ciKlass* _klass;

  uint     _ident;

  enum { FLAG_BITS   = 2 };

  enum {

         PERM_FLAG        = 1,

         SCAVENGABLE_FLAG = 2

       };

protected:

  ciObject();

  ciObject(oop o);

  ciObject(Handle h);

  ciObject(ciKlass* klass);

  jobject      handle()  const { return _handle; }

  // Get the VM oop that this object holds.

  oop get_oop() const {

    assert(_handle != NULL, "null oop");

    return JNIHandles::resolve_non_null(_handle);

  }

  void init_flags_from(oop x) {

    int flags = 0;

    if (x != NULL) {

      if (x->is_perm())

        flags |= PERM_FLAG;

      if (x->is_scavengable())

        flags |= SCAVENGABLE_FLAG;

    }

    _ident |= flags;

  }

  // Virtual behavior of the print() method.

  virtual void print_impl(outputStream* st) {}

  virtual const char* type_string() { return "ciObject"; }

  void set_ident(uint id);

public:

  // The klass of this ciObject.

  ciKlass* klass();

  // A number unique to this object.

  uint ident();

  // Are two ciObjects equal?

  bool equals(ciObject* obj);

  // A hash value for the convenience of compilers.

  int hash();

  // Tells if this oop has an encoding as a constant.

  // True if is_scavengable is false.

  // Also true if ScavengeRootsInCode is non-zero.

  // If it does not have an encoding, the compiler is responsible for

  // making other arrangements for dealing with the oop.

  // See ciEnv::make_array

  bool can_be_constant();

  // Tells if this oop should be made a constant.

  // True if is_scavengable is false or ScavengeRootsInCode > 1.

  bool should_be_constant();

  // Is this object guaranteed to be in the permanent part of the heap?

  // If so, CollectedHeap::can_elide_permanent_oop_store_barriers is relevant.

  // If the answer is false, no guarantees are made.

  bool is_perm() { return (_ident & PERM_FLAG) != 0; }

  // Might this object possibly move during a scavenge operation?

  // If the answer is true and ScavengeRootsInCode==0, the oop cannot be embedded in code.

  bool is_scavengable() { return (_ident & SCAVENGABLE_FLAG) != 0; }

  // The address which the compiler should embed into the

  // generated code to represent this oop.  This address

  // is not the true address of the oop -- it will get patched

  // during nmethod creation.

  //

  // Usage note: no address arithmetic allowed.  Oop must

  // be registered with the oopRecorder.

  jobject constant_encoding();

  // What kind of ciObject is this?

  virtual bool is_null_object() const       { return false; }

  virtual bool is_call_site() const         { return false; }

  virtual bool is_cpcache() const           { return false; }

  virtual bool is_instance()                { return false; }

  virtual bool is_method()                  { return false; }

  virtual bool is_method_data()             { return false; }

  virtual bool is_method_handle() const     { return false; }

  virtual bool is_array()                   { return false; }

  virtual bool is_obj_array()               { return false; }

  virtual bool is_type_array()              { return false; }

  virtual bool is_symbol()                  { return false; }

  virtual bool is_type()                    { return false; }

  virtual bool is_return_address()          { return false; }

  virtual bool is_klass()                   { return false; }

  virtual bool is_instance_klass()          { return false; }

  virtual bool is_method_klass()            { return false; }

  virtual bool is_array_klass()             { return false; }

  virtual bool is_obj_array_klass()         { return false; }

  virtual bool is_type_array_klass()        { return false; }

  virtual bool is_symbol_klass()            { return false; }

  virtual bool is_klass_klass()             { return false; }

  virtual bool is_instance_klass_klass()    { return false; }

  virtual bool is_array_klass_klass()       { return false; }

  virtual bool is_obj_array_klass_klass()   { return false; }

  virtual bool is_type_array_klass_klass()  { return false; }

  // Is this a type or value which has no associated class?

  // It is true of primitive types and null objects.

  virtual bool is_classless() const         { return false; }

  // Is this ciObject a Java Language Object?  That is,

  // is the ciObject an instance or an array

  virtual bool is_java_object()             { return false; }

  // Does this ciObject represent a Java Language class?

  // That is, is the ciObject an instanceKlass or arrayKlass?

  virtual bool is_java_klass()              { return false; }

  // Is this ciObject the ciInstanceKlass representing

  // java.lang.Object()?

  virtual bool is_java_lang_Object()        { return false; }

  // Does this ciObject refer to a real oop in the VM?

  //

  // Note: some ciObjects refer to oops which have yet to be

  // created.  We refer to these as "unloaded".  Specifically,

  // there are unloaded ciMethods, ciObjArrayKlasses, and

  // ciInstanceKlasses.  By convention the ciNullObject is

  // considered loaded, and primitive types are considered loaded.

  bool is_loaded() const {

    return handle() != NULL || is_classless();

  }

  // Subclass casting with assertions.

  ciNullObject*            as_null_object() {

    assert(is_null_object(), "bad cast");

    return (ciNullObject*)this;

  }

  ciCallSite*              as_call_site() {

    assert(is_call_site(), "bad cast");

    return (ciCallSite*) this;

  }

  ciCPCache*               as_cpcache() {

    assert(is_cpcache(), "bad cast");

    return (ciCPCache*) this;

  }

  ciInstance*              as_instance() {

    assert(is_instance(), "bad cast");

    return (ciInstance*)this;

  }

  ciMethod*                as_method() {

    assert(is_method(), "bad cast");

    return (ciMethod*)this;

  }

  ciMethodData*            as_method_data() {

    assert(is_method_data(), "bad cast");

    return (ciMethodData*)this;

  }

  ciMethodHandle*          as_method_handle() {

    assert(is_method_handle(), "bad cast");

    return (ciMethodHandle*) this;

  }

  ciArray*                 as_array() {

    assert(is_array(), "bad cast");

    return (ciArray*)this;

  }

  ciObjArray*              as_obj_array() {

    assert(is_obj_array(), "bad cast");

    return (ciObjArray*)this;

  }

  ciTypeArray*             as_type_array() {

    assert(is_type_array(), "bad cast");

    return (ciTypeArray*)this;

  }

  ciSymbol*                as_symbol() {

    assert(is_symbol(), "bad cast");

    return (ciSymbol*)this;

  }

  ciType*                  as_type() {

    assert(is_type(), "bad cast");

    return (ciType*)this;

  }

  ciReturnAddress*         as_return_address() {

    assert(is_return_address(), "bad cast");

    return (ciReturnAddress*)this;

  }

  ciKlass*                 as_klass() {

    assert(is_klass(), "bad cast");

    return (ciKlass*)this;

  }

  ciInstanceKlass*         as_instance_klass() {

    assert(is_instance_klass(), "bad cast");

    return (ciInstanceKlass*)this;

  }

  ciMethodKlass*           as_method_klass() {

    assert(is_method_klass(), "bad cast");

    return (ciMethodKlass*)this;

  }

  ciArrayKlass*            as_array_klass() {

    assert(is_array_klass(), "bad cast");

    return (ciArrayKlass*)this;

  }

  ciObjArrayKlass*         as_obj_array_klass() {

    assert(is_obj_array_klass(), "bad cast");

    return (ciObjArrayKlass*)this;

  }

  ciTypeArrayKlass*        as_type_array_klass() {

    assert(is_type_array_klass(), "bad cast");

    return (ciTypeArrayKlass*)this;

  }

  ciSymbolKlass*           as_symbol_klass() {

    assert(is_symbol_klass(), "bad cast");

    return (ciSymbolKlass*)this;

  }

  ciKlassKlass*            as_klass_klass() {

    assert(is_klass_klass(), "bad cast");

    return (ciKlassKlass*)this;

  }

  ciInstanceKlassKlass*    as_instance_klass_klass() {

    assert(is_instance_klass_klass(), "bad cast");

    return (ciInstanceKlassKlass*)this;

  }

  ciArrayKlassKlass*       as_array_klass_klass() {

    assert(is_array_klass_klass(), "bad cast");

    return (ciArrayKlassKlass*)this;

  }

  ciObjArrayKlassKlass*    as_obj_array_klass_klass() {

    assert(is_obj_array_klass_klass(), "bad cast");

    return (ciObjArrayKlassKlass*)this;

  }

  ciTypeArrayKlassKlass*   as_type_array_klass_klass() {

    assert(is_type_array_klass_klass(), "bad cast");

    return (ciTypeArrayKlassKlass*)this;

  }

  // Print debugging output about this ciObject.

  void print(outputStream* st = tty);

  // Print debugging output about the oop this ciObject represents.

  void print_oop(outputStream* st = tty);

};