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 /*

  * Copyright (c) 1999, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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 #ifndef SHARE_VM_CI_CIOBJECT_HPP

 #define SHARE_VM_CI_CIOBJECT_HPP

 #include "ci/ciClassList.hpp"

 #include "memory/allocation.hpp"

 #include "runtime/handles.hpp"

 #include "runtime/jniHandles.hpp"

 // 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_perm is true.

   // 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_perm is true 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_member_name()       const { 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;

   }

   ciMemberName*            as_member_name() {

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

     return (ciMemberName*)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;

   }

   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);

   void print() { print(tty); }  // GDB cannot handle default arguments

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

   void print_oop(outputStream* st = tty);

 };

 #endif // SHARE_VM_CI_CIOBJECT_HPP