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 /*

  * Copyright (c) 1999, 2012, 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

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "ci/ciObject.hpp"

 #include "ci/ciUtilities.hpp"

 #include "gc_interface/collectedHeap.inline.hpp"

 #include "oops/oop.inline2.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 `Klass*' and `Klass' are not

 // reflected in the interface and instead the Klass hierarchy

 // is directly modeled as the subclasses of ciKlass.

 // ------------------------------------------------------------------

 // ciObject::ciObject

 ciObject::ciObject(oop o) {

   ASSERT_IN_VM;

   if (ciObjectFactory::is_initialized()) {

     _handle = JNIHandles::make_local(o);

   } else {

     _handle = JNIHandles::make_global(o);

   }

   _klass = NULL;

   init_flags_from(o);

 }

 // ------------------------------------------------------------------

 // ciObject::ciObject

 //

 ciObject::ciObject(Handle h) {

   ASSERT_IN_VM;

   if (ciObjectFactory::is_initialized()) {

     _handle = JNIHandles::make_local(h());

   } else {

     _handle = JNIHandles::make_global(h);

   }

   _klass = NULL;

   init_flags_from(h());

 }

 // ------------------------------------------------------------------

 // ciObject::ciObject

 //

 // Unloaded klass/method variant.  `klass' is the klass of the unloaded

 // klass/method, if that makes sense.

 ciObject::ciObject(ciKlass* klass) {

   ASSERT_IN_VM;

   assert(klass != NULL, "must supply klass");

   _handle = NULL;

   _klass = klass;

 }

 // ------------------------------------------------------------------

 // ciObject::ciObject

 //

 // NULL variant.  Used only by ciNullObject.

 ciObject::ciObject() {

   ASSERT_IN_VM;

   _handle = NULL;

   _klass = NULL;

 }

 // ------------------------------------------------------------------

 // ciObject::klass

 //

 // Get the ciKlass of this ciObject.

 ciKlass* ciObject::klass() {

   if (_klass == NULL) {

     if (_handle == NULL) {

       // When both _klass and _handle are NULL, we are dealing

       // with the distinguished instance of ciNullObject.

       // No one should ask it for its klass.

       assert(is_null_object(), "must be null object");

       ShouldNotReachHere();

       return NULL;

     }

     GUARDED_VM_ENTRY(

       oop o = get_oop();

       _klass = CURRENT_ENV->get_klass(o->klass());

     );

   }

   return _klass;

 }

 // ------------------------------------------------------------------

 // ciObject::equals

 //

 // Are two ciObjects equal?

 bool ciObject::equals(ciObject* obj) {

   return (this == obj);

 }

 // ------------------------------------------------------------------

 // ciObject::hash

 //

 // A hash value for the convenience of compilers.

 //

 // Implementation note: we use the address of the ciObject as the

 // basis for the hash.  Use the _ident field, which is well-behaved.

 int ciObject::hash() {

   return ident() * 31;

 }

 // ------------------------------------------------------------------

 // ciObject::constant_encoding

 //

 // 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.

 //

 //

 //

 // Implementation note: we use the handle as the encoding.  The

 // nmethod constructor resolves the handle and patches in the oop.

 //

 // This method should be changed to return an generified address

 // to discourage use of the JNI handle.

 jobject ciObject::constant_encoding() {

   assert(is_null_object() || handle() != NULL, "cannot embed null pointer");

   assert(can_be_constant(), "oop must be NULL or perm");

   return handle();

 }

 // ------------------------------------------------------------------

 // ciObject::can_be_constant

 bool ciObject::can_be_constant() {

   if (ScavengeRootsInCode >= 1)  return true;  // now everybody can encode as a constant

   return handle() == NULL;

 }

 // ------------------------------------------------------------------

 // ciObject::should_be_constant()

 bool ciObject::should_be_constant() {

   if (ScavengeRootsInCode >= 2)  return true;  // force everybody to be a constant

   if (is_null_object()) return true;

   ciEnv* env = CURRENT_ENV;

     // We want Strings and Classes to be embeddable by default since

     // they used to be in the perm world.  Not all Strings used to be

     // embeddable but there's no easy way to distinguish the interned

     // from the regulars ones so just treat them all that way.

     if (klass() == env->String_klass() || klass() == env->Class_klass()) {

       return true;

     }

   if (EnableInvokeDynamic &&

       (klass()->is_subclass_of(env->MethodHandle_klass()) ||

        klass()->is_subclass_of(env->CallSite_klass()))) {

     assert(ScavengeRootsInCode >= 1, "must be");

     // We want to treat these aggressively.

     return true;

   }

   return handle() == NULL;

 }

 // ------------------------------------------------------------------

 // ciObject::should_be_constant()

 void ciObject::init_flags_from(oop x) {

   int flags = 0;

   if (x != NULL) {

     assert(Universe::heap()->is_in_reserved(x), "must be");

     if (x->is_scavengable())

       flags |= SCAVENGABLE_FLAG;

   }

   _ident |= flags;

 }

 // ------------------------------------------------------------------

 // ciObject::print

 //

 // Print debugging output about this ciObject.

 //

 // Implementation note: dispatch to the virtual print_impl behavior

 // for this ciObject.

 void ciObject::print(outputStream* st) {

   st->print("<%s", type_string());

   GUARDED_VM_ENTRY(print_impl(st);)

   st->print(" ident=%d %s address=0x%x>", ident(),

         is_scavengable() ? "SCAVENGABLE" : "",

         (address)this);

 }

 // ------------------------------------------------------------------

 // ciObject::print_oop

 //

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

 void ciObject::print_oop(outputStream* st) {

   if (is_null_object()) {

     st->print_cr("NULL");

   } else if (!is_loaded()) {

     st->print_cr("UNLOADED");

   } else {

     GUARDED_VM_ENTRY(get_oop()->print_on(st);)

   }

 }