1 /*
   2  * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 inline void MarkSweep::mark_object(oop obj) {
  26   // some marks may contain information we need to preserve so we store them away
  27   // and overwrite the mark.  We'll restore it at the end of markSweep.
  28   markOop mark = obj->mark();
  29   obj->set_mark(markOopDesc::prototype()->set_marked());
  30 
  31   if (mark->must_be_preserved(obj)) {
  32     preserve_mark(obj, mark);
  33   }
  34 }
  35 
  36 template <class T> inline void MarkSweep::follow_root(T* p) {
  37   assert(!Universe::heap()->is_in_reserved(p),
  38          "roots shouldn't be things within the heap");
  39 #ifdef VALIDATE_MARK_SWEEP
  40   if (ValidateMarkSweep) {
  41     guarantee(!_root_refs_stack->contains(p), "should only be in here once");
  42     _root_refs_stack->push(p);
  43   }
  44 #endif
  45   T heap_oop = oopDesc::load_heap_oop(p);
  46   if (!oopDesc::is_null(heap_oop)) {
  47     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
  48     if (!obj->mark()->is_marked()) {
  49       mark_object(obj);
  50       obj->follow_contents();
  51     }
  52   }
  53   follow_stack();
  54 }
  55 
  56 template <class T> inline void MarkSweep::mark_and_follow(T* p) {
  57 //  assert(Universe::heap()->is_in_reserved(p), "should be in object space");
  58   T heap_oop = oopDesc::load_heap_oop(p);
  59   if (!oopDesc::is_null(heap_oop)) {
  60     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
  61     if (!obj->mark()->is_marked()) {
  62       mark_object(obj);
  63       obj->follow_contents();
  64     }
  65   }
  66 }
  67 
  68 template <class T> inline void MarkSweep::mark_and_push(T* p) {
  69 //  assert(Universe::heap()->is_in_reserved(p), "should be in object space");
  70   T heap_oop = oopDesc::load_heap_oop(p);
  71   if (!oopDesc::is_null(heap_oop)) {
  72     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
  73     if (!obj->mark()->is_marked()) {
  74       mark_object(obj);
  75       _marking_stack->push(obj);
  76     }
  77   }
  78 }
  79 
  80 void MarkSweep::push_objarray(oop obj, size_t index) {
  81   ObjArrayTask task(obj, index);
  82   assert(task.is_valid(), "bad ObjArrayTask");
  83   _objarray_stack->push(task);
  84 }
  85 
  86 template <class T> inline void MarkSweep::adjust_pointer(T* p, bool isroot) {
  87   T heap_oop = oopDesc::load_heap_oop(p);
  88   if (!oopDesc::is_null(heap_oop)) {
  89     oop obj     = oopDesc::decode_heap_oop_not_null(heap_oop);
  90     oop new_obj = oop(obj->mark()->decode_pointer());
  91     assert(new_obj != NULL ||                         // is forwarding ptr?
  92            obj->mark() == markOopDesc::prototype() || // not gc marked?
  93            (UseBiasedLocking && obj->mark()->has_bias_pattern()) ||
  94                                                       // not gc marked?
  95            obj->is_shared(),                          // never forwarded?
  96            "should be forwarded");
  97     if (new_obj != NULL) {
  98       assert(Universe::heap()->is_in_reserved(new_obj),
  99              "should be in object space");
 100       oopDesc::encode_store_heap_oop_not_null(p, new_obj);
 101     }
 102   }
 103   VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot));
 104 }
 105 
 106 template <class T> inline void MarkSweep::KeepAliveClosure::do_oop_work(T* p) {
 107 #ifdef VALIDATE_MARK_SWEEP
 108   if (ValidateMarkSweep) {
 109     if (!Universe::heap()->is_in_reserved(p)) {
 110       _root_refs_stack->push(p);
 111     } else {
 112       _other_refs_stack->push(p);
 113     }
 114   }
 115 #endif
 116   mark_and_push(p);
 117 }