1 /*
   2  * Copyright (c) 2002, 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 PSScavenge::save_to_space_top_before_gc() {
  26   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  27   _to_space_top_before_gc = heap->young_gen()->to_space()->top();
  28 }
  29 
  30 template <class T> inline bool PSScavenge::should_scavenge(T* p) {
  31   T heap_oop = oopDesc::load_heap_oop(p);
  32   if (oopDesc::is_null(heap_oop)) return false;
  33   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
  34   return PSScavenge::is_obj_in_young((HeapWord*)obj);
  35 }
  36 
  37 template <class T>
  38 inline bool PSScavenge::should_scavenge(T* p, MutableSpace* to_space) {
  39   if (should_scavenge(p)) {
  40     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  41     // Skip objects copied to to_space since the scavenge started.
  42     HeapWord* const addr = (HeapWord*)obj;
  43     return addr < to_space_top_before_gc() || addr >= to_space->end();
  44   }
  45   return false;
  46 }
  47 
  48 template <class T>
  49 inline bool PSScavenge::should_scavenge(T* p, bool check_to_space) {
  50   if (check_to_space) {
  51     ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  52     return should_scavenge(p, heap->young_gen()->to_space());
  53   }
  54   return should_scavenge(p);
  55 }
  56 
  57 // Attempt to "claim" oop at p via CAS, push the new obj if successful
  58 // This version tests the oop* to make sure it is within the heap before
  59 // attempting marking.
  60 template <class T>
  61 inline void PSScavenge::copy_and_push_safe_barrier(PSPromotionManager* pm,
  62                                                    T*                  p) {
  63   assert(should_scavenge(p, true), "revisiting object?");
  64 
  65   oop o = oopDesc::load_decode_heap_oop_not_null(p);
  66   oop new_obj = o->is_forwarded()
  67         ? o->forwardee()
  68         : pm->copy_to_survivor_space(o);
  69   oopDesc::encode_store_heap_oop_not_null(p, new_obj);
  70 
  71   // We cannot mark without test, as some code passes us pointers
  72   // that are outside the heap.
  73   if ((!PSScavenge::is_obj_in_young((HeapWord*)p)) &&
  74       Universe::heap()->is_in_reserved(p)) {
  75     if (PSScavenge::is_obj_in_young((HeapWord*)new_obj)) {
  76       card_table()->inline_write_ref_field_gc(p, new_obj);
  77     }
  78   }
  79 }