1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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   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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  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
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  24 
  25 #ifndef SHARE_VM_GC_SERIAL_DEFNEWGENERATION_INLINE_HPP
  26 #define SHARE_VM_GC_SERIAL_DEFNEWGENERATION_INLINE_HPP
  27 
  28 #include "gc/serial/defNewGeneration.hpp"
  29 #include "gc/shared/cardTableRS.hpp"
  30 #include "gc/shared/genCollectedHeap.hpp"
  31 #include "gc/shared/genOopClosures.inline.hpp"
  32 #include "gc/shared/space.hpp"
  33 
  34 // Methods of protected closure types
  35 
  36 template <class T>
  37 inline void DefNewGeneration::KeepAliveClosure::do_oop_work(T* p) {
  38 #ifdef ASSERT
  39   {
  40     // We never expect to see a null reference being processed
  41     // as a weak reference.
  42     assert (!oopDesc::is_null(*p), "expected non-null ref");
  43     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  44     assert (oopDesc::is_oop(obj), "expected an oop while scanning weak refs");
  45   }
  46 #endif // ASSERT
  47 
  48   _cl->do_oop_nv(p);
  49 
  50   // Card marking is trickier for weak refs.
  51   // This oop is a 'next' field which was filled in while we
  52   // were discovering weak references. While we might not need
  53   // to take a special action to keep this reference alive, we
  54   // will need to dirty a card as the field was modified.
  55   //
  56   // Alternatively, we could create a method which iterates through
  57   // each generation, allowing them in turn to examine the modified
  58   // field.
  59   //
  60   // We could check that p is also in the old generation, but
  61   // dirty cards in the young gen are never scanned, so the
  62   // extra check probably isn't worthwhile.
  63   if (GenCollectedHeap::heap()->is_in_reserved(p)) {
  64     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  65     _rs->inline_write_ref_field_gc(p, obj);
  66   }
  67 }
  68 
  69 template <class T>
  70 inline void DefNewGeneration::FastKeepAliveClosure::do_oop_work(T* p) {
  71 #ifdef ASSERT
  72   {
  73     // We never expect to see a null reference being processed
  74     // as a weak reference.
  75     assert (!oopDesc::is_null(*p), "expected non-null ref");
  76     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  77     assert (oopDesc::is_oop(obj), "expected an oop while scanning weak refs");
  78   }
  79 #endif // ASSERT
  80 
  81   _cl->do_oop_nv(p);
  82 
  83   // Optimized for Defnew generation if it's the youngest generation:
  84   // we set a younger_gen card if we have an older->youngest
  85   // generation pointer.
  86   oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  87   if (((HeapWord*)obj < _boundary) && GenCollectedHeap::heap()->is_in_reserved(p)) {
  88     _rs->inline_write_ref_field_gc(p, obj);
  89   }
  90 }
  91 
  92 #endif // SHARE_VM_GC_SERIAL_DEFNEWGENERATION_INLINE_HPP