1 /*
   2  * Copyright (c) 2002, 2015, 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 #ifndef SHARE_VM_GC_PARALLEL_PSSCAVENGE_INLINE_HPP
  26 #define SHARE_VM_GC_PARALLEL_PSSCAVENGE_INLINE_HPP
  27 
  28 #include "gc/parallel/cardTableExtension.hpp"
  29 #include "gc/parallel/parallelScavengeHeap.hpp"
  30 #include "gc/parallel/psPromotionManager.inline.hpp"
  31 #include "gc/parallel/psScavenge.hpp"
  32 #include "logging/log.hpp"
  33 #include "memory/iterator.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "utilities/globalDefinitions.hpp"
  36 
  37 inline void PSScavenge::save_to_space_top_before_gc() {
  38   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  39   _to_space_top_before_gc = heap->young_gen()->to_space()->top();
  40 }
  41 
  42 template <class T> inline bool PSScavenge::should_scavenge(T* p) {
  43   T heap_oop = oopDesc::load_heap_oop(p);
  44   return PSScavenge::is_obj_in_young(heap_oop);
  45 }
  46 
  47 template <class T>
  48 inline bool PSScavenge::should_scavenge(T* p, MutableSpace* to_space) {
  49   if (should_scavenge(p)) {
  50     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  51     // Skip objects copied to to_space since the scavenge started.
  52     HeapWord* const addr = (HeapWord*)obj;
  53     return addr < to_space_top_before_gc() || addr >= to_space->end();
  54   }
  55   return false;
  56 }
  57 
  58 template <class T>
  59 inline bool PSScavenge::should_scavenge(T* p, bool check_to_space) {
  60   if (check_to_space) {
  61     ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  62     return should_scavenge(p, heap->young_gen()->to_space());
  63   }
  64   return should_scavenge(p);
  65 }
  66 
  67 template<bool promote_immediately>
  68 class PSRootsClosure: public OopClosure {
  69  private:
  70   PSPromotionManager* _promotion_manager;
  71 
  72  protected:
  73   template <class T> void do_oop_work(T *p) {
  74     if (PSScavenge::should_scavenge(p)) {
  75       // We never card mark roots, maybe call a func without test?
  76       _promotion_manager->copy_and_push_safe_barrier<T, promote_immediately>(p);
  77     }
  78   }
  79  public:
  80   PSRootsClosure(PSPromotionManager* pm) : _promotion_manager(pm) { }
  81   void do_oop(oop* p)       { PSRootsClosure::do_oop_work(p); }
  82   void do_oop(narrowOop* p) { PSRootsClosure::do_oop_work(p); }
  83 };
  84 
  85 typedef PSRootsClosure</*promote_immediately=*/false> PSScavengeRootsClosure;
  86 typedef PSRootsClosure</*promote_immediately=*/true> PSPromoteRootsClosure;
  87 
  88 // Scavenges a single oop in a ClassLoaderData.
  89 class PSScavengeFromCLDClosure: public OopClosure {
  90  private:
  91   PSPromotionManager* _pm;
  92   // Used to redirty a scanned cld if it has oops
  93   // pointing to the young generation after being scanned.
  94   ClassLoaderData*             _scanned_cld;
  95  public:
  96   PSScavengeFromCLDClosure(PSPromotionManager* pm) : _pm(pm), _scanned_cld(NULL) { }
  97   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
  98   void do_oop(oop* p)       {
  99     ParallelScavengeHeap* psh = ParallelScavengeHeap::heap();
 100     assert(!psh->is_in_reserved(p), "GC barrier needed");
 101     if (PSScavenge::should_scavenge(p)) {
 102       assert(PSScavenge::should_scavenge(p, true), "revisiting object?");
 103 
 104       oop o = *p;
 105       oop new_obj;
 106       if (o->is_forwarded()) {
 107         new_obj = o->forwardee();
 108       } else {
 109         new_obj = _pm->copy_to_survivor_space</*promote_immediately=*/false>(o);
 110       }
 111       oopDesc::encode_store_heap_oop_not_null(p, new_obj);
 112 
 113       if (PSScavenge::is_obj_in_young(new_obj)) {
 114         do_cld_barrier();
 115       }
 116     }
 117   }
 118 
 119   void set_scanned_cld(ClassLoaderData* cld) {
 120     assert(_scanned_cld == NULL || cld == NULL, "Should always only handling one cld at a time");
 121     _scanned_cld = cld;
 122   }
 123 
 124  private:
 125   void do_cld_barrier() {
 126     assert(_scanned_cld != NULL, "Should not be called without having a scanned cld");
 127     _scanned_cld->record_modified_oops();
 128   }

 129 };
 130 
 131 // Scavenges the oop in a ClassLoaderData.
 132 class PSScavengeCLDClosure: public CLDClosure {
 133  private:
 134   PSScavengeFromCLDClosure _oop_closure;
 135  protected:
 136  public:
 137   PSScavengeCLDClosure(PSPromotionManager* pm) : _oop_closure(pm) { }
 138   void do_cld(ClassLoaderData* cld) {
 139     // If the cld has not been dirtied we know that there's
 140     // no references into  the young gen and we can skip it.
 141 
 142     if (cld->has_modified_oops()) {
 143       // Setup the promotion manager to redirty this cld



 144       // if references are left in the young gen.
 145       _oop_closure.set_scanned_cld(cld);
 146 
 147       // Clean the cld since we're going to scavenge all the metadata.
 148       cld->oops_do(&_oop_closure, false, /*clear_modified_oops*/true);
 149 
 150       _oop_closure.set_scanned_cld(NULL);
 151     }
 152   }
 153 };
 154 
 155 
 156 #endif // SHARE_VM_GC_PARALLEL_PSSCAVENGE_INLINE_HPP
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