1 /*
   2  * Copyright (c) 2014, 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_G1_HEAPREGIONTYPE_HPP
  26 #define SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
  27 

  28 #include "memory/allocation.hpp"
  29 
  30 #define hrt_assert_is_valid(tag) \
  31   assert(is_valid((tag)), "invalid HR type: %u", (uint) (tag))
  32 
  33 class HeapRegionType VALUE_OBJ_CLASS_SPEC {
  34 private:
  35   // We encode the value of the heap region type so the generation can be
  36   // determined quickly. The tag is split into two parts:
  37   //
  38   //   major type (young, old, humongous, archive)           : top N-1 bits
  39   //   minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
  40   //
  41   // If there's need to increase the number of minor types in the
  42   // future, we'll have to increase the size of the latter and hence
  43   // decrease the size of the former.
  44   //
  45   // 0000 0 [ 0] Free
  46   //
  47   // 0001 0 [ 2] Young Mask
  48   // 0001 0 [ 2] Eden
  49   // 0001 1 [ 3] Survivor
  50   //
  51   // 0010 0 [ 4] Humongous Mask
  52   // 0100 0 [ 8] Pinned Mask
  53   // 0110 0 [12] Starts Humongous
  54   // 0110 1 [13] Continues Humongous
  55   //
  56   // 1000 0 [16] Old Mask
  57   //
  58   // 1100 0 [24] Archive
  59   typedef enum {
  60     FreeTag               = 0,
  61 
  62     YoungMask             = 2,
  63     EdenTag               = YoungMask,
  64     SurvTag               = YoungMask + 1,
  65 
  66     HumongousMask         = 4,
  67     PinnedMask            = 8,
  68     StartsHumongousTag    = HumongousMask | PinnedMask,
  69     ContinuesHumongousTag = HumongousMask | PinnedMask + 1,
  70 
  71     OldMask               = 16,
  72     OldTag                = OldMask,
  73 
  74     ArchiveTag            = PinnedMask | OldMask
  75   } Tag;
  76 
  77   volatile Tag _tag;
  78 
  79   static bool is_valid(Tag tag);
  80 
  81   Tag get() const {
  82     hrt_assert_is_valid(_tag);
  83     return _tag;
  84   }
  85 
  86   // Sets the type to 'tag'.
  87   void set(Tag tag) {
  88     hrt_assert_is_valid(tag);
  89     hrt_assert_is_valid(_tag);
  90     _tag = tag;
  91   }
  92 
  93   // Sets the type to 'tag', expecting the type to be 'before'. This
  94   // is available for when we want to add sanity checking to the type
  95   // transition.
  96   void set_from(Tag tag, Tag before) {
  97     hrt_assert_is_valid(tag);
  98     hrt_assert_is_valid(before);
  99     hrt_assert_is_valid(_tag);
 100     assert(_tag == before, "HR tag: %u, expected: %u new tag; %u", _tag, before, tag);
 101     _tag = tag;
 102   }
 103 
 104 public:
 105   // Queries
 106 
 107   bool is_free() const { return get() == FreeTag; }
 108 
 109   bool is_young()    const { return (get() & YoungMask) != 0; }
 110   bool is_eden()     const { return get() == EdenTag;  }
 111   bool is_survivor() const { return get() == SurvTag;  }
 112 
 113   bool is_humongous()           const { return (get() & HumongousMask) != 0;   }
 114   bool is_starts_humongous()    const { return get() == StartsHumongousTag;    }
 115   bool is_continues_humongous() const { return get() == ContinuesHumongousTag; }
 116 
 117   bool is_archive() const { return get() == ArchiveTag; }
 118 
 119   // is_old regions may or may not also be pinned
 120   bool is_old() const { return (get() & OldMask) != 0; }
 121 
 122   // is_pinned regions may be archive or humongous
 123   bool is_pinned() const { return (get() & PinnedMask) != 0; }
 124 
 125   // Setters
 126 
 127   void set_free() { set(FreeTag); }
 128 
 129   void set_eden()        { set_from(EdenTag, FreeTag); }
 130   void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
 131   void set_survivor()    { set_from(SurvTag, FreeTag); }
 132 
 133   void set_starts_humongous()    { set_from(StartsHumongousTag,    FreeTag); }
 134   void set_continues_humongous() { set_from(ContinuesHumongousTag, FreeTag); }
 135 
 136   void set_old() { set(OldTag); }
 137 
 138   void set_archive() { set_from(ArchiveTag, FreeTag); }
 139 
 140   // Misc
 141 
 142   const char* get_str() const;
 143   const char* get_short_str() const;

 144 
 145   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 146 };
 147 
 148 #endif // SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
--- EOF ---