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 "gc/g1/g1HeapRegionTraceType.hpp"
  29 #include "memory/allocation.hpp"
  30 
  31 #define hrt_assert_is_valid(tag) \
  32   assert(is_valid((tag)), "invalid HR type: %u", (uint) (tag))
  33 
  34 class HeapRegionType VALUE_OBJ_CLASS_SPEC {
  35 private:
  36   // We encode the value of the heap region type so the generation can be
  37   // determined quickly. The tag is split into two parts:
  38   //
  39   //   major type (young, old, humongous, archive)           : top N-1 bits
  40   //   minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
  41   //
  42   // If there's need to increase the number of minor types in the
  43   // future, we'll have to increase the size of the latter and hence
  44   // decrease the size of the former.
  45   //
  46   // 0000 0 [ 0] Free
  47   //
  48   // 0001 0 [ 2] Young Mask
  49   // 0001 0 [ 2] Eden
  50   // 0001 1 [ 3] Survivor
  51   //
  52   // 0010 0 [ 4] Humongous Mask
  53   // 0100 0 [ 8] Pinned Mask
  54   // 0110 0 [12] Starts Humongous
  55   // 0110 1 [13] Continues Humongous
  56   //
  57   // 1000 0 [16] Old Mask
  58   //
  59   // 1100 0 [24] Archive
  60   typedef enum {
  61     FreeTag               = 0,
  62 
  63     YoungMask             = 2,
  64     EdenTag               = YoungMask,
  65     SurvTag               = YoungMask + 1,
  66 
  67     HumongousMask         = 4,
  68     PinnedMask            = 8,
  69     StartsHumongousTag    = HumongousMask | PinnedMask,
  70     ContinuesHumongousTag = HumongousMask | PinnedMask + 1,
  71 
  72     OldMask               = 16,
  73     OldTag                = OldMask,
  74 
  75     ArchiveTag            = PinnedMask | OldMask
  76   } Tag;
  77 
  78   volatile Tag _tag;
  79 
  80   static bool is_valid(Tag tag);
  81 
  82   Tag get() const {
  83     hrt_assert_is_valid(_tag);
  84     return _tag;
  85   }
  86 
  87   // Sets the type to 'tag'.
  88   void set(Tag tag) {
  89     hrt_assert_is_valid(tag);
  90     hrt_assert_is_valid(_tag);
  91     _tag = tag;
  92   }
  93 
  94   // Sets the type to 'tag', expecting the type to be 'before'. This
  95   // is available for when we want to add sanity checking to the type
  96   // transition.
  97   void set_from(Tag tag, Tag before) {
  98     hrt_assert_is_valid(tag);
  99     hrt_assert_is_valid(before);
 100     hrt_assert_is_valid(_tag);
 101     assert(_tag == before, "HR tag: %u, expected: %u new tag; %u", _tag, before, tag);
 102     _tag = tag;
 103   }
 104 
 105 public:
 106   // Queries
 107 
 108   bool is_free() const { return get() == FreeTag; }
 109 
 110   bool is_young()    const { return (get() & YoungMask) != 0; }
 111   bool is_eden()     const { return get() == EdenTag;  }
 112   bool is_survivor() const { return get() == SurvTag;  }
 113 
 114   bool is_humongous()           const { return (get() & HumongousMask) != 0;   }
 115   bool is_starts_humongous()    const { return get() == StartsHumongousTag;    }
 116   bool is_continues_humongous() const { return get() == ContinuesHumongousTag; }
 117 
 118   bool is_archive() const { return get() == ArchiveTag; }
 119 
 120   // is_old regions may or may not also be pinned
 121   bool is_old() const { return (get() & OldMask) != 0; }
 122 
 123   // is_pinned regions may be archive or humongous
 124   bool is_pinned() const { return (get() & PinnedMask) != 0; }
 125 
 126   // Setters
 127 
 128   void set_free() { set(FreeTag); }
 129 
 130   void set_eden()        { set_from(EdenTag, FreeTag); }
 131   void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
 132   void set_survivor()    { set_from(SurvTag, FreeTag); }
 133 
 134   void set_starts_humongous()    { set_from(StartsHumongousTag,    FreeTag); }
 135   void set_continues_humongous() { set_from(ContinuesHumongousTag, FreeTag); }
 136 
 137   void set_old() { set(OldTag); }
 138 
 139   void set_archive() { set_from(ArchiveTag, FreeTag); }
 140 
 141   // Misc
 142 
 143   const char* get_str() const;
 144   const char* get_short_str() const;
 145   G1HeapRegionTraceType::Type get_trace_type();
 146 
 147   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 148 };
 149 
 150 #endif // SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
--- EOF ---