1 /*
   2  * Copyright (c) 2014, 2018, 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
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  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 
  30 #define hrt_assert_is_valid(tag) \
  31   assert(is_valid((tag)), "invalid HR type: %u", (uint) (tag))
  32 
  33 class HeapRegionType {
  34 friend class VMStructs;
  35 
  36 private:
  37   // We encode the value of the heap region type so the generation can be
  38   // determined quickly. The tag is split into two parts:
  39   //
  40   //   major type (young, old, humongous, archive)           : top N-1 bits
  41   //   minor type (eden / survivor, starts / cont hum, etc.) : bottom 1 bit
  42   //
  43   // If there's need to increase the number of minor types in the
  44   // future, we'll have to increase the size of the latter and hence
  45   // decrease the size of the former.
  46   //
  47   // 00000 0 [ 0] Free
  48   //
  49   // 00001 0 [ 2] Young Mask
  50   // 00001 0 [ 2] Eden
  51   // 00001 1 [ 3] Survivor
  52   //
  53   // 00010 0 [ 4] Humongous Mask
  54   // 00100 0 [ 8] Pinned Mask
  55   // 00110 0 [12] Starts Humongous
  56   // 00110 1 [13] Continues Humongous
  57   //
  58   // 01000 0 [16] Old Mask
  59   //
  60   // 10000 0 [32] Archive Mask
  61   // 11100 0 [56] Open Archive
  62   // 11100 1 [57] Closed Archive
  63   //
  64   typedef enum {
  65     FreeTag               = 0,
  66 
  67     YoungMask             = 2,
  68     EdenTag               = YoungMask,
  69     SurvTag               = YoungMask + 1,
  70 
  71     HumongousMask         = 4,
  72     PinnedMask            = 8,
  73     StartsHumongousTag    = HumongousMask | PinnedMask,
  74     ContinuesHumongousTag = HumongousMask | PinnedMask + 1,
  75 
  76     OldMask               = 16,
  77     OldTag                = OldMask,
  78 
  79     // Archive regions are regions with immutable content (i.e. not reclaimed, and
  80     // not allocated into during regular operation). They differ in the kind of references
  81     // allowed for the contained objects:
  82     // - Closed archive regions form a separate self-contained (closed) object graph
  83     // within the set of all of these regions. No references outside of closed
  84     // archive regions are allowed.
  85     // - Open archive regions have no restrictions on the references of their objects.
  86     // Objects within these regions are allowed to have references to objects
  87     // contained in any other kind of regions.
  88     ArchiveMask           = 32,
  89     OpenArchiveTag        = ArchiveMask | PinnedMask,
  90     ClosedArchiveTag      = ArchiveMask | PinnedMask + 1
  91   } Tag;
  92 
  93   volatile Tag _tag;
  94 
  95   static bool is_valid(Tag tag);
  96 
  97   Tag get() const {
  98     hrt_assert_is_valid(_tag);
  99     return _tag;
 100   }
 101 
 102   // Sets the type to 'tag'.
 103   void set(Tag tag) {
 104     hrt_assert_is_valid(tag);
 105     hrt_assert_is_valid(_tag);
 106     _tag = tag;
 107   }
 108 
 109   // Sets the type to 'tag', expecting the type to be 'before'. This
 110   // is available for when we want to add sanity checking to the type
 111   // transition.
 112   void set_from(Tag tag, Tag before) {
 113     hrt_assert_is_valid(tag);
 114     hrt_assert_is_valid(before);
 115     hrt_assert_is_valid(_tag);
 116     assert(_tag == before, "HR tag: %u, expected: %u new tag; %u", _tag, before, tag);
 117     _tag = tag;
 118   }
 119 
 120 public:
 121   // Queries
 122 
 123   bool is_free() const { return get() == FreeTag; }
 124 
 125   bool is_young()    const { return (get() & YoungMask) != 0; }
 126   bool is_eden()     const { return get() == EdenTag;  }
 127   bool is_survivor() const { return get() == SurvTag;  }
 128 
 129   bool is_humongous()           const { return (get() & HumongousMask) != 0;   }
 130   bool is_starts_humongous()    const { return get() == StartsHumongousTag;    }
 131   bool is_continues_humongous() const { return get() == ContinuesHumongousTag; }
 132 
 133   bool is_archive()        const { return (get() & ArchiveMask) != 0; }
 134   bool is_open_archive()   const { return get() == OpenArchiveTag; }
 135   bool is_closed_archive() const { return get() == ClosedArchiveTag; }
 136 
 137   // is_old regions may or may not also be pinned
 138   bool is_old() const { return (get() & OldMask) != 0; }
 139 
 140   bool is_old_or_humongous() const { return (get() & (OldMask | HumongousMask)) != 0; }
 141 
 142   bool is_old_or_humongous_or_archive() const { return (get() & (OldMask | HumongousMask | ArchiveMask)) != 0; }
 143 
 144   // is_pinned regions may be archive or humongous
 145   bool is_pinned() const { return (get() & PinnedMask) != 0; }
 146 
 147   // Setters
 148 
 149   void set_free() { set(FreeTag); }
 150 
 151   void set_eden()        { set_from(EdenTag, FreeTag); }
 152   void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
 153   void set_survivor()    { set_from(SurvTag, FreeTag); }
 154 
 155   void set_starts_humongous()    { set_from(StartsHumongousTag,    FreeTag); }
 156   void set_continues_humongous() { set_from(ContinuesHumongousTag, FreeTag); }
 157 
 158   void set_old() { set(OldTag); }
 159 
 160   // Change the current region type to be of an old region type if not already done so.
 161   // Returns whether the region type has been changed or not.
 162   bool relabel_as_old() {
 163     //assert(!is_free(), "Should not try to move Free region");
 164     assert(!is_humongous(), "Should not try to move Humongous region");
 165     if (is_old()) {
 166       return false;
 167     }
 168     if (is_eden()) {
 169       set_from(OldTag, EdenTag);
 170       return true;
 171     } else if (is_free()) {
 172       set_from(OldTag, FreeTag);
 173       return true;
 174     } else {
 175       set_from(OldTag, SurvTag);
 176       return true;
 177     }
 178   }
 179   void set_open_archive()   { set_from(OpenArchiveTag, FreeTag); }
 180   void set_closed_archive() { set_from(ClosedArchiveTag, FreeTag); }
 181 
 182   // Misc
 183 
 184   const char* get_str() const;
 185   const char* get_short_str() const;
 186   G1HeapRegionTraceType::Type get_trace_type();
 187 
 188   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 189 };
 190 
 191 #endif // SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP