1 /*
   2  * Copyright (c) 2014, 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_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "gc_implementation/g1/g1HeapRegionTraceType.hpp"
  30 
  31 #define hrt_assert_is_valid(tag) \
  32   assert(is_valid((tag)), err_msg("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, humongous)                         : 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      Young Mask
  49   // 0001 0 [ 2] Eden
  50   // 0001 1 [ 3] Survivor
  51   //
  52   // 0010 0      Humongous Mask
  53   // 0010 0 [ 4] Humongous Starts
  54   // 0010 1 [ 5] Humongous Continues
  55   //
  56   // 01000 [ 8] Old
  57   typedef enum {
  58     FreeTag       = 0,
  59 
  60     YoungMask     = 2,
  61     EdenTag       = YoungMask,
  62     SurvTag       = YoungMask + 1,
  63 
  64     HumMask       = 4,
  65     HumStartsTag  = HumMask,
  66     HumContTag    = HumMask + 1,
  67 
  68     OldTag        = 8
  69   } Tag;
  70 
  71   volatile Tag _tag;
  72 
  73   static bool is_valid(Tag tag);
  74 
  75   Tag get() const {
  76     hrt_assert_is_valid(_tag);
  77     return _tag;
  78   }
  79 
  80   // Sets the type to 'tag'.
  81   void set(Tag tag) {
  82     hrt_assert_is_valid(tag);
  83     hrt_assert_is_valid(_tag);
  84     _tag = tag;
  85   }
  86 
  87   // Sets the type to 'tag', expecting the type to be 'before'. This
  88   // is available for when we want to add sanity checking to the type
  89   // transition.
  90   void set_from(Tag tag, Tag before) {
  91     hrt_assert_is_valid(tag);
  92     hrt_assert_is_valid(before);
  93     hrt_assert_is_valid(_tag);
  94     assert(_tag == before,
  95            err_msg("HR tag: %u, expected: %u new tag; %u", _tag, before, tag));
  96     _tag = tag;
  97   }
  98 
  99 public:
 100   // Queries
 101 
 102   bool is_free() const { return get() == FreeTag; }
 103 
 104   bool is_young()    const { return (get() & YoungMask) != 0; }
 105   bool is_eden()     const { return get() == EdenTag;  }
 106   bool is_survivor() const { return get() == SurvTag;  }
 107 
 108   bool is_humongous()           const { return (get() & HumMask) != 0; }
 109   bool is_starts_humongous()    const { return get() == HumStartsTag;  }
 110   bool is_continues_humongous() const { return get() == HumContTag;    }
 111 
 112   bool is_old() const { return get() == OldTag; }
 113 
 114   bool is_old_or_humongous() const { return (get() & (OldTag | HumMask)) != 0; }
 115 
 116   // Setters
 117 
 118   void set_free() { set(FreeTag); }
 119 
 120   void set_eden()        { set_from(EdenTag, FreeTag); }
 121   void set_eden_pre_gc() { set_from(EdenTag, SurvTag); }
 122   void set_survivor()    { set_from(SurvTag, FreeTag); }
 123 
 124   void set_starts_humongous()    { set_from(HumStartsTag, FreeTag); }
 125   void set_continues_humongous() { set_from(HumContTag,   FreeTag); }
 126 
 127   void set_old() { set(OldTag); }
 128 
 129   // Misc
 130 
 131   const char* get_str() const;
 132   const char* get_short_str() const;
 133   G1HeapRegionTraceType::Type get_trace_type();
 134 
 135   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 136 };
 137 
 138 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONTYPE_HPP