1 /*
  2  * Copyright (c) 2003, 2019, 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.
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 23  */
 24 
 25 #ifndef SHARE_GC_PARALLEL_PSVIRTUALSPACE_HPP
 26 #define SHARE_GC_PARALLEL_PSVIRTUALSPACE_HPP
 27 
 28 #include "memory/allocation.hpp"
 29 #include "memory/virtualspace.hpp"
 30 
 31 // VirtualSpace for the parallel scavenge collector.
 32 //
 33 // VirtualSpace is data structure for committing a previously reserved address
 34 // range in smaller chunks.
 35 
 36 class PSVirtualSpace : public CHeapObj<mtGC> {
 37   friend class VMStructs;
 38  protected:
 39   // The space is committed/uncommitted in chunks of size _alignment.  The
 40   // ReservedSpace passed to initialize() must be aligned to this value.
 41   const size_t _alignment;
 42 
 43   // Reserved area
 44   char* _reserved_low_addr;
 45   char* _reserved_high_addr;
 46 
 47   // Committed area
 48   char* _committed_low_addr;
 49   char* _committed_high_addr;
 50 
 51   // The entire space has been committed and pinned in memory, no
 52   // os::commit_memory() or os::uncommit_memory().
 53   bool _special;
 54 
 55   // Convenience wrapper.
 56   inline static size_t pointer_delta(const char* left, const char* right);
 57 
 58  public:
 59   PSVirtualSpace(ReservedSpace rs, size_t alignment);
 60   PSVirtualSpace(ReservedSpace rs);
 61 
 62   ~PSVirtualSpace();
 63 
 64   // Eventually all instances should be created with the above 1- or 2-arg
 65   // constructors.  Then the 1st constructor below should become protected and
 66   // the 2nd ctor and initialize() removed.
 67   PSVirtualSpace(size_t alignment): _alignment(alignment) { }
 68   PSVirtualSpace();
 69   bool initialize(ReservedSpace rs, size_t commit_size);
 70 
 71   bool contains(void* p)      const;
 72 
 73   // Accessors (all sizes are bytes).
 74   size_t alignment()          const { return _alignment; }
 75   char* reserved_low_addr()   const { return _reserved_low_addr; }
 76   char* reserved_high_addr()  const { return _reserved_high_addr; }
 77   char* committed_low_addr()  const { return _committed_low_addr; }
 78   char* committed_high_addr() const { return _committed_high_addr; }
 79   bool  special()             const { return _special; }
 80 
 81   inline size_t committed_size()   const;
 82   inline size_t reserved_size()    const;
 83   inline size_t uncommitted_size() const;
 84 
 85   // Operations.
 86   inline  void   set_reserved(char* low_addr, char* high_addr, bool special);
 87   inline  void   set_reserved(ReservedSpace rs);
 88   inline  void   set_committed(char* low_addr, char* high_addr);
 89   virtual bool   expand_by(size_t bytes);
 90   virtual bool   shrink_by(size_t bytes);
 91   virtual size_t expand_into(PSVirtualSpace* space, size_t bytes);
 92   void           release();
 93 
 94 #ifndef PRODUCT
 95   // Debugging
 96   static  bool is_aligned(size_t val, size_t align);
 97           bool is_aligned(size_t val) const;
 98           bool is_aligned(char* val) const;
 99           void verify() const;
100   virtual bool grows_up() const   { return true; }
101           bool grows_down() const { return !grows_up(); }
102 
103   // Helper class to verify a space when entering/leaving a block.
104   class PSVirtualSpaceVerifier: public StackObj {
105    private:
106     const PSVirtualSpace* const _space;
107    public:
108     PSVirtualSpaceVerifier(PSVirtualSpace* space): _space(space) {
109       _space->verify();
110     }
111     ~PSVirtualSpaceVerifier() { _space->verify(); }
112   };
113 #endif
114 
115   virtual void print_space_boundaries_on(outputStream* st) const;
116 
117  // Included for compatibility with the original VirtualSpace.
118  public:
119   // Committed area
120   char* low()  const { return committed_low_addr(); }
121   char* high() const { return committed_high_addr(); }
122 
123   // Reserved area
124   char* low_boundary()  const { return reserved_low_addr(); }
125   char* high_boundary() const { return reserved_high_addr(); }
126 };
127 
128 // A virtual space that grows from high addresses to low addresses.
129 class PSVirtualSpaceHighToLow : public PSVirtualSpace {
130   friend class VMStructs;
131  public:
132   PSVirtualSpaceHighToLow(ReservedSpace rs, size_t alignment);
133   PSVirtualSpaceHighToLow(ReservedSpace rs);
134 
135   virtual bool   expand_by(size_t bytes);
136   virtual bool   shrink_by(size_t bytes);
137   virtual size_t expand_into(PSVirtualSpace* space, size_t bytes);
138 
139   virtual void print_space_boundaries_on(outputStream* st) const;
140 
141 #ifndef PRODUCT
142   // Debugging
143   virtual bool grows_up() const   { return false; }
144 #endif
145 };
146 
147 //
148 // PSVirtualSpace inlines.
149 //
150 inline size_t
151 PSVirtualSpace::pointer_delta(const char* left, const char* right) {
152   return ::pointer_delta((void *)left, (void*)right, sizeof(char));
153 }
154 
155 inline size_t PSVirtualSpace::committed_size() const {
156   return pointer_delta(committed_high_addr(), committed_low_addr());
157 }
158 
159 inline size_t PSVirtualSpace::reserved_size() const {
160   return pointer_delta(reserved_high_addr(), reserved_low_addr());
161 }
162 
163 inline size_t PSVirtualSpace::uncommitted_size() const {
164   return reserved_size() - committed_size();
165 }
166 
167 inline void PSVirtualSpace::set_reserved(char* low_addr, char* high_addr, bool special) {
168   _reserved_low_addr = low_addr;
169   _reserved_high_addr = high_addr;
170   _special = special;
171 }
172 
173 inline void PSVirtualSpace::set_reserved(ReservedSpace rs) {
174   set_reserved(rs.base(), rs.base() + rs.size(), rs.special());
175 }
176 
177 inline void PSVirtualSpace::set_committed(char* low_addr, char* high_addr) {
178   _committed_low_addr = low_addr;
179   _committed_high_addr = high_addr;
180 }
181 
182 #endif // SHARE_GC_PARALLEL_PSVIRTUALSPACE_HPP