promotionInfo.hpp revision 10123:f71b5a8a78b6 
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24
25#ifndef SHARE_VM_GC_CMS_PROMOTIONINFO_HPP
26#define SHARE_VM_GC_CMS_PROMOTIONINFO_HPP
27
28#include "gc/cms/freeChunk.hpp"
29#include "memory/allocation.hpp"
30
31// Forward declarations
32class CompactibleFreeListSpace;
33
34class PromotedObject VALUE_OBJ_CLASS_SPEC {
35 private:
36  enum {
37    promoted_mask  = right_n_bits(2),   // i.e. 0x3
38    displaced_mark = nth_bit(2),        // i.e. 0x4
39    next_mask      = ~(right_n_bits(3)) // i.e. ~(0x7)
40  };
41
42  // Below, we want _narrow_next in the "higher" 32 bit slot,
43  // whose position will depend on endian-ness of the platform.
44  // This is so that there is no interference with the
45  // cms_free_bit occupying bit position 7 (lsb == 0)
46  // when we are using compressed oops; see FreeChunk::is_free().
47  // We cannot move the cms_free_bit down because currently
48  // biased locking code assumes that age bits are contiguous
49  // with the lock bits. Even if that assumption were relaxed,
50  // the least position we could move this bit to would be
51  // to bit position 3, which would require 16 byte alignment.
52  typedef struct {
53#ifdef VM_LITTLE_ENDIAN
54    LP64_ONLY(narrowOop _pad;)
55              narrowOop _narrow_next;
56#else
57              narrowOop _narrow_next;
58    LP64_ONLY(narrowOop _pad;)
59#endif
60  } Data;
61
62  union {
63    intptr_t _next;
64    Data     _data;
65  };
66 public:
67  PromotedObject* next() const;
68  void setNext(PromotedObject* x);
69  inline void setPromotedMark() {
70    _next |= promoted_mask;
71    assert(!((FreeChunk*)this)->is_free(), "Error");
72  }
73  inline bool hasPromotedMark() const {
74    assert(!((FreeChunk*)this)->is_free(), "Error");
75    return (_next & promoted_mask) == promoted_mask;
76  }
77  inline void setDisplacedMark() {
78    _next |= displaced_mark;
79    assert(!((FreeChunk*)this)->is_free(), "Error");
80  }
81  inline bool hasDisplacedMark() const {
82    assert(!((FreeChunk*)this)->is_free(), "Error");
83    return (_next & displaced_mark) != 0;
84  }
85  inline void clear_next()        {
86    _next = 0;
87    assert(!((FreeChunk*)this)->is_free(), "Error");
88  }
89  debug_only(void *next_addr() { return (void *) &_next; })
90};
91
92class SpoolBlock: public FreeChunk {
93  friend class PromotionInfo;
94 protected:
95  SpoolBlock*  nextSpoolBlock;
96  size_t       bufferSize;        // number of usable words in this block
97  markOop*     displacedHdr;      // the displaced headers start here
98
99  // Note about bufferSize: it denotes the number of entries available plus 1;
100  // legal indices range from 1 through BufferSize - 1.  See the verification
101  // code verify() that counts the number of displaced headers spooled.
102  size_t computeBufferSize() {
103    return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
104  }
105
106 public:
107  void init() {
108    bufferSize = computeBufferSize();
109    displacedHdr = (markOop*)&displacedHdr;
110    nextSpoolBlock = NULL;
111  }
112
113  void print_on(outputStream* st) const;
114  void print() const { print_on(tty); }
115};
116
117class PromotionInfo VALUE_OBJ_CLASS_SPEC {
118  bool            _tracking;      // set if tracking
119  CompactibleFreeListSpace* _space; // the space to which this belongs
120  PromotedObject* _promoHead;     // head of list of promoted objects
121  PromotedObject* _promoTail;     // tail of list of promoted objects
122  SpoolBlock*     _spoolHead;     // first spooling block
123  SpoolBlock*     _spoolTail;     // last  non-full spooling block or null
124  SpoolBlock*     _splice_point;  // when _spoolTail is null, holds list tail
125  SpoolBlock*     _spareSpool;    // free spool buffer
126  size_t          _firstIndex;    // first active index in
127                                  // first spooling block (_spoolHead)
128  size_t          _nextIndex;     // last active index + 1 in last
129                                  // spooling block (_spoolTail)
130 private:
131  // ensure that spooling space exists; return true if there is spooling space
132  bool ensure_spooling_space_work();
133
134 public:
135  PromotionInfo() :
136    _tracking(0), _space(NULL),
137    _promoHead(NULL), _promoTail(NULL),
138    _spoolHead(NULL), _spoolTail(NULL),
139    _spareSpool(NULL), _firstIndex(1),
140    _nextIndex(1) {}
141
142  bool noPromotions() const {
143    assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
144    return _promoHead == NULL;
145  }
146  void startTrackingPromotions();
147  void stopTrackingPromotions(uint worker_id = 0);
148  bool tracking() const          { return _tracking;  }
149  void track(PromotedObject* trackOop);      // keep track of a promoted oop
150  // The following variant must be used when trackOop is not fully
151  // initialized and has a NULL klass:
152  void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop
153  void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
154  CompactibleFreeListSpace* space() const     { return _space; }
155  markOop nextDisplacedHeader(); // get next header & forward spool pointer
156  void    saveDisplacedHeader(markOop hdr);
157                                 // save header and forward spool
158
159  inline size_t refillSize() const;
160
161  SpoolBlock* getSpoolBlock();   // return a free spooling block
162  inline bool has_spooling_space() {
163    return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
164  }
165  // ensure that spooling space exists
166  bool ensure_spooling_space() {
167    return has_spooling_space() || ensure_spooling_space_work();
168  }
169  #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix)  \
170    void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
171  ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
172  #undef PROMOTED_OOPS_ITERATE_DECL
173  void promoted_oops_iterate(OopsInGenClosure* cl) {
174    promoted_oops_iterate_v(cl);
175  }
176  void verify()  const;
177  void reset() {
178    _promoHead = NULL;
179    _promoTail = NULL;
180    _spoolHead = NULL;
181    _spoolTail = NULL;
182    _spareSpool = NULL;
183    _firstIndex = 0;
184    _nextIndex = 0;
185
186  }
187
188  void print_on(outputStream* st) const;
189};
190
191
192#endif // SHARE_VM_GC_CMS_PROMOTIONINFO_HPP
193