1/*
2 * Copyright (c) 1998, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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 *
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23 */
24
25#ifndef SHARE_VM_CODE_OOPRECORDER_HPP
26#define SHARE_VM_CODE_OOPRECORDER_HPP
27
28#include "memory/universe.hpp"
29#include "runtime/handles.hpp"
30#include "utilities/growableArray.hpp"
31
32// Recording and retrieval of either oop relocations or metadata in compiled code.
33
34class CodeBlob;
35
36template <class T> class ValueRecorder : public StackObj {
37 public:
38  // A two-way mapping from positive indexes to oop handles.
39  // The zero index is reserved for a constant (sharable) null.
40  // Indexes may not be negative.
41
42  // Use the given arena to manage storage, if not NULL.
43  // By default, uses the current ResourceArea.
44  ValueRecorder(Arena* arena = NULL);
45
46  // Generate a new index on which nmethod::oop_addr_at will work.
47  // allocate_index and find_index never return the same index,
48  // and allocate_index never returns the same index twice.
49  // In fact, two successive calls to allocate_index return successive ints.
50  int allocate_index(T h) {
51    return add_handle(h, false);
52  }
53
54  // For a given jobject or Metadata*, this will return the same index
55  // repeatedly. The index can later be given to nmethod::oop_at or
56  // metadata_at to retrieve the oop.
57  // However, the oop must not be changed via nmethod::oop_addr_at.
58  int find_index(T h) {
59    int index = maybe_find_index(h);
60    if (index < 0) {  // previously unallocated
61      index = add_handle(h, true);
62    }
63    return index;
64  }
65
66  // returns the size of the generated oop/metadata table, for sizing the
67  // CodeBlob. Must be called after all oops are allocated!
68  int size();
69
70  // Retrieve the value at a given index.
71  T at(int index);
72
73  int count() {
74    if (_handles == NULL) return 0;
75    // there is always a NULL virtually present as first object
76    return _handles->length() + first_index;
77  }
78
79  // Helper function; returns false for NULL or Universe::non_oop_word().
80  bool is_real(T h) {
81    return h != NULL && h != (T)Universe::non_oop_word();
82  }
83
84  // copy the generated table to nmethod
85  void copy_values_to(nmethod* nm);
86
87  bool is_unused() { return _handles == NULL && !_complete; }
88#ifdef ASSERT
89  bool is_complete() { return _complete; }
90#endif
91
92 private:
93  // variant of find_index which does not allocate if not found (yields -1)
94  int maybe_find_index(T h);
95
96  // leaky hash table of handle => index, to help detect duplicate insertion
97  template <class X> class IndexCache : public ResourceObj {
98    // This class is only used by the ValueRecorder class.
99    friend class ValueRecorder;
100    enum {
101      _log_cache_size = 9,
102      _cache_size = (1<<_log_cache_size),
103      // Index entries are ints.  The LSBit is a collision indicator.
104      _collision_bit_shift = 0,
105      _collision_bit = 1,
106      _index_shift = _collision_bit_shift+1
107    };
108    int _cache[_cache_size];
109    static juint cache_index(X handle) {
110      juint ci = (int) (intptr_t) handle;
111      ci ^= ci >> (BitsPerByte*2);
112      ci += ci >> (BitsPerByte*1);
113      return ci & (_cache_size-1);
114    }
115    int* cache_location(X handle) {
116      return &_cache[ cache_index(handle) ];
117    }
118    static bool cache_location_collision(int* cloc) {
119      return ((*cloc) & _collision_bit) != 0;
120    }
121    static int cache_location_index(int* cloc) {
122      return (*cloc) >> _index_shift;
123    }
124    static void set_cache_location_index(int* cloc, int index) {
125      int cval0 = (*cloc);
126      int cval1 = (index << _index_shift);
127      if (cval0 != 0 && cval1 != cval0)  cval1 += _collision_bit;
128      (*cloc) = cval1;
129    }
130    IndexCache();
131  };
132
133  void maybe_initialize();
134  int add_handle(T h, bool make_findable);
135
136  enum { null_index = 0, first_index = 1, index_cache_threshold = 20 };
137
138  GrowableArray<T>*        _handles;  // ordered list (first is always NULL)
139  GrowableArray<int>*       _no_finds; // all unfindable indexes; usually empty
140  IndexCache<T>*           _indexes;  // map: handle -> its probable index
141  Arena*                    _arena;
142  bool                      _complete;
143
144#ifdef ASSERT
145  static int _find_index_calls, _hit_indexes, _missed_indexes;
146#endif
147};
148
149class OopRecorder;
150
151class ObjectLookup : public ResourceObj {
152 private:
153  class ObjectEntry {
154   private:
155    jobject _value;
156    int     _index;
157
158   public:
159    ObjectEntry(jobject value, int index) : _value(value), _index(index) {}
160    ObjectEntry() : _value(NULL), _index(0) {}
161    oop oop_value() const;
162    int index() { return _index; }
163  };
164
165  GrowableArray<ObjectEntry> _values;
166  unsigned int _gc_count;
167
168  // Utility sort functions
169  static int sort_by_address(oop a, oop b);
170  static int sort_by_address(ObjectEntry* a, ObjectEntry* b);
171  static int sort_oop_by_address(oop const& a, ObjectEntry const& b);
172
173 public:
174  ObjectLookup();
175
176  // Resort list if a GC has occurred since the last sort
177  void maybe_resort();
178  int find_index(jobject object, OopRecorder* oop_recorder);
179};
180
181class OopRecorder : public ResourceObj {
182 private:
183  ValueRecorder<jobject>      _oops;
184  ValueRecorder<Metadata*>    _metadata;
185  ObjectLookup*               _object_lookup;
186 public:
187  OopRecorder(Arena* arena = NULL, bool deduplicate = false): _oops(arena), _metadata(arena) {
188    if (deduplicate) {
189      _object_lookup = new ObjectLookup();
190    } else {
191      _object_lookup = NULL;
192    }
193  }
194
195  int allocate_oop_index(jobject h) {
196    return _oops.allocate_index(h);
197  }
198  virtual int find_index(jobject h) {
199    return _object_lookup != NULL ? _object_lookup->find_index(h, this) : _oops.find_index(h);
200  }
201  jobject oop_at(int index) {
202    return _oops.at(index);
203  }
204  int oop_size() {
205    return _oops.size();
206  }
207  int oop_count() {
208    return _oops.count();
209  }
210  bool is_real(jobject h) {
211    return _oops.is_real(h);
212  }
213
214  int allocate_metadata_index(Metadata* oop) {
215    return _metadata.allocate_index(oop);
216  }
217  virtual int find_index(Metadata* h) {
218    return _metadata.find_index(h);
219  }
220  Metadata* metadata_at(int index) {
221    return _metadata.at(index);
222  }
223  int metadata_size() {
224    return _metadata.size();
225  }
226  int metadata_count() {
227    return _metadata.count();
228  }
229  bool is_real(Metadata* h) {
230    return _metadata.is_real(h);
231  }
232
233  bool is_unused() {
234    return _oops.is_unused() && _metadata.is_unused();
235  }
236
237  void freeze() {
238    _oops.size();
239    _metadata.size();
240  }
241
242  void copy_values_to(nmethod* nm) {
243    if (!_oops.is_unused()) {
244      _oops.copy_values_to(nm);
245    }
246    if (!_metadata.is_unused()) {
247      _metadata.copy_values_to(nm);
248    }
249  }
250
251#ifdef ASSERT
252  bool is_complete() {
253    assert(_oops.is_complete() == _metadata.is_complete(), "must agree");
254    return _oops.is_complete();
255  }
256#endif
257};
258
259
260#endif // SHARE_VM_CODE_OOPRECORDER_HPP
261