summaryrefslogtreecommitdiffstats
path: root/layout/base/nsPresArena.cpp
blob: 8e7fb93746f0e69d0402e2bf457f2ea368f07aa1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* arena allocation for the frame tree and closely-related objects */

// Even on 32-bit systems, we allocate objects from the frame arena
// that require 8-byte alignment.  The cast to uintptr_t is needed
// because plarena isn't as careful about mask construction as it
// ought to be.
#define ALIGN_SHIFT 3
#define PL_ARENA_CONST_ALIGN_MASK ((uintptr_t(1) << ALIGN_SHIFT) - 1)
#include "plarena.h"
// plarena.h needs to be included first to make it use the above
// PL_ARENA_CONST_ALIGN_MASK in this file.

#include "nsPresArena.h"

#include "mozilla/Poison.h"
#include "nsDebug.h"
#include "nsArenaMemoryStats.h"
#include "nsPrintfCString.h"
#include "nsStyleContext.h"

#include <inttypes.h>

using namespace mozilla;

// Size to use for PLArena block allocations.
static const size_t ARENA_PAGE_SIZE = 8192;

nsPresArena::nsPresArena()
{
  PL_INIT_ARENA_POOL(&mPool, "PresArena", ARENA_PAGE_SIZE);
}

nsPresArena::~nsPresArena()
{
  ClearArenaRefPtrs();

#if defined(MOZ_HAVE_MEM_CHECKS)
  for (auto iter = mFreeLists.Iter(); !iter.Done(); iter.Next()) {
    FreeList* entry = iter.Get();
    nsTArray<void*>::index_type len;
    while ((len = entry->mEntries.Length())) {
      void* result = entry->mEntries.ElementAt(len - 1);
      entry->mEntries.RemoveElementAt(len - 1);
      MOZ_MAKE_MEM_UNDEFINED(result, entry->mEntrySize);
    }
  }
#endif

  PL_FinishArenaPool(&mPool);
}

/* inline */ void
nsPresArena::ClearArenaRefPtrWithoutDeregistering(void* aPtr,
                                                  ArenaObjectID aObjectID)
{
  switch (aObjectID) {
#define PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT(name_)                     \
    case eArenaObjectID_##name_:                                              \
      static_cast<ArenaRefPtr<name_>*>(aPtr)->ClearWithoutDeregistering();    \
      return;
#include "nsPresArenaObjectList.h"
#undef PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT
    default:
      break;
  }
  switch (aObjectID) {
#define PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(name_)                  \
    case eArenaObjectID_##name_:                                              \
      MOZ_ASSERT(false, #name_ " must be declared in nsPresArenaObjectList.h "\
                        "with PRES_ARENA_OBJECT_SUPPORTS_ARENAREFPTR");       \
      break;
#include "nsPresArenaObjectList.h"
#undef PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT
    default:
      MOZ_ASSERT(false, "unexpected ArenaObjectID value");
      break;
  }
}

void
nsPresArena::ClearArenaRefPtrs()
{
  for (auto iter = mArenaRefPtrs.Iter(); !iter.Done(); iter.Next()) {
    void* ptr = iter.Key();
    ArenaObjectID id = iter.UserData();
    ClearArenaRefPtrWithoutDeregistering(ptr, id);
  }
  mArenaRefPtrs.Clear();
}

void
nsPresArena::ClearArenaRefPtrs(ArenaObjectID aObjectID)
{
  for (auto iter = mArenaRefPtrs.Iter(); !iter.Done(); iter.Next()) {
    void* ptr = iter.Key();
    ArenaObjectID id = iter.UserData();
    if (id == aObjectID) {
      ClearArenaRefPtrWithoutDeregistering(ptr, id);
      iter.Remove();
    }
  }
}

void*
nsPresArena::Allocate(uint32_t aCode, size_t aSize)
{
  MOZ_ASSERT(aSize > 0, "PresArena cannot allocate zero bytes");

  // We only hand out aligned sizes
  aSize = PL_ARENA_ALIGN(&mPool, aSize);

  // If there is no free-list entry for this type already, we have
  // to create one now, to record its size.
  FreeList* list = mFreeLists.PutEntry(aCode);

  nsTArray<void*>::index_type len = list->mEntries.Length();
  if (list->mEntrySize == 0) {
    MOZ_ASSERT(len == 0, "list with entries but no recorded size");
    list->mEntrySize = aSize;
  } else {
    MOZ_ASSERT(list->mEntrySize == aSize,
               "different sizes for same object type code");
  }

  void* result;
  if (len > 0) {
    // LIFO behavior for best cache utilization
    result = list->mEntries.ElementAt(len - 1);
    list->mEntries.RemoveElementAt(len - 1);
#if defined(DEBUG)
    {
      MOZ_MAKE_MEM_DEFINED(result, list->mEntrySize);
      char* p = reinterpret_cast<char*>(result);
      char* limit = p + list->mEntrySize;
      for (; p < limit; p += sizeof(uintptr_t)) {
        uintptr_t val = *reinterpret_cast<uintptr_t*>(p);
        if (val != mozPoisonValue()) {
          MOZ_ReportAssertionFailure(
            nsPrintfCString("PresArena: poison overwritten; "
                            "wanted %.16" PRIx64 " "
                            "found %.16" PRIx64 " "
                            "errors in bits %.16" PRIx64 " ",
                            uint64_t(mozPoisonValue()),
                            uint64_t(val),
                            uint64_t(mozPoisonValue() ^ val)).get(),
            __FILE__, __LINE__);
          MOZ_CRASH();
        }
      }
    }
#endif
    MOZ_MAKE_MEM_UNDEFINED(result, list->mEntrySize);
    return result;
  }

  // Allocate a new chunk from the arena
  list->mEntriesEverAllocated++;
  PL_ARENA_ALLOCATE(result, &mPool, aSize);
  if (!result) {
    NS_ABORT_OOM(aSize);
  }
  return result;
}

void
nsPresArena::Free(uint32_t aCode, void* aPtr)
{
  // Try to recycle this entry.
  FreeList* list = mFreeLists.GetEntry(aCode);
  MOZ_ASSERT(list, "no free list for pres arena object");
  MOZ_ASSERT(list->mEntrySize > 0, "PresArena cannot free zero bytes");

  mozWritePoison(aPtr, list->mEntrySize);

  MOZ_MAKE_MEM_NOACCESS(aPtr, list->mEntrySize);
  list->mEntries.AppendElement(aPtr);
}

void
nsPresArena::AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                    nsArenaMemoryStats* aArenaStats)
{
  // We do a complicated dance here because we want to measure the
  // space taken up by the different kinds of objects in the arena,
  // but we don't have pointers to those objects.  And even if we did,
  // we wouldn't be able to use aMallocSizeOf on them, since they were
  // allocated out of malloc'd chunks of memory.  So we compute the
  // size of the arena as known by malloc and we add up the sizes of
  // all the objects that we care about.  Subtracting these two
  // quantities gives us a catch-all "other" number, which includes
  // slop in the arena itself as well as the size of objects that
  // we've not measured explicitly.

  size_t mallocSize = PL_SizeOfArenaPoolExcludingPool(&mPool, aMallocSizeOf);
  mallocSize += mFreeLists.SizeOfExcludingThis(aMallocSizeOf);

  size_t totalSizeInFreeLists = 0;
  for (auto iter = mFreeLists.Iter(); !iter.Done(); iter.Next()) {
    FreeList* entry = iter.Get();

    // Note that we're not measuring the size of the entries on the free
    // list here.  The free list knows how many objects we've allocated
    // ever (which includes any objects that may be on the FreeList's
    // |mEntries| at this point) and we're using that to determine the
    // total size of objects allocated with a given ID.
    size_t totalSize = entry->mEntrySize * entry->mEntriesEverAllocated;
    size_t* p;

    switch (NS_PTR_TO_INT32(entry->mKey)) {
#define FRAME_ID(classname)                               \
      case nsQueryFrame::classname##_id:                  \
        p = &aArenaStats->FRAME_ID_STAT_FIELD(classname); \
        break;
#include "nsFrameIdList.h"
#undef FRAME_ID
      case eArenaObjectID_nsLineBox:
        p = &aArenaStats->mLineBoxes;
        break;
      case eArenaObjectID_nsRuleNode:
        p = &aArenaStats->mRuleNodes;
        break;
      case eArenaObjectID_nsStyleContext:
        p = &aArenaStats->mStyleContexts;
        break;
#define STYLE_STRUCT(name_, checkdata_cb_)      \
        case eArenaObjectID_nsStyle##name_:
#include "nsStyleStructList.h"
#undef STYLE_STRUCT
        p = &aArenaStats->mStyleStructs;
        break;
      default:
        continue;
    }

    *p += totalSize;
    totalSizeInFreeLists += totalSize;
  }

  aArenaStats->mOther += mallocSize - totalSizeInFreeLists;
}