Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1 | // Copyright 2006-2008 the V8 project authors. All rights reserved. |
| 2 | // Redistribution and use in source and binary forms, with or without |
| 3 | // modification, are permitted provided that the following conditions are |
| 4 | // met: |
| 5 | // |
| 6 | // * Redistributions of source code must retain the above copyright |
| 7 | // notice, this list of conditions and the following disclaimer. |
| 8 | // * Redistributions in binary form must reproduce the above |
| 9 | // copyright notice, this list of conditions and the following |
| 10 | // disclaimer in the documentation and/or other materials provided |
| 11 | // with the distribution. |
| 12 | // * Neither the name of Google Inc. nor the names of its |
| 13 | // contributors may be used to endorse or promote products derived |
| 14 | // from this software without specific prior written permission. |
| 15 | // |
| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | |
| 28 | #include "v8.h" |
| 29 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 30 | #include "compilation-cache.h" |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 31 | #include "execution.h" |
Ben Murdoch | 3bec4d2 | 2010-07-22 14:51:16 +0100 | [diff] [blame] | 32 | #include "heap-profiler.h" |
Ben Murdoch | b8e0da2 | 2011-05-16 14:20:40 +0100 | [diff] [blame] | 33 | #include "gdb-jit.h" |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 34 | #include "global-handles.h" |
| 35 | #include "ic-inl.h" |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 36 | #include "liveobjectlist-inl.h" |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 37 | #include "mark-compact.h" |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 38 | #include "objects-visiting.h" |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 39 | #include "stub-cache.h" |
| 40 | |
| 41 | namespace v8 { |
| 42 | namespace internal { |
| 43 | |
| 44 | // ------------------------------------------------------------------------- |
| 45 | // MarkCompactCollector |
| 46 | |
| 47 | bool MarkCompactCollector::force_compaction_ = false; |
| 48 | bool MarkCompactCollector::compacting_collection_ = false; |
| 49 | bool MarkCompactCollector::compact_on_next_gc_ = false; |
| 50 | |
| 51 | int MarkCompactCollector::previous_marked_count_ = 0; |
| 52 | GCTracer* MarkCompactCollector::tracer_ = NULL; |
| 53 | |
| 54 | |
| 55 | #ifdef DEBUG |
| 56 | MarkCompactCollector::CollectorState MarkCompactCollector::state_ = IDLE; |
| 57 | |
| 58 | // Counters used for debugging the marking phase of mark-compact or mark-sweep |
| 59 | // collection. |
| 60 | int MarkCompactCollector::live_bytes_ = 0; |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 61 | int MarkCompactCollector::live_young_objects_size_ = 0; |
| 62 | int MarkCompactCollector::live_old_data_objects_size_ = 0; |
| 63 | int MarkCompactCollector::live_old_pointer_objects_size_ = 0; |
| 64 | int MarkCompactCollector::live_code_objects_size_ = 0; |
| 65 | int MarkCompactCollector::live_map_objects_size_ = 0; |
| 66 | int MarkCompactCollector::live_cell_objects_size_ = 0; |
| 67 | int MarkCompactCollector::live_lo_objects_size_ = 0; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 68 | #endif |
| 69 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 70 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 71 | void MarkCompactCollector::CollectGarbage() { |
| 72 | // Make sure that Prepare() has been called. The individual steps below will |
| 73 | // update the state as they proceed. |
| 74 | ASSERT(state_ == PREPARE_GC); |
| 75 | |
| 76 | // Prepare has selected whether to compact the old generation or not. |
| 77 | // Tell the tracer. |
| 78 | if (IsCompacting()) tracer_->set_is_compacting(); |
| 79 | |
| 80 | MarkLiveObjects(); |
| 81 | |
| 82 | if (FLAG_collect_maps) ClearNonLiveTransitions(); |
| 83 | |
| 84 | SweepLargeObjectSpace(); |
| 85 | |
| 86 | if (IsCompacting()) { |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 87 | GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_COMPACT); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 88 | EncodeForwardingAddresses(); |
| 89 | |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 90 | Heap::MarkMapPointersAsEncoded(true); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 91 | UpdatePointers(); |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 92 | Heap::MarkMapPointersAsEncoded(false); |
| 93 | PcToCodeCache::FlushPcToCodeCache(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 94 | |
| 95 | RelocateObjects(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 96 | } else { |
| 97 | SweepSpaces(); |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 98 | PcToCodeCache::FlushPcToCodeCache(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 99 | } |
| 100 | |
| 101 | Finish(); |
| 102 | |
| 103 | // Save the count of marked objects remaining after the collection and |
| 104 | // null out the GC tracer. |
| 105 | previous_marked_count_ = tracer_->marked_count(); |
| 106 | ASSERT(previous_marked_count_ == 0); |
| 107 | tracer_ = NULL; |
| 108 | } |
| 109 | |
| 110 | |
| 111 | void MarkCompactCollector::Prepare(GCTracer* tracer) { |
| 112 | // Rather than passing the tracer around we stash it in a static member |
| 113 | // variable. |
| 114 | tracer_ = tracer; |
| 115 | |
| 116 | #ifdef DEBUG |
| 117 | ASSERT(state_ == IDLE); |
| 118 | state_ = PREPARE_GC; |
| 119 | #endif |
| 120 | ASSERT(!FLAG_always_compact || !FLAG_never_compact); |
| 121 | |
| 122 | compacting_collection_ = |
| 123 | FLAG_always_compact || force_compaction_ || compact_on_next_gc_; |
| 124 | compact_on_next_gc_ = false; |
| 125 | |
| 126 | if (FLAG_never_compact) compacting_collection_ = false; |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 127 | if (!Heap::map_space()->MapPointersEncodable()) |
| 128 | compacting_collection_ = false; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 129 | if (FLAG_collect_maps) CreateBackPointers(); |
Ben Murdoch | b8e0da2 | 2011-05-16 14:20:40 +0100 | [diff] [blame] | 130 | #ifdef ENABLE_GDB_JIT_INTERFACE |
| 131 | if (FLAG_gdbjit) { |
| 132 | // If GDBJIT interface is active disable compaction. |
| 133 | compacting_collection_ = false; |
| 134 | } |
| 135 | #endif |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 136 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 137 | PagedSpaces spaces; |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 138 | for (PagedSpace* space = spaces.next(); |
| 139 | space != NULL; space = spaces.next()) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 140 | space->PrepareForMarkCompact(compacting_collection_); |
| 141 | } |
| 142 | |
| 143 | #ifdef DEBUG |
| 144 | live_bytes_ = 0; |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 145 | live_young_objects_size_ = 0; |
| 146 | live_old_pointer_objects_size_ = 0; |
| 147 | live_old_data_objects_size_ = 0; |
| 148 | live_code_objects_size_ = 0; |
| 149 | live_map_objects_size_ = 0; |
| 150 | live_cell_objects_size_ = 0; |
| 151 | live_lo_objects_size_ = 0; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 152 | #endif |
| 153 | } |
| 154 | |
| 155 | |
| 156 | void MarkCompactCollector::Finish() { |
| 157 | #ifdef DEBUG |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 158 | ASSERT(state_ == SWEEP_SPACES || state_ == RELOCATE_OBJECTS); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 159 | state_ = IDLE; |
| 160 | #endif |
| 161 | // The stub cache is not traversed during GC; clear the cache to |
| 162 | // force lazy re-initialization of it. This must be done after the |
| 163 | // GC, because it relies on the new address of certain old space |
| 164 | // objects (empty string, illegal builtin). |
| 165 | StubCache::Clear(); |
| 166 | |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 167 | ExternalStringTable::CleanUp(); |
| 168 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 169 | // If we've just compacted old space there's no reason to check the |
| 170 | // fragmentation limit. Just return. |
| 171 | if (HasCompacted()) return; |
| 172 | |
| 173 | // We compact the old generation on the next GC if it has gotten too |
| 174 | // fragmented (ie, we could recover an expected amount of space by |
| 175 | // reclaiming the waste and free list blocks). |
| 176 | static const int kFragmentationLimit = 15; // Percent. |
| 177 | static const int kFragmentationAllowed = 1 * MB; // Absolute. |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 178 | intptr_t old_gen_recoverable = 0; |
| 179 | intptr_t old_gen_used = 0; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 180 | |
| 181 | OldSpaces spaces; |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 182 | for (OldSpace* space = spaces.next(); space != NULL; space = spaces.next()) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 183 | old_gen_recoverable += space->Waste() + space->AvailableFree(); |
| 184 | old_gen_used += space->Size(); |
| 185 | } |
| 186 | |
| 187 | int old_gen_fragmentation = |
| 188 | static_cast<int>((old_gen_recoverable * 100.0) / old_gen_used); |
| 189 | if (old_gen_fragmentation > kFragmentationLimit && |
| 190 | old_gen_recoverable > kFragmentationAllowed) { |
| 191 | compact_on_next_gc_ = true; |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | |
| 196 | // ------------------------------------------------------------------------- |
| 197 | // Phase 1: tracing and marking live objects. |
| 198 | // before: all objects are in normal state. |
| 199 | // after: a live object's map pointer is marked as '00'. |
| 200 | |
| 201 | // Marking all live objects in the heap as part of mark-sweep or mark-compact |
| 202 | // collection. Before marking, all objects are in their normal state. After |
| 203 | // marking, live objects' map pointers are marked indicating that the object |
| 204 | // has been found reachable. |
| 205 | // |
| 206 | // The marking algorithm is a (mostly) depth-first (because of possible stack |
| 207 | // overflow) traversal of the graph of objects reachable from the roots. It |
| 208 | // uses an explicit stack of pointers rather than recursion. The young |
| 209 | // generation's inactive ('from') space is used as a marking stack. The |
| 210 | // objects in the marking stack are the ones that have been reached and marked |
| 211 | // but their children have not yet been visited. |
| 212 | // |
| 213 | // The marking stack can overflow during traversal. In that case, we set an |
| 214 | // overflow flag. When the overflow flag is set, we continue marking objects |
| 215 | // reachable from the objects on the marking stack, but no longer push them on |
| 216 | // the marking stack. Instead, we mark them as both marked and overflowed. |
| 217 | // When the stack is in the overflowed state, objects marked as overflowed |
| 218 | // have been reached and marked but their children have not been visited yet. |
| 219 | // After emptying the marking stack, we clear the overflow flag and traverse |
| 220 | // the heap looking for objects marked as overflowed, push them on the stack, |
| 221 | // and continue with marking. This process repeats until all reachable |
| 222 | // objects have been marked. |
| 223 | |
| 224 | static MarkingStack marking_stack; |
| 225 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 226 | class FlushCode : public AllStatic { |
| 227 | public: |
| 228 | static void AddCandidate(SharedFunctionInfo* shared_info) { |
| 229 | SetNextCandidate(shared_info, shared_function_info_candidates_head_); |
| 230 | shared_function_info_candidates_head_ = shared_info; |
| 231 | } |
| 232 | |
| 233 | |
| 234 | static void AddCandidate(JSFunction* function) { |
| 235 | ASSERT(function->unchecked_code() == |
| 236 | function->unchecked_shared()->unchecked_code()); |
| 237 | |
| 238 | SetNextCandidate(function, jsfunction_candidates_head_); |
| 239 | jsfunction_candidates_head_ = function; |
| 240 | } |
| 241 | |
| 242 | |
| 243 | static void ProcessCandidates() { |
| 244 | ProcessSharedFunctionInfoCandidates(); |
| 245 | ProcessJSFunctionCandidates(); |
| 246 | } |
| 247 | |
| 248 | private: |
| 249 | static void ProcessJSFunctionCandidates() { |
| 250 | Code* lazy_compile = Builtins::builtin(Builtins::LazyCompile); |
| 251 | |
| 252 | JSFunction* candidate = jsfunction_candidates_head_; |
| 253 | JSFunction* next_candidate; |
| 254 | while (candidate != NULL) { |
| 255 | next_candidate = GetNextCandidate(candidate); |
| 256 | |
| 257 | SharedFunctionInfo* shared = candidate->unchecked_shared(); |
| 258 | |
| 259 | Code* code = shared->unchecked_code(); |
| 260 | if (!code->IsMarked()) { |
| 261 | shared->set_code(lazy_compile); |
| 262 | candidate->set_code(lazy_compile); |
| 263 | } else { |
| 264 | candidate->set_code(shared->unchecked_code()); |
| 265 | } |
| 266 | |
| 267 | candidate = next_candidate; |
| 268 | } |
| 269 | |
| 270 | jsfunction_candidates_head_ = NULL; |
| 271 | } |
| 272 | |
| 273 | |
| 274 | static void ProcessSharedFunctionInfoCandidates() { |
| 275 | Code* lazy_compile = Builtins::builtin(Builtins::LazyCompile); |
| 276 | |
| 277 | SharedFunctionInfo* candidate = shared_function_info_candidates_head_; |
| 278 | SharedFunctionInfo* next_candidate; |
| 279 | while (candidate != NULL) { |
| 280 | next_candidate = GetNextCandidate(candidate); |
| 281 | SetNextCandidate(candidate, NULL); |
| 282 | |
| 283 | Code* code = candidate->unchecked_code(); |
| 284 | if (!code->IsMarked()) { |
| 285 | candidate->set_code(lazy_compile); |
| 286 | } |
| 287 | |
| 288 | candidate = next_candidate; |
| 289 | } |
| 290 | |
| 291 | shared_function_info_candidates_head_ = NULL; |
| 292 | } |
| 293 | |
| 294 | |
| 295 | static JSFunction** GetNextCandidateField(JSFunction* candidate) { |
| 296 | return reinterpret_cast<JSFunction**>( |
| 297 | candidate->address() + JSFunction::kCodeEntryOffset); |
| 298 | } |
| 299 | |
| 300 | |
| 301 | static JSFunction* GetNextCandidate(JSFunction* candidate) { |
| 302 | return *GetNextCandidateField(candidate); |
| 303 | } |
| 304 | |
| 305 | |
| 306 | static void SetNextCandidate(JSFunction* candidate, |
| 307 | JSFunction* next_candidate) { |
| 308 | *GetNextCandidateField(candidate) = next_candidate; |
| 309 | } |
| 310 | |
| 311 | |
| 312 | STATIC_ASSERT(kPointerSize <= Code::kHeaderSize - Code::kHeaderPaddingStart); |
| 313 | |
| 314 | |
| 315 | static SharedFunctionInfo** GetNextCandidateField( |
| 316 | SharedFunctionInfo* candidate) { |
| 317 | Code* code = candidate->unchecked_code(); |
| 318 | return reinterpret_cast<SharedFunctionInfo**>( |
| 319 | code->address() + Code::kHeaderPaddingStart); |
| 320 | } |
| 321 | |
| 322 | |
| 323 | static SharedFunctionInfo* GetNextCandidate(SharedFunctionInfo* candidate) { |
| 324 | return *GetNextCandidateField(candidate); |
| 325 | } |
| 326 | |
| 327 | |
| 328 | static void SetNextCandidate(SharedFunctionInfo* candidate, |
| 329 | SharedFunctionInfo* next_candidate) { |
| 330 | *GetNextCandidateField(candidate) = next_candidate; |
| 331 | } |
| 332 | |
| 333 | static JSFunction* jsfunction_candidates_head_; |
| 334 | |
| 335 | static SharedFunctionInfo* shared_function_info_candidates_head_; |
| 336 | }; |
| 337 | |
| 338 | JSFunction* FlushCode::jsfunction_candidates_head_ = NULL; |
| 339 | |
| 340 | SharedFunctionInfo* FlushCode::shared_function_info_candidates_head_ = NULL; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 341 | |
| 342 | static inline HeapObject* ShortCircuitConsString(Object** p) { |
| 343 | // Optimization: If the heap object pointed to by p is a non-symbol |
| 344 | // cons string whose right substring is Heap::empty_string, update |
| 345 | // it in place to its left substring. Return the updated value. |
| 346 | // |
| 347 | // Here we assume that if we change *p, we replace it with a heap object |
| 348 | // (ie, the left substring of a cons string is always a heap object). |
| 349 | // |
| 350 | // The check performed is: |
| 351 | // object->IsConsString() && !object->IsSymbol() && |
| 352 | // (ConsString::cast(object)->second() == Heap::empty_string()) |
| 353 | // except the maps for the object and its possible substrings might be |
| 354 | // marked. |
| 355 | HeapObject* object = HeapObject::cast(*p); |
| 356 | MapWord map_word = object->map_word(); |
| 357 | map_word.ClearMark(); |
| 358 | InstanceType type = map_word.ToMap()->instance_type(); |
| 359 | if ((type & kShortcutTypeMask) != kShortcutTypeTag) return object; |
| 360 | |
| 361 | Object* second = reinterpret_cast<ConsString*>(object)->unchecked_second(); |
| 362 | if (second != Heap::raw_unchecked_empty_string()) { |
| 363 | return object; |
| 364 | } |
| 365 | |
| 366 | // Since we don't have the object's start, it is impossible to update the |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 367 | // page dirty marks. Therefore, we only replace the string with its left |
| 368 | // substring when page dirty marks do not change. |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 369 | Object* first = reinterpret_cast<ConsString*>(object)->unchecked_first(); |
| 370 | if (!Heap::InNewSpace(object) && Heap::InNewSpace(first)) return object; |
| 371 | |
| 372 | *p = first; |
| 373 | return HeapObject::cast(first); |
| 374 | } |
| 375 | |
| 376 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 377 | class StaticMarkingVisitor : public StaticVisitorBase { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 378 | public: |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 379 | static inline void IterateBody(Map* map, HeapObject* obj) { |
| 380 | table_.GetVisitor(map)(map, obj); |
| 381 | } |
| 382 | |
| 383 | static void EnableCodeFlushing(bool enabled) { |
| 384 | if (enabled) { |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 385 | table_.Register(kVisitJSFunction, &VisitJSFunctionAndFlushCode); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 386 | table_.Register(kVisitSharedFunctionInfo, |
| 387 | &VisitSharedFunctionInfoAndFlushCode); |
| 388 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 389 | } else { |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 390 | table_.Register(kVisitJSFunction, &VisitJSFunction); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 391 | table_.Register(kVisitSharedFunctionInfo, |
| 392 | &VisitSharedFunctionInfoGeneric); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 393 | } |
| 394 | } |
| 395 | |
| 396 | static void Initialize() { |
| 397 | table_.Register(kVisitShortcutCandidate, |
| 398 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 399 | ConsString::BodyDescriptor, |
| 400 | void>::Visit); |
| 401 | |
| 402 | table_.Register(kVisitConsString, |
| 403 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 404 | ConsString::BodyDescriptor, |
| 405 | void>::Visit); |
| 406 | |
| 407 | |
| 408 | table_.Register(kVisitFixedArray, |
| 409 | &FlexibleBodyVisitor<StaticMarkingVisitor, |
| 410 | FixedArray::BodyDescriptor, |
| 411 | void>::Visit); |
| 412 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 413 | table_.Register(kVisitGlobalContext, |
| 414 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 415 | Context::MarkCompactBodyDescriptor, |
| 416 | void>::Visit); |
| 417 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 418 | table_.Register(kVisitByteArray, &DataObjectVisitor::Visit); |
| 419 | table_.Register(kVisitSeqAsciiString, &DataObjectVisitor::Visit); |
| 420 | table_.Register(kVisitSeqTwoByteString, &DataObjectVisitor::Visit); |
| 421 | |
| 422 | table_.Register(kVisitOddball, |
| 423 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 424 | Oddball::BodyDescriptor, |
| 425 | void>::Visit); |
| 426 | table_.Register(kVisitMap, |
| 427 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 428 | Map::BodyDescriptor, |
| 429 | void>::Visit); |
| 430 | |
| 431 | table_.Register(kVisitCode, &VisitCode); |
| 432 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 433 | table_.Register(kVisitSharedFunctionInfo, |
| 434 | &VisitSharedFunctionInfoAndFlushCode); |
| 435 | |
| 436 | table_.Register(kVisitJSFunction, |
| 437 | &VisitJSFunctionAndFlushCode); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 438 | |
| 439 | table_.Register(kVisitPropertyCell, |
| 440 | &FixedBodyVisitor<StaticMarkingVisitor, |
| 441 | JSGlobalPropertyCell::BodyDescriptor, |
| 442 | void>::Visit); |
| 443 | |
| 444 | table_.RegisterSpecializations<DataObjectVisitor, |
| 445 | kVisitDataObject, |
| 446 | kVisitDataObjectGeneric>(); |
| 447 | |
| 448 | table_.RegisterSpecializations<JSObjectVisitor, |
| 449 | kVisitJSObject, |
| 450 | kVisitJSObjectGeneric>(); |
| 451 | |
| 452 | table_.RegisterSpecializations<StructObjectVisitor, |
| 453 | kVisitStruct, |
| 454 | kVisitStructGeneric>(); |
| 455 | } |
| 456 | |
| 457 | INLINE(static void VisitPointer(Object** p)) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 458 | MarkObjectByPointer(p); |
| 459 | } |
| 460 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 461 | INLINE(static void VisitPointers(Object** start, Object** end)) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 462 | // Mark all objects pointed to in [start, end). |
| 463 | const int kMinRangeForMarkingRecursion = 64; |
| 464 | if (end - start >= kMinRangeForMarkingRecursion) { |
| 465 | if (VisitUnmarkedObjects(start, end)) return; |
| 466 | // We are close to a stack overflow, so just mark the objects. |
| 467 | } |
| 468 | for (Object** p = start; p < end; p++) MarkObjectByPointer(p); |
| 469 | } |
| 470 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 471 | static inline void VisitCodeTarget(RelocInfo* rinfo) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 472 | ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode())); |
| 473 | Code* code = Code::GetCodeFromTargetAddress(rinfo->target_address()); |
| 474 | if (FLAG_cleanup_ics_at_gc && code->is_inline_cache_stub()) { |
| 475 | IC::Clear(rinfo->pc()); |
| 476 | // Please note targets for cleared inline cached do not have to be |
| 477 | // marked since they are contained in Heap::non_monomorphic_cache(). |
| 478 | } else { |
| 479 | MarkCompactCollector::MarkObject(code); |
| 480 | } |
| 481 | } |
| 482 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 483 | static void VisitGlobalPropertyCell(RelocInfo* rinfo) { |
| 484 | ASSERT(rinfo->rmode() == RelocInfo::GLOBAL_PROPERTY_CELL); |
| 485 | Object* cell = rinfo->target_cell(); |
| 486 | Object* old_cell = cell; |
| 487 | VisitPointer(&cell); |
| 488 | if (cell != old_cell) { |
| 489 | rinfo->set_target_cell(reinterpret_cast<JSGlobalPropertyCell*>(cell)); |
| 490 | } |
| 491 | } |
| 492 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 493 | static inline void VisitDebugTarget(RelocInfo* rinfo) { |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 494 | ASSERT((RelocInfo::IsJSReturn(rinfo->rmode()) && |
| 495 | rinfo->IsPatchedReturnSequence()) || |
| 496 | (RelocInfo::IsDebugBreakSlot(rinfo->rmode()) && |
| 497 | rinfo->IsPatchedDebugBreakSlotSequence())); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 498 | HeapObject* code = Code::GetCodeFromTargetAddress(rinfo->call_address()); |
| 499 | MarkCompactCollector::MarkObject(code); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 500 | } |
| 501 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 502 | // Mark object pointed to by p. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 503 | INLINE(static void MarkObjectByPointer(Object** p)) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 504 | if (!(*p)->IsHeapObject()) return; |
| 505 | HeapObject* object = ShortCircuitConsString(p); |
| 506 | MarkCompactCollector::MarkObject(object); |
| 507 | } |
| 508 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 509 | // Visit an unmarked object. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 510 | static inline void VisitUnmarkedObject(HeapObject* obj) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 511 | #ifdef DEBUG |
| 512 | ASSERT(Heap::Contains(obj)); |
| 513 | ASSERT(!obj->IsMarked()); |
| 514 | #endif |
| 515 | Map* map = obj->map(); |
| 516 | MarkCompactCollector::SetMark(obj); |
| 517 | // Mark the map pointer and the body. |
| 518 | MarkCompactCollector::MarkObject(map); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 519 | IterateBody(map, obj); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 520 | } |
| 521 | |
| 522 | // Visit all unmarked objects pointed to by [start, end). |
| 523 | // Returns false if the operation fails (lack of stack space). |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 524 | static inline bool VisitUnmarkedObjects(Object** start, Object** end) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 525 | // Return false is we are close to the stack limit. |
| 526 | StackLimitCheck check; |
| 527 | if (check.HasOverflowed()) return false; |
| 528 | |
| 529 | // Visit the unmarked objects. |
| 530 | for (Object** p = start; p < end; p++) { |
| 531 | if (!(*p)->IsHeapObject()) continue; |
| 532 | HeapObject* obj = HeapObject::cast(*p); |
| 533 | if (obj->IsMarked()) continue; |
| 534 | VisitUnmarkedObject(obj); |
| 535 | } |
| 536 | return true; |
| 537 | } |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 538 | |
| 539 | static inline void VisitExternalReference(Address* p) { } |
| 540 | static inline void VisitRuntimeEntry(RelocInfo* rinfo) { } |
| 541 | |
| 542 | private: |
| 543 | class DataObjectVisitor { |
| 544 | public: |
| 545 | template<int size> |
| 546 | static void VisitSpecialized(Map* map, HeapObject* object) { |
| 547 | } |
| 548 | |
| 549 | static void Visit(Map* map, HeapObject* object) { |
| 550 | } |
| 551 | }; |
| 552 | |
| 553 | typedef FlexibleBodyVisitor<StaticMarkingVisitor, |
| 554 | JSObject::BodyDescriptor, |
| 555 | void> JSObjectVisitor; |
| 556 | |
| 557 | typedef FlexibleBodyVisitor<StaticMarkingVisitor, |
| 558 | StructBodyDescriptor, |
| 559 | void> StructObjectVisitor; |
| 560 | |
| 561 | static void VisitCode(Map* map, HeapObject* object) { |
| 562 | reinterpret_cast<Code*>(object)->CodeIterateBody<StaticMarkingVisitor>(); |
| 563 | } |
| 564 | |
| 565 | // Code flushing support. |
| 566 | |
| 567 | // How many collections newly compiled code object will survive before being |
| 568 | // flushed. |
| 569 | static const int kCodeAgeThreshold = 5; |
| 570 | |
| 571 | inline static bool HasSourceCode(SharedFunctionInfo* info) { |
| 572 | Object* undefined = Heap::raw_unchecked_undefined_value(); |
| 573 | return (info->script() != undefined) && |
| 574 | (reinterpret_cast<Script*>(info->script())->source() != undefined); |
| 575 | } |
| 576 | |
| 577 | |
| 578 | inline static bool IsCompiled(JSFunction* function) { |
| 579 | return |
| 580 | function->unchecked_code() != Builtins::builtin(Builtins::LazyCompile); |
| 581 | } |
| 582 | |
| 583 | |
| 584 | inline static bool IsCompiled(SharedFunctionInfo* function) { |
| 585 | return |
| 586 | function->unchecked_code() != Builtins::builtin(Builtins::LazyCompile); |
| 587 | } |
| 588 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 589 | inline static bool IsFlushable(JSFunction* function) { |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 590 | SharedFunctionInfo* shared_info = function->unchecked_shared(); |
| 591 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 592 | // Code is either on stack, in compilation cache or referenced |
| 593 | // by optimized version of function. |
| 594 | if (function->unchecked_code()->IsMarked()) { |
| 595 | shared_info->set_code_age(0); |
| 596 | return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 597 | } |
| 598 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 599 | // We do not flush code for optimized functions. |
| 600 | if (function->code() != shared_info->unchecked_code()) { |
| 601 | return false; |
| 602 | } |
| 603 | |
| 604 | return IsFlushable(shared_info); |
| 605 | } |
| 606 | |
| 607 | inline static bool IsFlushable(SharedFunctionInfo* shared_info) { |
| 608 | // Code is either on stack, in compilation cache or referenced |
| 609 | // by optimized version of function. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 610 | if (shared_info->unchecked_code()->IsMarked()) { |
| 611 | shared_info->set_code_age(0); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 612 | return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 613 | } |
| 614 | |
| 615 | // The function must be compiled and have the source code available, |
| 616 | // to be able to recompile it in case we need the function again. |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 617 | if (!(shared_info->is_compiled() && HasSourceCode(shared_info))) { |
| 618 | return false; |
| 619 | } |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 620 | |
| 621 | // We never flush code for Api functions. |
| 622 | Object* function_data = shared_info->function_data(); |
| 623 | if (function_data->IsHeapObject() && |
| 624 | (SafeMap(function_data)->instance_type() == |
| 625 | FUNCTION_TEMPLATE_INFO_TYPE)) { |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 626 | return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 627 | } |
| 628 | |
| 629 | // Only flush code for functions. |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 630 | if (shared_info->code()->kind() != Code::FUNCTION) return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 631 | |
| 632 | // Function must be lazy compilable. |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 633 | if (!shared_info->allows_lazy_compilation()) return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 634 | |
| 635 | // If this is a full script wrapped in a function we do no flush the code. |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 636 | if (shared_info->is_toplevel()) return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 637 | |
| 638 | // Age this shared function info. |
| 639 | if (shared_info->code_age() < kCodeAgeThreshold) { |
| 640 | shared_info->set_code_age(shared_info->code_age() + 1); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 641 | return false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 642 | } |
| 643 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 644 | return true; |
| 645 | } |
| 646 | |
| 647 | |
| 648 | static bool FlushCodeForFunction(JSFunction* function) { |
| 649 | if (!IsFlushable(function)) return false; |
| 650 | |
| 651 | // This function's code looks flushable. But we have to postpone the |
| 652 | // decision until we see all functions that point to the same |
| 653 | // SharedFunctionInfo because some of them might be optimized. |
| 654 | // That would make the nonoptimized version of the code nonflushable, |
| 655 | // because it is required for bailing out from optimized code. |
| 656 | FlushCode::AddCandidate(function); |
| 657 | return true; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 658 | } |
| 659 | |
| 660 | |
| 661 | static inline Map* SafeMap(Object* obj) { |
| 662 | MapWord map_word = HeapObject::cast(obj)->map_word(); |
| 663 | map_word.ClearMark(); |
| 664 | map_word.ClearOverflow(); |
| 665 | return map_word.ToMap(); |
| 666 | } |
| 667 | |
| 668 | |
| 669 | static inline bool IsJSBuiltinsObject(Object* obj) { |
| 670 | return obj->IsHeapObject() && |
| 671 | (SafeMap(obj)->instance_type() == JS_BUILTINS_OBJECT_TYPE); |
| 672 | } |
| 673 | |
| 674 | |
| 675 | static inline bool IsValidNotBuiltinContext(Object* ctx) { |
| 676 | if (!ctx->IsHeapObject()) return false; |
| 677 | |
| 678 | Map* map = SafeMap(ctx); |
| 679 | if (!(map == Heap::raw_unchecked_context_map() || |
| 680 | map == Heap::raw_unchecked_catch_context_map() || |
| 681 | map == Heap::raw_unchecked_global_context_map())) { |
| 682 | return false; |
| 683 | } |
| 684 | |
| 685 | Context* context = reinterpret_cast<Context*>(ctx); |
| 686 | |
| 687 | if (IsJSBuiltinsObject(context->global())) { |
| 688 | return false; |
| 689 | } |
| 690 | |
| 691 | return true; |
| 692 | } |
| 693 | |
| 694 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 695 | static void VisitSharedFunctionInfoGeneric(Map* map, HeapObject* object) { |
Kristian Monsen | 0d5e116 | 2010-09-30 15:31:59 +0100 | [diff] [blame] | 696 | SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(object); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 697 | |
| 698 | if (shared->IsInobjectSlackTrackingInProgress()) shared->DetachInitialMap(); |
| 699 | |
Kristian Monsen | 0d5e116 | 2010-09-30 15:31:59 +0100 | [diff] [blame] | 700 | FixedBodyVisitor<StaticMarkingVisitor, |
| 701 | SharedFunctionInfo::BodyDescriptor, |
| 702 | void>::Visit(map, object); |
| 703 | } |
| 704 | |
| 705 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 706 | static void VisitSharedFunctionInfoAndFlushCode(Map* map, |
| 707 | HeapObject* object) { |
| 708 | VisitSharedFunctionInfoAndFlushCodeGeneric(map, object, false); |
| 709 | } |
| 710 | |
| 711 | |
| 712 | static void VisitSharedFunctionInfoAndFlushCodeGeneric( |
| 713 | Map* map, HeapObject* object, bool known_flush_code_candidate) { |
| 714 | SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(object); |
| 715 | |
| 716 | if (shared->IsInobjectSlackTrackingInProgress()) shared->DetachInitialMap(); |
| 717 | |
| 718 | if (!known_flush_code_candidate) { |
| 719 | known_flush_code_candidate = IsFlushable(shared); |
| 720 | if (known_flush_code_candidate) FlushCode::AddCandidate(shared); |
| 721 | } |
| 722 | |
| 723 | VisitSharedFunctionInfoFields(object, known_flush_code_candidate); |
| 724 | } |
| 725 | |
| 726 | |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 727 | static void VisitCodeEntry(Address entry_address) { |
| 728 | Object* code = Code::GetObjectFromEntryAddress(entry_address); |
| 729 | Object* old_code = code; |
| 730 | VisitPointer(&code); |
| 731 | if (code != old_code) { |
| 732 | Memory::Address_at(entry_address) = |
| 733 | reinterpret_cast<Code*>(code)->entry(); |
| 734 | } |
| 735 | } |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 736 | |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 737 | |
| 738 | static void VisitJSFunctionAndFlushCode(Map* map, HeapObject* object) { |
| 739 | JSFunction* jsfunction = reinterpret_cast<JSFunction*>(object); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 740 | // The function must have a valid context and not be a builtin. |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 741 | bool flush_code_candidate = false; |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 742 | if (IsValidNotBuiltinContext(jsfunction->unchecked_context())) { |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 743 | flush_code_candidate = FlushCodeForFunction(jsfunction); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 744 | } |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 745 | |
| 746 | if (!flush_code_candidate) { |
| 747 | MarkCompactCollector::MarkObject( |
| 748 | jsfunction->unchecked_shared()->unchecked_code()); |
| 749 | |
| 750 | if (jsfunction->unchecked_code()->kind() == Code::OPTIMIZED_FUNCTION) { |
| 751 | // For optimized functions we should retain both non-optimized version |
| 752 | // of it's code and non-optimized version of all inlined functions. |
| 753 | // This is required to support bailing out from inlined code. |
| 754 | DeoptimizationInputData* data = |
| 755 | reinterpret_cast<DeoptimizationInputData*>( |
| 756 | jsfunction->unchecked_code()->unchecked_deoptimization_data()); |
| 757 | |
| 758 | FixedArray* literals = data->UncheckedLiteralArray(); |
| 759 | |
| 760 | for (int i = 0, count = data->InlinedFunctionCount()->value(); |
| 761 | i < count; |
| 762 | i++) { |
| 763 | JSFunction* inlined = reinterpret_cast<JSFunction*>(literals->get(i)); |
| 764 | MarkCompactCollector::MarkObject( |
| 765 | inlined->unchecked_shared()->unchecked_code()); |
| 766 | } |
| 767 | } |
| 768 | } |
| 769 | |
| 770 | VisitJSFunctionFields(map, |
| 771 | reinterpret_cast<JSFunction*>(object), |
| 772 | flush_code_candidate); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 773 | } |
| 774 | |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 775 | |
| 776 | static void VisitJSFunction(Map* map, HeapObject* object) { |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 777 | VisitJSFunctionFields(map, |
| 778 | reinterpret_cast<JSFunction*>(object), |
| 779 | false); |
| 780 | } |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 781 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 782 | |
| 783 | #define SLOT_ADDR(obj, offset) \ |
| 784 | reinterpret_cast<Object**>((obj)->address() + offset) |
| 785 | |
| 786 | |
| 787 | static inline void VisitJSFunctionFields(Map* map, |
| 788 | JSFunction* object, |
| 789 | bool flush_code_candidate) { |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 790 | VisitPointers(SLOT_ADDR(object, JSFunction::kPropertiesOffset), |
| 791 | SLOT_ADDR(object, JSFunction::kCodeEntryOffset)); |
| 792 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 793 | if (!flush_code_candidate) { |
| 794 | VisitCodeEntry(object->address() + JSFunction::kCodeEntryOffset); |
| 795 | } else { |
| 796 | // Don't visit code object. |
| 797 | |
| 798 | // Visit shared function info to avoid double checking of it's |
| 799 | // flushability. |
| 800 | SharedFunctionInfo* shared_info = object->unchecked_shared(); |
| 801 | if (!shared_info->IsMarked()) { |
| 802 | Map* shared_info_map = shared_info->map(); |
| 803 | MarkCompactCollector::SetMark(shared_info); |
| 804 | MarkCompactCollector::MarkObject(shared_info_map); |
| 805 | VisitSharedFunctionInfoAndFlushCodeGeneric(shared_info_map, |
| 806 | shared_info, |
| 807 | true); |
| 808 | } |
| 809 | } |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 810 | |
| 811 | VisitPointers(SLOT_ADDR(object, |
| 812 | JSFunction::kCodeEntryOffset + kPointerSize), |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 813 | SLOT_ADDR(object, JSFunction::kNonWeakFieldsEndOffset)); |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 814 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 815 | // Don't visit the next function list field as it is a weak reference. |
Steve Block | 791712a | 2010-08-27 10:21:07 +0100 | [diff] [blame] | 816 | } |
| 817 | |
| 818 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 819 | static void VisitSharedFunctionInfoFields(HeapObject* object, |
| 820 | bool flush_code_candidate) { |
| 821 | VisitPointer(SLOT_ADDR(object, SharedFunctionInfo::kNameOffset)); |
| 822 | |
| 823 | if (!flush_code_candidate) { |
| 824 | VisitPointer(SLOT_ADDR(object, SharedFunctionInfo::kCodeOffset)); |
| 825 | } |
| 826 | |
| 827 | VisitPointers(SLOT_ADDR(object, SharedFunctionInfo::kScopeInfoOffset), |
| 828 | SLOT_ADDR(object, SharedFunctionInfo::kSize)); |
| 829 | } |
| 830 | |
| 831 | #undef SLOT_ADDR |
| 832 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 833 | typedef void (*Callback)(Map* map, HeapObject* object); |
| 834 | |
| 835 | static VisitorDispatchTable<Callback> table_; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 836 | }; |
| 837 | |
| 838 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 839 | VisitorDispatchTable<StaticMarkingVisitor::Callback> |
| 840 | StaticMarkingVisitor::table_; |
| 841 | |
| 842 | |
| 843 | class MarkingVisitor : public ObjectVisitor { |
| 844 | public: |
| 845 | void VisitPointer(Object** p) { |
| 846 | StaticMarkingVisitor::VisitPointer(p); |
| 847 | } |
| 848 | |
| 849 | void VisitPointers(Object** start, Object** end) { |
| 850 | StaticMarkingVisitor::VisitPointers(start, end); |
| 851 | } |
| 852 | |
| 853 | void VisitCodeTarget(RelocInfo* rinfo) { |
| 854 | StaticMarkingVisitor::VisitCodeTarget(rinfo); |
| 855 | } |
| 856 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 857 | void VisitGlobalPropertyCell(RelocInfo* rinfo) { |
| 858 | StaticMarkingVisitor::VisitGlobalPropertyCell(rinfo); |
| 859 | } |
| 860 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 861 | void VisitDebugTarget(RelocInfo* rinfo) { |
| 862 | StaticMarkingVisitor::VisitDebugTarget(rinfo); |
| 863 | } |
| 864 | }; |
| 865 | |
| 866 | |
| 867 | class CodeMarkingVisitor : public ThreadVisitor { |
| 868 | public: |
| 869 | void VisitThread(ThreadLocalTop* top) { |
| 870 | for (StackFrameIterator it(top); !it.done(); it.Advance()) { |
| 871 | MarkCompactCollector::MarkObject(it.frame()->unchecked_code()); |
| 872 | } |
| 873 | } |
| 874 | }; |
| 875 | |
| 876 | |
| 877 | class SharedFunctionInfoMarkingVisitor : public ObjectVisitor { |
| 878 | public: |
| 879 | void VisitPointers(Object** start, Object** end) { |
| 880 | for (Object** p = start; p < end; p++) VisitPointer(p); |
| 881 | } |
| 882 | |
| 883 | void VisitPointer(Object** slot) { |
| 884 | Object* obj = *slot; |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 885 | if (obj->IsSharedFunctionInfo()) { |
| 886 | SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(obj); |
| 887 | MarkCompactCollector::MarkObject(shared->unchecked_code()); |
| 888 | MarkCompactCollector::MarkObject(shared); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 889 | } |
| 890 | } |
| 891 | }; |
| 892 | |
| 893 | |
| 894 | void MarkCompactCollector::PrepareForCodeFlushing() { |
| 895 | if (!FLAG_flush_code) { |
| 896 | StaticMarkingVisitor::EnableCodeFlushing(false); |
| 897 | return; |
| 898 | } |
| 899 | |
| 900 | #ifdef ENABLE_DEBUGGER_SUPPORT |
| 901 | if (Debug::IsLoaded() || Debug::has_break_points()) { |
| 902 | StaticMarkingVisitor::EnableCodeFlushing(false); |
| 903 | return; |
| 904 | } |
| 905 | #endif |
| 906 | StaticMarkingVisitor::EnableCodeFlushing(true); |
| 907 | |
Iain Merrick | 9ac36c9 | 2010-09-13 15:29:50 +0100 | [diff] [blame] | 908 | // Ensure that empty descriptor array is marked. Method MarkDescriptorArray |
| 909 | // relies on it being marked before any other descriptor array. |
| 910 | MarkObject(Heap::raw_unchecked_empty_descriptor_array()); |
| 911 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 912 | // Make sure we are not referencing the code from the stack. |
| 913 | for (StackFrameIterator it; !it.done(); it.Advance()) { |
Iain Merrick | 9ac36c9 | 2010-09-13 15:29:50 +0100 | [diff] [blame] | 914 | MarkObject(it.frame()->unchecked_code()); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 915 | } |
| 916 | |
| 917 | // Iterate the archived stacks in all threads to check if |
| 918 | // the code is referenced. |
| 919 | CodeMarkingVisitor code_marking_visitor; |
| 920 | ThreadManager::IterateArchivedThreads(&code_marking_visitor); |
| 921 | |
| 922 | SharedFunctionInfoMarkingVisitor visitor; |
| 923 | CompilationCache::IterateFunctions(&visitor); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 924 | HandleScopeImplementer::Iterate(&visitor); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 925 | |
Iain Merrick | 9ac36c9 | 2010-09-13 15:29:50 +0100 | [diff] [blame] | 926 | ProcessMarkingStack(); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 927 | } |
| 928 | |
| 929 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 930 | // Visitor class for marking heap roots. |
| 931 | class RootMarkingVisitor : public ObjectVisitor { |
| 932 | public: |
| 933 | void VisitPointer(Object** p) { |
| 934 | MarkObjectByPointer(p); |
| 935 | } |
| 936 | |
| 937 | void VisitPointers(Object** start, Object** end) { |
| 938 | for (Object** p = start; p < end; p++) MarkObjectByPointer(p); |
| 939 | } |
| 940 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 941 | private: |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 942 | void MarkObjectByPointer(Object** p) { |
| 943 | if (!(*p)->IsHeapObject()) return; |
| 944 | |
| 945 | // Replace flat cons strings in place. |
| 946 | HeapObject* object = ShortCircuitConsString(p); |
| 947 | if (object->IsMarked()) return; |
| 948 | |
| 949 | Map* map = object->map(); |
| 950 | // Mark the object. |
| 951 | MarkCompactCollector::SetMark(object); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 952 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 953 | // Mark the map pointer and body, and push them on the marking stack. |
| 954 | MarkCompactCollector::MarkObject(map); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 955 | StaticMarkingVisitor::IterateBody(map, object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 956 | |
| 957 | // Mark all the objects reachable from the map and body. May leave |
| 958 | // overflowed objects in the heap. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 959 | MarkCompactCollector::EmptyMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 960 | } |
| 961 | }; |
| 962 | |
| 963 | |
| 964 | // Helper class for pruning the symbol table. |
| 965 | class SymbolTableCleaner : public ObjectVisitor { |
| 966 | public: |
| 967 | SymbolTableCleaner() : pointers_removed_(0) { } |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 968 | |
| 969 | virtual void VisitPointers(Object** start, Object** end) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 970 | // Visit all HeapObject pointers in [start, end). |
| 971 | for (Object** p = start; p < end; p++) { |
| 972 | if ((*p)->IsHeapObject() && !HeapObject::cast(*p)->IsMarked()) { |
| 973 | // Check if the symbol being pruned is an external symbol. We need to |
| 974 | // delete the associated external data as this symbol is going away. |
| 975 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 976 | // Since no objects have yet been moved we can safely access the map of |
| 977 | // the object. |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 978 | if ((*p)->IsExternalString()) { |
| 979 | Heap::FinalizeExternalString(String::cast(*p)); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 980 | } |
| 981 | // Set the entry to null_value (as deleted). |
| 982 | *p = Heap::raw_unchecked_null_value(); |
| 983 | pointers_removed_++; |
| 984 | } |
| 985 | } |
| 986 | } |
| 987 | |
| 988 | int PointersRemoved() { |
| 989 | return pointers_removed_; |
| 990 | } |
| 991 | private: |
| 992 | int pointers_removed_; |
| 993 | }; |
| 994 | |
| 995 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 996 | // Implementation of WeakObjectRetainer for mark compact GCs. All marked objects |
| 997 | // are retained. |
| 998 | class MarkCompactWeakObjectRetainer : public WeakObjectRetainer { |
| 999 | public: |
| 1000 | virtual Object* RetainAs(Object* object) { |
| 1001 | MapWord first_word = HeapObject::cast(object)->map_word(); |
| 1002 | if (first_word.IsMarked()) { |
| 1003 | return object; |
| 1004 | } else { |
| 1005 | return NULL; |
| 1006 | } |
| 1007 | } |
| 1008 | }; |
| 1009 | |
| 1010 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1011 | void MarkCompactCollector::MarkUnmarkedObject(HeapObject* object) { |
| 1012 | ASSERT(!object->IsMarked()); |
| 1013 | ASSERT(Heap::Contains(object)); |
| 1014 | if (object->IsMap()) { |
| 1015 | Map* map = Map::cast(object); |
| 1016 | if (FLAG_cleanup_caches_in_maps_at_gc) { |
| 1017 | map->ClearCodeCache(); |
| 1018 | } |
| 1019 | SetMark(map); |
| 1020 | if (FLAG_collect_maps && |
| 1021 | map->instance_type() >= FIRST_JS_OBJECT_TYPE && |
| 1022 | map->instance_type() <= JS_FUNCTION_TYPE) { |
| 1023 | MarkMapContents(map); |
| 1024 | } else { |
| 1025 | marking_stack.Push(map); |
| 1026 | } |
| 1027 | } else { |
| 1028 | SetMark(object); |
| 1029 | marking_stack.Push(object); |
| 1030 | } |
| 1031 | } |
| 1032 | |
| 1033 | |
| 1034 | void MarkCompactCollector::MarkMapContents(Map* map) { |
| 1035 | MarkDescriptorArray(reinterpret_cast<DescriptorArray*>( |
| 1036 | *HeapObject::RawField(map, Map::kInstanceDescriptorsOffset))); |
| 1037 | |
| 1038 | // Mark the Object* fields of the Map. |
| 1039 | // Since the descriptor array has been marked already, it is fine |
| 1040 | // that one of these fields contains a pointer to it. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1041 | Object** start_slot = HeapObject::RawField(map, |
| 1042 | Map::kPointerFieldsBeginOffset); |
| 1043 | |
| 1044 | Object** end_slot = HeapObject::RawField(map, Map::kPointerFieldsEndOffset); |
| 1045 | |
| 1046 | StaticMarkingVisitor::VisitPointers(start_slot, end_slot); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1047 | } |
| 1048 | |
| 1049 | |
| 1050 | void MarkCompactCollector::MarkDescriptorArray( |
| 1051 | DescriptorArray* descriptors) { |
| 1052 | if (descriptors->IsMarked()) return; |
| 1053 | // Empty descriptor array is marked as a root before any maps are marked. |
| 1054 | ASSERT(descriptors != Heap::raw_unchecked_empty_descriptor_array()); |
| 1055 | SetMark(descriptors); |
| 1056 | |
| 1057 | FixedArray* contents = reinterpret_cast<FixedArray*>( |
| 1058 | descriptors->get(DescriptorArray::kContentArrayIndex)); |
| 1059 | ASSERT(contents->IsHeapObject()); |
| 1060 | ASSERT(!contents->IsMarked()); |
| 1061 | ASSERT(contents->IsFixedArray()); |
| 1062 | ASSERT(contents->length() >= 2); |
| 1063 | SetMark(contents); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1064 | // Contents contains (value, details) pairs. If the details say that |
| 1065 | // the type of descriptor is MAP_TRANSITION, CONSTANT_TRANSITION, or |
| 1066 | // NULL_DESCRIPTOR, we don't mark the value as live. Only for |
| 1067 | // MAP_TRANSITION and CONSTANT_TRANSITION is the value an Object* (a |
| 1068 | // Map*). |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1069 | for (int i = 0; i < contents->length(); i += 2) { |
| 1070 | // If the pair (value, details) at index i, i+1 is not |
| 1071 | // a transition or null descriptor, mark the value. |
| 1072 | PropertyDetails details(Smi::cast(contents->get(i + 1))); |
| 1073 | if (details.type() < FIRST_PHANTOM_PROPERTY_TYPE) { |
| 1074 | HeapObject* object = reinterpret_cast<HeapObject*>(contents->get(i)); |
| 1075 | if (object->IsHeapObject() && !object->IsMarked()) { |
| 1076 | SetMark(object); |
| 1077 | marking_stack.Push(object); |
| 1078 | } |
| 1079 | } |
| 1080 | } |
| 1081 | // The DescriptorArray descriptors contains a pointer to its contents array, |
| 1082 | // but the contents array is already marked. |
| 1083 | marking_stack.Push(descriptors); |
| 1084 | } |
| 1085 | |
| 1086 | |
| 1087 | void MarkCompactCollector::CreateBackPointers() { |
| 1088 | HeapObjectIterator iterator(Heap::map_space()); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 1089 | for (HeapObject* next_object = iterator.next(); |
| 1090 | next_object != NULL; next_object = iterator.next()) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1091 | if (next_object->IsMap()) { // Could also be ByteArray on free list. |
| 1092 | Map* map = Map::cast(next_object); |
| 1093 | if (map->instance_type() >= FIRST_JS_OBJECT_TYPE && |
| 1094 | map->instance_type() <= JS_FUNCTION_TYPE) { |
| 1095 | map->CreateBackPointers(); |
| 1096 | } else { |
| 1097 | ASSERT(map->instance_descriptors() == Heap::empty_descriptor_array()); |
| 1098 | } |
| 1099 | } |
| 1100 | } |
| 1101 | } |
| 1102 | |
| 1103 | |
| 1104 | static int OverflowObjectSize(HeapObject* obj) { |
| 1105 | // Recover the normal map pointer, it might be marked as live and |
| 1106 | // overflowed. |
| 1107 | MapWord map_word = obj->map_word(); |
| 1108 | map_word.ClearMark(); |
| 1109 | map_word.ClearOverflow(); |
| 1110 | return obj->SizeFromMap(map_word.ToMap()); |
| 1111 | } |
| 1112 | |
| 1113 | |
| 1114 | // Fill the marking stack with overflowed objects returned by the given |
| 1115 | // iterator. Stop when the marking stack is filled or the end of the space |
| 1116 | // is reached, whichever comes first. |
| 1117 | template<class T> |
| 1118 | static void ScanOverflowedObjects(T* it) { |
| 1119 | // The caller should ensure that the marking stack is initially not full, |
| 1120 | // so that we don't waste effort pointlessly scanning for objects. |
| 1121 | ASSERT(!marking_stack.is_full()); |
| 1122 | |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 1123 | for (HeapObject* object = it->next(); object != NULL; object = it->next()) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1124 | if (object->IsOverflowed()) { |
| 1125 | object->ClearOverflow(); |
| 1126 | ASSERT(object->IsMarked()); |
| 1127 | ASSERT(Heap::Contains(object)); |
| 1128 | marking_stack.Push(object); |
| 1129 | if (marking_stack.is_full()) return; |
| 1130 | } |
| 1131 | } |
| 1132 | } |
| 1133 | |
| 1134 | |
| 1135 | bool MarkCompactCollector::IsUnmarkedHeapObject(Object** p) { |
| 1136 | return (*p)->IsHeapObject() && !HeapObject::cast(*p)->IsMarked(); |
| 1137 | } |
| 1138 | |
| 1139 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1140 | void MarkCompactCollector::MarkSymbolTable() { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1141 | SymbolTable* symbol_table = Heap::raw_unchecked_symbol_table(); |
| 1142 | // Mark the symbol table itself. |
| 1143 | SetMark(symbol_table); |
| 1144 | // Explicitly mark the prefix. |
| 1145 | MarkingVisitor marker; |
| 1146 | symbol_table->IteratePrefix(&marker); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1147 | ProcessMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1148 | } |
| 1149 | |
| 1150 | |
| 1151 | void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) { |
| 1152 | // Mark the heap roots including global variables, stack variables, |
| 1153 | // etc., and all objects reachable from them. |
Steve Block | d0582a6 | 2009-12-15 09:54:21 +0000 | [diff] [blame] | 1154 | Heap::IterateStrongRoots(visitor, VISIT_ONLY_STRONG); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1155 | |
| 1156 | // Handle the symbol table specially. |
| 1157 | MarkSymbolTable(); |
| 1158 | |
| 1159 | // There may be overflowed objects in the heap. Visit them now. |
| 1160 | while (marking_stack.overflowed()) { |
| 1161 | RefillMarkingStack(); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1162 | EmptyMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1163 | } |
| 1164 | } |
| 1165 | |
| 1166 | |
| 1167 | void MarkCompactCollector::MarkObjectGroups() { |
| 1168 | List<ObjectGroup*>* object_groups = GlobalHandles::ObjectGroups(); |
| 1169 | |
| 1170 | for (int i = 0; i < object_groups->length(); i++) { |
| 1171 | ObjectGroup* entry = object_groups->at(i); |
| 1172 | if (entry == NULL) continue; |
| 1173 | |
| 1174 | List<Object**>& objects = entry->objects_; |
| 1175 | bool group_marked = false; |
| 1176 | for (int j = 0; j < objects.length(); j++) { |
| 1177 | Object* object = *objects[j]; |
| 1178 | if (object->IsHeapObject() && HeapObject::cast(object)->IsMarked()) { |
| 1179 | group_marked = true; |
| 1180 | break; |
| 1181 | } |
| 1182 | } |
| 1183 | |
| 1184 | if (!group_marked) continue; |
| 1185 | |
| 1186 | // An object in the group is marked, so mark as gray all white heap |
| 1187 | // objects in the group. |
| 1188 | for (int j = 0; j < objects.length(); ++j) { |
| 1189 | if ((*objects[j])->IsHeapObject()) { |
| 1190 | MarkObject(HeapObject::cast(*objects[j])); |
| 1191 | } |
| 1192 | } |
| 1193 | // Once the entire group has been colored gray, set the object group |
| 1194 | // to NULL so it won't be processed again. |
| 1195 | delete object_groups->at(i); |
| 1196 | object_groups->at(i) = NULL; |
| 1197 | } |
| 1198 | } |
| 1199 | |
| 1200 | |
| 1201 | // Mark all objects reachable from the objects on the marking stack. |
| 1202 | // Before: the marking stack contains zero or more heap object pointers. |
| 1203 | // After: the marking stack is empty, and all objects reachable from the |
| 1204 | // marking stack have been marked, or are overflowed in the heap. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1205 | void MarkCompactCollector::EmptyMarkingStack() { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1206 | while (!marking_stack.is_empty()) { |
| 1207 | HeapObject* object = marking_stack.Pop(); |
| 1208 | ASSERT(object->IsHeapObject()); |
| 1209 | ASSERT(Heap::Contains(object)); |
| 1210 | ASSERT(object->IsMarked()); |
| 1211 | ASSERT(!object->IsOverflowed()); |
| 1212 | |
| 1213 | // Because the object is marked, we have to recover the original map |
| 1214 | // pointer and use it to mark the object's body. |
| 1215 | MapWord map_word = object->map_word(); |
| 1216 | map_word.ClearMark(); |
| 1217 | Map* map = map_word.ToMap(); |
| 1218 | MarkObject(map); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1219 | |
| 1220 | StaticMarkingVisitor::IterateBody(map, object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1221 | } |
| 1222 | } |
| 1223 | |
| 1224 | |
| 1225 | // Sweep the heap for overflowed objects, clear their overflow bits, and |
| 1226 | // push them on the marking stack. Stop early if the marking stack fills |
| 1227 | // before sweeping completes. If sweeping completes, there are no remaining |
| 1228 | // overflowed objects in the heap so the overflow flag on the markings stack |
| 1229 | // is cleared. |
| 1230 | void MarkCompactCollector::RefillMarkingStack() { |
| 1231 | ASSERT(marking_stack.overflowed()); |
| 1232 | |
| 1233 | SemiSpaceIterator new_it(Heap::new_space(), &OverflowObjectSize); |
| 1234 | ScanOverflowedObjects(&new_it); |
| 1235 | if (marking_stack.is_full()) return; |
| 1236 | |
| 1237 | HeapObjectIterator old_pointer_it(Heap::old_pointer_space(), |
| 1238 | &OverflowObjectSize); |
| 1239 | ScanOverflowedObjects(&old_pointer_it); |
| 1240 | if (marking_stack.is_full()) return; |
| 1241 | |
| 1242 | HeapObjectIterator old_data_it(Heap::old_data_space(), &OverflowObjectSize); |
| 1243 | ScanOverflowedObjects(&old_data_it); |
| 1244 | if (marking_stack.is_full()) return; |
| 1245 | |
| 1246 | HeapObjectIterator code_it(Heap::code_space(), &OverflowObjectSize); |
| 1247 | ScanOverflowedObjects(&code_it); |
| 1248 | if (marking_stack.is_full()) return; |
| 1249 | |
| 1250 | HeapObjectIterator map_it(Heap::map_space(), &OverflowObjectSize); |
| 1251 | ScanOverflowedObjects(&map_it); |
| 1252 | if (marking_stack.is_full()) return; |
| 1253 | |
| 1254 | HeapObjectIterator cell_it(Heap::cell_space(), &OverflowObjectSize); |
| 1255 | ScanOverflowedObjects(&cell_it); |
| 1256 | if (marking_stack.is_full()) return; |
| 1257 | |
| 1258 | LargeObjectIterator lo_it(Heap::lo_space(), &OverflowObjectSize); |
| 1259 | ScanOverflowedObjects(&lo_it); |
| 1260 | if (marking_stack.is_full()) return; |
| 1261 | |
| 1262 | marking_stack.clear_overflowed(); |
| 1263 | } |
| 1264 | |
| 1265 | |
| 1266 | // Mark all objects reachable (transitively) from objects on the marking |
| 1267 | // stack. Before: the marking stack contains zero or more heap object |
| 1268 | // pointers. After: the marking stack is empty and there are no overflowed |
| 1269 | // objects in the heap. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1270 | void MarkCompactCollector::ProcessMarkingStack() { |
| 1271 | EmptyMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1272 | while (marking_stack.overflowed()) { |
| 1273 | RefillMarkingStack(); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1274 | EmptyMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1275 | } |
| 1276 | } |
| 1277 | |
| 1278 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1279 | void MarkCompactCollector::ProcessObjectGroups() { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1280 | bool work_to_do = true; |
| 1281 | ASSERT(marking_stack.is_empty()); |
| 1282 | while (work_to_do) { |
| 1283 | MarkObjectGroups(); |
| 1284 | work_to_do = !marking_stack.is_empty(); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1285 | ProcessMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1286 | } |
| 1287 | } |
| 1288 | |
| 1289 | |
| 1290 | void MarkCompactCollector::MarkLiveObjects() { |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 1291 | GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_MARK); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 1292 | // The recursive GC marker detects when it is nearing stack overflow, |
| 1293 | // and switches to a different marking system. JS interrupts interfere |
| 1294 | // with the C stack limit check. |
| 1295 | PostponeInterruptsScope postpone; |
| 1296 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1297 | #ifdef DEBUG |
| 1298 | ASSERT(state_ == PREPARE_GC); |
| 1299 | state_ = MARK_LIVE_OBJECTS; |
| 1300 | #endif |
| 1301 | // The to space contains live objects, the from space is used as a marking |
| 1302 | // stack. |
| 1303 | marking_stack.Initialize(Heap::new_space()->FromSpaceLow(), |
| 1304 | Heap::new_space()->FromSpaceHigh()); |
| 1305 | |
| 1306 | ASSERT(!marking_stack.overflowed()); |
| 1307 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1308 | PrepareForCodeFlushing(); |
| 1309 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1310 | RootMarkingVisitor root_visitor; |
| 1311 | MarkRoots(&root_visitor); |
| 1312 | |
| 1313 | // The objects reachable from the roots are marked, yet unreachable |
| 1314 | // objects are unmarked. Mark objects reachable from object groups |
| 1315 | // containing at least one marked object, and continue until no new |
| 1316 | // objects are reachable from the object groups. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1317 | ProcessObjectGroups(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1318 | |
| 1319 | // The objects reachable from the roots or object groups are marked, |
| 1320 | // yet unreachable objects are unmarked. Mark objects reachable |
| 1321 | // only from weak global handles. |
| 1322 | // |
| 1323 | // First we identify nonlive weak handles and mark them as pending |
| 1324 | // destruction. |
| 1325 | GlobalHandles::IdentifyWeakHandles(&IsUnmarkedHeapObject); |
| 1326 | // Then we mark the objects and process the transitive closure. |
| 1327 | GlobalHandles::IterateWeakRoots(&root_visitor); |
| 1328 | while (marking_stack.overflowed()) { |
| 1329 | RefillMarkingStack(); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1330 | EmptyMarkingStack(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1331 | } |
| 1332 | |
| 1333 | // Repeat the object groups to mark unmarked groups reachable from the |
| 1334 | // weak roots. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1335 | ProcessObjectGroups(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1336 | |
| 1337 | // Prune the symbol table removing all symbols only pointed to by the |
| 1338 | // symbol table. Cannot use symbol_table() here because the symbol |
| 1339 | // table is marked. |
| 1340 | SymbolTable* symbol_table = Heap::raw_unchecked_symbol_table(); |
| 1341 | SymbolTableCleaner v; |
| 1342 | symbol_table->IterateElements(&v); |
| 1343 | symbol_table->ElementsRemoved(v.PointersRemoved()); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 1344 | ExternalStringTable::Iterate(&v); |
| 1345 | ExternalStringTable::CleanUp(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1346 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 1347 | // Process the weak references. |
| 1348 | MarkCompactWeakObjectRetainer mark_compact_object_retainer; |
| 1349 | Heap::ProcessWeakReferences(&mark_compact_object_retainer); |
| 1350 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1351 | // Remove object groups after marking phase. |
| 1352 | GlobalHandles::RemoveObjectGroups(); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 1353 | |
| 1354 | // Flush code from collected candidates. |
| 1355 | FlushCode::ProcessCandidates(); |
Ben Murdoch | e0cee9b | 2011-05-25 10:26:03 +0100 | [diff] [blame^] | 1356 | |
| 1357 | // Clean up dead objects from the runtime profiler. |
| 1358 | RuntimeProfiler::RemoveDeadSamples(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1359 | } |
| 1360 | |
| 1361 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1362 | #ifdef DEBUG |
| 1363 | void MarkCompactCollector::UpdateLiveObjectCount(HeapObject* obj) { |
| 1364 | live_bytes_ += obj->Size(); |
| 1365 | if (Heap::new_space()->Contains(obj)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1366 | live_young_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1367 | } else if (Heap::map_space()->Contains(obj)) { |
| 1368 | ASSERT(obj->IsMap()); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1369 | live_map_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1370 | } else if (Heap::cell_space()->Contains(obj)) { |
| 1371 | ASSERT(obj->IsJSGlobalPropertyCell()); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1372 | live_cell_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1373 | } else if (Heap::old_pointer_space()->Contains(obj)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1374 | live_old_pointer_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1375 | } else if (Heap::old_data_space()->Contains(obj)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1376 | live_old_data_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1377 | } else if (Heap::code_space()->Contains(obj)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1378 | live_code_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1379 | } else if (Heap::lo_space()->Contains(obj)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1380 | live_lo_objects_size_ += obj->Size(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1381 | } else { |
| 1382 | UNREACHABLE(); |
| 1383 | } |
| 1384 | } |
| 1385 | #endif // DEBUG |
| 1386 | |
| 1387 | |
| 1388 | void MarkCompactCollector::SweepLargeObjectSpace() { |
| 1389 | #ifdef DEBUG |
| 1390 | ASSERT(state_ == MARK_LIVE_OBJECTS); |
| 1391 | state_ = |
| 1392 | compacting_collection_ ? ENCODE_FORWARDING_ADDRESSES : SWEEP_SPACES; |
| 1393 | #endif |
| 1394 | // Deallocate unmarked objects and clear marked bits for marked objects. |
| 1395 | Heap::lo_space()->FreeUnmarkedObjects(); |
| 1396 | } |
| 1397 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1398 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1399 | // Safe to use during marking phase only. |
| 1400 | bool MarkCompactCollector::SafeIsMap(HeapObject* object) { |
| 1401 | MapWord metamap = object->map_word(); |
| 1402 | metamap.ClearMark(); |
| 1403 | return metamap.ToMap()->instance_type() == MAP_TYPE; |
| 1404 | } |
| 1405 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1406 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1407 | void MarkCompactCollector::ClearNonLiveTransitions() { |
Shimeng (Simon) Wang | 8a31eba | 2010-12-06 19:01:33 -0800 | [diff] [blame] | 1408 | HeapObjectIterator map_iterator(Heap::map_space(), &SizeOfMarkedObject); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1409 | // Iterate over the map space, setting map transitions that go from |
| 1410 | // a marked map to an unmarked map to null transitions. At the same time, |
| 1411 | // set all the prototype fields of maps back to their original value, |
| 1412 | // dropping the back pointers temporarily stored in the prototype field. |
| 1413 | // Setting the prototype field requires following the linked list of |
| 1414 | // back pointers, reversing them all at once. This allows us to find |
| 1415 | // those maps with map transitions that need to be nulled, and only |
| 1416 | // scan the descriptor arrays of those maps, not all maps. |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 1417 | // All of these actions are carried out only on maps of JSObjects |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1418 | // and related subtypes. |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 1419 | for (HeapObject* obj = map_iterator.next(); |
| 1420 | obj != NULL; obj = map_iterator.next()) { |
| 1421 | Map* map = reinterpret_cast<Map*>(obj); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1422 | if (!map->IsMarked() && map->IsByteArray()) continue; |
| 1423 | |
| 1424 | ASSERT(SafeIsMap(map)); |
| 1425 | // Only JSObject and subtypes have map transitions and back pointers. |
| 1426 | if (map->instance_type() < FIRST_JS_OBJECT_TYPE) continue; |
| 1427 | if (map->instance_type() > JS_FUNCTION_TYPE) continue; |
Kristian Monsen | 0d5e116 | 2010-09-30 15:31:59 +0100 | [diff] [blame] | 1428 | |
| 1429 | if (map->IsMarked() && map->attached_to_shared_function_info()) { |
| 1430 | // This map is used for inobject slack tracking and has been detached |
| 1431 | // from SharedFunctionInfo during the mark phase. |
| 1432 | // Since it survived the GC, reattach it now. |
| 1433 | map->unchecked_constructor()->unchecked_shared()->AttachInitialMap(map); |
| 1434 | } |
| 1435 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1436 | // Follow the chain of back pointers to find the prototype. |
| 1437 | Map* current = map; |
| 1438 | while (SafeIsMap(current)) { |
| 1439 | current = reinterpret_cast<Map*>(current->prototype()); |
| 1440 | ASSERT(current->IsHeapObject()); |
| 1441 | } |
| 1442 | Object* real_prototype = current; |
| 1443 | |
| 1444 | // Follow back pointers, setting them to prototype, |
| 1445 | // clearing map transitions when necessary. |
| 1446 | current = map; |
| 1447 | bool on_dead_path = !current->IsMarked(); |
| 1448 | Object* next; |
| 1449 | while (SafeIsMap(current)) { |
| 1450 | next = current->prototype(); |
| 1451 | // There should never be a dead map above a live map. |
| 1452 | ASSERT(on_dead_path || current->IsMarked()); |
| 1453 | |
| 1454 | // A live map above a dead map indicates a dead transition. |
| 1455 | // This test will always be false on the first iteration. |
| 1456 | if (on_dead_path && current->IsMarked()) { |
| 1457 | on_dead_path = false; |
| 1458 | current->ClearNonLiveTransitions(real_prototype); |
| 1459 | } |
| 1460 | *HeapObject::RawField(current, Map::kPrototypeOffset) = |
| 1461 | real_prototype; |
| 1462 | current = reinterpret_cast<Map*>(next); |
| 1463 | } |
| 1464 | } |
| 1465 | } |
| 1466 | |
| 1467 | // ------------------------------------------------------------------------- |
| 1468 | // Phase 2: Encode forwarding addresses. |
| 1469 | // When compacting, forwarding addresses for objects in old space and map |
| 1470 | // space are encoded in their map pointer word (along with an encoding of |
| 1471 | // their map pointers). |
| 1472 | // |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 1473 | // The excact encoding is described in the comments for class MapWord in |
| 1474 | // objects.h. |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1475 | // |
| 1476 | // An address range [start, end) can have both live and non-live objects. |
| 1477 | // Maximal non-live regions are marked so they can be skipped on subsequent |
| 1478 | // sweeps of the heap. A distinguished map-pointer encoding is used to mark |
| 1479 | // free regions of one-word size (in which case the next word is the start |
| 1480 | // of a live object). A second distinguished map-pointer encoding is used |
| 1481 | // to mark free regions larger than one word, and the size of the free |
| 1482 | // region (including the first word) is written to the second word of the |
| 1483 | // region. |
| 1484 | // |
| 1485 | // Any valid map page offset must lie in the object area of the page, so map |
| 1486 | // page offsets less than Page::kObjectStartOffset are invalid. We use a |
| 1487 | // pair of distinguished invalid map encodings (for single word and multiple |
| 1488 | // words) to indicate free regions in the page found during computation of |
| 1489 | // forwarding addresses and skipped over in subsequent sweeps. |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1490 | |
| 1491 | |
| 1492 | // Encode a free region, defined by the given start address and size, in the |
| 1493 | // first word or two of the region. |
| 1494 | void EncodeFreeRegion(Address free_start, int free_size) { |
| 1495 | ASSERT(free_size >= kIntSize); |
| 1496 | if (free_size == kIntSize) { |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 1497 | Memory::uint32_at(free_start) = MarkCompactCollector::kSingleFreeEncoding; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1498 | } else { |
| 1499 | ASSERT(free_size >= 2 * kIntSize); |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 1500 | Memory::uint32_at(free_start) = MarkCompactCollector::kMultiFreeEncoding; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1501 | Memory::int_at(free_start + kIntSize) = free_size; |
| 1502 | } |
| 1503 | |
| 1504 | #ifdef DEBUG |
| 1505 | // Zap the body of the free region. |
| 1506 | if (FLAG_enable_slow_asserts) { |
| 1507 | for (int offset = 2 * kIntSize; |
| 1508 | offset < free_size; |
| 1509 | offset += kPointerSize) { |
| 1510 | Memory::Address_at(free_start + offset) = kZapValue; |
| 1511 | } |
| 1512 | } |
| 1513 | #endif |
| 1514 | } |
| 1515 | |
| 1516 | |
| 1517 | // Try to promote all objects in new space. Heap numbers and sequential |
| 1518 | // strings are promoted to the code space, large objects to large object space, |
| 1519 | // and all others to the old space. |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1520 | inline MaybeObject* MCAllocateFromNewSpace(HeapObject* object, |
| 1521 | int object_size) { |
| 1522 | MaybeObject* forwarded; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1523 | if (object_size > Heap::MaxObjectSizeInPagedSpace()) { |
| 1524 | forwarded = Failure::Exception(); |
| 1525 | } else { |
| 1526 | OldSpace* target_space = Heap::TargetSpace(object); |
| 1527 | ASSERT(target_space == Heap::old_pointer_space() || |
| 1528 | target_space == Heap::old_data_space()); |
| 1529 | forwarded = target_space->MCAllocateRaw(object_size); |
| 1530 | } |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1531 | Object* result; |
| 1532 | if (!forwarded->ToObject(&result)) { |
| 1533 | result = Heap::new_space()->MCAllocateRaw(object_size)->ToObjectUnchecked(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1534 | } |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1535 | return result; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1536 | } |
| 1537 | |
| 1538 | |
| 1539 | // Allocation functions for the paged spaces call the space's MCAllocateRaw. |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1540 | MUST_USE_RESULT inline MaybeObject* MCAllocateFromOldPointerSpace( |
| 1541 | HeapObject* ignore, |
| 1542 | int object_size) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1543 | return Heap::old_pointer_space()->MCAllocateRaw(object_size); |
| 1544 | } |
| 1545 | |
| 1546 | |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1547 | MUST_USE_RESULT inline MaybeObject* MCAllocateFromOldDataSpace( |
| 1548 | HeapObject* ignore, |
| 1549 | int object_size) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1550 | return Heap::old_data_space()->MCAllocateRaw(object_size); |
| 1551 | } |
| 1552 | |
| 1553 | |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1554 | MUST_USE_RESULT inline MaybeObject* MCAllocateFromCodeSpace( |
| 1555 | HeapObject* ignore, |
| 1556 | int object_size) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1557 | return Heap::code_space()->MCAllocateRaw(object_size); |
| 1558 | } |
| 1559 | |
| 1560 | |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1561 | MUST_USE_RESULT inline MaybeObject* MCAllocateFromMapSpace( |
| 1562 | HeapObject* ignore, |
| 1563 | int object_size) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1564 | return Heap::map_space()->MCAllocateRaw(object_size); |
| 1565 | } |
| 1566 | |
| 1567 | |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 1568 | MUST_USE_RESULT inline MaybeObject* MCAllocateFromCellSpace(HeapObject* ignore, |
| 1569 | int object_size) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1570 | return Heap::cell_space()->MCAllocateRaw(object_size); |
| 1571 | } |
| 1572 | |
| 1573 | |
| 1574 | // The forwarding address is encoded at the same offset as the current |
| 1575 | // to-space object, but in from space. |
| 1576 | inline void EncodeForwardingAddressInNewSpace(HeapObject* old_object, |
| 1577 | int object_size, |
| 1578 | Object* new_object, |
| 1579 | int* ignored) { |
| 1580 | int offset = |
| 1581 | Heap::new_space()->ToSpaceOffsetForAddress(old_object->address()); |
| 1582 | Memory::Address_at(Heap::new_space()->FromSpaceLow() + offset) = |
| 1583 | HeapObject::cast(new_object)->address(); |
| 1584 | } |
| 1585 | |
| 1586 | |
| 1587 | // The forwarding address is encoded in the map pointer of the object as an |
| 1588 | // offset (in terms of live bytes) from the address of the first live object |
| 1589 | // in the page. |
| 1590 | inline void EncodeForwardingAddressInPagedSpace(HeapObject* old_object, |
| 1591 | int object_size, |
| 1592 | Object* new_object, |
| 1593 | int* offset) { |
| 1594 | // Record the forwarding address of the first live object if necessary. |
| 1595 | if (*offset == 0) { |
| 1596 | Page::FromAddress(old_object->address())->mc_first_forwarded = |
| 1597 | HeapObject::cast(new_object)->address(); |
| 1598 | } |
| 1599 | |
| 1600 | MapWord encoding = |
| 1601 | MapWord::EncodeAddress(old_object->map()->address(), *offset); |
| 1602 | old_object->set_map_word(encoding); |
| 1603 | *offset += object_size; |
| 1604 | ASSERT(*offset <= Page::kObjectAreaSize); |
| 1605 | } |
| 1606 | |
| 1607 | |
| 1608 | // Most non-live objects are ignored. |
| 1609 | inline void IgnoreNonLiveObject(HeapObject* object) {} |
| 1610 | |
| 1611 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1612 | // Function template that, given a range of addresses (eg, a semispace or a |
| 1613 | // paged space page), iterates through the objects in the range to clear |
| 1614 | // mark bits and compute and encode forwarding addresses. As a side effect, |
| 1615 | // maximal free chunks are marked so that they can be skipped on subsequent |
| 1616 | // sweeps. |
| 1617 | // |
| 1618 | // The template parameters are an allocation function, a forwarding address |
| 1619 | // encoding function, and a function to process non-live objects. |
| 1620 | template<MarkCompactCollector::AllocationFunction Alloc, |
| 1621 | MarkCompactCollector::EncodingFunction Encode, |
| 1622 | MarkCompactCollector::ProcessNonLiveFunction ProcessNonLive> |
| 1623 | inline void EncodeForwardingAddressesInRange(Address start, |
| 1624 | Address end, |
| 1625 | int* offset) { |
| 1626 | // The start address of the current free region while sweeping the space. |
| 1627 | // This address is set when a transition from live to non-live objects is |
| 1628 | // encountered. A value (an encoding of the 'next free region' pointer) |
| 1629 | // is written to memory at this address when a transition from non-live to |
| 1630 | // live objects is encountered. |
| 1631 | Address free_start = NULL; |
| 1632 | |
| 1633 | // A flag giving the state of the previously swept object. Initially true |
| 1634 | // to ensure that free_start is initialized to a proper address before |
| 1635 | // trying to write to it. |
| 1636 | bool is_prev_alive = true; |
| 1637 | |
| 1638 | int object_size; // Will be set on each iteration of the loop. |
| 1639 | for (Address current = start; current < end; current += object_size) { |
| 1640 | HeapObject* object = HeapObject::FromAddress(current); |
| 1641 | if (object->IsMarked()) { |
| 1642 | object->ClearMark(); |
| 1643 | MarkCompactCollector::tracer()->decrement_marked_count(); |
| 1644 | object_size = object->Size(); |
| 1645 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1646 | // Allocation cannot fail, because we are compacting the space. |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1647 | Object* forwarded = Alloc(object, object_size)->ToObjectUnchecked(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1648 | Encode(object, object_size, forwarded, offset); |
| 1649 | |
| 1650 | #ifdef DEBUG |
| 1651 | if (FLAG_gc_verbose) { |
| 1652 | PrintF("forward %p -> %p.\n", object->address(), |
| 1653 | HeapObject::cast(forwarded)->address()); |
| 1654 | } |
| 1655 | #endif |
| 1656 | if (!is_prev_alive) { // Transition from non-live to live. |
Steve Block | d0582a6 | 2009-12-15 09:54:21 +0000 | [diff] [blame] | 1657 | EncodeFreeRegion(free_start, static_cast<int>(current - free_start)); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1658 | is_prev_alive = true; |
| 1659 | } |
| 1660 | } else { // Non-live object. |
| 1661 | object_size = object->Size(); |
| 1662 | ProcessNonLive(object); |
| 1663 | if (is_prev_alive) { // Transition from live to non-live. |
| 1664 | free_start = current; |
| 1665 | is_prev_alive = false; |
| 1666 | } |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 1667 | LiveObjectList::ProcessNonLive(object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1668 | } |
| 1669 | } |
| 1670 | |
| 1671 | // If we ended on a free region, mark it. |
Steve Block | d0582a6 | 2009-12-15 09:54:21 +0000 | [diff] [blame] | 1672 | if (!is_prev_alive) { |
| 1673 | EncodeFreeRegion(free_start, static_cast<int>(end - free_start)); |
| 1674 | } |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1675 | } |
| 1676 | |
| 1677 | |
| 1678 | // Functions to encode the forwarding pointers in each compactable space. |
| 1679 | void MarkCompactCollector::EncodeForwardingAddressesInNewSpace() { |
| 1680 | int ignored; |
| 1681 | EncodeForwardingAddressesInRange<MCAllocateFromNewSpace, |
| 1682 | EncodeForwardingAddressInNewSpace, |
| 1683 | IgnoreNonLiveObject>( |
| 1684 | Heap::new_space()->bottom(), |
| 1685 | Heap::new_space()->top(), |
| 1686 | &ignored); |
| 1687 | } |
| 1688 | |
| 1689 | |
| 1690 | template<MarkCompactCollector::AllocationFunction Alloc, |
| 1691 | MarkCompactCollector::ProcessNonLiveFunction ProcessNonLive> |
| 1692 | void MarkCompactCollector::EncodeForwardingAddressesInPagedSpace( |
| 1693 | PagedSpace* space) { |
| 1694 | PageIterator it(space, PageIterator::PAGES_IN_USE); |
| 1695 | while (it.has_next()) { |
| 1696 | Page* p = it.next(); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1697 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1698 | // The offset of each live object in the page from the first live object |
| 1699 | // in the page. |
| 1700 | int offset = 0; |
| 1701 | EncodeForwardingAddressesInRange<Alloc, |
| 1702 | EncodeForwardingAddressInPagedSpace, |
| 1703 | ProcessNonLive>( |
| 1704 | p->ObjectAreaStart(), |
| 1705 | p->AllocationTop(), |
| 1706 | &offset); |
| 1707 | } |
| 1708 | } |
| 1709 | |
| 1710 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1711 | // We scavange new space simultaneously with sweeping. This is done in two |
| 1712 | // passes. |
| 1713 | // The first pass migrates all alive objects from one semispace to another or |
| 1714 | // promotes them to old space. Forwading address is written directly into |
| 1715 | // first word of object without any encoding. If object is dead we are writing |
| 1716 | // NULL as a forwarding address. |
| 1717 | // The second pass updates pointers to new space in all spaces. It is possible |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1718 | // to encounter pointers to dead objects during traversal of dirty regions we |
| 1719 | // should clear them to avoid encountering them during next dirty regions |
| 1720 | // iteration. |
| 1721 | static void MigrateObject(Address dst, |
| 1722 | Address src, |
| 1723 | int size, |
| 1724 | bool to_old_space) { |
| 1725 | if (to_old_space) { |
| 1726 | Heap::CopyBlockToOldSpaceAndUpdateRegionMarks(dst, src, size); |
| 1727 | } else { |
| 1728 | Heap::CopyBlock(dst, src, size); |
| 1729 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1730 | |
| 1731 | Memory::Address_at(src) = dst; |
| 1732 | } |
| 1733 | |
| 1734 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1735 | class StaticPointersToNewGenUpdatingVisitor : public |
| 1736 | StaticNewSpaceVisitor<StaticPointersToNewGenUpdatingVisitor> { |
| 1737 | public: |
| 1738 | static inline void VisitPointer(Object** p) { |
| 1739 | if (!(*p)->IsHeapObject()) return; |
| 1740 | |
| 1741 | HeapObject* obj = HeapObject::cast(*p); |
| 1742 | Address old_addr = obj->address(); |
| 1743 | |
| 1744 | if (Heap::new_space()->Contains(obj)) { |
| 1745 | ASSERT(Heap::InFromSpace(*p)); |
| 1746 | *p = HeapObject::FromAddress(Memory::Address_at(old_addr)); |
| 1747 | } |
| 1748 | } |
| 1749 | }; |
| 1750 | |
| 1751 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1752 | // Visitor for updating pointers from live objects in old spaces to new space. |
| 1753 | // It does not expect to encounter pointers to dead objects. |
| 1754 | class PointersToNewGenUpdatingVisitor: public ObjectVisitor { |
| 1755 | public: |
| 1756 | void VisitPointer(Object** p) { |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1757 | StaticPointersToNewGenUpdatingVisitor::VisitPointer(p); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1758 | } |
| 1759 | |
| 1760 | void VisitPointers(Object** start, Object** end) { |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1761 | for (Object** p = start; p < end; p++) { |
| 1762 | StaticPointersToNewGenUpdatingVisitor::VisitPointer(p); |
| 1763 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1764 | } |
| 1765 | |
| 1766 | void VisitCodeTarget(RelocInfo* rinfo) { |
| 1767 | ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode())); |
| 1768 | Object* target = Code::GetCodeFromTargetAddress(rinfo->target_address()); |
| 1769 | VisitPointer(&target); |
| 1770 | rinfo->set_target_address(Code::cast(target)->instruction_start()); |
| 1771 | } |
| 1772 | |
| 1773 | void VisitDebugTarget(RelocInfo* rinfo) { |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1774 | ASSERT((RelocInfo::IsJSReturn(rinfo->rmode()) && |
| 1775 | rinfo->IsPatchedReturnSequence()) || |
| 1776 | (RelocInfo::IsDebugBreakSlot(rinfo->rmode()) && |
| 1777 | rinfo->IsPatchedDebugBreakSlotSequence())); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1778 | Object* target = Code::GetCodeFromTargetAddress(rinfo->call_address()); |
| 1779 | VisitPointer(&target); |
| 1780 | rinfo->set_call_address(Code::cast(target)->instruction_start()); |
| 1781 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1782 | }; |
| 1783 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1784 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1785 | // Visitor for updating pointers from live objects in old spaces to new space. |
| 1786 | // It can encounter pointers to dead objects in new space when traversing map |
| 1787 | // space (see comment for MigrateObject). |
| 1788 | static void UpdatePointerToNewGen(HeapObject** p) { |
| 1789 | if (!(*p)->IsHeapObject()) return; |
| 1790 | |
| 1791 | Address old_addr = (*p)->address(); |
| 1792 | ASSERT(Heap::InFromSpace(*p)); |
| 1793 | |
| 1794 | Address new_addr = Memory::Address_at(old_addr); |
| 1795 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1796 | if (new_addr == NULL) { |
| 1797 | // We encountered pointer to a dead object. Clear it so we will |
| 1798 | // not visit it again during next iteration of dirty regions. |
| 1799 | *p = NULL; |
| 1800 | } else { |
| 1801 | *p = HeapObject::FromAddress(new_addr); |
| 1802 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1803 | } |
| 1804 | |
| 1805 | |
| 1806 | static String* UpdateNewSpaceReferenceInExternalStringTableEntry(Object **p) { |
| 1807 | Address old_addr = HeapObject::cast(*p)->address(); |
| 1808 | Address new_addr = Memory::Address_at(old_addr); |
| 1809 | return String::cast(HeapObject::FromAddress(new_addr)); |
| 1810 | } |
| 1811 | |
| 1812 | |
| 1813 | static bool TryPromoteObject(HeapObject* object, int object_size) { |
| 1814 | Object* result; |
| 1815 | |
| 1816 | if (object_size > Heap::MaxObjectSizeInPagedSpace()) { |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1817 | MaybeObject* maybe_result = |
| 1818 | Heap::lo_space()->AllocateRawFixedArray(object_size); |
| 1819 | if (maybe_result->ToObject(&result)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1820 | HeapObject* target = HeapObject::cast(result); |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1821 | MigrateObject(target->address(), object->address(), object_size, true); |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 1822 | MarkCompactCollector::tracer()-> |
| 1823 | increment_promoted_objects_size(object_size); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1824 | return true; |
| 1825 | } |
| 1826 | } else { |
| 1827 | OldSpace* target_space = Heap::TargetSpace(object); |
| 1828 | |
| 1829 | ASSERT(target_space == Heap::old_pointer_space() || |
| 1830 | target_space == Heap::old_data_space()); |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1831 | MaybeObject* maybe_result = target_space->AllocateRaw(object_size); |
| 1832 | if (maybe_result->ToObject(&result)) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1833 | HeapObject* target = HeapObject::cast(result); |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1834 | MigrateObject(target->address(), |
| 1835 | object->address(), |
| 1836 | object_size, |
| 1837 | target_space == Heap::old_pointer_space()); |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 1838 | MarkCompactCollector::tracer()-> |
| 1839 | increment_promoted_objects_size(object_size); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1840 | return true; |
| 1841 | } |
| 1842 | } |
| 1843 | |
| 1844 | return false; |
| 1845 | } |
| 1846 | |
| 1847 | |
| 1848 | static void SweepNewSpace(NewSpace* space) { |
| 1849 | Heap::CheckNewSpaceExpansionCriteria(); |
| 1850 | |
| 1851 | Address from_bottom = space->bottom(); |
| 1852 | Address from_top = space->top(); |
| 1853 | |
| 1854 | // Flip the semispaces. After flipping, to space is empty, from space has |
| 1855 | // live objects. |
| 1856 | space->Flip(); |
| 1857 | space->ResetAllocationInfo(); |
| 1858 | |
| 1859 | int size = 0; |
| 1860 | int survivors_size = 0; |
| 1861 | |
| 1862 | // First pass: traverse all objects in inactive semispace, remove marks, |
| 1863 | // migrate live objects and write forwarding addresses. |
| 1864 | for (Address current = from_bottom; current < from_top; current += size) { |
| 1865 | HeapObject* object = HeapObject::FromAddress(current); |
| 1866 | |
| 1867 | if (object->IsMarked()) { |
| 1868 | object->ClearMark(); |
| 1869 | MarkCompactCollector::tracer()->decrement_marked_count(); |
| 1870 | |
| 1871 | size = object->Size(); |
| 1872 | survivors_size += size; |
| 1873 | |
| 1874 | // Aggressively promote young survivors to the old space. |
| 1875 | if (TryPromoteObject(object, size)) { |
| 1876 | continue; |
| 1877 | } |
| 1878 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1879 | // Promotion failed. Just migrate object to another semispace. |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1880 | // Allocation cannot fail at this point: semispaces are of equal size. |
John Reck | 5913587 | 2010-11-02 12:39:01 -0700 | [diff] [blame] | 1881 | Object* target = space->AllocateRaw(size)->ToObjectUnchecked(); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1882 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1883 | MigrateObject(HeapObject::cast(target)->address(), |
| 1884 | current, |
| 1885 | size, |
| 1886 | false); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1887 | } else { |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 1888 | // Process the dead object before we write a NULL into its header. |
| 1889 | LiveObjectList::ProcessNonLive(object); |
| 1890 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1891 | size = object->Size(); |
| 1892 | Memory::Address_at(current) = NULL; |
| 1893 | } |
| 1894 | } |
| 1895 | |
| 1896 | // Second pass: find pointers to new space and update them. |
| 1897 | PointersToNewGenUpdatingVisitor updating_visitor; |
| 1898 | |
| 1899 | // Update pointers in to space. |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 1900 | Address current = space->bottom(); |
| 1901 | while (current < space->top()) { |
| 1902 | HeapObject* object = HeapObject::FromAddress(current); |
| 1903 | current += |
| 1904 | StaticPointersToNewGenUpdatingVisitor::IterateBody(object->map(), |
| 1905 | object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1906 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1907 | |
| 1908 | // Update roots. |
| 1909 | Heap::IterateRoots(&updating_visitor, VISIT_ALL_IN_SCAVENGE); |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 1910 | LiveObjectList::IterateElements(&updating_visitor); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1911 | |
| 1912 | // Update pointers in old spaces. |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 1913 | Heap::IterateDirtyRegions(Heap::old_pointer_space(), |
| 1914 | &Heap::IteratePointersInDirtyRegion, |
| 1915 | &UpdatePointerToNewGen, |
| 1916 | Heap::WATERMARK_SHOULD_BE_VALID); |
| 1917 | |
| 1918 | Heap::lo_space()->IterateDirtyRegions(&UpdatePointerToNewGen); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1919 | |
| 1920 | // Update pointers from cells. |
| 1921 | HeapObjectIterator cell_iterator(Heap::cell_space()); |
| 1922 | for (HeapObject* cell = cell_iterator.next(); |
| 1923 | cell != NULL; |
| 1924 | cell = cell_iterator.next()) { |
| 1925 | if (cell->IsJSGlobalPropertyCell()) { |
| 1926 | Address value_address = |
| 1927 | reinterpret_cast<Address>(cell) + |
| 1928 | (JSGlobalPropertyCell::kValueOffset - kHeapObjectTag); |
| 1929 | updating_visitor.VisitPointer(reinterpret_cast<Object**>(value_address)); |
| 1930 | } |
| 1931 | } |
| 1932 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 1933 | // Update pointer from the global contexts list. |
| 1934 | updating_visitor.VisitPointer(Heap::global_contexts_list_address()); |
| 1935 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1936 | // Update pointers from external string table. |
| 1937 | Heap::UpdateNewSpaceReferencesInExternalStringTable( |
| 1938 | &UpdateNewSpaceReferenceInExternalStringTableEntry); |
| 1939 | |
| 1940 | // All pointers were updated. Update auxiliary allocation info. |
| 1941 | Heap::IncrementYoungSurvivorsCounter(survivors_size); |
| 1942 | space->set_age_mark(space->top()); |
Ben Murdoch | e0cee9b | 2011-05-25 10:26:03 +0100 | [diff] [blame^] | 1943 | |
| 1944 | // Update JSFunction pointers from the runtime profiler. |
| 1945 | RuntimeProfiler::UpdateSamplesAfterScavenge(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1946 | } |
| 1947 | |
| 1948 | |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 1949 | static void SweepSpace(PagedSpace* space) { |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1950 | PageIterator it(space, PageIterator::PAGES_IN_USE); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1951 | |
| 1952 | // During sweeping of paged space we are trying to find longest sequences |
| 1953 | // of pages without live objects and free them (instead of putting them on |
| 1954 | // the free list). |
| 1955 | |
| 1956 | // Page preceding current. |
| 1957 | Page* prev = Page::FromAddress(NULL); |
| 1958 | |
| 1959 | // First empty page in a sequence. |
| 1960 | Page* first_empty_page = Page::FromAddress(NULL); |
| 1961 | |
| 1962 | // Page preceding first empty page. |
| 1963 | Page* prec_first_empty_page = Page::FromAddress(NULL); |
| 1964 | |
| 1965 | // If last used page of space ends with a sequence of dead objects |
| 1966 | // we can adjust allocation top instead of puting this free area into |
| 1967 | // the free list. Thus during sweeping we keep track of such areas |
| 1968 | // and defer their deallocation until the sweeping of the next page |
| 1969 | // is done: if one of the next pages contains live objects we have |
| 1970 | // to put such area into the free list. |
| 1971 | Address last_free_start = NULL; |
| 1972 | int last_free_size = 0; |
| 1973 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1974 | while (it.has_next()) { |
| 1975 | Page* p = it.next(); |
| 1976 | |
| 1977 | bool is_previous_alive = true; |
| 1978 | Address free_start = NULL; |
| 1979 | HeapObject* object; |
| 1980 | |
| 1981 | for (Address current = p->ObjectAreaStart(); |
| 1982 | current < p->AllocationTop(); |
| 1983 | current += object->Size()) { |
| 1984 | object = HeapObject::FromAddress(current); |
| 1985 | if (object->IsMarked()) { |
| 1986 | object->ClearMark(); |
| 1987 | MarkCompactCollector::tracer()->decrement_marked_count(); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 1988 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1989 | if (!is_previous_alive) { // Transition from free to live. |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 1990 | space->DeallocateBlock(free_start, |
| 1991 | static_cast<int>(current - free_start), |
| 1992 | true); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1993 | is_previous_alive = true; |
| 1994 | } |
| 1995 | } else { |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 1996 | MarkCompactCollector::ReportDeleteIfNeeded(object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 1997 | if (is_previous_alive) { // Transition from live to free. |
| 1998 | free_start = current; |
| 1999 | is_previous_alive = false; |
| 2000 | } |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 2001 | LiveObjectList::ProcessNonLive(object); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2002 | } |
| 2003 | // The object is now unmarked for the call to Size() at the top of the |
| 2004 | // loop. |
| 2005 | } |
| 2006 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2007 | bool page_is_empty = (p->ObjectAreaStart() == p->AllocationTop()) |
| 2008 | || (!is_previous_alive && free_start == p->ObjectAreaStart()); |
| 2009 | |
| 2010 | if (page_is_empty) { |
| 2011 | // This page is empty. Check whether we are in the middle of |
| 2012 | // sequence of empty pages and start one if not. |
| 2013 | if (!first_empty_page->is_valid()) { |
| 2014 | first_empty_page = p; |
| 2015 | prec_first_empty_page = prev; |
| 2016 | } |
| 2017 | |
| 2018 | if (!is_previous_alive) { |
| 2019 | // There are dead objects on this page. Update space accounting stats |
| 2020 | // without putting anything into free list. |
| 2021 | int size_in_bytes = static_cast<int>(p->AllocationTop() - free_start); |
| 2022 | if (size_in_bytes > 0) { |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 2023 | space->DeallocateBlock(free_start, size_in_bytes, false); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2024 | } |
| 2025 | } |
| 2026 | } else { |
| 2027 | // This page is not empty. Sequence of empty pages ended on the previous |
| 2028 | // one. |
| 2029 | if (first_empty_page->is_valid()) { |
| 2030 | space->FreePages(prec_first_empty_page, prev); |
| 2031 | prec_first_empty_page = first_empty_page = Page::FromAddress(NULL); |
| 2032 | } |
| 2033 | |
| 2034 | // If there is a free ending area on one of the previous pages we have |
| 2035 | // deallocate that area and put it on the free list. |
| 2036 | if (last_free_size > 0) { |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2037 | Page::FromAddress(last_free_start)-> |
| 2038 | SetAllocationWatermark(last_free_start); |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 2039 | space->DeallocateBlock(last_free_start, last_free_size, true); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2040 | last_free_start = NULL; |
| 2041 | last_free_size = 0; |
| 2042 | } |
| 2043 | |
| 2044 | // If the last region of this page was not live we remember it. |
| 2045 | if (!is_previous_alive) { |
| 2046 | ASSERT(last_free_size == 0); |
| 2047 | last_free_size = static_cast<int>(p->AllocationTop() - free_start); |
| 2048 | last_free_start = free_start; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2049 | } |
| 2050 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2051 | |
| 2052 | prev = p; |
| 2053 | } |
| 2054 | |
| 2055 | // We reached end of space. See if we need to adjust allocation top. |
| 2056 | Address new_allocation_top = NULL; |
| 2057 | |
| 2058 | if (first_empty_page->is_valid()) { |
| 2059 | // Last used pages in space are empty. We can move allocation top backwards |
| 2060 | // to the beginning of first empty page. |
| 2061 | ASSERT(prev == space->AllocationTopPage()); |
| 2062 | |
| 2063 | new_allocation_top = first_empty_page->ObjectAreaStart(); |
| 2064 | } |
| 2065 | |
| 2066 | if (last_free_size > 0) { |
| 2067 | // There was a free ending area on the previous page. |
| 2068 | // Deallocate it without putting it into freelist and move allocation |
| 2069 | // top to the beginning of this free area. |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 2070 | space->DeallocateBlock(last_free_start, last_free_size, false); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2071 | new_allocation_top = last_free_start; |
| 2072 | } |
| 2073 | |
| 2074 | if (new_allocation_top != NULL) { |
| 2075 | #ifdef DEBUG |
| 2076 | Page* new_allocation_top_page = Page::FromAllocationTop(new_allocation_top); |
| 2077 | if (!first_empty_page->is_valid()) { |
| 2078 | ASSERT(new_allocation_top_page == space->AllocationTopPage()); |
| 2079 | } else if (last_free_size > 0) { |
| 2080 | ASSERT(new_allocation_top_page == prec_first_empty_page); |
| 2081 | } else { |
| 2082 | ASSERT(new_allocation_top_page == first_empty_page); |
| 2083 | } |
| 2084 | #endif |
| 2085 | |
| 2086 | space->SetTop(new_allocation_top); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2087 | } |
| 2088 | } |
| 2089 | |
| 2090 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2091 | void MarkCompactCollector::EncodeForwardingAddresses() { |
| 2092 | ASSERT(state_ == ENCODE_FORWARDING_ADDRESSES); |
| 2093 | // Objects in the active semispace of the young generation may be |
| 2094 | // relocated to the inactive semispace (if not promoted). Set the |
| 2095 | // relocation info to the beginning of the inactive semispace. |
| 2096 | Heap::new_space()->MCResetRelocationInfo(); |
| 2097 | |
| 2098 | // Compute the forwarding pointers in each space. |
| 2099 | EncodeForwardingAddressesInPagedSpace<MCAllocateFromOldPointerSpace, |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2100 | ReportDeleteIfNeeded>( |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2101 | Heap::old_pointer_space()); |
| 2102 | |
| 2103 | EncodeForwardingAddressesInPagedSpace<MCAllocateFromOldDataSpace, |
| 2104 | IgnoreNonLiveObject>( |
| 2105 | Heap::old_data_space()); |
| 2106 | |
| 2107 | EncodeForwardingAddressesInPagedSpace<MCAllocateFromCodeSpace, |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2108 | ReportDeleteIfNeeded>( |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2109 | Heap::code_space()); |
| 2110 | |
| 2111 | EncodeForwardingAddressesInPagedSpace<MCAllocateFromCellSpace, |
| 2112 | IgnoreNonLiveObject>( |
| 2113 | Heap::cell_space()); |
| 2114 | |
| 2115 | |
| 2116 | // Compute new space next to last after the old and code spaces have been |
| 2117 | // compacted. Objects in new space can be promoted to old or code space. |
| 2118 | EncodeForwardingAddressesInNewSpace(); |
| 2119 | |
| 2120 | // Compute map space last because computing forwarding addresses |
| 2121 | // overwrites non-live objects. Objects in the other spaces rely on |
| 2122 | // non-live map pointers to get the sizes of non-live objects. |
| 2123 | EncodeForwardingAddressesInPagedSpace<MCAllocateFromMapSpace, |
| 2124 | IgnoreNonLiveObject>( |
| 2125 | Heap::map_space()); |
| 2126 | |
| 2127 | // Write relocation info to the top page, so we can use it later. This is |
| 2128 | // done after promoting objects from the new space so we get the correct |
| 2129 | // allocation top. |
| 2130 | Heap::old_pointer_space()->MCWriteRelocationInfoToPage(); |
| 2131 | Heap::old_data_space()->MCWriteRelocationInfoToPage(); |
| 2132 | Heap::code_space()->MCWriteRelocationInfoToPage(); |
| 2133 | Heap::map_space()->MCWriteRelocationInfoToPage(); |
| 2134 | Heap::cell_space()->MCWriteRelocationInfoToPage(); |
| 2135 | } |
| 2136 | |
| 2137 | |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2138 | class MapIterator : public HeapObjectIterator { |
| 2139 | public: |
| 2140 | MapIterator() : HeapObjectIterator(Heap::map_space(), &SizeCallback) { } |
| 2141 | |
| 2142 | explicit MapIterator(Address start) |
| 2143 | : HeapObjectIterator(Heap::map_space(), start, &SizeCallback) { } |
| 2144 | |
| 2145 | private: |
| 2146 | static int SizeCallback(HeapObject* unused) { |
| 2147 | USE(unused); |
| 2148 | return Map::kSize; |
| 2149 | } |
| 2150 | }; |
| 2151 | |
| 2152 | |
| 2153 | class MapCompact { |
| 2154 | public: |
| 2155 | explicit MapCompact(int live_maps) |
| 2156 | : live_maps_(live_maps), |
| 2157 | to_evacuate_start_(Heap::map_space()->TopAfterCompaction(live_maps)), |
| 2158 | map_to_evacuate_it_(to_evacuate_start_), |
| 2159 | first_map_to_evacuate_( |
| 2160 | reinterpret_cast<Map*>(HeapObject::FromAddress(to_evacuate_start_))) { |
| 2161 | } |
| 2162 | |
| 2163 | void CompactMaps() { |
| 2164 | // As we know the number of maps to evacuate beforehand, |
| 2165 | // we stop then there is no more vacant maps. |
| 2166 | for (Map* next_vacant_map = NextVacantMap(); |
| 2167 | next_vacant_map; |
| 2168 | next_vacant_map = NextVacantMap()) { |
| 2169 | EvacuateMap(next_vacant_map, NextMapToEvacuate()); |
| 2170 | } |
| 2171 | |
| 2172 | #ifdef DEBUG |
| 2173 | CheckNoMapsToEvacuate(); |
| 2174 | #endif |
| 2175 | } |
| 2176 | |
| 2177 | void UpdateMapPointersInRoots() { |
| 2178 | Heap::IterateRoots(&map_updating_visitor_, VISIT_ONLY_STRONG); |
| 2179 | GlobalHandles::IterateWeakRoots(&map_updating_visitor_); |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 2180 | LiveObjectList::IterateElements(&map_updating_visitor_); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2181 | } |
| 2182 | |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2183 | void UpdateMapPointersInPagedSpace(PagedSpace* space) { |
| 2184 | ASSERT(space != Heap::map_space()); |
| 2185 | |
| 2186 | PageIterator it(space, PageIterator::PAGES_IN_USE); |
| 2187 | while (it.has_next()) { |
| 2188 | Page* p = it.next(); |
| 2189 | UpdateMapPointersInRange(p->ObjectAreaStart(), p->AllocationTop()); |
| 2190 | } |
| 2191 | } |
| 2192 | |
| 2193 | void UpdateMapPointersInNewSpace() { |
| 2194 | NewSpace* space = Heap::new_space(); |
| 2195 | UpdateMapPointersInRange(space->bottom(), space->top()); |
| 2196 | } |
| 2197 | |
| 2198 | void UpdateMapPointersInLargeObjectSpace() { |
| 2199 | LargeObjectIterator it(Heap::lo_space()); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2200 | for (HeapObject* obj = it.next(); obj != NULL; obj = it.next()) |
| 2201 | UpdateMapPointersInObject(obj); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2202 | } |
| 2203 | |
| 2204 | void Finish() { |
| 2205 | Heap::map_space()->FinishCompaction(to_evacuate_start_, live_maps_); |
| 2206 | } |
| 2207 | |
| 2208 | private: |
| 2209 | int live_maps_; |
| 2210 | Address to_evacuate_start_; |
| 2211 | MapIterator vacant_map_it_; |
| 2212 | MapIterator map_to_evacuate_it_; |
| 2213 | Map* first_map_to_evacuate_; |
| 2214 | |
| 2215 | // Helper class for updating map pointers in HeapObjects. |
| 2216 | class MapUpdatingVisitor: public ObjectVisitor { |
| 2217 | public: |
| 2218 | void VisitPointer(Object** p) { |
| 2219 | UpdateMapPointer(p); |
| 2220 | } |
| 2221 | |
| 2222 | void VisitPointers(Object** start, Object** end) { |
| 2223 | for (Object** p = start; p < end; p++) UpdateMapPointer(p); |
| 2224 | } |
| 2225 | |
| 2226 | private: |
| 2227 | void UpdateMapPointer(Object** p) { |
| 2228 | if (!(*p)->IsHeapObject()) return; |
| 2229 | HeapObject* old_map = reinterpret_cast<HeapObject*>(*p); |
| 2230 | |
| 2231 | // Moved maps are tagged with overflowed map word. They are the only |
| 2232 | // objects those map word is overflowed as marking is already complete. |
| 2233 | MapWord map_word = old_map->map_word(); |
| 2234 | if (!map_word.IsOverflowed()) return; |
| 2235 | |
| 2236 | *p = GetForwardedMap(map_word); |
| 2237 | } |
| 2238 | }; |
| 2239 | |
| 2240 | static MapUpdatingVisitor map_updating_visitor_; |
| 2241 | |
| 2242 | static Map* NextMap(MapIterator* it, HeapObject* last, bool live) { |
| 2243 | while (true) { |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2244 | HeapObject* next = it->next(); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2245 | ASSERT(next != NULL); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2246 | if (next == last) |
| 2247 | return NULL; |
| 2248 | ASSERT(!next->IsOverflowed()); |
| 2249 | ASSERT(!next->IsMarked()); |
| 2250 | ASSERT(next->IsMap() || FreeListNode::IsFreeListNode(next)); |
| 2251 | if (next->IsMap() == live) |
| 2252 | return reinterpret_cast<Map*>(next); |
| 2253 | } |
| 2254 | } |
| 2255 | |
| 2256 | Map* NextVacantMap() { |
| 2257 | Map* map = NextMap(&vacant_map_it_, first_map_to_evacuate_, false); |
| 2258 | ASSERT(map == NULL || FreeListNode::IsFreeListNode(map)); |
| 2259 | return map; |
| 2260 | } |
| 2261 | |
| 2262 | Map* NextMapToEvacuate() { |
| 2263 | Map* map = NextMap(&map_to_evacuate_it_, NULL, true); |
| 2264 | ASSERT(map != NULL); |
| 2265 | ASSERT(map->IsMap()); |
| 2266 | return map; |
| 2267 | } |
| 2268 | |
| 2269 | static void EvacuateMap(Map* vacant_map, Map* map_to_evacuate) { |
| 2270 | ASSERT(FreeListNode::IsFreeListNode(vacant_map)); |
| 2271 | ASSERT(map_to_evacuate->IsMap()); |
| 2272 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2273 | ASSERT(Map::kSize % 4 == 0); |
| 2274 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2275 | Heap::CopyBlockToOldSpaceAndUpdateRegionMarks(vacant_map->address(), |
| 2276 | map_to_evacuate->address(), |
| 2277 | Map::kSize); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2278 | |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2279 | ASSERT(vacant_map->IsMap()); // Due to memcpy above. |
| 2280 | |
| 2281 | MapWord forwarding_map_word = MapWord::FromMap(vacant_map); |
| 2282 | forwarding_map_word.SetOverflow(); |
| 2283 | map_to_evacuate->set_map_word(forwarding_map_word); |
| 2284 | |
| 2285 | ASSERT(map_to_evacuate->map_word().IsOverflowed()); |
| 2286 | ASSERT(GetForwardedMap(map_to_evacuate->map_word()) == vacant_map); |
| 2287 | } |
| 2288 | |
| 2289 | static Map* GetForwardedMap(MapWord map_word) { |
| 2290 | ASSERT(map_word.IsOverflowed()); |
| 2291 | map_word.ClearOverflow(); |
| 2292 | Map* new_map = map_word.ToMap(); |
| 2293 | ASSERT_MAP_ALIGNED(new_map->address()); |
| 2294 | return new_map; |
| 2295 | } |
| 2296 | |
| 2297 | static int UpdateMapPointersInObject(HeapObject* obj) { |
| 2298 | ASSERT(!obj->IsMarked()); |
| 2299 | Map* map = obj->map(); |
| 2300 | ASSERT(Heap::map_space()->Contains(map)); |
| 2301 | MapWord map_word = map->map_word(); |
| 2302 | ASSERT(!map_word.IsMarked()); |
| 2303 | if (map_word.IsOverflowed()) { |
| 2304 | Map* new_map = GetForwardedMap(map_word); |
| 2305 | ASSERT(Heap::map_space()->Contains(new_map)); |
| 2306 | obj->set_map(new_map); |
| 2307 | |
| 2308 | #ifdef DEBUG |
| 2309 | if (FLAG_gc_verbose) { |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 2310 | PrintF("update %p : %p -> %p\n", |
| 2311 | obj->address(), |
| 2312 | reinterpret_cast<void*>(map), |
| 2313 | reinterpret_cast<void*>(new_map)); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2314 | } |
| 2315 | #endif |
| 2316 | } |
| 2317 | |
| 2318 | int size = obj->SizeFromMap(map); |
| 2319 | obj->IterateBody(map->instance_type(), size, &map_updating_visitor_); |
| 2320 | return size; |
| 2321 | } |
| 2322 | |
| 2323 | static void UpdateMapPointersInRange(Address start, Address end) { |
| 2324 | HeapObject* object; |
| 2325 | int size; |
| 2326 | for (Address current = start; current < end; current += size) { |
| 2327 | object = HeapObject::FromAddress(current); |
| 2328 | size = UpdateMapPointersInObject(object); |
| 2329 | ASSERT(size > 0); |
| 2330 | } |
| 2331 | } |
| 2332 | |
| 2333 | #ifdef DEBUG |
| 2334 | void CheckNoMapsToEvacuate() { |
| 2335 | if (!FLAG_enable_slow_asserts) |
| 2336 | return; |
| 2337 | |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2338 | for (HeapObject* obj = map_to_evacuate_it_.next(); |
| 2339 | obj != NULL; obj = map_to_evacuate_it_.next()) |
| 2340 | ASSERT(FreeListNode::IsFreeListNode(obj)); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2341 | } |
| 2342 | #endif |
| 2343 | }; |
| 2344 | |
| 2345 | MapCompact::MapUpdatingVisitor MapCompact::map_updating_visitor_; |
| 2346 | |
| 2347 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2348 | void MarkCompactCollector::SweepSpaces() { |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 2349 | GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_SWEEP); |
| 2350 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2351 | ASSERT(state_ == SWEEP_SPACES); |
| 2352 | ASSERT(!IsCompacting()); |
| 2353 | // Noncompacting collections simply sweep the spaces to clear the mark |
| 2354 | // bits and free the nonlive blocks (for old and map spaces). We sweep |
| 2355 | // the map space last because freeing non-live maps overwrites them and |
| 2356 | // the other spaces rely on possibly non-live maps to get the sizes for |
| 2357 | // non-live objects. |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 2358 | SweepSpace(Heap::old_pointer_space()); |
| 2359 | SweepSpace(Heap::old_data_space()); |
| 2360 | SweepSpace(Heap::code_space()); |
| 2361 | SweepSpace(Heap::cell_space()); |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 2362 | { GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_SWEEP_NEWSPACE); |
| 2363 | SweepNewSpace(Heap::new_space()); |
| 2364 | } |
Kristian Monsen | 80d68ea | 2010-09-08 11:05:35 +0100 | [diff] [blame] | 2365 | SweepSpace(Heap::map_space()); |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2366 | |
| 2367 | Heap::IterateDirtyRegions(Heap::map_space(), |
| 2368 | &Heap::IteratePointersInDirtyMapsRegion, |
| 2369 | &UpdatePointerToNewGen, |
| 2370 | Heap::WATERMARK_SHOULD_BE_VALID); |
| 2371 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 2372 | intptr_t live_maps_size = Heap::map_space()->Size(); |
| 2373 | int live_maps = static_cast<int>(live_maps_size / Map::kSize); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2374 | ASSERT(live_map_objects_size_ == live_maps_size); |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2375 | |
| 2376 | if (Heap::map_space()->NeedsCompaction(live_maps)) { |
| 2377 | MapCompact map_compact(live_maps); |
| 2378 | |
| 2379 | map_compact.CompactMaps(); |
| 2380 | map_compact.UpdateMapPointersInRoots(); |
| 2381 | |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2382 | PagedSpaces spaces; |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2383 | for (PagedSpace* space = spaces.next(); |
| 2384 | space != NULL; space = spaces.next()) { |
Leon Clarke | e46be81 | 2010-01-19 14:06:41 +0000 | [diff] [blame] | 2385 | if (space == Heap::map_space()) continue; |
| 2386 | map_compact.UpdateMapPointersInPagedSpace(space); |
| 2387 | } |
| 2388 | map_compact.UpdateMapPointersInNewSpace(); |
| 2389 | map_compact.UpdateMapPointersInLargeObjectSpace(); |
| 2390 | |
| 2391 | map_compact.Finish(); |
| 2392 | } |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2393 | } |
| 2394 | |
| 2395 | |
| 2396 | // Iterate the live objects in a range of addresses (eg, a page or a |
| 2397 | // semispace). The live regions of the range have been linked into a list. |
| 2398 | // The first live region is [first_live_start, first_live_end), and the last |
| 2399 | // address in the range is top. The callback function is used to get the |
| 2400 | // size of each live object. |
| 2401 | int MarkCompactCollector::IterateLiveObjectsInRange( |
| 2402 | Address start, |
| 2403 | Address end, |
| 2404 | HeapObjectCallback size_func) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2405 | int live_objects_size = 0; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2406 | Address current = start; |
| 2407 | while (current < end) { |
| 2408 | uint32_t encoded_map = Memory::uint32_at(current); |
| 2409 | if (encoded_map == kSingleFreeEncoding) { |
| 2410 | current += kPointerSize; |
| 2411 | } else if (encoded_map == kMultiFreeEncoding) { |
| 2412 | current += Memory::int_at(current + kIntSize); |
| 2413 | } else { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2414 | int size = size_func(HeapObject::FromAddress(current)); |
| 2415 | current += size; |
| 2416 | live_objects_size += size; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2417 | } |
| 2418 | } |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2419 | return live_objects_size; |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2420 | } |
| 2421 | |
| 2422 | |
| 2423 | int MarkCompactCollector::IterateLiveObjects(NewSpace* space, |
| 2424 | HeapObjectCallback size_f) { |
| 2425 | ASSERT(MARK_LIVE_OBJECTS < state_ && state_ <= RELOCATE_OBJECTS); |
| 2426 | return IterateLiveObjectsInRange(space->bottom(), space->top(), size_f); |
| 2427 | } |
| 2428 | |
| 2429 | |
| 2430 | int MarkCompactCollector::IterateLiveObjects(PagedSpace* space, |
| 2431 | HeapObjectCallback size_f) { |
| 2432 | ASSERT(MARK_LIVE_OBJECTS < state_ && state_ <= RELOCATE_OBJECTS); |
| 2433 | int total = 0; |
| 2434 | PageIterator it(space, PageIterator::PAGES_IN_USE); |
| 2435 | while (it.has_next()) { |
| 2436 | Page* p = it.next(); |
| 2437 | total += IterateLiveObjectsInRange(p->ObjectAreaStart(), |
| 2438 | p->AllocationTop(), |
| 2439 | size_f); |
| 2440 | } |
| 2441 | return total; |
| 2442 | } |
| 2443 | |
| 2444 | |
| 2445 | // ------------------------------------------------------------------------- |
| 2446 | // Phase 3: Update pointers |
| 2447 | |
| 2448 | // Helper class for updating pointers in HeapObjects. |
| 2449 | class UpdatingVisitor: public ObjectVisitor { |
| 2450 | public: |
| 2451 | void VisitPointer(Object** p) { |
| 2452 | UpdatePointer(p); |
| 2453 | } |
| 2454 | |
| 2455 | void VisitPointers(Object** start, Object** end) { |
| 2456 | // Mark all HeapObject pointers in [start, end) |
| 2457 | for (Object** p = start; p < end; p++) UpdatePointer(p); |
| 2458 | } |
| 2459 | |
| 2460 | void VisitCodeTarget(RelocInfo* rinfo) { |
| 2461 | ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode())); |
| 2462 | Object* target = Code::GetCodeFromTargetAddress(rinfo->target_address()); |
| 2463 | VisitPointer(&target); |
| 2464 | rinfo->set_target_address( |
| 2465 | reinterpret_cast<Code*>(target)->instruction_start()); |
| 2466 | } |
| 2467 | |
Steve Block | 3ce2e20 | 2009-11-05 08:53:23 +0000 | [diff] [blame] | 2468 | void VisitDebugTarget(RelocInfo* rinfo) { |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2469 | ASSERT((RelocInfo::IsJSReturn(rinfo->rmode()) && |
| 2470 | rinfo->IsPatchedReturnSequence()) || |
| 2471 | (RelocInfo::IsDebugBreakSlot(rinfo->rmode()) && |
| 2472 | rinfo->IsPatchedDebugBreakSlotSequence())); |
Steve Block | 3ce2e20 | 2009-11-05 08:53:23 +0000 | [diff] [blame] | 2473 | Object* target = Code::GetCodeFromTargetAddress(rinfo->call_address()); |
| 2474 | VisitPointer(&target); |
| 2475 | rinfo->set_call_address( |
| 2476 | reinterpret_cast<Code*>(target)->instruction_start()); |
| 2477 | } |
| 2478 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2479 | private: |
| 2480 | void UpdatePointer(Object** p) { |
| 2481 | if (!(*p)->IsHeapObject()) return; |
| 2482 | |
| 2483 | HeapObject* obj = HeapObject::cast(*p); |
| 2484 | Address old_addr = obj->address(); |
| 2485 | Address new_addr; |
| 2486 | ASSERT(!Heap::InFromSpace(obj)); |
| 2487 | |
| 2488 | if (Heap::new_space()->Contains(obj)) { |
| 2489 | Address forwarding_pointer_addr = |
| 2490 | Heap::new_space()->FromSpaceLow() + |
| 2491 | Heap::new_space()->ToSpaceOffsetForAddress(old_addr); |
| 2492 | new_addr = Memory::Address_at(forwarding_pointer_addr); |
| 2493 | |
| 2494 | #ifdef DEBUG |
| 2495 | ASSERT(Heap::old_pointer_space()->Contains(new_addr) || |
| 2496 | Heap::old_data_space()->Contains(new_addr) || |
| 2497 | Heap::new_space()->FromSpaceContains(new_addr) || |
| 2498 | Heap::lo_space()->Contains(HeapObject::FromAddress(new_addr))); |
| 2499 | |
| 2500 | if (Heap::new_space()->FromSpaceContains(new_addr)) { |
| 2501 | ASSERT(Heap::new_space()->FromSpaceOffsetForAddress(new_addr) <= |
| 2502 | Heap::new_space()->ToSpaceOffsetForAddress(old_addr)); |
| 2503 | } |
| 2504 | #endif |
| 2505 | |
| 2506 | } else if (Heap::lo_space()->Contains(obj)) { |
| 2507 | // Don't move objects in the large object space. |
| 2508 | return; |
| 2509 | |
| 2510 | } else { |
| 2511 | #ifdef DEBUG |
| 2512 | PagedSpaces spaces; |
| 2513 | PagedSpace* original_space = spaces.next(); |
| 2514 | while (original_space != NULL) { |
| 2515 | if (original_space->Contains(obj)) break; |
| 2516 | original_space = spaces.next(); |
| 2517 | } |
| 2518 | ASSERT(original_space != NULL); |
| 2519 | #endif |
| 2520 | new_addr = MarkCompactCollector::GetForwardingAddressInOldSpace(obj); |
| 2521 | ASSERT(original_space->Contains(new_addr)); |
| 2522 | ASSERT(original_space->MCSpaceOffsetForAddress(new_addr) <= |
| 2523 | original_space->MCSpaceOffsetForAddress(old_addr)); |
| 2524 | } |
| 2525 | |
| 2526 | *p = HeapObject::FromAddress(new_addr); |
| 2527 | |
| 2528 | #ifdef DEBUG |
| 2529 | if (FLAG_gc_verbose) { |
| 2530 | PrintF("update %p : %p -> %p\n", |
| 2531 | reinterpret_cast<Address>(p), old_addr, new_addr); |
| 2532 | } |
| 2533 | #endif |
| 2534 | } |
| 2535 | }; |
| 2536 | |
| 2537 | |
| 2538 | void MarkCompactCollector::UpdatePointers() { |
| 2539 | #ifdef DEBUG |
| 2540 | ASSERT(state_ == ENCODE_FORWARDING_ADDRESSES); |
| 2541 | state_ = UPDATE_POINTERS; |
| 2542 | #endif |
| 2543 | UpdatingVisitor updating_visitor; |
Ben Murdoch | e0cee9b | 2011-05-25 10:26:03 +0100 | [diff] [blame^] | 2544 | RuntimeProfiler::UpdateSamplesAfterCompact(&updating_visitor); |
Steve Block | d0582a6 | 2009-12-15 09:54:21 +0000 | [diff] [blame] | 2545 | Heap::IterateRoots(&updating_visitor, VISIT_ONLY_STRONG); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2546 | GlobalHandles::IterateWeakRoots(&updating_visitor); |
| 2547 | |
Ben Murdoch | f87a203 | 2010-10-22 12:50:53 +0100 | [diff] [blame] | 2548 | // Update the pointer to the head of the weak list of global contexts. |
| 2549 | updating_visitor.VisitPointer(&Heap::global_contexts_list_); |
| 2550 | |
Steve Block | 1e0659c | 2011-05-24 12:43:12 +0100 | [diff] [blame] | 2551 | LiveObjectList::IterateElements(&updating_visitor); |
| 2552 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2553 | int live_maps_size = IterateLiveObjects(Heap::map_space(), |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2554 | &UpdatePointersInOldObject); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2555 | int live_pointer_olds_size = IterateLiveObjects(Heap::old_pointer_space(), |
| 2556 | &UpdatePointersInOldObject); |
| 2557 | int live_data_olds_size = IterateLiveObjects(Heap::old_data_space(), |
| 2558 | &UpdatePointersInOldObject); |
| 2559 | int live_codes_size = IterateLiveObjects(Heap::code_space(), |
| 2560 | &UpdatePointersInOldObject); |
| 2561 | int live_cells_size = IterateLiveObjects(Heap::cell_space(), |
| 2562 | &UpdatePointersInOldObject); |
| 2563 | int live_news_size = IterateLiveObjects(Heap::new_space(), |
| 2564 | &UpdatePointersInNewObject); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2565 | |
| 2566 | // Large objects do not move, the map word can be updated directly. |
| 2567 | LargeObjectIterator it(Heap::lo_space()); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 2568 | for (HeapObject* obj = it.next(); obj != NULL; obj = it.next()) { |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2569 | UpdatePointersInNewObject(obj); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame] | 2570 | } |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2571 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2572 | USE(live_maps_size); |
| 2573 | USE(live_pointer_olds_size); |
| 2574 | USE(live_data_olds_size); |
| 2575 | USE(live_codes_size); |
| 2576 | USE(live_cells_size); |
| 2577 | USE(live_news_size); |
| 2578 | ASSERT(live_maps_size == live_map_objects_size_); |
| 2579 | ASSERT(live_data_olds_size == live_old_data_objects_size_); |
| 2580 | ASSERT(live_pointer_olds_size == live_old_pointer_objects_size_); |
| 2581 | ASSERT(live_codes_size == live_code_objects_size_); |
| 2582 | ASSERT(live_cells_size == live_cell_objects_size_); |
| 2583 | ASSERT(live_news_size == live_young_objects_size_); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2584 | } |
| 2585 | |
| 2586 | |
| 2587 | int MarkCompactCollector::UpdatePointersInNewObject(HeapObject* obj) { |
| 2588 | // Keep old map pointers |
| 2589 | Map* old_map = obj->map(); |
| 2590 | ASSERT(old_map->IsHeapObject()); |
| 2591 | |
| 2592 | Address forwarded = GetForwardingAddressInOldSpace(old_map); |
| 2593 | |
| 2594 | ASSERT(Heap::map_space()->Contains(old_map)); |
| 2595 | ASSERT(Heap::map_space()->Contains(forwarded)); |
| 2596 | #ifdef DEBUG |
| 2597 | if (FLAG_gc_verbose) { |
| 2598 | PrintF("update %p : %p -> %p\n", obj->address(), old_map->address(), |
| 2599 | forwarded); |
| 2600 | } |
| 2601 | #endif |
| 2602 | // Update the map pointer. |
| 2603 | obj->set_map(reinterpret_cast<Map*>(HeapObject::FromAddress(forwarded))); |
| 2604 | |
| 2605 | // We have to compute the object size relying on the old map because |
| 2606 | // map objects are not relocated yet. |
| 2607 | int obj_size = obj->SizeFromMap(old_map); |
| 2608 | |
| 2609 | // Update pointers in the object body. |
| 2610 | UpdatingVisitor updating_visitor; |
| 2611 | obj->IterateBody(old_map->instance_type(), obj_size, &updating_visitor); |
| 2612 | return obj_size; |
| 2613 | } |
| 2614 | |
| 2615 | |
| 2616 | int MarkCompactCollector::UpdatePointersInOldObject(HeapObject* obj) { |
| 2617 | // Decode the map pointer. |
| 2618 | MapWord encoding = obj->map_word(); |
| 2619 | Address map_addr = encoding.DecodeMapAddress(Heap::map_space()); |
| 2620 | ASSERT(Heap::map_space()->Contains(HeapObject::FromAddress(map_addr))); |
| 2621 | |
| 2622 | // At this point, the first word of map_addr is also encoded, cannot |
| 2623 | // cast it to Map* using Map::cast. |
| 2624 | Map* map = reinterpret_cast<Map*>(HeapObject::FromAddress(map_addr)); |
| 2625 | int obj_size = obj->SizeFromMap(map); |
| 2626 | InstanceType type = map->instance_type(); |
| 2627 | |
| 2628 | // Update map pointer. |
| 2629 | Address new_map_addr = GetForwardingAddressInOldSpace(map); |
| 2630 | int offset = encoding.DecodeOffset(); |
| 2631 | obj->set_map_word(MapWord::EncodeAddress(new_map_addr, offset)); |
| 2632 | |
| 2633 | #ifdef DEBUG |
| 2634 | if (FLAG_gc_verbose) { |
| 2635 | PrintF("update %p : %p -> %p\n", obj->address(), |
| 2636 | map_addr, new_map_addr); |
| 2637 | } |
| 2638 | #endif |
| 2639 | |
| 2640 | // Update pointers in the object body. |
| 2641 | UpdatingVisitor updating_visitor; |
| 2642 | obj->IterateBody(type, obj_size, &updating_visitor); |
| 2643 | return obj_size; |
| 2644 | } |
| 2645 | |
| 2646 | |
| 2647 | Address MarkCompactCollector::GetForwardingAddressInOldSpace(HeapObject* obj) { |
| 2648 | // Object should either in old or map space. |
| 2649 | MapWord encoding = obj->map_word(); |
| 2650 | |
| 2651 | // Offset to the first live object's forwarding address. |
| 2652 | int offset = encoding.DecodeOffset(); |
| 2653 | Address obj_addr = obj->address(); |
| 2654 | |
| 2655 | // Find the first live object's forwarding address. |
| 2656 | Page* p = Page::FromAddress(obj_addr); |
| 2657 | Address first_forwarded = p->mc_first_forwarded; |
| 2658 | |
| 2659 | // Page start address of forwarded address. |
| 2660 | Page* forwarded_page = Page::FromAddress(first_forwarded); |
| 2661 | int forwarded_offset = forwarded_page->Offset(first_forwarded); |
| 2662 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2663 | // Find end of allocation in the page of first_forwarded. |
| 2664 | int mc_top_offset = forwarded_page->AllocationWatermarkOffset(); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2665 | |
| 2666 | // Check if current object's forward pointer is in the same page |
| 2667 | // as the first live object's forwarding pointer |
| 2668 | if (forwarded_offset + offset < mc_top_offset) { |
| 2669 | // In the same page. |
| 2670 | return first_forwarded + offset; |
| 2671 | } |
| 2672 | |
| 2673 | // Must be in the next page, NOTE: this may cross chunks. |
| 2674 | Page* next_page = forwarded_page->next_page(); |
| 2675 | ASSERT(next_page->is_valid()); |
| 2676 | |
| 2677 | offset -= (mc_top_offset - forwarded_offset); |
| 2678 | offset += Page::kObjectStartOffset; |
| 2679 | |
| 2680 | ASSERT_PAGE_OFFSET(offset); |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2681 | ASSERT(next_page->OffsetToAddress(offset) < next_page->AllocationTop()); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2682 | |
| 2683 | return next_page->OffsetToAddress(offset); |
| 2684 | } |
| 2685 | |
| 2686 | |
| 2687 | // ------------------------------------------------------------------------- |
| 2688 | // Phase 4: Relocate objects |
| 2689 | |
| 2690 | void MarkCompactCollector::RelocateObjects() { |
| 2691 | #ifdef DEBUG |
| 2692 | ASSERT(state_ == UPDATE_POINTERS); |
| 2693 | state_ = RELOCATE_OBJECTS; |
| 2694 | #endif |
| 2695 | // Relocates objects, always relocate map objects first. Relocating |
| 2696 | // objects in other space relies on map objects to get object size. |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2697 | int live_maps_size = IterateLiveObjects(Heap::map_space(), |
| 2698 | &RelocateMapObject); |
| 2699 | int live_pointer_olds_size = IterateLiveObjects(Heap::old_pointer_space(), |
| 2700 | &RelocateOldPointerObject); |
| 2701 | int live_data_olds_size = IterateLiveObjects(Heap::old_data_space(), |
| 2702 | &RelocateOldDataObject); |
| 2703 | int live_codes_size = IterateLiveObjects(Heap::code_space(), |
| 2704 | &RelocateCodeObject); |
| 2705 | int live_cells_size = IterateLiveObjects(Heap::cell_space(), |
| 2706 | &RelocateCellObject); |
| 2707 | int live_news_size = IterateLiveObjects(Heap::new_space(), |
| 2708 | &RelocateNewObject); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2709 | |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2710 | USE(live_maps_size); |
| 2711 | USE(live_pointer_olds_size); |
| 2712 | USE(live_data_olds_size); |
| 2713 | USE(live_codes_size); |
| 2714 | USE(live_cells_size); |
| 2715 | USE(live_news_size); |
| 2716 | ASSERT(live_maps_size == live_map_objects_size_); |
| 2717 | ASSERT(live_data_olds_size == live_old_data_objects_size_); |
| 2718 | ASSERT(live_pointer_olds_size == live_old_pointer_objects_size_); |
| 2719 | ASSERT(live_codes_size == live_code_objects_size_); |
| 2720 | ASSERT(live_cells_size == live_cell_objects_size_); |
| 2721 | ASSERT(live_news_size == live_young_objects_size_); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2722 | |
| 2723 | // Flip from and to spaces |
| 2724 | Heap::new_space()->Flip(); |
| 2725 | |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2726 | Heap::new_space()->MCCommitRelocationInfo(); |
| 2727 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2728 | // Set age_mark to bottom in to space |
| 2729 | Address mark = Heap::new_space()->bottom(); |
| 2730 | Heap::new_space()->set_age_mark(mark); |
| 2731 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2732 | PagedSpaces spaces; |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2733 | for (PagedSpace* space = spaces.next(); space != NULL; space = spaces.next()) |
| 2734 | space->MCCommitRelocationInfo(); |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2735 | |
| 2736 | Heap::CheckNewSpaceExpansionCriteria(); |
| 2737 | Heap::IncrementYoungSurvivorsCounter(live_news_size); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2738 | } |
| 2739 | |
| 2740 | |
| 2741 | int MarkCompactCollector::RelocateMapObject(HeapObject* obj) { |
| 2742 | // Recover map pointer. |
| 2743 | MapWord encoding = obj->map_word(); |
| 2744 | Address map_addr = encoding.DecodeMapAddress(Heap::map_space()); |
| 2745 | ASSERT(Heap::map_space()->Contains(HeapObject::FromAddress(map_addr))); |
| 2746 | |
| 2747 | // Get forwarding address before resetting map pointer |
| 2748 | Address new_addr = GetForwardingAddressInOldSpace(obj); |
| 2749 | |
| 2750 | // Reset map pointer. The meta map object may not be copied yet so |
| 2751 | // Map::cast does not yet work. |
| 2752 | obj->set_map(reinterpret_cast<Map*>(HeapObject::FromAddress(map_addr))); |
| 2753 | |
| 2754 | Address old_addr = obj->address(); |
| 2755 | |
| 2756 | if (new_addr != old_addr) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2757 | // Move contents. |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2758 | Heap::MoveBlockToOldSpaceAndUpdateRegionMarks(new_addr, |
| 2759 | old_addr, |
| 2760 | Map::kSize); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2761 | } |
| 2762 | |
| 2763 | #ifdef DEBUG |
| 2764 | if (FLAG_gc_verbose) { |
| 2765 | PrintF("relocate %p -> %p\n", old_addr, new_addr); |
| 2766 | } |
| 2767 | #endif |
| 2768 | |
| 2769 | return Map::kSize; |
| 2770 | } |
| 2771 | |
| 2772 | |
| 2773 | static inline int RestoreMap(HeapObject* obj, |
| 2774 | PagedSpace* space, |
| 2775 | Address new_addr, |
| 2776 | Address map_addr) { |
| 2777 | // This must be a non-map object, and the function relies on the |
| 2778 | // assumption that the Map space is compacted before the other paged |
| 2779 | // spaces (see RelocateObjects). |
| 2780 | |
| 2781 | // Reset map pointer. |
| 2782 | obj->set_map(Map::cast(HeapObject::FromAddress(map_addr))); |
| 2783 | |
| 2784 | int obj_size = obj->Size(); |
| 2785 | ASSERT_OBJECT_SIZE(obj_size); |
| 2786 | |
| 2787 | ASSERT(space->MCSpaceOffsetForAddress(new_addr) <= |
| 2788 | space->MCSpaceOffsetForAddress(obj->address())); |
| 2789 | |
| 2790 | #ifdef DEBUG |
| 2791 | if (FLAG_gc_verbose) { |
| 2792 | PrintF("relocate %p -> %p\n", obj->address(), new_addr); |
| 2793 | } |
| 2794 | #endif |
| 2795 | |
| 2796 | return obj_size; |
| 2797 | } |
| 2798 | |
| 2799 | |
| 2800 | int MarkCompactCollector::RelocateOldNonCodeObject(HeapObject* obj, |
| 2801 | PagedSpace* space) { |
| 2802 | // Recover map pointer. |
| 2803 | MapWord encoding = obj->map_word(); |
| 2804 | Address map_addr = encoding.DecodeMapAddress(Heap::map_space()); |
| 2805 | ASSERT(Heap::map_space()->Contains(map_addr)); |
| 2806 | |
| 2807 | // Get forwarding address before resetting map pointer. |
| 2808 | Address new_addr = GetForwardingAddressInOldSpace(obj); |
| 2809 | |
| 2810 | // Reset the map pointer. |
| 2811 | int obj_size = RestoreMap(obj, space, new_addr, map_addr); |
| 2812 | |
| 2813 | Address old_addr = obj->address(); |
| 2814 | |
| 2815 | if (new_addr != old_addr) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2816 | // Move contents. |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2817 | if (space == Heap::old_data_space()) { |
| 2818 | Heap::MoveBlock(new_addr, old_addr, obj_size); |
| 2819 | } else { |
| 2820 | Heap::MoveBlockToOldSpaceAndUpdateRegionMarks(new_addr, |
| 2821 | old_addr, |
| 2822 | obj_size); |
| 2823 | } |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2824 | } |
| 2825 | |
| 2826 | ASSERT(!HeapObject::FromAddress(new_addr)->IsCode()); |
| 2827 | |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2828 | HeapObject* copied_to = HeapObject::FromAddress(new_addr); |
Ben Murdoch | e0cee9b | 2011-05-25 10:26:03 +0100 | [diff] [blame^] | 2829 | if (copied_to->IsSharedFunctionInfo()) { |
| 2830 | PROFILE(SFIMoveEvent(old_addr, new_addr)); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2831 | } |
Ben Murdoch | 3bec4d2 | 2010-07-22 14:51:16 +0100 | [diff] [blame] | 2832 | HEAP_PROFILE(ObjectMoveEvent(old_addr, new_addr)); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2833 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2834 | return obj_size; |
| 2835 | } |
| 2836 | |
| 2837 | |
| 2838 | int MarkCompactCollector::RelocateOldPointerObject(HeapObject* obj) { |
| 2839 | return RelocateOldNonCodeObject(obj, Heap::old_pointer_space()); |
| 2840 | } |
| 2841 | |
| 2842 | |
| 2843 | int MarkCompactCollector::RelocateOldDataObject(HeapObject* obj) { |
| 2844 | return RelocateOldNonCodeObject(obj, Heap::old_data_space()); |
| 2845 | } |
| 2846 | |
| 2847 | |
| 2848 | int MarkCompactCollector::RelocateCellObject(HeapObject* obj) { |
| 2849 | return RelocateOldNonCodeObject(obj, Heap::cell_space()); |
| 2850 | } |
| 2851 | |
| 2852 | |
| 2853 | int MarkCompactCollector::RelocateCodeObject(HeapObject* obj) { |
| 2854 | // Recover map pointer. |
| 2855 | MapWord encoding = obj->map_word(); |
| 2856 | Address map_addr = encoding.DecodeMapAddress(Heap::map_space()); |
| 2857 | ASSERT(Heap::map_space()->Contains(HeapObject::FromAddress(map_addr))); |
| 2858 | |
| 2859 | // Get forwarding address before resetting map pointer |
| 2860 | Address new_addr = GetForwardingAddressInOldSpace(obj); |
| 2861 | |
| 2862 | // Reset the map pointer. |
| 2863 | int obj_size = RestoreMap(obj, Heap::code_space(), new_addr, map_addr); |
| 2864 | |
| 2865 | Address old_addr = obj->address(); |
| 2866 | |
| 2867 | if (new_addr != old_addr) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2868 | // Move contents. |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2869 | Heap::MoveBlock(new_addr, old_addr, obj_size); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2870 | } |
| 2871 | |
| 2872 | HeapObject* copied_to = HeapObject::FromAddress(new_addr); |
| 2873 | if (copied_to->IsCode()) { |
| 2874 | // May also update inline cache target. |
| 2875 | Code::cast(copied_to)->Relocate(new_addr - old_addr); |
| 2876 | // Notify the logger that compiled code has moved. |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2877 | PROFILE(CodeMoveEvent(old_addr, new_addr)); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2878 | } |
Ben Murdoch | 3bec4d2 | 2010-07-22 14:51:16 +0100 | [diff] [blame] | 2879 | HEAP_PROFILE(ObjectMoveEvent(old_addr, new_addr)); |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2880 | |
| 2881 | return obj_size; |
| 2882 | } |
| 2883 | |
| 2884 | |
| 2885 | int MarkCompactCollector::RelocateNewObject(HeapObject* obj) { |
| 2886 | int obj_size = obj->Size(); |
| 2887 | |
| 2888 | // Get forwarding address |
| 2889 | Address old_addr = obj->address(); |
| 2890 | int offset = Heap::new_space()->ToSpaceOffsetForAddress(old_addr); |
| 2891 | |
| 2892 | Address new_addr = |
| 2893 | Memory::Address_at(Heap::new_space()->FromSpaceLow() + offset); |
| 2894 | |
| 2895 | #ifdef DEBUG |
| 2896 | if (Heap::new_space()->FromSpaceContains(new_addr)) { |
| 2897 | ASSERT(Heap::new_space()->FromSpaceOffsetForAddress(new_addr) <= |
| 2898 | Heap::new_space()->ToSpaceOffsetForAddress(old_addr)); |
| 2899 | } else { |
| 2900 | ASSERT(Heap::TargetSpace(obj) == Heap::old_pointer_space() || |
| 2901 | Heap::TargetSpace(obj) == Heap::old_data_space()); |
| 2902 | } |
| 2903 | #endif |
| 2904 | |
| 2905 | // New and old addresses cannot overlap. |
Ben Murdoch | 7f4d5bd | 2010-06-15 11:15:29 +0100 | [diff] [blame] | 2906 | if (Heap::InNewSpace(HeapObject::FromAddress(new_addr))) { |
| 2907 | Heap::CopyBlock(new_addr, old_addr, obj_size); |
| 2908 | } else { |
| 2909 | Heap::CopyBlockToOldSpaceAndUpdateRegionMarks(new_addr, |
| 2910 | old_addr, |
| 2911 | obj_size); |
| 2912 | } |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2913 | |
| 2914 | #ifdef DEBUG |
| 2915 | if (FLAG_gc_verbose) { |
| 2916 | PrintF("relocate %p -> %p\n", old_addr, new_addr); |
| 2917 | } |
| 2918 | #endif |
| 2919 | |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2920 | HeapObject* copied_to = HeapObject::FromAddress(new_addr); |
Ben Murdoch | e0cee9b | 2011-05-25 10:26:03 +0100 | [diff] [blame^] | 2921 | if (copied_to->IsSharedFunctionInfo()) { |
| 2922 | PROFILE(SFIMoveEvent(old_addr, new_addr)); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2923 | } |
Ben Murdoch | 3bec4d2 | 2010-07-22 14:51:16 +0100 | [diff] [blame] | 2924 | HEAP_PROFILE(ObjectMoveEvent(old_addr, new_addr)); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2925 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2926 | return obj_size; |
| 2927 | } |
| 2928 | |
| 2929 | |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2930 | void MarkCompactCollector::ReportDeleteIfNeeded(HeapObject* obj) { |
Ben Murdoch | b8e0da2 | 2011-05-16 14:20:40 +0100 | [diff] [blame] | 2931 | #ifdef ENABLE_GDB_JIT_INTERFACE |
| 2932 | if (obj->IsCode()) { |
| 2933 | GDBJITInterface::RemoveCode(reinterpret_cast<Code*>(obj)); |
| 2934 | } |
| 2935 | #endif |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2936 | #ifdef ENABLE_LOGGING_AND_PROFILING |
| 2937 | if (obj->IsCode()) { |
Steve Block | 6ded16b | 2010-05-10 14:33:55 +0100 | [diff] [blame] | 2938 | PROFILE(CodeDeleteEvent(obj->address())); |
Leon Clarke | d91b9f7 | 2010-01-27 17:25:45 +0000 | [diff] [blame] | 2939 | } |
| 2940 | #endif |
| 2941 | } |
| 2942 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 2943 | |
Shimeng (Simon) Wang | 8a31eba | 2010-12-06 19:01:33 -0800 | [diff] [blame] | 2944 | int MarkCompactCollector::SizeOfMarkedObject(HeapObject* obj) { |
| 2945 | MapWord map_word = obj->map_word(); |
| 2946 | map_word.ClearMark(); |
| 2947 | return obj->SizeFromMap(map_word.ToMap()); |
| 2948 | } |
| 2949 | |
| 2950 | |
Iain Merrick | 7568138 | 2010-08-19 15:07:18 +0100 | [diff] [blame] | 2951 | void MarkCompactCollector::Initialize() { |
| 2952 | StaticPointersToNewGenUpdatingVisitor::Initialize(); |
| 2953 | StaticMarkingVisitor::Initialize(); |
| 2954 | } |
| 2955 | |
| 2956 | |
Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame] | 2957 | } } // namespace v8::internal |