[heap] Cleanup: Remove WAS_SWEPT flag.

src/heap/spaces.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ skipping 289 matching lines @@
     POINTERS_FROM_HERE_ARE_INTERESTING,
     SCAN_ON_SCAVENGE,
     IN_FROM_SPACE,  // Mutually exclusive with IN_TO_SPACE.
     IN_TO_SPACE,    // All pages in new space has one of these two set.
     NEW_SPACE_BELOW_AGE_MARK,
     EVACUATION_CANDIDATE,
     RESCAN_ON_EVACUATION,
     NEVER_EVACUATE,  // May contain immortal immutables.
     POPULAR_PAGE,    // Slots buffer of this page overflowed on the previous GC.
 
-    // WAS_SWEPT indicates that marking bits have been cleared by the sweeper,
-    // otherwise marking bits are still intact.
-    WAS_SWEPT,
-
     // Large objects can have a progress bar in their page header. These object
     // are scanned in increments and will be kept black while being scanned.
     // Even if the mutator writes to them they will be kept black and a white
     // to grey transition is performed in the value.
     HAS_PROGRESS_BAR,
 
     // This flag is intended to be used for testing. Works only when both
     // FLAG_stress_compaction and FLAG_manual_evacuation_candidates_selection
     // are set. It forces the page to become an evacuation candidate at next
     // candidates selection cycle.
@@ skipping 21 matching lines @@
   // |kCompactingAborted|: Parallel compaction has been aborted, which should
   //   for now only happen in OOM scenarios.
   enum ParallelCompactingState {
     kCompactingDone,
     kCompactingInProgress,
     kCompactingFinalize,
     kCompactingAborted,
   };
 
   // |kSweepingDone|: The page state when sweeping is complete or sweeping must
-  //   not be performed on that page.
-  // |kSweepingFinalize|: A sweeper thread is done sweeping this page and will
-  //   not touch the page memory anymore.
+  //   not be performed on that page. Sweeper threads that are done with their
+  //   work will set this value and not touch the page anymore.
+  // |kSweepingPending|: This page is ready for parallel sweeping.
   // |kSweepingInProgress|: This page is currently swept by a sweeper thread.
-  // |kSweepingPending|: This page is ready for parallel sweeping.
-  enum ParallelSweepingState {
+  enum ConcurrentSweepingState {
     kSweepingDone,
-    kSweepingFinalize,
+    kSweepingPending,
     kSweepingInProgress,
-    kSweepingPending
   };
 
   // Every n write barrier invocations we go to runtime even though
   // we could have handled it in generated code.  This lets us check
   // whether we have hit the limit and should do some more marking.
   static const int kWriteBarrierCounterGranularity = 500;
 
   static const int kPointersToHereAreInterestingMask =
       1 << POINTERS_TO_HERE_ARE_INTERESTING;
 
@@ skipping 173 matching lines @@
   // Set or clear multiple flags at a time. The flags in the mask
   // are set to the value in "flags", the rest retain the current value
   // in flags_.
   void SetFlags(intptr_t flags, intptr_t mask) {
     flags_ = (flags_ & ~mask) | (flags & mask);
   }
 
   // Return all current flags.
   intptr_t GetFlags() { return flags_; }
 
-  AtomicValue<ParallelSweepingState>& parallel_sweeping_state() {
-    return parallel_sweeping_;
+  AtomicValue<ConcurrentSweepingState>& concurrent_sweeping_state() {
+    return concurrent_sweeping_;
   }
 
   AtomicValue<ParallelCompactingState>& parallel_compaction_state() {
     return parallel_compaction_;
   }
 
   bool TryLock() { return mutex_->TryLock(); }
 
   base::Mutex* mutex() { return mutex_; }
 
-  // WaitUntilSweepingCompleted only works when concurrent sweeping is in
-  // progress. In particular, when we know that right before this call a
-  // sweeper thread was sweeping this page.
-  void WaitUntilSweepingCompleted() {
-    mutex_->Lock();
-    mutex_->Unlock();
-    DCHECK(SweepingCompleted());
-  }
-
-  bool SweepingCompleted() {
-    return parallel_sweeping_state().Value() <= kSweepingFinalize;
-  }
-
   // Manage live byte count (count of bytes known to be live,
   // because they are marked black).
   void ResetLiveBytes() {
     if (FLAG_gc_verbose) {
       PrintF("ResetLiveBytes:%p:%x->0\n", static_cast<void*>(this),
              live_byte_count_);
     }
     live_byte_count_ = 0;
   }
 
@@ skipping 158 matching lines @@
   // Count of bytes marked black on page.
   int live_byte_count_;
   SlotsBuffer* slots_buffer_;
   SkipList* skip_list_;
   intptr_t write_barrier_counter_;
   // Assuming the initial allocation on a page is sequential,
   // count highest number of bytes ever allocated on the page.
   AtomicValue<intptr_t> high_water_mark_;
 
   base::Mutex* mutex_;
-  AtomicValue<ParallelSweepingState> parallel_sweeping_;
+  AtomicValue<ConcurrentSweepingState> concurrent_sweeping_;
   AtomicValue<ParallelCompactingState> parallel_compaction_;
 
   // PagedSpace free-list statistics.
   AtomicNumber<intptr_t> available_in_small_free_list_;
   AtomicNumber<intptr_t> available_in_medium_free_list_;
   AtomicNumber<intptr_t> available_in_large_free_list_;
   AtomicNumber<intptr_t> available_in_huge_free_list_;
   AtomicNumber<intptr_t> non_available_small_blocks_;
 
   // next_chunk_ holds a pointer of type MemoryChunk
@@ skipping 85 matching lines @@
   // Page size mask.
   static const intptr_t kPageAlignmentMask = (1 << kPageSizeBits) - 1;
 
   inline void ClearGCFields();
 
   static inline Page* Initialize(Heap* heap, MemoryChunk* chunk,
                                  Executability executable, PagedSpace* owner);
 
   void InitializeAsAnchor(PagedSpace* owner);
 
-  bool WasSwept() { return IsFlagSet(WAS_SWEPT); }
-  void SetWasSwept() { SetFlag(WAS_SWEPT); }
-  void ClearWasSwept() { ClearFlag(WAS_SWEPT); }
+  // WaitUntilSweepingCompleted only works when concurrent sweeping is in
+  // progress. In particular, when we know that right before this call a
+  // sweeper thread was sweeping this page.
+  void WaitUntilSweepingCompleted() {
+    mutex_->Lock();
+    mutex_->Unlock();
+    DCHECK(SweepingCompleted());
+  }
+
+  bool SweepingCompleted() {

[Hannes Payer (out of office), 2016/01/25 11:15:44]

Let's rename that to SweepingDone to reflect the actual state.

[Michael Lippautz, 2016/01/25 11:46:39]

Done.

+    return concurrent_sweeping_state().Value() == kSweepingDone;
+  }
 
   void ResetFreeListStatistics();
 
   int LiveBytesFromFreeList() {
     return static_cast<int>(
         area_size() - non_available_small_blocks() -
         available_in_small_free_list() - available_in_medium_free_list() -
         available_in_large_free_list() - available_in_huge_free_list());
   }
 
@@ skipping 1189 matching lines @@
     int old_linear_size = static_cast<int>(limit() - top());
     Free(top(), old_linear_size);
     SetTopAndLimit(NULL, NULL);
   }
 
   void Allocate(int bytes) { accounting_stats_.AllocateBytes(bytes); }
 
   void IncreaseCapacity(int size);
 
   // Releases an unused page and shrinks the space.
-  void ReleasePage(Page* page);
+  void ReleasePage(Page* page, bool evict_free_list_items);
 
   // The dummy page that anchors the linked list of pages.
   Page* anchor() { return &anchor_; }
 
 #ifdef VERIFY_HEAP
   // Verify integrity of this space.
   virtual void Verify(ObjectVisitor* visitor);
 
   // Overridden by subclasses to verify space-specific object
   // properties (e.g., only maps or free-list nodes are in map space).
   virtual void VerifyObject(HeapObject* obj) {}
 #endif
 
 #ifdef DEBUG
   // Print meta info and objects in this space.
   void Print() override;
 
   // Reports statistics for the space
   void ReportStatistics();
 
   // Report code object related statistics
   void CollectCodeStatistics();
   static void ReportCodeStatistics(Isolate* isolate);
   static void ResetCodeStatistics(Isolate* isolate);
 #endif
 
-  // Evacuation candidates are swept by evacuator.  Needs to return a valid
-  // result before _and_ after evacuation has finished.
-  static bool ShouldBeSweptBySweeperThreads(Page* p) {
-    return !p->IsEvacuationCandidate() &&
-           !p->IsFlagSet(Page::RESCAN_ON_EVACUATION) && !p->WasSwept();
-  }
-
   // This function tries to steal size_in_bytes memory from the sweeper threads
   // free-lists. If it does not succeed stealing enough memory, it will wait
   // for the sweeper threads to finish sweeping.
   // It returns true when sweeping is completed and false otherwise.
   bool EnsureSweeperProgress(intptr_t size_in_bytes);
 
   Page* FirstPage() { return anchor_.next_page(); }
   Page* LastPage() { return anchor_.prev_page(); }
 
   void EvictEvacuationCandidatesFromLinearAllocationArea();
@@ skipping 1088 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_