heap: Remove dead code in compaction and update style

Change-Id: I44f7b77fc6ae86cbc3ad54b12e2229e5e6db1aee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1581339
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653531}

third_party/blink/renderer/platform/heap/heap_compact.cc

@@ -124,12 +124,6 @@ class HeapCompact::MovableObjectFixups final {
         slot, std::pair<void*, MovingObjectCallback>(callback_data, callback));
   }
 
-  void RemoveFixupCallback(MovableReference* slot) {
-    auto it = fixup_callbacks_.find(slot);
-    if (it != fixup_callbacks_.end())
-      fixup_callbacks_.erase(it);
-  }
-
   void RelocateInteriorFixups(Address from, Address to, size_t size) {
     SparseHeapBitmap* range = interiors_->HasRange(from, size);
     if (LIKELY(!range))
@@ -271,7 +265,7 @@ class HeapCompact::MovableObjectFixups final {
  private:
   void VerifyUpdatedSlot(MovableReference* slot);
 
-  ThreadHeap* heap_;
+  ThreadHeap* const heap_;
 
   // Tracking movable and updatable references. For now, we keep a
   // map which for each movable object, recording the slot that
@@ -321,13 +315,7 @@ void HeapCompact::MovableObjectFixups::VerifyUpdatedSlot(
 #endif  // DCHECK_IS_ON()
 }
 
-HeapCompact::HeapCompact(ThreadHeap* heap)
-    : heap_(heap),
-      do_compact_(false),
-      gc_count_since_last_compaction_(0),
-      free_list_size_(0),
-      compactable_arenas_(0u),
-      last_fixup_count_for_testing_(0) {
+HeapCompact::HeapCompact(ThreadHeap* heap) : heap_(heap) {
   // The heap compaction implementation assumes the contiguous range,
   //
   //   [Vector1ArenaIndex, HashTableArenaIndex]
@@ -420,13 +408,6 @@ void HeapCompact::Initialize(ThreadState* state) {
   force_compaction_gc_ = false;
 }
 
-void HeapCompact::RemoveSlot(MovableReference* slot) {
-  auto it = traced_slots_.find(slot);
-  if (it != traced_slots_.end())
-    traced_slots_.erase(it);
-  Fixups().RemoveFixupCallback(slot);
-}
-
 void HeapCompact::RegisterMovingObjectReference(MovableReference* slot) {
   CHECK(heap_->LookupPageForAddress(reinterpret_cast<Address>(slot)));
 

third_party/blink/renderer/platform/heap/heap_compact.h

@@ -52,10 +52,6 @@ class PLATFORM_EXPORT HeapCompact final {
   explicit HeapCompact(ThreadHeap*);
   ~HeapCompact();
 
-  // Remove slot from traced_slots_ when a registered slot is destructed by
-  // mutator
-  void RemoveSlot(MovableReference* slot);
-
   // Determine if a GC for the given type and reason should also perform
   // additional heap compaction.
   //
@@ -143,13 +139,7 @@ class PLATFORM_EXPORT HeapCompact final {
  private:
   class MovableObjectFixups;
 
-  // Sample the amount of fragmentation and heap memory currently residing
-  // on the freelists of the arenas we're able to compact. The computed
-  // numbers will be subsequently used to determine if a heap compaction
-  // is on order (shouldCompact().)
-  void UpdateHeapResidency();
-
-  // Parameters controlling when compaction should be done:
+  static bool force_compaction_gc_;
 
   // Number of GCs that must have passed since last compaction GC.
   static const int kGCCountSinceLastCompactionThreshold = 10;
@@ -158,32 +148,35 @@ class PLATFORM_EXPORT HeapCompact final {
   // should be considered.
   static const size_t kFreeListSizeThreshold = 512 * 1024;
 
-  ThreadHeap* const heap_;
+  // Sample the amount of fragmentation and heap memory currently residing
+  // on the freelists of the arenas we're able to compact. The computed
+  // numbers will be subsequently used to determine if a heap compaction
+  // is on order (shouldCompact().)
+  void UpdateHeapResidency();
 
   MovableObjectFixups& Fixups();
 
+  ThreadHeap* const heap_;
   std::unique_ptr<MovableObjectFixups> fixups_;
 
+  // The set is to remember slots that traced during
+  // marking phases. The mapping between the slots and the backing stores are
+  // created at the atomic pause phase.
+  HashSet<MovableReference*> traced_slots_;
+
   // Set to |true| when a compacting sweep will go ahead.
-  bool do_compact_;
-  size_t gc_count_since_last_compaction_;
+  bool do_compact_ = false;
+  size_t gc_count_since_last_compaction_ = 0;
 
   // Last reported freelist size, across all compactable arenas.
-  size_t free_list_size_;
+  size_t free_list_size_ = 0;
+
+  size_t last_fixup_count_for_testing_ = 0;
 
   // If compacting, i'th heap arena will be compacted
   // if corresponding bit is set. Indexes are in
   // the range of BlinkGC::ArenaIndices.
-  unsigned compactable_arenas_;
-
-  // The set is to remember slots that traced during
-  // marking phases. The mapping between the slots and the backing stores are
-  // created at the atomic pause phase.
-  HashSet<MovableReference*> traced_slots_;
-
-  size_t last_fixup_count_for_testing_;
-
-  static bool force_compaction_gc_;
+  unsigned compactable_arenas_ = 0u;
 };
 
 }  // namespace blink