[heap] Remove unswept bytes counter

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 038cb1cc17a0f3645de3392ed4d557258acdfd4e..0720e9c30965e153c190bfe3e0ae5dd0217108f8 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -1454,8 +1454,9 @@ class AllocationStats BASE_EMBEDDED {
   // Zero out all the allocation statistics (i.e., no capacity).
   void Clear() {
     capacity_ = 0;
-    max_capacity_ = 0;
     size_ = 0;
+    committed_ = 0;
+    max_committed_ = 0;
   }
 
   void ClearSize() { size_ = capacity_; }
@@ -1468,8 +1469,9 @@ class AllocationStats BASE_EMBEDDED {
 
   // Accessors for the allocation statistics.
   intptr_t Capacity() { return capacity_; }
-  intptr_t MaxCapacity() { return max_capacity_; }
   intptr_t Size() { return size_; }
+  intptr_t Committed() { return committed_; }
+  intptr_t MaxCommitted() { return max_committed_; }
 
   // Grow the space by adding available bytes.  They are initially marked as
   // being in use (part of the size), but will normally be immediately freed,
@@ -1477,9 +1479,6 @@ class AllocationStats BASE_EMBEDDED {
   void ExpandSpace(int size_in_bytes) {
     capacity_ += size_in_bytes;
     size_ += size_in_bytes;
-    if (capacity_ > max_capacity_) {
-      max_capacity_ = capacity_;
-    }
     DCHECK(size_ >= 0);
   }
 
@@ -1501,35 +1500,56 @@ class AllocationStats BASE_EMBEDDED {
   // Free allocated bytes, making them available (size -> available).
   void DeallocateBytes(intptr_t size_in_bytes) {
     size_ -= size_in_bytes;
-    DCHECK(size_ >= 0);
+    DCHECK_GE(size_, 0);
   }
 
   // Merge {other} into {this}.
   void Merge(const AllocationStats& other) {
     capacity_ += other.capacity_;
     size_ += other.size_;
-    if (other.max_capacity_ > max_capacity_) {
-      max_capacity_ = other.max_capacity_;
+    committed_ += other.committed_;
+    if (committed_ > max_committed_) {
+      max_committed_ = committed_;
     }
   }
 
   void DecreaseCapacity(intptr_t size_in_bytes) {
     capacity_ -= size_in_bytes;
     DCHECK_GE(capacity_, 0);
+    DCHECK_GE(capacity_, size_);
   }
 
   void IncreaseCapacity(intptr_t size_in_bytes) { capacity_ += size_in_bytes; }
 
+  void CommitMemory(intptr_t size_in_bytes) {
+    DCHECK_GE(size_in_bytes, 0);
+    committed_ += size_in_bytes;
+    if (committed_ > max_committed_) {
+      max_committed_ = committed_;
+    }
+  }
+
+  void UncommitMemory(intptr_t size_in_bytes) {
+    DCHECK_GE(size_in_bytes, 0);
+    DCHECK_GE(committed_, size_in_bytes);
+    committed_ -= size_in_bytes;
+  }
+
  private:
   // |capacity_|: The number of object-area bytes (i.e., not including page
-  // bookkeeping structures) currently in the space.
+  //   bookkeeping structures) currently in the space.
   intptr_t capacity_;
 
-  // |max_capacity_|: The maximum capacity ever observed.
-  intptr_t max_capacity_;
-
   // |size_|: The number of allocated bytes.
   intptr_t size_;
+
+  // |committed_|: The number of bytes committed in the corresponding space,
+  //   including page headers. Note that committed memory does not need to
+  //   be larger than capacity/size, as memory can be moved to other spaces.
+  intptr_t committed_;
+
+  // |max_committed_|: The maximum number of bytes committed ever observed.
+  intptr_t max_committed_;
 };
 
 
@@ -1630,6 +1650,10 @@ class FreeList {
  public:
   explicit FreeList(PagedSpace* owner);
 
+  // The method concatenates {other} into {this} and returns the added bytes,
+  // including waste.
+  //
+  // Can be used concurrently.
   intptr_t Concatenate(FreeList* other);
 
   // Clear the free list.
@@ -1808,12 +1832,11 @@ class PagedSpace : public Space {
   // Current capacity without growing (Size() + Available()).
   intptr_t Capacity() { return accounting_stats_.Capacity(); }
 
-  // Total amount of memory committed for this space.  For paged
-  // spaces this equals the capacity.
-  intptr_t CommittedMemory() override { return Capacity(); }
+  // Total amount of memory committed for this space.
+  intptr_t CommittedMemory() override { return accounting_stats_.Committed(); }
 
   // The maximum amount of memory ever committed for this space.
-  intptr_t MaximumCommittedMemory() { return accounting_stats_.MaxCapacity(); }
+  intptr_t MaximumCommittedMemory() { return accounting_stats_.MaxCommitted(); }
 
   // Approximate amount of physical memory committed for this space.
   size_t CommittedPhysicalMemory() override;
@@ -1955,22 +1978,6 @@ class PagedSpace : public Space {
            !p->IsFlagSet(Page::RESCAN_ON_EVACUATION) && !p->WasSwept();
   }
 
-  void IncrementUnsweptFreeBytes(intptr_t by) { unswept_free_bytes_ += by; }
-
-  void IncreaseUnsweptFreeBytes(Page* p) {
-    DCHECK(ShouldBeSweptBySweeperThreads(p));
-    unswept_free_bytes_ += (p->area_size() - p->LiveBytes());
-  }
-
-  void DecrementUnsweptFreeBytes(intptr_t by) { unswept_free_bytes_ -= by; }
-
-  void DecreaseUnsweptFreeBytes(Page* p) {
-    DCHECK(ShouldBeSweptBySweeperThreads(p));
-    unswept_free_bytes_ -= (p->area_size() - p->LiveBytes());
-  }
-
-  void ResetUnsweptFreeBytes() { unswept_free_bytes_ = 0; }
-
   // 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.
@@ -2053,10 +2060,6 @@ class PagedSpace : public Space {
   // Normal allocation information.
   AllocationInfo allocation_info_;
 
-  // The number of free bytes which could be reclaimed by advancing the
-  // concurrent sweeper threads.
-  intptr_t unswept_free_bytes_;
-
   // The sweeper threads iterate over the list of pointer and data space pages
   // and sweep these pages concurrently. They will stop sweeping after the
   // end_of_unswept_pages_ page.