[heap] Add compaction space.

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/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 73 matching lines @@
 
 #define DCHECK_OBJECT_SIZE(size) \
   DCHECK((0 < size) && (size <= Page::kMaxRegularHeapObjectSize))
 
 #define DCHECK_PAGE_OFFSET(offset) \
   DCHECK((Page::kObjectStartOffset <= offset) && (offset <= Page::kPageSize))
 
 #define DCHECK_MAP_PAGE_INDEX(index) \
   DCHECK((0 <= index) && (index <= MapSpace::kMaxMapPageIndex))
 
-
+class AllocationInfo;
+class CompactionSpace;
+class FreeList;
+class MemoryAllocator;
+class MemoryChunk;
 class PagedSpace;
-class MemoryAllocator;
-class AllocationInfo;
 class Space;
-class FreeList;
-class MemoryChunk;
 
 class MarkBit {
  public:
   typedef uint32_t CellType;
 
   inline MarkBit(CellType* cell, CellType mask) : cell_(cell), mask_(mask) {}
 
 #ifdef DEBUG
   bool operator==(const MarkBit& other) {
     return cell_ == other.cell_ && mask_ == other.mask_;
@@ skipping 1348 matching lines @@
     size_ -= size_in_bytes;
     DCHECK(size_ >= 0);
   }
 
   // Waste free bytes (available -> waste).
   void WasteBytes(int size_in_bytes) {
     DCHECK(size_in_bytes >= 0);
     waste_ += size_in_bytes;
   }
 
+  // Merge {other} into {this}.
+  void Merge(const AllocationStats& other) {
+    capacity_ += other.capacity_;
+    size_ += other.size_;
+    waste_ += other.waste_;
+    if (other.max_capacity_ > max_capacity_) {
+      max_capacity_ = other.max_capacity_;
+    }
+  }
+
  private:
   intptr_t capacity_;
   intptr_t max_capacity_;
   intptr_t size_;
   intptr_t waste_;
 };
 
 
 // -----------------------------------------------------------------------------
 // Free lists for old object spaces
@@ skipping 210 matching lines @@
 
 
 STATIC_ASSERT(sizeof(AllocationResult) == kPointerSize);
 
 
 class PagedSpace : public Space {
  public:
   // Creates a space with an id.
   PagedSpace(Heap* heap, AllocationSpace id, Executability executable);
 
-  virtual ~PagedSpace() {}
+  virtual ~PagedSpace() { TearDown(); }
 
   // Set up the space using the given address range of virtual memory (from
   // the memory allocator's initial chunk) if possible.  If the block of
   // addresses is not big enough to contain a single page-aligned page, a
   // fresh chunk will be allocated.
   bool SetUp();
 
   // Returns true if the space has been successfully set up and not
   // subsequently torn down.
   bool HasBeenSetUp();
 
-  // Cleans up the space, frees all pages in this space except those belonging
-  // to the initial chunk, uncommits addresses in the initial chunk.
-  void TearDown();

[Michael Lippautz, 2015/08/26 13:49:58]

Let's remove one of the landmines and make TearDown() private and implicitly
called by the destructor (?)

-
   // Checks whether an object/address is in this space.
   inline bool Contains(Address a);
   inline bool Contains(HeapObject* o);
   // Unlike Contains() methods it is safe to call this one even for addresses
   // of unmapped memory.
   bool ContainsSafe(Address addr);
 
   // Given an address occupied by a live object, return that object if it is
   // in this space, or a Smi if it is not.  The implementation iterates over
   // objects in the page containing the address, the cost is linear in the
@@ skipping 187 matching lines @@
   void EvictEvacuationCandidatesFromFreeLists();
 
   bool CanExpand();
 
   // Returns the number of total pages in this space.
   int CountTotalPages();
 
   // Return size of allocatable area on a page in this space.
   inline int AreaSize() { return area_size_; }
 
   void CreateEmergencyMemory();

[Michael Lippautz, 2015/08/26 13:49:58]

The plan is to move those to the compaction space (in some form) and remove it
here.

   void FreeEmergencyMemory();
   void UseEmergencyMemory();
   intptr_t MaxEmergencyMemoryAllocated();
 
   bool HasEmergencyMemory() { return emergency_memory_ != NULL; }
 
+  // Merges {other} into the current space. Note that this modifies {other},
+  // e.g., removes its bump pointer area and resets statistics.
+  void MergeCompactionSpace(CompactionSpace* other);
+
  protected:
   FreeList* free_list() { return &free_list_; }
 
+  // Cleans up the space, frees all pages in this space except those belonging

[Michael Lippautz, 2015/08/26 13:49:58]

Just following decl order here.

+  // to the initial chunk, uncommits addresses in the initial chunk.
+  void TearDown();
+
+  // Expands the space by allocating a fixed number of pages. Returns false if
+  // it cannot allocate requested number of pages from OS, or if the hard heap
+  // size limit has been hit.
+  bool Expand();
+
+  // Generic fast case allocation function that tries linear allocation at the
+  // address denoted by top in allocation_info_.
+  inline HeapObject* AllocateLinearly(int size_in_bytes);
+
+  // Generic fast case allocation function that tries aligned linear allocation
+  // at the address denoted by top in allocation_info_. Writes the aligned
+  // allocation size, which includes the filler size, to size_in_bytes.
+  inline HeapObject* AllocateLinearlyAligned(int* size_in_bytes,
+                                             AllocationAlignment alignment);
+
+  // If sweeping is still in progress try to sweep unswept pages. If that is
+  // not successful, wait for the sweeper threads and re-try free-list
+  // allocation.
+  MUST_USE_RESULT HeapObject* WaitForSweeperThreadsAndRetryAllocation(
+      int size_in_bytes);
+
+  // Slow path of AllocateRaw.  This function is space-dependent.
+  MUST_USE_RESULT HeapObject* SlowAllocateRaw(int size_in_bytes);
+
   int area_size_;
 
   // Accounting information for this space.
   AllocationStats accounting_stats_;
 
   // The dummy page that anchors the double linked list of pages.
   Page anchor_;
 
   // The space's free list.
   FreeList free_list_;
 
   // 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.
   Page* end_of_unswept_pages_;
 
   // Emergency memory is the memory of a full page for a given space, allocated
   // conservatively before evacuating a page. If compaction fails due to out
   // of memory error the emergency memory can be used to complete compaction.
   // If not used, the emergency memory is released after compaction.
   MemoryChunk* emergency_memory_;
 
-  // Expands the space by allocating a fixed number of pages. Returns false if
-  // it cannot allocate requested number of pages from OS, or if the hard heap
-  // size limit has been hit.
-  bool Expand();
-
-  // Generic fast case allocation function that tries linear allocation at the
-  // address denoted by top in allocation_info_.
-  inline HeapObject* AllocateLinearly(int size_in_bytes);
-
-  // Generic fast case allocation function that tries aligned linear allocation
-  // at the address denoted by top in allocation_info_. Writes the aligned
-  // allocation size, which includes the filler size, to size_in_bytes.
-  inline HeapObject* AllocateLinearlyAligned(int* size_in_bytes,
-                                             AllocationAlignment alignment);
-
-  // If sweeping is still in progress try to sweep unswept pages. If that is
-  // not successful, wait for the sweeper threads and re-try free-list
-  // allocation.
-  MUST_USE_RESULT HeapObject* WaitForSweeperThreadsAndRetryAllocation(
-      int size_in_bytes);
-
-  // Slow path of AllocateRaw.  This function is space-dependent.
-  MUST_USE_RESULT HeapObject* SlowAllocateRaw(int size_in_bytes);
-
   friend class PageIterator;
   friend class MarkCompactCollector;
 };
 
 
 class NumberAndSizeInfo BASE_EMBEDDED {
  public:
   NumberAndSizeInfo() : number_(0), bytes_(0) {}
 
   int number() const { return number_; }
@@ skipping 655 matching lines @@
   Address top_on_previous_step_;
 
   HistogramInfo* allocated_histogram_;
   HistogramInfo* promoted_histogram_;
 
   bool EnsureAllocation(int size_in_bytes, AllocationAlignment alignment);
 
   friend class SemiSpaceIterator;
 };
 
+// -----------------------------------------------------------------------------
+// Compaction space that is used temporarily during compaction.
+
+class CompactionSpace : public PagedSpace {
+ public:
+  CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
+      : PagedSpace(heap, id, executable) {}
+};
+
 
 // -----------------------------------------------------------------------------
 // Old object space (includes the old space of objects and code space)
 
 class OldSpace : public PagedSpace {
  public:
   // Creates an old space object. The constructor does not allocate pages
   // from OS.
   OldSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}
@@ skipping 181 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_