[heap] Refactor heap object iteration

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 <list>
 #include <memory>
 #include <unordered_set>
@@ skipping 799 matching lines @@
   // x64 and ia32 architectures.
   static const int kMaxCodePageSize = 512 * MB;
 
  private:
   static inline LargePage* Initialize(Heap* heap, MemoryChunk* chunk,
                                       Executability executable, Space* owner);
 
   friend class MemoryAllocator;
 };
 
-
 // ----------------------------------------------------------------------------
 // Space is the abstract superclass for all allocation spaces.
 class Space : public Malloced {
  public:
   Space(Heap* heap, AllocationSpace id, Executability executable)
       : allocation_observers_(new List<AllocationObserver*>()),
         allocation_observers_paused_(false),
         heap_(heap),
         id_(id),
         executable_(executable),
@@ skipping 85 matching lines @@
   AllocationSpace id_;
   Executability executable_;
 
   // Keeps track of committed memory in a space.
   size_t committed_;
   size_t max_committed_;
 
   DISALLOW_COPY_AND_ASSIGN(Space);
 };
 
+// An abstraction of allocation and relocation pointers in a page-structured
+// space.
+class AllocationInfo {
+ public:
+  AllocationInfo() : original_top_(nullptr), top_(nullptr), limit_(nullptr) {}
+  AllocationInfo(Address top, Address limit)
+      : original_top_(top), top_(top), limit_(limit) {}
+
+  void Reset(Address top, Address limit) {
+    original_top_ = top;
+    set_top(top);
+    set_limit(limit);
+  }
+
+  Address original_top() {
+    SLOW_DCHECK(top_ == NULL ||
+                (reinterpret_cast<intptr_t>(top_) & kHeapObjectTagMask) == 0);
+    return original_top_;
+  }
+
+  INLINE(void set_top(Address top)) {
+    SLOW_DCHECK(top == NULL ||
+                (reinterpret_cast<intptr_t>(top) & kHeapObjectTagMask) == 0);
+    top_ = top;
+  }
+
+  INLINE(Address top()) const {
+    SLOW_DCHECK(top_ == NULL ||
+                (reinterpret_cast<intptr_t>(top_) & kHeapObjectTagMask) == 0);
+    return top_;
+  }
+
+  Address* top_address() { return &top_; }
+
+  INLINE(void set_limit(Address limit)) { limit_ = limit; }
+
+  INLINE(Address limit()) const { return limit_; }
+
+  Address* limit_address() { return &limit_; }
+
+#ifdef DEBUG
+  bool VerifyPagedAllocation() {
+    return (Page::FromAllocationAreaAddress(top_) ==
+            Page::FromAllocationAreaAddress(limit_)) &&
+           (top_ <= limit_);
+  }
+#endif
+
+ private:
+  // The original top address when the allocation info was initialized.
+  Address original_top_;
+  // Current allocation top.
+  Address top_;
+  // Current allocation limit.
+  Address limit_;
+};
+
+class SpaceWithInlineAllocationArea : public Space {
+ public:
+  SpaceWithInlineAllocationArea(Heap* heap, AllocationSpace id,
+                                Executability executable)
+      : Space(heap, id, executable), allocation_info_(nullptr, nullptr) {}
+
+  Address top() { return allocation_info_.top(); }
+  Address limit() { return allocation_info_.limit(); }
+
+  Address* allocation_top_address() { return allocation_info_.top_address(); }
+
+  Address* allocation_limit_address() {
+    return allocation_info_.limit_address();
+  }
+
+ protected:
+  AllocationInfo allocation_info_;
+};
 
 class MemoryChunkValidator {
   // Computed offsets should match the compiler generated ones.
   STATIC_ASSERT(MemoryChunk::kSizeOffset == offsetof(MemoryChunk, size_));
 
   // Validate our estimates on the header size.
   STATIC_ASSERT(sizeof(MemoryChunk) <= MemoryChunk::kHeaderSize);
   STATIC_ASSERT(sizeof(LargePage) <= MemoryChunk::kHeaderSize);
   STATIC_ASSERT(sizeof(Page) <= MemoryChunk::kHeaderSize);
 };
@@ skipping 473 matching lines @@
  private:
   PAGE_TYPE* p_;
 };
 
 typedef PageIteratorImpl<Page> PageIterator;
 typedef PageIteratorImpl<LargePage> LargePageIterator;
 
 class PageRange {
  public:
   typedef PageIterator iterator;
+
+  explicit PageRange(Page* page) : PageRange(page, page->next_page()) {}
   PageRange(Page* begin, Page* end) : begin_(begin), end_(end) {}
-  explicit PageRange(Page* page) : PageRange(page, page->next_page()) {}
+  inline PageRange(Address start, Address limit);
+
   iterator begin() { return iterator(begin_); }
   iterator end() { return iterator(end_); }
 
  private:
   Page* begin_;
   Page* end_;
 };
 
 // -----------------------------------------------------------------------------
 // Heap object iterator in new/old/map spaces.
 //
 // A HeapObjectIterator iterates objects from the bottom of the given space
 // to its top or from the bottom of the given page to its top.
 //
 // If objects are allocated in the page during iteration the iterator may
 // or may not iterate over those objects.  The caller must create a new
 // iterator in order to be sure to visit these new objects.
 class V8_EXPORT_PRIVATE HeapObjectIterator : public ObjectIterator {
  public:
-  // Creates a new object iterator in a given space.
   explicit HeapObjectIterator(PagedSpace* space);
+  explicit HeapObjectIterator(NewSpace* space);
   explicit HeapObjectIterator(Page* page);
 
   // Advance to the next object, skipping free spaces and other fillers and
   // skipping the special garbage section of which there is one per space.
   // Returns nullptr when the iteration has ended.
   inline HeapObject* Next() override;
 
  private:
+  inline Page* current_page() { return (*next_page_)->prev_page(); }
   // Fast (inlined) path of next().
   inline HeapObject* FromCurrentPage();
 
   // Slow path of next(), goes into the next page.  Returns false if the
   // iteration has ended.
   bool AdvanceToNextPage();
 
   Address cur_addr_;  // Current iteration point.
   Address cur_end_;   // End iteration point.
-  PagedSpace* space_;
+  SpaceWithInlineAllocationArea* space_;
   PageRange page_range_;
-  PageRange::iterator current_page_;
+  PageRange::iterator next_page_;
 };
 
-
-// -----------------------------------------------------------------------------
-// A space has a circular list of pages. The next page can be accessed via
-// Page::next_page() call.
-
-// An abstraction of allocation and relocation pointers in a page-structured
-// space.
-class AllocationInfo {
- public:
-  AllocationInfo() : original_top_(nullptr), top_(nullptr), limit_(nullptr) {}
-  AllocationInfo(Address top, Address limit)
-      : original_top_(top), top_(top), limit_(limit) {}
-
-  void Reset(Address top, Address limit) {
-    original_top_ = top;
-    set_top(top);
-    set_limit(limit);
-  }
-
-  Address original_top() {
-    SLOW_DCHECK(top_ == NULL ||
-                (reinterpret_cast<intptr_t>(top_) & kHeapObjectTagMask) == 0);
-    return original_top_;
-  }
-
-  INLINE(void set_top(Address top)) {
-    SLOW_DCHECK(top == NULL ||
-                (reinterpret_cast<intptr_t>(top) & kHeapObjectTagMask) == 0);
-    top_ = top;
-  }
-
-  INLINE(Address top()) const {
-    SLOW_DCHECK(top_ == NULL ||
-                (reinterpret_cast<intptr_t>(top_) & kHeapObjectTagMask) == 0);
-    return top_;
-  }
-
-  Address* top_address() { return &top_; }
-
-  INLINE(void set_limit(Address limit)) {
-    limit_ = limit;
-  }
-
-  INLINE(Address limit()) const {
-    return limit_;
-  }
-
-  Address* limit_address() { return &limit_; }
-
-#ifdef DEBUG
-  bool VerifyPagedAllocation() {
-    return (Page::FromAllocationAreaAddress(top_) ==
-            Page::FromAllocationAreaAddress(limit_)) &&
-           (top_ <= limit_);
-  }
-#endif
-
- private:
-  // The original top address when the allocation info was initialized.
-  Address original_top_;
-  // Current allocation top.
-  Address top_;
-  // Current allocation limit.
-  Address limit_;
-};
-
-
 // An abstraction of the accounting statistics of a page-structured space.
 //
 // The stats are only set by functions that ensure they stay balanced. These
 // functions increase or decrease one of the non-capacity stats in conjunction
 // with capacity, or else they always balance increases and decreases to the
 // non-capacity stats.
 class AllocationStats BASE_EMBEDDED {
  public:
   AllocationStats() { Clear(); }
 
@@ skipping 329 matching lines @@
 
  private:
   LocalAllocationBuffer(Heap* heap, AllocationInfo allocation_info);
 
   void Close();
 
   Heap* heap_;
   AllocationInfo allocation_info_;
 };
 
-class NewSpacePageRange {
- public:
-  typedef PageRange::iterator iterator;
-  inline NewSpacePageRange(Address start, Address limit);
-  iterator begin() { return range_.begin(); }
-  iterator end() { return range_.end(); }
-
- private:
-  PageRange range_;
-};
-
-class PagedSpace : public Space {
+class PagedSpace : public SpaceWithInlineAllocationArea {
  public:
   typedef PageIterator iterator;
 
   static const intptr_t kCompactionMemoryWanted = 500 * KB;
 
   // Creates a space with an id.
   PagedSpace(Heap* heap, AllocationSpace id, Executability executable);
 
   ~PagedSpace() override { TearDown(); }
 
@@ skipping 57 matching lines @@
   size_t Size() override { return accounting_stats_.Size(); }
 
   // As size, but the bytes in lazily swept pages are estimated and the bytes
   // in the current linear allocation area are not included.
   size_t SizeOfObjects() override;
 
   // Wasted bytes in this space.  These are just the bytes that were thrown away
   // due to being too small to use for allocation.
   virtual size_t Waste() { return free_list_.wasted_bytes(); }
 
-  // Returns the allocation pointer in this space.
-  Address top() { return allocation_info_.top(); }
-  Address limit() { return allocation_info_.limit(); }
-
-  // The allocation top address.
-  Address* allocation_top_address() { return allocation_info_.top_address(); }
-
-  // The allocation limit address.
-  Address* allocation_limit_address() {
-    return allocation_info_.limit_address();
-  }
-
   enum UpdateSkipList { UPDATE_SKIP_LIST, IGNORE_SKIP_LIST };
 
   // Allocate the requested number of bytes in the space if possible, return a
   // failure object if not. Only use IGNORE_SKIP_LIST if the skip list is going
   // to be manually updated later.
   MUST_USE_RESULT inline AllocationResult AllocateRawUnaligned(
       int size_in_bytes, UpdateSkipList update_skip_list = UPDATE_SKIP_LIST);
 
   MUST_USE_RESULT inline AllocationResult AllocateRawUnalignedSynchronized(
       int size_in_bytes);
@@ skipping 152 matching lines @@
 
   // 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_;
-
   // Mutex guarding any concurrent access to the space.
   base::Mutex space_mutex_;
 
   friend class IncrementalMarking;
   friend class MarkCompactCollector;
 
   // Used in cctest.
   friend class HeapTester;
 };
 
@@ skipping 194 matching lines @@
   // The end of iteration.
   Address limit_;
 };
 
 // -----------------------------------------------------------------------------
 // The young generation space.
 //
 // The new space consists of a contiguous pair of semispaces.  It simply
 // forwards most functions to the appropriate semispace.
 
-class NewSpace : public Space {
+class NewSpace : public SpaceWithInlineAllocationArea {
  public:
   typedef PageIterator iterator;
 
   explicit NewSpace(Heap* heap)
-      : Space(heap, NEW_SPACE, NOT_EXECUTABLE),
+      : SpaceWithInlineAllocationArea(heap, NEW_SPACE, NOT_EXECUTABLE),
         to_space_(heap, kToSpace),
         from_space_(heap, kFromSpace),
         reservation_(),
         top_on_previous_step_(0),
         allocated_histogram_(nullptr),
         promoted_histogram_(nullptr) {}
 
   inline bool Contains(HeapObject* o);
   inline bool ContainsSlow(Address a);
   inline bool Contains(Object* o);
@@ skipping 115 matching lines @@
   }
 
   bool IsAtMaximumCapacity() { return TotalCapacity() == MaximumCapacity(); }
 
   // Returns the initial capacity of a semispace.
   size_t InitialTotalCapacity() {
     DCHECK(to_space_.minimum_capacity() == from_space_.minimum_capacity());
     return to_space_.minimum_capacity();
   }
 
-  // Return the address of the allocation pointer in the active semispace.
-  Address top() {
-    DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.top()));
-    return allocation_info_.top();
-  }
-
-  // Return the address of the allocation pointer limit in the active semispace.
-  Address limit() {
-    DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.limit()));
-    return allocation_info_.limit();
-  }
-
   // Return the address of the first object in the active semispace.
   Address bottom() { return to_space_.space_start(); }
 
   // Get the age mark of the inactive semispace.
   Address age_mark() { return from_space_.age_mark(); }
   // Set the age mark in the active semispace.
   void set_age_mark(Address mark) { to_space_.set_age_mark(mark); }
 
-  // The allocation top and limit address.
-  Address* allocation_top_address() { return allocation_info_.top_address(); }
-
-  // The allocation limit address.
-  Address* allocation_limit_address() {
-    return allocation_info_.limit_address();
-  }
-
   MUST_USE_RESULT INLINE(AllocationResult AllocateRawAligned(
       int size_in_bytes, AllocationAlignment alignment));
 
   MUST_USE_RESULT INLINE(
       AllocationResult AllocateRawUnaligned(int size_in_bytes));
 
   MUST_USE_RESULT INLINE(AllocationResult AllocateRaw(
       int size_in_bytes, AllocationAlignment alignment));
 
   MUST_USE_RESULT inline AllocationResult AllocateRawSynchronized(
@@ skipping 96 matching lines @@
   // Update allocation info to match the current to-space page.
   void UpdateAllocationInfo();
 
   base::Mutex mutex_;
 
   // The semispaces.
   SemiSpace to_space_;
   SemiSpace from_space_;
   base::VirtualMemory reservation_;
 
-  // Allocation pointer and limit for normal allocation and allocation during
-  // mark-compact collection.
-  AllocationInfo allocation_info_;
-
   Address top_on_previous_step_;
 
   HistogramInfo* allocated_histogram_;
   HistogramInfo* promoted_histogram_;
 
   bool EnsureAllocation(int size_in_bytes, AllocationAlignment alignment);
 
   // If we are doing inline allocation in steps, this method performs the 'step'
   // operation. top is the memory address of the bump pointer at the last
   // inline allocation (i.e. it determines the numbers of bytes actually
@@ skipping 247 matching lines @@
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
   LargePageIterator lo_iterator_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_