[heap] Register end of black areas to support faster filtering of invalid slots.

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>
 
@@ skipping 332 matching lines @@
       kWriteBarrierCounterOffset +
       kIntptrSize         // intptr_t write_barrier_counter_
       + kPointerSize      // AtomicValue high_water_mark_
       + kPointerSize      // base::Mutex* mutex_
       + kPointerSize      // base::AtomicWord concurrent_sweeping_
       + 2 * kPointerSize  // AtomicNumber free-list statistics
       + kPointerSize      // AtomicValue next_chunk_
       + kPointerSize      // AtomicValue prev_chunk_
       // FreeListCategory categories_[kNumberOfCategories]
       + FreeListCategory::kSize * kNumberOfCategories +
-      kPointerSize;  // LocalArrayBufferTracker* local_tracker_;
+      kPointerSize     // LocalArrayBufferTracker* local_tracker_;
+      + kPointerSize;  // base::HashMap* black_area_end_marker_map_;
 
   // We add some more space to the computed header size to amount for missing
   // alignment requirements in our computation.
   // Try to get kHeaderSize properly aligned on 32-bit and 64-bit machines.
   static const size_t kHeaderSize = kMinHeaderSize;
 
   static const int kBodyOffset =
       CODE_POINTER_ALIGN(kHeaderSize + Bitmap::kSize);
 
   // The start offset of the object area in a page. Aligned to both maps and
@@ skipping 221 matching lines @@
     owner_ = reinterpret_cast<Address>(space) + kPageHeaderTag;
     DCHECK((reinterpret_cast<intptr_t>(owner_) & kPageHeaderTagMask) ==
            kPageHeaderTag);
   }
 
   bool HasPageHeader() { return owner() != nullptr; }
 
   void InsertAfter(MemoryChunk* other);
   void Unlink();
 
+  void ReleaseBlackAreaEndMarkerMap() {
+    if (black_area_end_marker_map_) {
+      delete black_area_end_marker_map_;

[Michael Lippautz, 2016/08/10 16:05:42]

nit: we usually also add
  black_area_end_marker_map_ = nullptr;

[Hannes Payer (out of office), 2016/08/11 10:51:56]

Done.

+    }
+  }
+
+  bool IsBlackAreaEndMarker(Address address) {
+    if (black_area_end_marker_map_) {
+      return black_area_end_marker_map_->Lookup(
+          reinterpret_cast<void*>(address), ObjectHash(address));
+    }
+    return false;
+  }
+
+  void AddBlackAreaEndMarker(Address address) {
+    if (!black_area_end_marker_map_) {
+      black_area_end_marker_map_ =
+          new base::HashMap(base::HashMap::PointersMatch, 8);
+    }
+    black_area_end_marker_map_->InsertNew(reinterpret_cast<void*>(address),
+                                          ObjectHash(address));
+  }
+
+  bool HasBlackAreas() { return black_area_end_marker_map_ != nullptr; }
+
  protected:
   static MemoryChunk* Initialize(Heap* heap, Address base, size_t size,
                                  Address area_start, Address area_end,
                                  Executability executable, Space* owner,
                                  base::VirtualMemory* reservation);
 
   // Should be called when memory chunk is about to be freed.
   void ReleaseAllocatedMemory();
 
   base::VirtualMemory* reserved_memory() { return &reservation_; }
@@ skipping 48 matching lines @@
 
   // next_chunk_ holds a pointer of type MemoryChunk
   base::AtomicValue<MemoryChunk*> next_chunk_;
   // prev_chunk_ holds a pointer of type MemoryChunk
   base::AtomicValue<MemoryChunk*> prev_chunk_;
 
   FreeListCategory categories_[kNumberOfCategories];
 
   LocalArrayBufferTracker* local_tracker_;
 
+  // Stores the end addresses of black areas.
+  base::HashMap* black_area_end_marker_map_;

[Michael Lippautz, 2016/08/10 16:05:42]

How about std::unordered_map?

[Hannes Payer (out of office), 2016/08/11 10:51:56]

Using std::unordered_set which is sufficient.

+
  private:
   void InitializeReservedMemory() { reservation_.Reset(); }
 
   friend class MemoryAllocator;
   friend class MemoryChunkValidator;
 };
 
 // -----------------------------------------------------------------------------
 // A page is a memory chunk of a size 1MB. Large object pages may be larger.
 //
@@ skipping 801 matching lines @@
 
 
 // -----------------------------------------------------------------------------
 // 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() : top_(nullptr), limit_(nullptr) {}
-  AllocationInfo(Address top, Address limit) : top_(top), limit_(limit) {}
+  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() { return original_top_; }

[Michael Lippautz, 2016/08/10 16:05:41]

nit: Let's add the SLOW_DCHECK (like below) so that we immediately see that this
is supposed to be tagged or untagged. (it probably should be untagged, like
top())

[Hannes Payer (out of office), 2016/08/11 10:51:56]

Done.

+
   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_;
@@ skipping 13 matching lines @@
 
 #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
@@ skipping 1450 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_