[heap] Make compaction space accept external memory.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index c90f8b43de0a4dd4e72c35c28d321ce665ea927f..6af599e02be64f7fd4758f0c9fee10da6b7cd8e2 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -1591,7 +1591,7 @@ class FreeList {
   // This method returns how much memory can be allocated after freeing
   // maximum_freed memory.
   static inline int GuaranteedAllocatable(int maximum_freed) {
-    if (maximum_freed < kSmallListMin) {
+    if (maximum_freed <= kSmallListMin) {
       return 0;
     } else if (maximum_freed <= kSmallListMax) {
       return kSmallAllocationMax;
@@ -1631,24 +1631,23 @@ class FreeList {
   FreeListCategory* large_list() { return &large_list_; }
   FreeListCategory* huge_list() { return &huge_list_; }
 
-  static const int kSmallListMin = 0x20 * kPointerSize;
-
  private:
   // The size range of blocks, in bytes.
   static const int kMinBlockSize = 3 * kPointerSize;
   static const int kMaxBlockSize = Page::kMaxRegularHeapObjectSize;
 
-  FreeSpace* FindNodeFor(int size_in_bytes, int* node_size);
-
-  PagedSpace* owner_;
-  Heap* heap_;
-
+  static const int kSmallListMin = 0x1f * kPointerSize;
   static const int kSmallListMax = 0xff * kPointerSize;
   static const int kMediumListMax = 0x7ff * kPointerSize;
   static const int kLargeListMax = 0x3fff * kPointerSize;
-  static const int kSmallAllocationMax = kSmallListMin - kPointerSize;
+  static const int kSmallAllocationMax = kSmallListMin;
   static const int kMediumAllocationMax = kSmallListMax;
   static const int kLargeAllocationMax = kMediumListMax;
+
+  FreeSpace* FindNodeFor(int size_in_bytes, int* node_size);
+
+  PagedSpace* owner_;
+  Heap* heap_;
   FreeListCategory small_list_;
   FreeListCategory medium_list_;
   FreeListCategory large_list_;
@@ -1806,6 +1805,9 @@ class PagedSpace : public Space {
   MUST_USE_RESULT inline AllocationResult AllocateRawUnaligned(
       int size_in_bytes);
 
+  MUST_USE_RESULT inline AllocationResult AllocateRawUnalignedSynchronized(
+      int size_in_bytes);
+
   // Allocate the requested number of bytes in the space double aligned if
   // possible, return a failure object if not.
   MUST_USE_RESULT inline AllocationResult AllocateRawAligned(
@@ -2002,8 +2004,11 @@ class PagedSpace : public Space {
   // If not used, the emergency memory is released after compaction.
   MemoryChunk* emergency_memory_;
 
-  friend class PageIterator;
+  // Mutex guarding any concurrent access to the space.
+  base::Mutex space_mutex_;
+
   friend class MarkCompactCollector;
+  friend class PageIterator;
 };
 
 
@@ -2685,6 +2690,12 @@ class CompactionSpace : public PagedSpace {
   CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}
 
+  // Adds external memory starting at {start} of {size_in_bytes} to the space.
+  void AddExternalMemory(Address start, int size_in_bytes) {
+    IncreaseCapacity(size_in_bytes);
+    Free(start, size_in_bytes);
+  }
+
  protected:
   // The space is temporary and not included in any snapshots.
   virtual bool snapshotable() { return false; }