[heap] Make compaction space accept external memory.

BUG=chromium:524425
LOG=N

Review URL: https://codereview.chromium.org/1322523004

Cr-Commit-Position: refs/heads/master@{#30428}

src/heap/spaces-inl.h

@@ -356,6 +356,13 @@ AllocationResult PagedSpace::AllocateRawUnaligned(int size_in_bytes) {
 }
 
 
+AllocationResult PagedSpace::AllocateRawUnalignedSynchronized(
+    int size_in_bytes) {
+  base::LockGuard<base::Mutex> lock_guard(&space_mutex_);
+  return AllocateRawUnaligned(size_in_bytes);
+}
+
+
 // Raw allocation.
 AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
                                                 AllocationAlignment alignment) {

src/heap/spaces.cc

@@ -2219,7 +2219,6 @@ FreeSpace* FreeListCategory::PickNodeFromList(int size_in_bytes,
 
 
 void FreeListCategory::Free(FreeSpace* free_space, int size_in_bytes) {
-  DCHECK_LE(FreeList::kSmallListMin, size_in_bytes);
   free_space->set_next(top());
   set_top(free_space);
   if (end_ == NULL) {
@@ -2274,7 +2273,7 @@ int FreeList::Free(Address start, int size_in_bytes) {
   Page* page = Page::FromAddress(start);
 
   // Early return to drop too-small blocks on the floor.
-  if (size_in_bytes < kSmallListMin) {
+  if (size_in_bytes <= kSmallListMin) {
     page->add_non_available_small_blocks(size_in_bytes);
     return size_in_bytes;
   }

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; }

test/cctest/test-spaces.cc

@@ -441,6 +441,91 @@ TEST(CompactionSpace) {
 }
 
 
+TEST(CompactionSpaceUsingExternalMemory) {
+  const int kObjectSize = 512;
+
+  Isolate* isolate = CcTest::i_isolate();
+  Heap* heap = isolate->heap();
+  MemoryAllocator* allocator = new MemoryAllocator(isolate);
+  CHECK(allocator != nullptr);
+  CHECK(allocator->SetUp(heap->MaxReserved(), heap->MaxExecutableSize()));
+  TestMemoryAllocatorScope test_scope(isolate, allocator);
+
+  CompactionSpace* compaction_space =
+      new CompactionSpace(heap, OLD_SPACE, NOT_EXECUTABLE);
+  CHECK(compaction_space != NULL);
+  CHECK(compaction_space->SetUp());
+
+  OldSpace* old_space = new OldSpace(heap, OLD_SPACE, NOT_EXECUTABLE);
+  CHECK(old_space != NULL);
+  CHECK(old_space->SetUp());
+
+  // The linear allocation area already counts as used bytes, making
+  // exact testing impossible.
+  heap->DisableInlineAllocation();
+
+  // Test:
+  // * Allocate a backing store in old_space.
+  // * Compute the number num_rest_objects of kObjectSize objects that fit into
+  //   of available memory.
+  //   kNumRestObjects.
+  // * Add the rest of available memory to the compaction space.
+  // * Allocate kNumRestObjects in the compaction space.
+  // * Allocate one object more.
+  // * Merge the compaction space and compare the expected number of pages.
+
+  // Allocate a single object in old_space to initialize a backing page.
+  old_space->AllocateRawUnaligned(kObjectSize).ToObjectChecked();
+  // Compute the number of objects that fit into the rest in old_space.
+  intptr_t rest = static_cast<int>(old_space->Available());
+  CHECK_GT(rest, 0);
+  intptr_t num_rest_objects = rest / kObjectSize;
+  // After allocating num_rest_objects in compaction_space we allocate a bit
+  // more.
+  const intptr_t kAdditionalCompactionMemory = kObjectSize;
+  // We expect a single old_space page.
+  const intptr_t kExpectedInitialOldSpacePages = 1;
+  // We expect a single additional page in compaction space because we mostly
+  // use external memory.
+  const intptr_t kExpectedCompactionPages = 1;
+  // We expect two pages to be reachable from old_space in the end.
+  const intptr_t kExpectedOldSpacePagesAfterMerge = 2;
+
+  Object* chunk =
+      old_space->AllocateRawUnaligned(static_cast<int>(rest)).ToObjectChecked();
+  CHECK_EQ(old_space->CountTotalPages(), kExpectedInitialOldSpacePages);
+  CHECK(chunk != nullptr);
+  CHECK(chunk->IsHeapObject());
+
+  CHECK_EQ(compaction_space->CountTotalPages(), 0);
+  CHECK_EQ(compaction_space->Capacity(), 0);
+  // Make the rest of memory available for compaction.
+  compaction_space->AddExternalMemory(HeapObject::cast(chunk)->address(),
+                                      static_cast<int>(rest));
+  CHECK_EQ(compaction_space->CountTotalPages(), 0);
+  CHECK_EQ(compaction_space->Capacity(), rest);
+  while (num_rest_objects-- > 0) {
+    compaction_space->AllocateRawUnaligned(kObjectSize).ToObjectChecked();
+  }
+  // We only used external memory so far.
+  CHECK_EQ(compaction_space->CountTotalPages(), 0);
+  // Additional allocation.
+  compaction_space->AllocateRawUnaligned(kAdditionalCompactionMemory)
+      .ToObjectChecked();
+  // Now the compaction space shouldve also acquired a page.
+  CHECK_EQ(compaction_space->CountTotalPages(), kExpectedCompactionPages);
+
+  old_space->MergeCompactionSpace(compaction_space);
+  CHECK_EQ(old_space->CountTotalPages(), kExpectedOldSpacePagesAfterMerge);
+
+  delete compaction_space;
+  delete old_space;
+
+  allocator->TearDown();
+  delete allocator;
+}
+
+
 TEST(LargeObjectSpace) {
   v8::V8::Initialize();