Revert of [heap] Introduce parallel compaction algorithm.

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index f98120bd5066fd279083079912c4ab153796062d..8f75d5fd630b1a7c627de902d79850807b23845a 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -80,7 +80,8 @@
       code_range_(NULL),
       free_list_(0),
       allocation_list_(0),
-      current_allocation_block_index_(0) {}
+      current_allocation_block_index_(0),
+      emergency_block_() {}
 
 
 bool CodeRange::SetUp(size_t requested) {
@@ -139,6 +140,7 @@
   current_allocation_block_index_ = 0;
 
   LOG(isolate_, NewEvent("CodeRange", code_range_->address(), requested));
+  ReserveEmergencyBlock();
   return true;
 }
 
@@ -271,6 +273,24 @@
 void CodeRange::ReleaseBlock(const FreeBlock* block) {
   base::LockGuard<base::Mutex> guard(&code_range_mutex_);
   free_list_.Add(*block);
+}
+
+
+void CodeRange::ReserveEmergencyBlock() {
+  const size_t requested_size = MemoryAllocator::CodePageAreaSize();
+  if (emergency_block_.size == 0) {
+    ReserveBlock(requested_size, &emergency_block_);
+  } else {
+    DCHECK(emergency_block_.size >= requested_size);
+  }
+}
+
+
+void CodeRange::ReleaseEmergencyBlock() {
+  if (emergency_block_.size != 0) {
+    ReleaseBlock(&emergency_block_);
+    emergency_block_.size = 0;
+  }
 }
 
 
@@ -472,7 +492,6 @@
   chunk->progress_bar_ = 0;
   chunk->high_water_mark_.SetValue(static_cast<intptr_t>(area_start - base));
   chunk->set_parallel_sweeping(SWEEPING_DONE);
-  chunk->parallel_compaction_state().SetValue(kCompactingDone);
   chunk->mutex_ = NULL;
   chunk->available_in_small_free_list_ = 0;
   chunk->available_in_medium_free_list_ = 0;
@@ -955,7 +974,8 @@
     : Space(heap, space, executable),
       free_list_(this),
       unswept_free_bytes_(0),
-      end_of_unswept_pages_(NULL) {
+      end_of_unswept_pages_(NULL),
+      emergency_memory_(NULL) {
   area_size_ = MemoryAllocator::PageAreaSize(space);
   accounting_stats_.Clear();
 
@@ -983,37 +1003,30 @@
 }
 
 
-void PagedSpace::MoveOverFreeMemory(PagedSpace* other) {
-  DCHECK(identity() == other->identity());
-  // Destroy the linear allocation space of {other}. This is needed to
-  //   (a) not waste the memory and
-  //   (b) keep the rest of the chunk in an iterable state (filler is needed).
-  other->EmptyAllocationInfo();
-
-  // Move over the free list. Concatenate makes sure that the source free list
-  // gets properly reset after moving over all nodes.
-  intptr_t freed_bytes = free_list_.Concatenate(other->free_list());
-  other->accounting_stats_.AllocateBytes(freed_bytes);
-  // We do not adjust accounting_stats_ for {this} as we treat the received
-  // memory as borrowed, i.e., the originating space keeps track of its
-  // capacity. Other stats, e.g. accounting_stats_.{size_,waste_} are properly
-  // maintained by allocating and freeing blocks.
-}
-
-
 void PagedSpace::MergeCompactionSpace(CompactionSpace* other) {
   // Unmerged fields:
   //   area_size_
   //   allocation_info_
+  //   emergency_memory_
   //   end_of_unswept_pages_
   //   unswept_free_bytes_
   //   anchor_
 
-  MoveOverFreeMemory(other);
+  // It only makes sense to merge compatible spaces.
+  DCHECK(identity() == other->identity());
+
+  // Destroy the linear allocation space of {other}. This is needed to (a) not
+  // waste the memory and (b) keep the rest of the chunk in an iterable state
+  // (filler is needed).
+  int linear_size = static_cast<int>(other->limit() - other->top());
+  other->Free(other->top(), linear_size);
+
+  // Move over the free list.
+  free_list_.Concatenate(other->free_list());
 
   // Update and clear accounting statistics.
   accounting_stats_.Merge(other->accounting_stats_);
-  other->accounting_stats_.Reset();
+  other->accounting_stats_.Clear();
 
   // Move over pages.
   PageIterator it(other);
@@ -1097,6 +1110,9 @@
   if (!heap()->deserialization_complete()) p->MarkNeverEvacuate();
 
   DCHECK(Capacity() <= heap()->MaxOldGenerationSize());
+  DCHECK(heap()->CommittedOldGenerationMemory() <=
+         heap()->MaxOldGenerationSize() +
+             PagedSpace::MaxEmergencyMemoryAllocated());
 
   p->InsertAfter(anchor_.prev_page());
 
@@ -1163,6 +1179,51 @@
 
   DCHECK(Capacity() > 0);
   accounting_stats_.ShrinkSpace(AreaSize());
+}
+
+
+intptr_t PagedSpace::MaxEmergencyMemoryAllocated() {
+  // New space and large object space.
+  static const int spaces_without_emergency_memory = 2;
+  static const int spaces_with_emergency_memory =
+      LAST_SPACE - FIRST_SPACE + 1 - spaces_without_emergency_memory;
+  return Page::kPageSize * spaces_with_emergency_memory;
+}
+
+
+void PagedSpace::CreateEmergencyMemory() {
+  if (identity() == CODE_SPACE) {
+    // Make the emergency block available to the allocator.
+    CodeRange* code_range = heap()->isolate()->code_range();
+    if (code_range != NULL && code_range->valid()) {
+      code_range->ReleaseEmergencyBlock();
+    }
+    DCHECK(MemoryAllocator::CodePageAreaSize() == AreaSize());
+  }
+  emergency_memory_ = heap()->isolate()->memory_allocator()->AllocateChunk(
+      AreaSize(), AreaSize(), executable(), this);
+}
+
+
+void PagedSpace::FreeEmergencyMemory() {
+  Page* page = static_cast<Page*>(emergency_memory_);
+  DCHECK(page->LiveBytes() == 0);
+  DCHECK(AreaSize() == page->area_size());
+  DCHECK(!free_list_.ContainsPageFreeListItems(page));
+  heap()->isolate()->memory_allocator()->Free(page);
+  emergency_memory_ = NULL;
+}
+
+
+void PagedSpace::UseEmergencyMemory() {
+  // Page::Initialize makes the chunk into a real page and adds it to the
+  // accounting for this space.  Unlike PagedSpace::Expand, we don't check
+  // CanExpand first, so we can go over the limits a little here.  That's OK,
+  // because we are in the process of compacting which will free up at least as
+  // much memory as it allocates.
+  Page* page = Page::Initialize(heap(), emergency_memory_, executable(), this);
+  page->InsertAfter(anchor_.prev_page());
+  emergency_memory_ = NULL;
 }