Revert of "[heap] Switch to 500k pages"

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index 33bd05b89e61d6dc6655eeb1bbcbda77c34e39d9..95d5687a8fa4010fa6523c04d0e34018cc396639 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -617,21 +617,6 @@
   set_next_chunk(NULL);
 }
 
-void MemoryAllocator::ShrinkChunk(MemoryChunk* chunk, size_t bytes_to_shrink) {
-  DCHECK_GE(bytes_to_shrink, static_cast<size_t>(base::OS::CommitPageSize()));
-  DCHECK_EQ(0, bytes_to_shrink % base::OS::CommitPageSize());
-  Address free_start = chunk->area_end_ - bytes_to_shrink;
-  // Don't adjust the size of the page. The area is just uncomitted but not
-  // released.
-  chunk->area_end_ -= bytes_to_shrink;
-  UncommitBlock(free_start, bytes_to_shrink);
-  if (chunk->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
-    if (chunk->reservation_.IsReserved())
-      chunk->reservation_.Guard(chunk->area_end_);
-    else
-      base::OS::Guard(chunk->area_end_, base::OS::CommitPageSize());
-  }
-}
 
 MemoryChunk* MemoryAllocator::AllocateChunk(intptr_t reserve_area_size,
                                             intptr_t commit_area_size,
@@ -779,47 +764,6 @@
   available_in_free_list_ = 0;
 }
 
-size_t Page::ShrinkToHighWaterMark() {
-  // Shrink pages to high water mark. The water mark points either to a filler
-  // or the area_end.
-  HeapObject* filler = HeapObject::FromAddress(HighWaterMark());
-  if (filler->address() == area_end()) return 0;
-  CHECK(filler->IsFiller());
-  if (!filler->IsFreeSpace()) return 0;
-
-#ifdef DEBUG
-  // Check the the filler is indeed the last filler on the page.
-  HeapObjectIterator it(this);
-  HeapObject* filler2 = nullptr;
-  for (HeapObject* obj = it.Next(); obj != nullptr; obj = it.Next()) {
-    filler2 = HeapObject::FromAddress(obj->address() + obj->Size());
-  }
-  if (filler2 == nullptr || filler2->address() == area_end()) return 0;
-  DCHECK(filler2->IsFiller());
-  DCHECK_EQ(filler->address(), filler2->address());
-#endif  // DEBUG
-
-  size_t unused = RoundDown(
-      static_cast<size_t>(area_end() - filler->address() - FreeSpace::kSize),
-      base::OS::CommitPageSize());
-  if (unused > 0) {
-    if (FLAG_trace_gc_verbose) {
-      PrintIsolate(heap()->isolate(), "Shrinking page %p: end %p -> %p\n",
-                   reinterpret_cast<void*>(this),
-                   reinterpret_cast<void*>(area_end()),
-                   reinterpret_cast<void*>(area_end() - unused));
-    }
-    heap()->CreateFillerObjectAt(
-        filler->address(),
-        static_cast<int>(area_end() - filler->address() - unused),
-        ClearRecordedSlots::kNo);
-    heap()->memory_allocator()->ShrinkChunk(this, unused);
-    CHECK(filler->IsFiller());
-    CHECK_EQ(filler->address() + filler->Size(), area_end());
-  }
-  return unused;
-}
-
 void MemoryAllocator::PartialFreeMemory(MemoryChunk* chunk,
                                         Address start_free) {
   // We do not allow partial shrink for code.
@@ -1291,25 +1235,17 @@
   return Smi::FromInt(0);
 }
 
-void PagedSpace::ShrinkImmortalImmovablePages() {
-  DCHECK(!heap()->deserialization_complete());
-  MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
-  EmptyAllocationInfo();
-  ResetFreeList();
-
-  for (Page* page : *this) {
-    DCHECK(page->IsFlagSet(Page::NEVER_EVACUATE));
-    size_t unused = page->ShrinkToHighWaterMark();
-    accounting_stats_.DecreaseCapacity(static_cast<intptr_t>(unused));
-    AccountUncommitted(unused);
-  }
-}
-
 bool PagedSpace::Expand() {
-  const int size = AreaSize();
+  int size = AreaSize();
+  if (snapshotable() && !HasPages()) {
+    size = Snapshot::SizeOfFirstPage(heap()->isolate(), identity());
+  }
+
   if (!heap()->CanExpandOldGeneration(size)) return false;
+
   Page* p = heap()->memory_allocator()->AllocatePage(size, this, executable());
   if (p == nullptr) return false;
+
   AccountCommitted(static_cast<intptr_t>(p->size()));
 
   // Pages created during bootstrapping may contain immortal immovable objects.
@@ -1400,6 +1336,7 @@
 
 void PagedSpace::ReleasePage(Page* page) {
   DCHECK_EQ(page->LiveBytes(), 0);
+  DCHECK_EQ(AreaSize(), page->area_size());
   DCHECK_EQ(page->owner(), this);
 
   free_list_.EvictFreeListItems(page);
@@ -1418,8 +1355,10 @@
   }
 
   AccountUncommitted(static_cast<intptr_t>(page->size()));
-  accounting_stats_.ShrinkSpace(page->area_size());
   heap()->memory_allocator()->Free<MemoryAllocator::kPreFreeAndQueue>(page);
+
+  DCHECK(Capacity() > 0);
+  accounting_stats_.ShrinkSpace(AreaSize());
 }
 
 #ifdef DEBUG