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 7b8a2f2f05a69906c4cf5796659009bb02aa61d8..b31aaf3998fd98a370b3a329dcfb992c12f9e112 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -595,21 +595,6 @@
   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,
@@ -1228,50 +1213,17 @@
   return Smi::FromInt(0);
 }
 
-void PagedSpace::ShrinkPagesToHighWaterMark() {
-  MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
-  EmptyAllocationInfo();
-  ResetFreeList();
-
-  for (Page* page : *this) {
-    // Only shrink immortal immovable pages after deserialization.
-    if (!page->IsFlagSet(Page::NEVER_EVACUATE)) continue;
-
-    // In order to shrink the page, we need to find the last filler. Since
-    // a GC could've happened we need to manually traverse the page to find
-    // any free space at the end.
-    HeapObjectIterator it(page);
-    HeapObject* filler = nullptr;
-    for (HeapObject* obj = it.Next(); obj != nullptr; obj = it.Next()) {
-      filler = HeapObject::FromAddress(obj->address() + obj->Size());
-    }
-    if (filler == nullptr || filler->address() == page->area_end()) continue;
-    CHECK(filler->IsFiller());
-    if (!filler->IsFreeSpace()) continue;
-
-    size_t unused =
-        RoundDown(static_cast<size_t>(page->area_end() - filler->address() -
-                                      FreeSpace::kSize),
-                  base::OS::CommitPageSize());
-    if (unused > 0) {
-      heap()->CreateFillerObjectAt(
-          filler->address(),
-          static_cast<int>(page->area_end() - filler->address() - unused),
-          ClearRecordedSlots::kNo);
-      heap()->memory_allocator()->ShrinkChunk(page, unused);
-      CHECK(filler->IsFiller());
-      CHECK_EQ(filler->address() + filler->Size(), page->area_end());
-      accounting_stats_.DecreaseCapacity(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.
@@ -1352,6 +1304,7 @@
 
 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);
@@ -1371,7 +1324,7 @@
   heap()->memory_allocator()->Free<MemoryAllocator::kPreFreeAndQueue>(page);
 
   DCHECK(Capacity() > 0);
-  accounting_stats_.ShrinkSpace(page->area_size());
+  accounting_stats_.ShrinkSpace(AreaSize());
 }
 
 #ifdef DEBUG