🏄 [heap] Add page evacuation mode for new->old

src/heap/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/spaces.h"
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/heap/slot-set.h"
@@ skipping 1143 matching lines @@
 bool PagedSpace::Expand() {
   int size = AreaSize();
   if (snapshotable() && !HasPages()) {
     size = Snapshot::SizeOfFirstPage(heap()->isolate(), identity());
   }
 
   if (!heap()->CanExpandOldGeneration(size)) return false;
 
   Page* p =
       heap()->memory_allocator()->AllocatePage<Page>(size, this, executable());
-  if (p == NULL) return false;
+  if (p == nullptr) return false;
 
   AccountCommitted(static_cast<intptr_t>(p->size()));
 
   // Pages created during bootstrapping may contain immortal immovable objects.
   if (!heap()->deserialization_complete()) p->MarkNeverEvacuate();
 
   // When incremental marking was activated, old space pages are allocated
   // black.
   if (heap()->incremental_marking()->black_allocation() &&
       identity() == OLD_SPACE) {
@@ skipping 635 matching lines @@
            page->IsFlagSet(MemoryChunk::IN_FROM_SPACE));
   }
 }
 
 
 void SemiSpace::Reset() {
   DCHECK_NE(anchor_.next_page(), &anchor_);
   current_page_ = anchor_.next_page();
 }
 
+void SemiSpace::ReplaceWithEmptyPage(NewSpacePage* old_page) {
+  NewSpacePage* new_page =
+      heap()->memory_allocator()->AllocatePage<NewSpacePage>(
+          NewSpacePage::kAllocatableMemory, this, executable());
+  Bitmap::Clear(new_page);
+  new_page->SetFlags(old_page->GetFlags(), NewSpacePage::kCopyAllFlags);
+  new_page->set_next_page(old_page->next_page());
+  new_page->set_prev_page(old_page->prev_page());
+  old_page->next_page()->set_prev_page(new_page);
+  old_page->prev_page()->set_next_page(new_page);
+  heap()->CreateFillerObjectAt(new_page->area_start(), new_page->area_size(),
+                               ClearRecordedSlots::kNo);
+}
 
 void SemiSpace::Swap(SemiSpace* from, SemiSpace* to) {
   // We won't be swapping semispaces without data in them.
   DCHECK_NE(from->anchor_.next_page(), &from->anchor_);
   DCHECK_NE(to->anchor_.next_page(), &to->anchor_);
 
   intptr_t saved_to_space_flags = to->current_page()->GetFlags();
 
   // We swap all properties but id_.
   std::swap(from->current_capacity_, to->current_capacity_);
@@ skipping 1297 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8