[heap] Minor MC: Add evacuation phase

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index bbb3402c0c29b8fa80242673f8a84a0528d26e06..cf283b40d19dfd23424b4fbf00eb64e559c0b30d 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -1226,6 +1226,14 @@ void PagedSpace::RefillFreeList() {
         p->Unlink();
         p->set_owner(this);
         p->InsertAfter(anchor_.prev_page());
+      } else {
+        CHECK_EQ(this, p->owner());
+        // Regular refill on main thread.
+        if (p->available_in_free_list() < kPageReuseThreshold) {
+          // Relink categories with only little memory left previous to anchor.
+          p->Unlink();
+          p->InsertAfter(anchor()->prev_page());
+        }
       }
       added += RelinkFreeListCategories(p);
       added += p->wasted_memory();
@@ -1306,6 +1314,31 @@ Object* PagedSpace::FindObject(Address addr) {
   return Smi::kZero;
 }
 
+Page* PagedSpace::RemovePageSafe() {
+  base::LockGuard<base::Mutex> guard(mutex());
+
+  if (anchor()->next_page() == anchor() ||
+      anchor()->next_page()->available_in_free_list() < kPageReuseThreshold)
+    return nullptr;
+
+  Page* page = anchor()->next_page();
+  AccountUncommitted(page->size());
+  accounting_stats_.DeallocateBytes(page->LiveBytesFromFreeList());
+  accounting_stats_.DecreaseCapacity(page->size());
+  page->Unlink();
+  UnlinkFreeListCategories(page);
+  return page;
+}
+
+void PagedSpace::AddPage(Page* page) {
+  AccountCommitted(page->size());
+  accounting_stats_.IncreaseCapacity(page->size());
+  accounting_stats_.AllocateBytes(page->LiveBytesFromFreeList());
+  page->set_owner(this);
+  RelinkFreeListCategories(page);
+  page->InsertAfter(anchor()->prev_page());
+}
+
 void PagedSpace::ShrinkImmortalImmovablePages() {
   DCHECK(!heap()->deserialization_complete());
   MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
@@ -1446,6 +1479,7 @@ void PagedSpace::Verify(ObjectVisitor* visitor) {
   bool allocation_pointer_found_in_space =
       (allocation_info_.top() == allocation_info_.limit());
   for (Page* page : *this) {
+    if (page->IsFlagSet(Page::CANNOT_BE_VERIFIED)) continue;
     CHECK(page->owner() == this);
     if (page == Page::FromAllocationAreaAddress(allocation_info_.top())) {
       allocation_pointer_found_in_space = true;
@@ -1847,6 +1881,16 @@ void NewSpace::Verify() {
       CHECK(!Page::FromAllocationAreaAddress(current)->ContainsLimit(top()) ||
             current < top());
 
+      if (Page::FromAddress(current)->IsFlagSet(Page::CANNOT_BE_VERIFIED)) {
+        Page* page = Page::FromAddress(current);
+        if (page->next_page()->is_anchor()) {
+          current = top();
+        } else {
+          current = Page::FromAddress(current)->area_end();
+        }
+        continue;
+      }
+
       HeapObject* object = HeapObject::FromAddress(current);
 
       // The first word should be a map, and we expect all map pointers to
@@ -2835,7 +2879,6 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
   const int kMaxPagesToSweep = 1;
 
   // Allocation in this space has failed.
-
   MarkCompactCollector* collector = heap()->mark_compact_collector();
   // Sweeping is still in progress.
   if (collector->sweeping_in_progress()) {
@@ -2856,6 +2899,17 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
       object = free_list_.Allocate(static_cast<size_t>(size_in_bytes));
       if (object != nullptr) return object;
     }
+  } else if (is_local()) {
+    // Sweeping not in progress and we are on a {CompactionSpace}.
+    Page* page = heap()->old_space()->RemovePageSafe();
+    if (page != nullptr) {
+      PrintF("Reusing page: available free list memory: %" PRIuS "\n",
+             page->available_in_free_list());
+      AddPage(page);
+      HeapObject* object =
+          free_list_.Allocate(static_cast<size_t>(size_in_bytes));
+      if (object != nullptr) return object;
+    }
   }
 
   if (heap()->ShouldExpandOldGenerationOnAllocationFailure() && Expand()) {