[heap] Remove border page

src/heap/spaces-inl.h

 // 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.
 
 #ifndef V8_HEAP_SPACES_INL_H_
 #define V8_HEAP_SPACES_INL_H_
 
 #include "src/heap/incremental-marking.h"
 #include "src/heap/spaces.h"
 #include "src/isolate.h"
@@ skipping 147 matching lines @@
   return to_space_.ContainsSlow(a);
 }
 
 bool NewSpace::FromSpaceContainsSlow(Address a) {
   return from_space_.ContainsSlow(a);
 }
 
 bool NewSpace::ToSpaceContains(Object* o) { return to_space_.Contains(o); }
 bool NewSpace::FromSpaceContains(Object* o) { return from_space_.Contains(o); }
 
+size_t NewSpace::AllocatedSinceLastGC() {
+  Page* top_page = Page::FromAllocationAreaAddress(top());
+  size_t allocated = 0;
+  // If top gets reset to be in the range of pages that are below the age
+  // mark, this loop will not trigger and we return 0 (invalid).
+  for (Page* current_page = top_page;
+       !current_page->InIntermediateGeneration() &&
+       current_page != to_space_.anchor();
+       current_page = current_page->prev_page()) {
+    allocated += (top_page == current_page)
+                     ? static_cast<size_t>(top() - current_page->area_start())
+                     : Page::kAllocatableMemory;

[Hannes Payer (out of office), 2016/09/27 08:28:31]

This method is not precise. Fragmentation at the end of a page is counted as
allocated.

[Michael Lippautz, 2016/09/27 11:13:47]

Ack. Let's try changing this in a different CL as it affects heuristics.

+  }
+  return allocated;
+}
+
 // --------------------------------------------------------------------------
 // AllocationResult
 
 AllocationSpace AllocationResult::RetrySpace() {
   DCHECK(IsRetry());
   return static_cast<AllocationSpace>(Smi::cast(object_)->value());
 }
 
 Page* Page::Initialize(Heap* heap, MemoryChunk* chunk, Executability executable,
                        SemiSpace* owner) {
@@ skipping 457 matching lines @@
     other->allocation_info_.Reset(nullptr, nullptr);
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_INL_H_