[heap] Properly adjust live bytes for pages where we abort evacaution

src/heap/mark-compact.cc

 // Copyright 2012 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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 3484 matching lines @@
 #endif  // VERIFY_HEAP
 
 bool MarkCompactCollector::VisitLiveObjects(MemoryChunk* page,
                                             HeapObjectVisitor* visitor,
                                             IterationMode mode) {
 #ifdef VERIFY_HEAP
   VerifyAllBlackObjects(page);
 #endif  // VERIFY_HEAP
 
   LiveObjectIterator<kBlackObjects> it(page);
-  HeapObject* object = NULL;
-  while ((object = it.Next()) != NULL) {
+  HeapObject* object = nullptr;
+  while ((object = it.Next()) != nullptr) {
     DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
     if (!visitor->Visit(object)) {
       if (mode == kClearMarkbits) {
         page->markbits()->ClearRange(
             page->AddressToMarkbitIndex(page->area_start()),
             page->AddressToMarkbitIndex(object->address()));
+        LiveObjectIterator<kBlackObjects> it2(page);

[ulan, 2016/01/14 15:46:38]

Let's move this code into a separate function named something like
RecomputeLiveBytes().

[Michael Lippautz, 2016/01/14 16:01:46]

RecomputeLiveBytes it is.

+        int new_live_size = 0;
+        while ((object = it2.Next()) != nullptr) {
+          new_live_size += object->Size();
+        }
+        DCHECK_LT(new_live_size, page->LiveBytes());
+        page->IncrementLiveBytes(new_live_size - page->LiveBytes());

[ulan, 2016/01/14 15:46:38]

I think adding new page->SetLiveBytes(new_live_size) would be better.

Otherwise, we are passing negative number to IncrementLiveBytes.

[Michael Lippautz, 2016/01/14 16:01:45]

SetLiveBytes() it is.

       }
       return false;
     }
   }
   if (mode == kClearMarkbits) {
     Bitmap::Clear(page);
   }
   return true;
 }
 
@@ skipping 531 matching lines @@
     MarkBit mark_bit = Marking::MarkBitFrom(host);
     if (Marking::IsBlack(mark_bit)) {
       RelocInfo rinfo(isolate(), pc, RelocInfo::CODE_TARGET, 0, host);
       RecordRelocSlot(&rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8