[heap] Buffer counter updates for new space evacuation.

src/heap/spaces.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_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ skipping 577 matching lines @@
 
   // Manage live byte count (count of bytes known to be live,
   // because they are marked black).
   void ResetLiveBytes() {
     if (FLAG_gc_verbose) {
       PrintF("ResetLiveBytes:%p:%x->0\n", static_cast<void*>(this),
              live_byte_count_);
     }
     live_byte_count_ = 0;
   }
+
   void IncrementLiveBytes(int by) {
     if (FLAG_gc_verbose) {
       printf("UpdateLiveBytes:%p:%x%c=%x->%x\n", static_cast<void*>(this),
              live_byte_count_, ((by < 0) ? '-' : '+'), ((by < 0) ? -by : by),
              live_byte_count_ + by);
     }
     live_byte_count_ += by;
+    DCHECK_GE(live_byte_count_, 0);
     DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
   }
+
   int LiveBytes() {
-    DCHECK(static_cast<unsigned>(live_byte_count_) <= size_);
+    DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
     return live_byte_count_;
   }
 
   int write_barrier_counter() {
     return static_cast<int>(write_barrier_counter_);
   }
 
   void set_write_barrier_counter(int counter) {
     write_barrier_counter_ = counter;
   }
@@ skipping 2601 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_