Don't verify evacuation when it is not completed.

BUG=

Review URL: https://codereview.chromium.org/756553002

Cr-Commit-Position: refs/heads/master@{#25478}

src/heap/mark-compact.cc

@@ -47,7 +47,7 @@ MarkCompactCollector::MarkCompactCollector(Heap* heap)
       was_marked_incrementally_(false),
       sweeping_in_progress_(false),
       pending_sweeper_jobs_semaphore_(0),
-      sequential_sweeping_(false),
+      evacuation_(false),
       migration_slots_buffer_(NULL),
       heap_(heap),
       code_flusher_(NULL),
@@ -487,7 +487,7 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
   heap()->paged_space(OLD_POINTER_SPACE)->ResetUnsweptFreeBytes();
 
 #ifdef VERIFY_HEAP
-  if (FLAG_verify_heap) {
+  if (FLAG_verify_heap && !evacuation()) {
     VerifyEvacuation(heap_);
   }
 #endif
@@ -3393,6 +3393,7 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
   {
     GCTracer::Scope gc_scope(heap()->tracer(),
                              GCTracer::Scope::MC_EVACUATE_PAGES);
+    EvacuationScope evacuation_scope(this);
     EvacuatePages();
   }
 
@@ -4139,7 +4140,6 @@ void MarkCompactCollector::SweepSpaces() {
     GCTracer::Scope sweep_scope(heap()->tracer(),
                                 GCTracer::Scope::MC_SWEEP_OLDSPACE);
     {
-      SequentialSweepingScope scope(this);
       SweepSpace(heap()->old_pointer_space(), CONCURRENT_SWEEPING);
       SweepSpace(heap()->old_data_space(), CONCURRENT_SWEEPING);
     }

src/heap/mark-compact.h

@@ -643,11 +643,9 @@ class MarkCompactCollector {
   // Checks if sweeping is in progress right now on any space.
   bool sweeping_in_progress() { return sweeping_in_progress_; }
 
-  void set_sequential_sweeping(bool sequential_sweeping) {
-    sequential_sweeping_ = sequential_sweeping;
-  }
+  void set_evacuation(bool evacuation) { evacuation_ = evacuation; }
 
-  bool sequential_sweeping() const { return sequential_sweeping_; }
+  bool evacuation() const { return evacuation_; }
 
   // Mark the global table which maps weak objects to dependent code without
   // marking its contents.
@@ -704,7 +702,7 @@ class MarkCompactCollector {
 
   base::Semaphore pending_sweeper_jobs_semaphore_;
 
-  bool sequential_sweeping_;
+  bool evacuation_;
 
   SlotsBufferAllocator slots_buffer_allocator_;
 
@@ -934,14 +932,14 @@ class MarkBitCellIterator BASE_EMBEDDED {
 };
 
 
-class SequentialSweepingScope BASE_EMBEDDED {
+class EvacuationScope BASE_EMBEDDED {
  public:
-  explicit SequentialSweepingScope(MarkCompactCollector* collector)
+  explicit EvacuationScope(MarkCompactCollector* collector)
       : collector_(collector) {
-    collector_->set_sequential_sweeping(true);
+    collector_->set_evacuation(true);
   }
 
-  ~SequentialSweepingScope() { collector_->set_sequential_sweeping(false); }
+  ~EvacuationScope() { collector_->set_evacuation(false); }
 
  private:
   MarkCompactCollector* collector_;