Re-enable parallel pointer updates.

BUG=chromium:578883
LOG=NO

Review URL: https://codereview.chromium.org/1811653002

Cr-Commit-Position: refs/heads/master@{#34838}

src/base/platform/semaphore.cc

@@ -94,8 +94,7 @@ Semaphore::~Semaphore() {
 
 void Semaphore::Signal() {
   int result = sem_post(&native_handle_);
-  DCHECK_EQ(0, result);
-  USE(result);
+  CHECK_EQ(0, result);
 }
 
 

src/flag-definitions.h

@@ -693,7 +693,7 @@ DEFINE_INT(max_incremental_marking_finalization_rounds, 3,
 DEFINE_BOOL(black_allocation, false, "use black allocation")
 DEFINE_BOOL(concurrent_sweeping, true, "use concurrent sweeping")
 DEFINE_BOOL(parallel_compaction, true, "use parallel compaction")
-DEFINE_BOOL(parallel_pointer_update, false,
+DEFINE_BOOL(parallel_pointer_update, true,
             "use parallel pointer update during compaction")
 DEFINE_BOOL(trace_incremental_marking, false,
             "trace progress of the incremental marking")

src/heap/mark-compact.cc

@@ -3585,14 +3585,16 @@ int NumberOfPointerUpdateTasks(int pages) {
 
 template <PointerDirection direction>
 void UpdatePointersInParallel(Heap* heap) {
-  PageParallelJob<PointerUpdateJobTraits<direction> > job(
-      heap, heap->isolate()->cancelable_task_manager());
+  PageParallelJob<PointerUpdateJobTraits<direction> >* job =
+      new PageParallelJob<PointerUpdateJobTraits<direction> >(
+          heap, heap->isolate()->cancelable_task_manager());
   RememberedSet<direction>::IterateMemoryChunks(
-      heap, [&job](MemoryChunk* chunk) { job.AddPage(chunk, 0); });
+      heap, [job](MemoryChunk* chunk) { job->AddPage(chunk, 0); });
   PointersUpdatingVisitor visitor(heap);
-  int num_pages = job.NumberOfPages();
+  int num_pages = job->NumberOfPages();
   int num_tasks = NumberOfPointerUpdateTasks(num_pages);
-  job.Run(num_tasks, [&visitor](int i) { return &visitor; });
+  job->Run(num_tasks, [&visitor](int i) { return &visitor; });
+  delete job;
 }
 
 void MarkCompactCollector::UpdatePointersAfterEvacuation() {