Remove parallel sweeping mode, it's no longer used

src/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/v8.h"
 
 #include "src/base/atomicops.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/cpu-profiler.h"
@@ skipping 187 matching lines @@
     while (current < limit) {
       HeapObject* object = HeapObject::FromAddress(current);
       object->Iterate(&visitor);
       current += object->Size();
     }
   }
 }
 
 
 static void VerifyEvacuation(PagedSpace* space) {
-  // TODO(hpayer): Bring back VerifyEvacuation for parallel-concurrently
-  // swept pages.
-  if ((FLAG_concurrent_sweeping || FLAG_parallel_sweeping) &&
-      !space->is_iterable()) return;
+  // TODO(hpayer): Bring back VerifyEvacuation for concurrently swept pages.
+  if (FLAG_concurrent_sweeping && !space->is_iterable()) return;
   PageIterator it(space);
 
   while (it.has_next()) {
     Page* p = it.next();
     if (p->IsEvacuationCandidate()) continue;
     VerifyEvacuation(p->area_start(), p->area_end());
   }
 }
 
 
@@ skipping 3918 matching lines @@
         // Adjust unswept free bytes because releasing a page expects said
         // counter to be accurate for unswept pages.
         space->IncreaseUnsweptFreeBytes(p);
         space->ReleasePage(p);
         continue;
       }
       unused_page_present = true;
     }
 
     switch (sweeper) {
-      case CONCURRENT_CONSERVATIVE:
-      case PARALLEL_CONSERVATIVE: {
+      case CONCURRENT_CONSERVATIVE: {
         if (!parallel_sweeping_active) {
           if (FLAG_gc_verbose) {
             PrintF("Sweeping 0x%" V8PRIxPTR " conservatively.\n",
                    reinterpret_cast<intptr_t>(p));
           }
           SweepConservatively<SWEEP_ON_MAIN_THREAD>(space, NULL, p);
           pages_swept++;
           parallel_sweeping_active = true;
         } else {
           if (FLAG_gc_verbose) {
@@ skipping 40 matching lines @@
   heap()->FreeQueuedChunks();
 }
 
 
 void MarkCompactCollector::SweepSpaces() {
   GCTracer::Scope gc_scope(tracer_, GCTracer::Scope::MC_SWEEP);
 #ifdef DEBUG
   state_ = SWEEP_SPACES;
 #endif
   SweeperType how_to_sweep = CONCURRENT_CONSERVATIVE;
-  if (FLAG_parallel_sweeping) how_to_sweep = PARALLEL_CONSERVATIVE;
-  if (FLAG_concurrent_sweeping) how_to_sweep = CONCURRENT_CONSERVATIVE;
-
   if (sweep_precisely_) how_to_sweep = PRECISE;
 
   MoveEvacuationCandidatesToEndOfPagesList();
 
   // Noncompacting collections simply sweep the spaces to clear the mark
   // bits and free the nonlive blocks (for old and map spaces).  We sweep
   // the map space last because freeing non-live maps overwrites them and
   // the other spaces rely on possibly non-live maps to get the sizes for
   // non-live objects.
   { GCTracer::Scope sweep_scope(tracer_, GCTracer::Scope::MC_SWEEP_OLDSPACE);
     { SequentialSweepingScope scope(this);
       SweepSpace(heap()->old_pointer_space(), how_to_sweep);
       SweepSpace(heap()->old_data_space(), how_to_sweep);
     }
 
-    if (how_to_sweep == PARALLEL_CONSERVATIVE ||
-        how_to_sweep == CONCURRENT_CONSERVATIVE) {
+    if (how_to_sweep == CONCURRENT_CONSERVATIVE) {
       StartSweeperThreads();
     }
-
-    if (how_to_sweep == PARALLEL_CONSERVATIVE) {
-      EnsureSweepingCompleted();
-    }
   }
   RemoveDeadInvalidatedCode();
 
   { GCTracer::Scope sweep_scope(tracer_, GCTracer::Scope::MC_SWEEP_CODE);
     SweepSpace(heap()->code_space(), PRECISE);
   }
 
   { GCTracer::Scope sweep_scope(tracer_, GCTracer::Scope::MC_SWEEP_CELL);
     SweepSpace(heap()->cell_space(), PRECISE);
     SweepSpace(heap()->property_cell_space(), PRECISE);
@@ skipping 248 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal