Revert of Reland concurrent sweeping of code space.

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/v8.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 208 matching lines @@
   VerifyEvacuation(heap->new_space());
 
   VerifyEvacuationVisitor visitor;
   heap->IterateStrongRoots(&visitor, VISIT_ALL);
 }
 #endif  // VERIFY_HEAP
 
 
 void MarkCompactCollector::SetUp() {
   free_list_old_space_.Reset(new FreeList(heap_->old_space()));
-  free_list_code_space_.Reset(new FreeList(heap_->code_space()));
   EnsureMarkingDequeIsReserved();
   EnsureMarkingDequeIsCommitted(kMinMarkingDequeSize);
 }
 
 
 void MarkCompactCollector::TearDown() {
   AbortCompaction();
   delete marking_deque_memory_;
 }
 
@@ skipping 122 matching lines @@
   ClearInvalidStoreAndSlotsBufferEntries();
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyValidStoreAndSlotsBufferEntries(heap_);
   }
 #endif
 
   SweepSpaces();
 
+#ifdef VERIFY_HEAP
+  VerifyWeakEmbeddedObjectsInCode();
+  if (FLAG_omit_map_checks_for_leaf_maps) {
+    VerifyOmittedMapChecks();
+  }
+#endif
+
   Finish();
 
   if (marking_parity_ == EVEN_MARKING_PARITY) {
     marking_parity_ = ODD_MARKING_PARITY;
   } else {
     DCHECK(marking_parity_ == ODD_MARKING_PARITY);
     marking_parity_ = EVEN_MARKING_PARITY;
   }
 }
 
@@ skipping 106 matching lines @@
 
   Heap* heap_;
   PagedSpace* space_;
 
   DISALLOW_COPY_AND_ASSIGN(SweeperTask);
 };
 
 
 void MarkCompactCollector::StartSweeperThreads() {
   DCHECK(free_list_old_space_.get()->IsEmpty());
-  DCHECK(free_list_code_space_.get()->IsEmpty());
   V8::GetCurrentPlatform()->CallOnBackgroundThread(
       new SweeperTask(heap(), heap()->old_space()),
       v8::Platform::kShortRunningTask);
-  V8::GetCurrentPlatform()->CallOnBackgroundThread(
-      new SweeperTask(heap(), heap()->code_space()),
-      v8::Platform::kShortRunningTask);
 }
 
 
-void MarkCompactCollector::SweepOrWaitUntilSweepingCompleted(Page* page) {
-  PagedSpace* owner = reinterpret_cast<PagedSpace*>(page->owner());
-  if (!page->SweepingCompleted()) {
-    SweepInParallel(page, owner);
-    if (!page->SweepingCompleted()) {
-      // We were not able to sweep that page, i.e., a concurrent
-      // sweeper thread currently owns this page. Wait for the sweeper
-      // thread to be done with this page.
-      page->WaitUntilSweepingCompleted();
-    }
-  }
-}
-
-
 void MarkCompactCollector::EnsureSweepingCompleted() {
   DCHECK(sweeping_in_progress_ == true);
 
   // If sweeping is not completed or not running at all, we try to complete it
   // here.
   if (!heap()->concurrent_sweeping_enabled() || !IsSweepingCompleted()) {
     SweepInParallel(heap()->paged_space(OLD_SPACE), 0);
-    SweepInParallel(heap()->paged_space(CODE_SPACE), 0);
   }
   // Wait twice for both jobs.
   if (heap()->concurrent_sweeping_enabled()) {
     pending_sweeper_jobs_semaphore_.Wait();
-    pending_sweeper_jobs_semaphore_.Wait();
   }
   ParallelSweepSpacesComplete();
   sweeping_in_progress_ = false;
   RefillFreeList(heap()->paged_space(OLD_SPACE));
-  RefillFreeList(heap()->paged_space(CODE_SPACE));
   heap()->paged_space(OLD_SPACE)->ResetUnsweptFreeBytes();
-  heap()->paged_space(CODE_SPACE)->ResetUnsweptFreeBytes();
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap && !evacuation()) {
     VerifyEvacuation(heap_);
   }
 #endif
 }
 
 
 bool MarkCompactCollector::IsSweepingCompleted() {
   if (!pending_sweeper_jobs_semaphore_.WaitFor(
           base::TimeDelta::FromSeconds(0))) {
     return false;
   }
   pending_sweeper_jobs_semaphore_.Signal();
   return true;
 }
 
 
 void MarkCompactCollector::RefillFreeList(PagedSpace* space) {
   FreeList* free_list;
 
   if (space == heap()->old_space()) {
     free_list = free_list_old_space_.get();
-  } else if (space == heap()->code_space()) {
-    free_list = free_list_code_space_.get();
   } else {
     // Any PagedSpace might invoke RefillFreeLists, so we need to make sure
     // to only refill them for the old space.
     return;
   }
 
   intptr_t freed_bytes = space->free_list()->Concatenate(free_list);
   space->AddToAccountingStats(freed_bytes);
   space->DecrementUnsweptFreeBytes(freed_bytes);
 }
@@ skipping 2912 matching lines @@
   DCHECK_EQ(skip_list_mode == REBUILD_SKIP_LIST,
             space->identity() == CODE_SPACE);
   DCHECK((p->skip_list() == NULL) || (skip_list_mode == REBUILD_SKIP_LIST));
   DCHECK(parallelism == MarkCompactCollector::SWEEP_ON_MAIN_THREAD ||
          sweeping_mode == SWEEP_ONLY);
 
   Address free_start = p->area_start();
   DCHECK(reinterpret_cast<intptr_t>(free_start) % (32 * kPointerSize) == 0);
   int offsets[16];
 
-  // If we use the skip list for code space pages, we have to lock the skip
-  // list because it could be accessed concurrently by the runtime or the
-  // deoptimizer.
   SkipList* skip_list = p->skip_list();
+  int curr_region = -1;
   if ((skip_list_mode == REBUILD_SKIP_LIST) && skip_list) {
     skip_list->Clear();
   }
 
   intptr_t freed_bytes = 0;
   intptr_t max_freed_bytes = 0;
-  int curr_region = -1;
 
   for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
     Address cell_base = it.CurrentCellBase();
     MarkBit::CellType* cell = it.CurrentCell();
     int live_objects = MarkWordToObjectStarts(*cell, offsets);
     int live_index = 0;
     for (; live_objects != 0; live_objects--) {
       Address free_end = cell_base + offsets[live_index++] * kPointerSize;
       if (free_end != free_start) {
         int size = static_cast<int>(free_end - free_start);
@@ skipping 738 matching lines @@
 
 int MarkCompactCollector::SweepInParallel(Page* page, PagedSpace* space) {
   int max_freed = 0;
   if (page->TryLock()) {
     // If this page was already swept in the meantime, we can return here.
     if (page->parallel_sweeping() != MemoryChunk::SWEEPING_PENDING) {
       page->mutex()->Unlock();
       return 0;
     }
     page->set_parallel_sweeping(MemoryChunk::SWEEPING_IN_PROGRESS);
-    FreeList* free_list;
+    FreeList* free_list = free_list_old_space_.get();
     FreeList private_free_list(space);
-    if (space->identity() == CODE_SPACE) {
-      free_list = free_list_code_space_.get();
-      max_freed =
-          Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, REBUILD_SKIP_LIST,
-                IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL);
-    } else {
-      free_list = free_list_old_space_.get();
-      max_freed =
-          Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, IGNORE_SKIP_LIST,
-                IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL);
-    }
+    max_freed = Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, IGNORE_SKIP_LIST,
+                      IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL);
     free_list->Concatenate(&private_free_list);
     page->mutex()->Unlock();
   }
   return max_freed;
 }
 
 
 void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) {
   space->ClearStats();
 
@@ skipping 37 matching lines @@
       unused_page_present = true;
     }
 
     switch (sweeper) {
       case CONCURRENT_SWEEPING:
         if (!parallel_sweeping_active) {
           if (FLAG_gc_verbose) {
             PrintF("Sweeping 0x%" V8PRIxPTR ".\n",
                    reinterpret_cast<intptr_t>(p));
           }
-          if (space->identity() == CODE_SPACE) {
-            if (FLAG_zap_code_space) {
-              Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
-                    ZAP_FREE_SPACE>(space, NULL, p, NULL);
-            } else {
-              Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
-                    IGNORE_FREE_SPACE>(space, NULL, p, NULL);
-            }
-          } else {
-            DCHECK(space->identity() == OLD_SPACE);
-            Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST,
-                  IGNORE_FREE_SPACE>(space, NULL, p, NULL);
-          }
+          Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST,
+                IGNORE_FREE_SPACE>(space, NULL, p, NULL);
           pages_swept++;
           parallel_sweeping_active = true;
         } else {
           if (FLAG_gc_verbose) {
             PrintF("Sweeping 0x%" V8PRIxPTR " in parallel.\n",
                    reinterpret_cast<intptr_t>(p));
           }
           p->set_parallel_sweeping(MemoryChunk::SWEEPING_PENDING);
           space->IncreaseUnsweptFreeBytes(p);
         }
         space->set_end_of_unswept_pages(p);
         break;
       case SEQUENTIAL_SWEEPING: {
         if (FLAG_gc_verbose) {
           PrintF("Sweeping 0x%" V8PRIxPTR ".\n", reinterpret_cast<intptr_t>(p));
         }
-        if (space->identity() == CODE_SPACE) {
-          if (FLAG_zap_code_space) {
-            Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
-                  ZAP_FREE_SPACE>(space, NULL, p, NULL);
-          } else {
-            Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
-                  IGNORE_FREE_SPACE>(space, NULL, p, NULL);
-          }
+        if (space->identity() == CODE_SPACE && FLAG_zap_code_space) {
+          Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
+                ZAP_FREE_SPACE>(space, NULL, p, NULL);
+        } else if (space->identity() == CODE_SPACE) {
+          Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST,
+                IGNORE_FREE_SPACE>(space, NULL, p, NULL);
         } else {
-          DCHECK(space->identity() == OLD_SPACE ||
-                 space->identity() == MAP_SPACE);
           Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST,
                 IGNORE_FREE_SPACE>(space, NULL, p, NULL);
         }
         pages_swept++;
         break;
       }
       default: { UNREACHABLE(); }
     }
   }
 
@@ skipping 19 matching lines @@
 #endif
 
   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(heap()->tracer(),
-                                  GCTracer::Scope::MC_SWEEP_OLDSPACE);
-      SweepSpace(heap()->old_space(), CONCURRENT_SWEEPING);
-    }
-    {
-      GCTracer::Scope sweep_scope(heap()->tracer(),
-                                  GCTracer::Scope::MC_SWEEP_CODE);
-      SweepSpace(heap()->code_space(), CONCURRENT_SWEEPING);
-    }
-
+    GCTracer::Scope sweep_scope(heap()->tracer(),
+                                GCTracer::Scope::MC_SWEEP_OLDSPACE);
+    { SweepSpace(heap()->old_space(), CONCURRENT_SWEEPING); }
     sweeping_in_progress_ = true;
     if (heap()->concurrent_sweeping_enabled()) {
       StartSweeperThreads();
     }
   }
+  RemoveDeadInvalidatedCode();
 
-  RemoveDeadInvalidatedCode();
+  {
+    GCTracer::Scope sweep_scope(heap()->tracer(),
+                                GCTracer::Scope::MC_SWEEP_CODE);
+    SweepSpace(heap()->code_space(), SEQUENTIAL_SWEEPING);
+  }
 
   EvacuateNewSpaceAndCandidates();
 
   heap()->FreeDeadArrayBuffers(false);
 
   // ClearNonLiveReferences depends on precise sweeping of map space to
   // detect whether unmarked map became dead in this collection or in one
   // of the previous ones.
   {
     GCTracer::Scope sweep_scope(heap()->tracer(),
@@ skipping 32 matching lines @@
       p->set_parallel_sweeping(MemoryChunk::SWEEPING_DONE);
       p->SetWasSwept();
     }
     DCHECK(p->parallel_sweeping() == MemoryChunk::SWEEPING_DONE);
   }
 }
 
 
 void MarkCompactCollector::ParallelSweepSpacesComplete() {
   ParallelSweepSpaceComplete(heap()->old_space());
-  ParallelSweepSpaceComplete(heap()->code_space());
 }
 
 
 void MarkCompactCollector::EnableCodeFlushing(bool enable) {
   if (isolate()->debug()->is_active()) enable = false;
 
   if (enable) {
     if (code_flusher_ != NULL) return;
     code_flusher_ = new CodeFlusher(isolate());
   } else {
@@ skipping 298 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }  // namespace internal
 }  // namespace v8