Reland concurrent sweeping of code space.

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 38008c3f19dae7c9b804e7837ff8f8a6058b17f0..4435ff4a46ca1db370a195a762c497b965cdb96a 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -226,6 +226,7 @@ static void VerifyEvacuation(Heap* 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);
 }
@@ -366,13 +367,6 @@ void MarkCompactCollector::CollectGarbage() {
 
   SweepSpaces();
 
-#ifdef VERIFY_HEAP
-  VerifyWeakEmbeddedObjectsInCode();
-  if (FLAG_omit_map_checks_for_leaf_maps) {
-    VerifyOmittedMapChecks();
-  }
-#endif
-
   Finish();
 
   if (marking_parity_ == EVEN_MARKING_PARITY) {
@@ -499,9 +493,13 @@ class MarkCompactCollector::SweeperTask : public v8::Task {
 
 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);
 }
 
 
@@ -512,15 +510,19 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
   // 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()) {
@@ -530,6 +532,21 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
 }
 
 
+void MarkCompactCollector::EnsureSweepingCompleted(Page* page,
+                                                   PagedSpace* space) {
+  if (!page->SweepingCompleted()) {
+    SweepInParallel(page, space);
+    if (!page->SweepingCompleted()) {
+      // We were not able to sweep that page, i.e., a concurrent
+      // sweeper thread currently owns this page.
+      // TODO(hpayer): This may introduce a huge pause here. We
+      // just care about finish sweeping of the scan on scavenge page.
+      EnsureSweepingCompleted();
+    }
+  }
+}
+
+
 bool MarkCompactCollector::IsSweepingCompleted() {
   if (!pending_sweeper_jobs_semaphore_.WaitFor(
           base::TimeDelta::FromSeconds(0))) {
@@ -545,6 +562,8 @@ void MarkCompactCollector::RefillFreeList(PagedSpace* space) {
 
   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.
@@ -3493,14 +3512,17 @@ static int Sweep(PagedSpace* space, FreeList* free_list, Page* p,
   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();
@@ -4164,10 +4186,19 @@ int MarkCompactCollector::SweepInParallel(PagedSpace* space,
 int MarkCompactCollector::SweepInParallel(Page* page, PagedSpace* space) {
   int max_freed = 0;
   if (page->TryParallelSweeping()) {
-    FreeList* free_list = free_list_old_space_.get();
+    FreeList* free_list;
     FreeList private_free_list(space);
-    max_freed = Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, IGNORE_SKIP_LIST,
-                      IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL);
+    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);
+    }
     free_list->Concatenate(&private_free_list);
   }
   return max_freed;
@@ -4224,8 +4255,19 @@ void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) {
             PrintF("Sweeping 0x%" V8PRIxPTR ".\n",
                    reinterpret_cast<intptr_t>(p));
           }
-          Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST,
-                IGNORE_FREE_SPACE>(space, NULL, p, NULL);
+          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);
+          }
           pages_swept++;
           parallel_sweeping_active = true;
         } else {
@@ -4242,13 +4284,17 @@ void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) {
         if (FLAG_gc_verbose) {
           PrintF("Sweeping 0x%" V8PRIxPTR ".\n", reinterpret_cast<intptr_t>(p));
         }
-        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);
+        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 ||
+                 space->identity() == MAP_SPACE);
           Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST,
                 IGNORE_FREE_SPACE>(space, NULL, p, NULL);
         }
@@ -4288,19 +4334,22 @@ void MarkCompactCollector::SweepSpaces() {
   // 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_OLDSPACE);
+      SweepSpace(heap()->old_space(), CONCURRENT_SWEEPING);
+    }
+    {
+      GCTracer::Scope sweep_scope(heap()->tracer(),
+                                  GCTracer::Scope::MC_SWEEP_CODE);
+      SweepSpace(heap()->code_space(), CONCURRENT_SWEEPING);
+    }
+
     sweeping_in_progress_ = true;
     if (heap()->concurrent_sweeping_enabled()) {
       StartSweeperThreads();
     }
   }
-  {
-    GCTracer::Scope sweep_scope(heap()->tracer(),
-                                GCTracer::Scope::MC_SWEEP_CODE);
-    SweepSpace(heap()->code_space(), SEQUENTIAL_SWEEPING);
-  }
 
   EvacuateNewSpaceAndCandidates();
 
@@ -4353,6 +4402,7 @@ void MarkCompactCollector::ParallelSweepSpaceComplete(PagedSpace* space) {
 
 void MarkCompactCollector::ParallelSweepSpacesComplete() {
   ParallelSweepSpaceComplete(heap()->old_space());
+  ParallelSweepSpaceComplete(heap()->code_space());
 }