Retain maps for several garbage collections

test/cctest/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1481 matching lines @@
   return count;
 }
 
 
 TEST(TestInternalWeakLists) {
   v8::V8::Initialize();
 
   // Some flags turn Scavenge collections into Mark-sweep collections
   // and hence are incompatible with this test case.
   if (FLAG_gc_global || FLAG_stress_compaction) return;
+  FLAG_retain_maps_for_n_gc = 0;
 
   static const int kNumTestContexts = 10;
 
   Isolate* isolate = CcTest::i_isolate();
   Heap* heap = isolate->heap();
   HandleScope scope(isolate);
   v8::Handle<v8::Context> ctx[kNumTestContexts];
 
   CHECK_EQ(0, CountNativeContexts());
 
@@ skipping 1402 matching lines @@
   return map->transitions()->number_of_transitions();
 }
 
 
 // Test that map transitions are cleared and maps are collected with
 // incremental marking as well.
 TEST(Regress1465) {
   i::FLAG_stress_compaction = false;
   i::FLAG_allow_natives_syntax = true;
   i::FLAG_trace_incremental_marking = true;
+  i::FLAG_retain_maps_for_n_gc = 0;
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
   static const int transitions_count = 256;
 
   CompileRun("function F() {}");
   {
     AlwaysAllocateScope always_allocate(CcTest::i_isolate());
     for (int i = 0; i < transitions_count; i++) {
       EmbeddedVector<char, 64> buffer;
       SNPrintF(buffer, "var o = new F; o.prop%d = %d;", i, i);
@@ skipping 42 matching lines @@
 
 
 static void AddPropertyTo(
     int gc_count, Handle<JSObject> object, const char* property_name) {
   Isolate* isolate = CcTest::i_isolate();
   Factory* factory = isolate->factory();
   Handle<String> prop_name = factory->InternalizeUtf8String(property_name);
   Handle<Smi> twenty_three(Smi::FromInt(23), isolate);
   i::FLAG_gc_interval = gc_count;
   i::FLAG_gc_global = true;
+  i::FLAG_retain_maps_for_n_gc = 0;
   CcTest::heap()->set_allocation_timeout(gc_count);
   JSReceiver::SetProperty(object, prop_name, twenty_three, SLOPPY).Check();
 }
 
 
 TEST(TransitionArrayShrinksDuringAllocToZero) {
   i::FLAG_stress_compaction = false;
   i::FLAG_allow_natives_syntax = true;
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
@@ skipping 1202 matching lines @@
     Handle<JSFunction> bar_handle =
         v8::Utils::OpenHandle(
             *v8::Handle<v8::Function>::Cast(
                 CcTest::global()->Get(v8_str("bar"))));
     CHECK_EQ(bar_handle->code(), function_bar);
   }
 
   // Now make sure that a gc should get rid of the function, even though we
   // still have the allocation site alive.
   for (int i = 0; i < 4; i++) {
-    heap->CollectAllGarbage(Heap::kNoGCFlags);
+    heap->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
   }
 
   // TODO(mvstanton): this test fails when FLAG_vector_ics is true because
   // monomorphic load ics are preserved, but also strongly walked. They
   // end up keeping function bar alive.
 
   // The site still exists because of our global handle, but the code is no
   // longer referred to by dependent_code().
   DependentCode::GroupStartIndexes starts(site->dependent_code());
   int index = starts.at(DependentCode::kAllocationSiteTransitionChangedGroup);
@@ skipping 90 matching lines @@
 
 
 TEST(NoWeakHashTableLeakWithIncrementalMarking) {
   if (i::FLAG_always_opt || !i::FLAG_crankshaft) return;
   if (!i::FLAG_incremental_marking) return;
   // TODO(mvstanton): vector ics need weak support.
   if (FLAG_vector_ics) return;
   i::FLAG_weak_embedded_objects_in_optimized_code = true;
   i::FLAG_allow_natives_syntax = true;
   i::FLAG_compilation_cache = false;
+  i::FLAG_retain_maps_for_n_gc = 0;
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
   v8::internal::Heap* heap = CcTest::heap();
 
   if (!isolate->use_crankshaft()) return;
   HandleScope outer_scope(heap->isolate());
   for (int i = 0; i < 3; i++) {
     SimulateIncrementalMarking(heap);
     {
       LocalContext context;
@@ skipping 775 matching lines @@
   Handle<GlobalObject> global(CcTest::i_isolate()->context()->global_object());
   Handle<JSArray> array = factory->NewJSArray(2);
 
   Handle<String> name = factory->InternalizeUtf8String("testArray");
   JSReceiver::SetProperty(global, name, array, SLOPPY).Check();
   CompileRun("testArray[0] = 1; testArray[1] = 2; testArray.shift();");
   heap->CollectGarbage(OLD_POINTER_SPACE);
 }
 
 
+void CheckMapRetainingFor(int n) {
+  FLAG_retain_maps_for_n_gc = n;
+  Isolate* isolate = CcTest::i_isolate();
+  Heap* heap = isolate->heap();
+  Handle<WeakCell> weak_cell;
+  {
+    HandleScope inner_scope(isolate);
+    Handle<Map> map = Map::Create(isolate, 1);
+    weak_cell = inner_scope.CloseAndEscape(Map::WeakCellForMap(map));
+  }
+  CHECK(!weak_cell->cleared());
+  int retaining_count =
+      Min(FLAG_retain_maps_for_n_gc,
+          Map::kRetainingCounterStart - Map::kRetainingCounterEnd);
+  for (int i = 0; i < retaining_count; i++) {
+    heap->CollectGarbage(OLD_POINTER_SPACE);
+  }
+  CHECK(!weak_cell->cleared());
+  heap->CollectGarbage(OLD_POINTER_SPACE);
+  CHECK(weak_cell->cleared());
+}
+
+
+TEST(MapRetaining) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  CheckMapRetainingFor(FLAG_retain_maps_for_n_gc);
+  CheckMapRetainingFor(0);
+  CheckMapRetainingFor(Map::kRetainingCounterStart - Map::kRetainingCounterEnd);
+  CheckMapRetainingFor(Map::kRetainingCounterStart - Map::kRetainingCounterEnd +
+                       1);
+}
+
+
 #ifdef DEBUG
 TEST(PathTracer) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
 
   v8::Local<v8::Value> result = CompileRun("'abc'");
   Handle<Object> o = v8::Utils::OpenHandle(*result);
   CcTest::i_isolate()->heap()->TracePathToObject(*o);
 }
 #endif  // DEBUG