Debug garbage collector does not correctly remove cross-gen garbage

runtime/vm/heap.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/heap.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
@@ skipping 345 matching lines @@
 #ifndef PRODUCT
 void Heap::UpdateClassHeapStatsBeforeGC(Heap::Space space) {
   ClassTable* class_table = isolate()->class_table();
   if (space == kNew) {
     class_table->ResetCountersNew();
   } else {
     class_table->ResetCountersOld();
   }
 }
 #endif
 

[rmacnak, 2017/06/30 22:24:56]

Two lines between functions (clang-format doesn't handle everything).

[danunez, 2017/06/30 22:33:58]

Done.

+void Heap::EvacuateNewSpaceGarbage(Thread* thread, GCReason reason) {
+  ASSERT(reason == kFull);
+  if (BeginNewSpaceGC(thread)) {
+    RecordBeforeGC(kNew, kFull);
+    VMTagScope tagScope(thread, VMTag::kGCNewSpaceTagId);
+    TIMELINE_FUNCTION_GC_DURATION(thread, "CollectNewGeneration");

[rmacnak, 2017/06/30 22:24:56]

"EvacuateNewGeneration"

[danunez, 2017/06/30 22:33:58]

Done.

+    NOT_IN_PRODUCT(UpdateClassHeapStatsBeforeGC(kNew));
+    new_space_.Evacuate();
+    NOT_IN_PRODUCT(isolate()->class_table()->UpdatePromoted());
+    RecordAfterGC(kNew);
+    PrintStats();
+    NOT_IN_PRODUCT(PrintStatsToTimeline(&tds));
+    EndNewSpaceGC();
+  }
+}
 

[rmacnak, 2017/06/30 22:24:56]

Two lines

[danunez, 2017/06/30 22:33:58]

Done.

 void Heap::CollectNewSpaceGarbage(Thread* thread,
                                   ApiCallbacks api_callbacks,
                                   GCReason reason) {
   ASSERT((reason == kNewSpace) || (reason == kFull));
   if (BeginNewSpaceGC(thread)) {
     bool invoke_api_callbacks = (api_callbacks == kInvokeApiCallbacks);
     RecordBeforeGC(kNew, reason);
     VMTagScope tagScope(thread, VMTag::kGCNewSpaceTagId);
     TIMELINE_FUNCTION_GC_DURATION(thread, "CollectNewGeneration");
     NOT_IN_PRODUCT(UpdateClassHeapStatsBeforeGC(kNew));
@@ skipping 59 matching lines @@
     CollectOldSpaceGarbage(thread, kInvokeApiCallbacks, kOldSpace);
   } else {
     ASSERT(space == kNew);
     CollectNewSpaceGarbage(thread, kInvokeApiCallbacks, kNewSpace);
   }
 }
 
 
 void Heap::CollectAllGarbage() {
   Thread* thread = Thread::Current();
-  CollectNewSpaceGarbage(thread, kInvokeApiCallbacks, kFull);
+
+  // New space is evacuated so this GC will collect all dead objects
+  // kept alive by a cross-generational pointer.
+  EvacuateNewSpaceGarbage(thread, kFull);
   CollectOldSpaceGarbage(thread, kInvokeApiCallbacks, kFull);
 }
 
 
 void Heap::WaitForSweeperTasks(Thread* thread) {
   MonitorLocker ml(old_space_.tasks_lock());
   while (old_space_.tasks() > 0) {
     ml.WaitWithSafepointCheck(thread);
   }
 }
@@ skipping 419 matching lines @@
   Dart::vm_isolate()->heap()->WriteProtect(false);
 }
 
 
 WritableVMIsolateScope::~WritableVMIsolateScope() {
   ASSERT(Dart::vm_isolate()->heap()->UsedInWords(Heap::kNew) == 0);
   Dart::vm_isolate()->heap()->WriteProtect(true);
 }
 
 }  // namespace dart