Oilpan: complete current sweep before preparing for new GC.

Source/platform/heap/ThreadState.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
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@@ skipping 719 matching lines @@
         break;
     case IdleGCScheduled:
     case PreciseGCScheduled:
     case FullGCScheduled:
         checkThread();
         VERIFY_STATE_TRANSITION(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == FullGCScheduled || m_gcState == StoppingOtherThreads || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);
         completeSweep();
         break;
     case StoppingOtherThreads:
         checkThread();
         VERIFY_STATE_TRANSITION(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == FullGCScheduled || m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);

[haraken, 2015/05/21 23:01:35]

I think you can now remove a couple of states from here, since it's guaranteed
that sweeping is no progress at this point.

[sof, 2015/05/22 05:07:05]

Maybe, not so sure -- sweeping might be forbidden when collectGarbage() is
called.

[haraken, 2015/05/22 05:13:05]

Since you're calling completeSweep() before setting the StoppingOtherThreads
state, I think we can remove Sweeping, SweepingAndIdleGCScheduled and
SweepingAndPreciseGCScheduled.

Instead you can add ASSERT(!isSweepInProgress()).

-        completeSweep();
         break;
     case GCRunning:
         ASSERT(!isInGC());
         VERIFY_STATE_TRANSITION(m_gcState != GCRunning);
         break;
     case EagerSweepScheduled:
     case LazySweepScheduled:
         ASSERT(isInGC());
         VERIFY_STATE_TRANSITION(m_gcState == GCRunning);
         break;
@@ skipping 577 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink