Improve debuggability of failed GCState transitions.

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
  * 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
@@ skipping 609 matching lines @@
 void ThreadState::schedulePreciseGC()
 {
     if (isSweepingInProgress()) {
         setGCState(SweepingAndPreciseGCScheduled);
         return;
     }
 
     setGCState(PreciseGCScheduled);
 }
 
+namespace {
+
+#define UNEXPECTED_GCSTATE(s) case ThreadState::s: RELEASE_ASSERT_WITH_MESSAGE(false, "Unexpected transition while in GCState " #s); return
+
+void unexpectedGCState(ThreadState::GCState gcState)
+{
+    switch (gcState) {
+        UNEXPECTED_GCSTATE(NoGCScheduled);

[sof, 2015/03/13 10:49:32]

The presubmit script enforced this indentation.

+        UNEXPECTED_GCSTATE(IdleGCScheduled);
+        UNEXPECTED_GCSTATE(PreciseGCScheduled);
+        UNEXPECTED_GCSTATE(GCScheduledForTesting);
+        UNEXPECTED_GCSTATE(StoppingOtherThreads);
+        UNEXPECTED_GCSTATE(GCRunning);
+        UNEXPECTED_GCSTATE(EagerSweepScheduled);
+        UNEXPECTED_GCSTATE(LazySweepScheduled);
+        UNEXPECTED_GCSTATE(Sweeping);
+        UNEXPECTED_GCSTATE(SweepingAndIdleGCScheduled);
+        UNEXPECTED_GCSTATE(SweepingAndPreciseGCScheduled);
+    default:
+        ASSERT_NOT_REACHED();
+        return;
+    }
+}
+
+#undef UNEXPECTED_GCSTATE
+
+} // namespace
+
+#define VERIFY_STATE_TRANSITION(condition) if (UNLIKELY(!(condition))) unexpectedGCState(m_gcState)
+
 void ThreadState::setGCState(GCState gcState)
 {
     switch (gcState) {
     case NoGCScheduled:
         checkThread();
-        RELEASE_ASSERT(m_gcState == StoppingOtherThreads || m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled);
+        VERIFY_STATE_TRANSITION(m_gcState == StoppingOtherThreads || m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled);
         break;
     case IdleGCScheduled:
     case PreciseGCScheduled:
     case GCScheduledForTesting:
         checkThread();
-        RELEASE_ASSERT(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == GCScheduledForTesting || m_gcState == StoppingOtherThreads || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);
+        VERIFY_STATE_TRANSITION(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == GCScheduledForTesting || m_gcState == StoppingOtherThreads || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);
         completeSweep();
         break;
     case StoppingOtherThreads:
         checkThread();
-        RELEASE_ASSERT(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == GCScheduledForTesting || m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);
+        VERIFY_STATE_TRANSITION(m_gcState == NoGCScheduled || m_gcState == IdleGCScheduled || m_gcState == PreciseGCScheduled || m_gcState == GCScheduledForTesting || m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled);
         completeSweep();
         break;
     case GCRunning:
         ASSERT(!isInGC());
-        RELEASE_ASSERT(m_gcState != GCRunning);
+        VERIFY_STATE_TRANSITION(m_gcState != GCRunning);
         break;
     case EagerSweepScheduled:
     case LazySweepScheduled:
         ASSERT(isInGC());
-        RELEASE_ASSERT(m_gcState == GCRunning);
+        VERIFY_STATE_TRANSITION(m_gcState == GCRunning);
         break;
     case Sweeping:
         checkThread();
-        RELEASE_ASSERT(m_gcState == EagerSweepScheduled || m_gcState == LazySweepScheduled);
+        VERIFY_STATE_TRANSITION(m_gcState == EagerSweepScheduled || m_gcState == LazySweepScheduled);
         break;
     case SweepingAndIdleGCScheduled:
     case SweepingAndPreciseGCScheduled:
         checkThread();
-        RELEASE_ASSERT(m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled || m_gcState == StoppingOtherThreads);
+        VERIFY_STATE_TRANSITION(m_gcState == Sweeping || m_gcState == SweepingAndIdleGCScheduled || m_gcState == SweepingAndPreciseGCScheduled || m_gcState == StoppingOtherThreads);
         break;
     default:
         ASSERT_NOT_REACHED();
     }
     m_gcState = gcState;
 }
 
+#undef VERIFY_STATE_TRANSITION
+
 ThreadState::GCState ThreadState::gcState() const
 {
     return m_gcState;
 }
 
 void ThreadState::didV8GC()
 {
     checkThread();
     m_didV8GCAfterLastGC = true;
 }
@@ skipping 516 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