Revert of Simple BlinkGC heap compaction.

third_party/WebKit/Source/platform/heap/ThreadState.cpp

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index 9d4756afcd7872b7c32fd9090c8a7de75c8bb326..f5b8a6545385aa544b24d3ad064841ae8215952e 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -38,7 +38,6 @@
 #include "platform/heap/CallbackStack.h"
 #include "platform/heap/Handle.h"
 #include "platform/heap/Heap.h"
-#include "platform/heap/HeapCompact.h"
 #include "platform/heap/PagePool.h"
 #include "platform/heap/SafePoint.h"
 #include "platform/heap/Visitor.h"
@@ -80,7 +79,7 @@
 
 const size_t defaultAllocatedObjectSizeThreshold = 100 * 1024;
 
-const char* ThreadState::gcReasonString(BlinkGC::GCReason reason) {
+const char* gcReasonString(BlinkGC::GCReason reason) {
   switch (reason) {
     case BlinkGC::IdleGC:
       return "IdleGC";
@@ -505,7 +504,6 @@
   // Due to the complexity, we just forbid allocations.
   NoAllocationScope noAllocationScope(this);
 
-  GCForbiddenScope gcForbiddenScope(this);
   std::unique_ptr<Visitor> visitor =
       Visitor::create(this, BlinkGC::ThreadLocalWeakProcessing);
 
@@ -1001,7 +999,7 @@
     return;
 
   // If a safe point is entered while initiating a GC, we clearly do
-  // not want to do another as part of that -- the safe point is only
+  // not want to do another as part that -- the safe point is only
   // entered after checking if a scheduled GC ought to run first.
   // Prevent that from happening by marking GCs as forbidden while
   // one is initiated and later running.
@@ -1042,34 +1040,6 @@
     m_arenas[i]->makeConsistentForGC();
 }
 
-void ThreadState::compact() {
-  if (!heap().compaction()->isCompacting())
-    return;
-
-  SweepForbiddenScope scope(this);
-  ScriptForbiddenIfMainThreadScope scriptForbiddenScope;
-  NoAllocationScope noAllocationScope(this);
-
-  // Compaction is done eagerly and before the mutator threads get
-  // to run again. Doing it lazily is problematic, as the mutator's
-  // references to live objects could suddenly be invalidated by
-  // compaction of a page/heap. We do know all the references to
-  // the relocating objects just after marking, but won't later.
-  // (e.g., stack references could have been created, new objects
-  // created which refer to old collection objects, and so on.)
-
-  // Compact the hash table backing store arena first, it usually has
-  // higher fragmentation and is larger.
-  //
-  // TODO: implement bail out wrt any overall deadline, not compacting
-  // the remaining arenas if the time budget has been exceeded.
-  heap().compaction()->startThreadCompaction();
-  for (int i = BlinkGC::HashTableArenaIndex; i >= BlinkGC::Vector1ArenaIndex;
-       --i)
-    static_cast<NormalPageArena*>(m_arenas[i])->sweepAndCompact();
-  heap().compaction()->finishThreadCompaction();
-}
-
 void ThreadState::makeConsistentForMutator() {
   ASSERT(isInGC());
   for (int i = 0; i < BlinkGC::NumberOfArenas; ++i)
@@ -1153,19 +1123,9 @@
 
   eagerSweep();
 
-  // Any sweep compaction must happen after pre-finalizers and eager
-  // sweeping, as it will finalize dead objects in compactable arenas
-  // (e.g., backing stores for container objects.)
-  //
-  // As per-contract for prefinalizers, those finalizable objects must
-  // still be accessible when the prefinalizer runs, hence we cannot
-  // schedule compaction until those have run. Similarly for eager sweeping.
-  compact();
-
 #if defined(ADDRESS_SANITIZER)
   poisonAllHeaps();
 #endif
-
   if (previousGCState == EagerSweepScheduled) {
     // Eager sweeping should happen only in testing.
     completeSweep();
@@ -1714,7 +1674,7 @@
   RELEASE_ASSERT(!isGCForbidden());
   completeSweep();
 
-  GCForbiddenScope gcForbiddenScope(this);
+  std::unique_ptr<Visitor> visitor = Visitor::create(this, gcType);
 
   SafePointScope safePointScope(stackState, this);
 
@@ -1724,12 +1684,6 @@
   // Try to park the other threads. If we're unable to, bail out of the GC.
   if (!parkThreadsScope.parkThreads())
     return;
-
-  BlinkGC::GCType visitorType = gcType;
-  if (heap().compaction()->shouldCompact(this, gcType, reason))
-    visitorType = heap().compaction()->initialize(this);
-
-  std::unique_ptr<Visitor> visitor = Visitor::create(this, visitorType);
 
   ScriptForbiddenIfMainThreadScope scriptForbidden;
 
@@ -1743,7 +1697,7 @@
 
   // Disallow allocation during garbage collection (but not during the
   // finalization that happens when the visitorScope is torn down).
-  NoAllocationScope noAllocationScope(this);
+  ThreadState::NoAllocationScope noAllocationScope(this);
 
   heap().commitCallbackStacks();
   heap().preGC();
@@ -1831,11 +1785,10 @@
     // ahead while it is running, hence the termination GC does not enter a
     // safepoint. VisitorScope will not enter also a safepoint scope for
     // ThreadTerminationGC.
-    GCForbiddenScope gcForbiddenScope(this);
     std::unique_ptr<Visitor> visitor =
         Visitor::create(this, BlinkGC::ThreadTerminationGC);
 
-    NoAllocationScope noAllocationScope(this);
+    ThreadState::NoAllocationScope noAllocationScope(this);
 
     heap().commitCallbackStacks();
     preGC();