Oilpan: Remove Heap::s_lastGCWasConservative

Source/platform/heap/Heap.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 1803 matching lines @@
 #if !ENABLE(ASSERT)
     if (s_heapDoesNotContainCache->lookup(address))
         return nullptr;
 #endif
 
     if (BasePage* page = lookup(address)) {
         ASSERT(page->contains(address));
         ASSERT(!page->orphaned());
         ASSERT(!s_heapDoesNotContainCache->lookup(address));
         page->checkAndMarkPointer(visitor, address);
-        // FIXME: We only need to set the conservative flag if
-        // checkAndMarkPointer actually marked the pointer.
-        s_lastGCWasConservative = true;
         return address;
     }
 
 #if !ENABLE(ASSERT)
     s_heapDoesNotContainCache->addEntry(address);
 #else
     if (!s_heapDoesNotContainCache->lookup(address))
         s_heapDoesNotContainCache->addEntry(address);
 #endif
     return nullptr;
@@ skipping 179 matching lines @@
 
     GCScope gcScope(state, stackState, gcType);
     // Check if we successfully parked the other threads.  If not we bail out of
     // the GC.
     if (!gcScope.allThreadsParked())
         return;
 
     if (state->isMainThread())
         ScriptForbiddenScope::enter();
 
-    s_lastGCWasConservative = false;
-
     TRACE_EVENT2("blink_gc", "Heap::collectGarbage",
         "lazySweeping", gcType == ThreadState::GCWithoutSweep,
         "gcReason", gcReasonString(reason));
     TRACE_EVENT_SCOPED_SAMPLING_STATE("blink_gc", "BlinkGC");
     double timeStamp = WTF::currentTimeMS();
 #if ENABLE(GC_PROFILING)
     gcScope.visitor()->objectGraph().clear();
 #endif
 
     // Disallow allocation during garbage collection (but not during the
     // finalization that happens when the gcScope is torn down).
     ThreadState::NoAllocationScope noAllocationScope(state);
 
     preGC();
 
     StackFrameDepthScope stackDepthScope;
 
     size_t totalObjectSize = Heap::allocatedObjectSize() + Heap::markedObjectSize();
     Heap::resetHeapCounters();
 
     // 1. Trace persistent roots.
     ThreadState::visitPersistentRoots(gcScope.visitor());
 
-    // 2. Trace objects reachable from the persistent roots including
-    // ephemerons.
-    processMarkingStack(gcScope.visitor());
-
-    // 3. Trace objects reachable from the stack.  We do this independent of the
+    // 2. Trace objects reachable from the stack.  We do this independent of the
     // given stackState since other threads might have a different stack state.
     ThreadState::visitStackRoots(gcScope.visitor());
 
-    // 4. Trace objects reachable from the stack "roots" including ephemerons.
-    // Only do the processing if we found a pointer to an object on one of the
-    // thread stacks.
-    if (lastGCWasConservative())
-        processMarkingStack(gcScope.visitor());
+    // 3. Transitive closure to trace objects including ephemerons.
+    processMarkingStack(gcScope.visitor());
 
     postMarkingProcessing(gcScope.visitor());
     globalWeakProcessing(gcScope.visitor());
 
     // Now we can delete all orphaned pages because there are no dangling
     // pointers to the orphaned pages.  (If we have such dangling pointers,
     // we should have crashed during marking before getting here.)
     orphanedPagePool()->decommitOrphanedPages();
 
     postGC(gcType);
@@ skipping 270 matching lines @@
     s_markedObjectSize = 0;
     s_externalObjectSizeAtLastGC = WTF::Partitions::totalSizeOfCommittedPages();
 }
 
 CallbackStack* Heap::s_markingStack;
 CallbackStack* Heap::s_postMarkingCallbackStack;
 CallbackStack* Heap::s_globalWeakCallbackStack;
 CallbackStack* Heap::s_ephemeronStack;
 HeapDoesNotContainCache* Heap::s_heapDoesNotContainCache;
 bool Heap::s_shutdownCalled = false;
-bool Heap::s_lastGCWasConservative = false;
 FreePagePool* Heap::s_freePagePool;
 OrphanedPagePool* Heap::s_orphanedPagePool;
 Heap::RegionTree* Heap::s_regionTree = nullptr;
 size_t Heap::s_allocatedObjectSize = 0;
 size_t Heap::s_allocatedSpace = 0;
 size_t Heap::s_markedObjectSize = 0;
 // We don't want to use 0 KB for the initial value because it may end up
 // triggering the first GC of some thread too prematurely.
 size_t Heap::s_estimatedLiveObjectSize = 512 * 1024;
 size_t Heap::s_externalObjectSizeAtLastGC = 0;
 double Heap::s_estimatedMarkingTimePerByte = 0.0;
 
 } // namespace blink