Bug 1512042 - Try using SegmentedVector for gray root buffers r=pbone

js/src/gc/GC.cpp

@@ -5003,7 +5003,7 @@ void GCRuntime::getNextSweepGroup() {
       zone->setNeedsIncrementalBarrier(false);
       zone->changeGCState(Zone::MarkBlackOnly, Zone::NoGC);
       zone->arenas.unmarkPreMarkedFreeCells();
-      zone->gcGrayRoots().clearAndFree();
+      zone->gcGrayRoots().Clear();
     }
 
     for (SweepGroupCompartmentsIter comp(rt); !comp.done(); comp.next()) {

js/src/gc/Marking.cpp

@@ -2716,7 +2716,7 @@ void GCMarker::checkZone(void* p) {
 size_t GCMarker::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
   size_t size = stack.sizeOfExcludingThis(mallocSizeOf);
   for (ZonesIter zone(runtime(), WithAtoms); !zone.done(); zone.next()) {
-    size += zone->gcGrayRoots().sizeOfExcludingThis(mallocSizeOf);
+    size += zone->gcGrayRoots().SizeOfExcludingThis(mallocSizeOf);
   }
   return size;
 }

js/src/gc/RootMarking.cpp

@@ -506,7 +506,7 @@ void js::gc::GCRuntime::bufferGrayRoots() {
   //               and the zone's buffers have been cleared.
   MOZ_ASSERT(grayBufferState == GrayBufferState::Unused);
   for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
-    MOZ_ASSERT(zone->gcGrayRoots().empty());
+    MOZ_ASSERT(zone->gcGrayRoots().IsEmpty());
   }
 
   BufferGrayRootsTracer grayBufferer(rt);
@@ -542,7 +542,7 @@ inline void BufferGrayRootsTracer::bufferRoot(T* thing) {
     // incremental GCs (when we do gray root buffering).
     SetMaybeAliveFlag(thing);
 
-    if (!zone->gcGrayRoots().append(tenured)) {
+    if (!zone->gcGrayRoots().Append(tenured)) {
       bufferingGrayRootsFailed = true;
     }
   }
@@ -553,12 +553,12 @@ void GCRuntime::markBufferedGrayRoots(JS::Zone* zone) {
   MOZ_ASSERT(zone->isGCMarkingBlackAndGray() || zone->isGCCompacting());
 
   auto& roots = zone->gcGrayRoots();
-  if (roots.empty()) {
+  if (roots.IsEmpty()) {
     return;
   }
 
-  for (size_t i = 0; i < roots.length(); i++) {
-    Cell* cell = roots[i];
+  for (auto iter = roots.Iter(); !iter.Done(); iter.Next()) {
+    Cell* cell = iter.Get();
 
     // Bug 1203273: Check for bad pointers on OSX and output diagnostics.
 #if defined(XP_DARWIN) && defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED)
@@ -583,7 +583,7 @@ void GCRuntime::resetBufferedGrayRoots() const {
       grayBufferState != GrayBufferState::Okay,
       "Do not clear the gray buffers unless we are Failed or becoming Unused");
   for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
-    zone->gcGrayRoots().clearAndFree();
+    zone->gcGrayRoots().Clear();
   }
 }
 

js/src/gc/Zone.h

@@ -9,6 +9,7 @@
 
 #include "mozilla/Atomics.h"
 #include "mozilla/HashFunctions.h"
+#include "mozilla/SegmentedVector.h"
 
 #include "gc/FindSCCs.h"
 #include "js/GCHashTable.h"
@@ -375,7 +376,9 @@ class Zone : public JS::shadow::Zone,
   CompartmentVector& compartments() { return compartments_.ref(); }
 
   // This zone's gray roots.
-  typedef js::Vector<js::gc::Cell*, 0, js::SystemAllocPolicy> GrayRootVector;
+  using GrayRootVector = mozilla::SegmentedVector<js::gc::Cell*,
+                                                  1024 * sizeof(js::gc::Cell*),
+                                                  js::SystemAllocPolicy>;
 
  private:
   js::ZoneOrGCTaskData<GrayRootVector> gcGrayRoots_;