Remove unboxed objects from GC

2 files changed, 3 insertions, 112 deletions

diff --git a/js/src/gc/Marking.cpp b/js/src/gc/Marking.cpp
index 3ea4c9d29f..47d2314c1a 100644
--- a/js/src/gc/Marking.cpp
+++ b/js/src/gc/Marking.cpp
@@ -18,6 +18,7 @@
 #include "builtin/ModuleObject.h"
 #include "gc/GCInternals.h"
 #include "gc/Policy.h"
+#include "gc/StoreBuffer-inl.h"
 #include "jit/IonCode.h"
 #include "js/SliceBudget.h"
 #include "vm/ArgumentsObject.h"
@@ -28,7 +29,6 @@
 #include "vm/Shape.h"
 #include "vm/Symbol.h"
 #include "vm/TypedArrayObject.h"
-#include "vm/UnboxedObject.h"
 #include "wasm/WasmJS.h"
 
 #include "jscompartmentinlines.h"
@@ -37,7 +37,6 @@
 
 #include "gc/Nursery-inl.h"
 #include "vm/String-inl.h"
-#include "vm/UnboxedObject-inl.h"
 
 using namespace js;
 using namespace js::gc;
@@ -1395,14 +1394,6 @@ js::ObjectGroup::traceChildren(JSTracer* trc)
     if (maybePreliminaryObjects())
         maybePreliminaryObjects()->trace(trc);
 
-    if (maybeUnboxedLayout())
-        unboxedLayout().trace(trc);
-
-    if (ObjectGroup* unboxedGroup = maybeOriginalUnboxedGroup()) {
-        TraceManuallyBarrieredEdge(trc, &unboxedGroup, "group_original_unboxed_group");
-        setOriginalUnboxedGroup(unboxedGroup);
-    }
-
     if (JSObject* descr = maybeTypeDescr()) {
         TraceManuallyBarrieredEdge(trc, &descr, "group_type_descr");
         setTypeDescr(&descr->as<TypeDescr>());
@@ -1436,12 +1427,6 @@ js::GCMarker::lazilyMarkChildren(ObjectGroup* group)
     if (group->maybePreliminaryObjects())
         group->maybePreliminaryObjects()->trace(this);
 
-    if (group->maybeUnboxedLayout())
-        group->unboxedLayout().trace(this);
-
-    if (ObjectGroup* unboxedGroup = group->maybeOriginalUnboxedGroup())
-        traverseEdge(group, unboxedGroup);
-
     if (TypeDescr* descr = group->maybeTypeDescr())
         traverseEdge(group, static_cast<JSObject*>(descr));
 
@@ -1484,23 +1469,6 @@ CallTraceHook(Functor f, JSTracer* trc, JSObject* obj, CheckGeneration check, Ar
         return nullptr;
     }
 
-    if (clasp == &UnboxedPlainObject::class_) {
-        JSObject** pexpando = obj->as<UnboxedPlainObject>().addressOfExpando();
-        if (*pexpando)
-            f(pexpando, mozilla::Forward<Args>(args)...);
-
-        UnboxedPlainObject& unboxed = obj->as<UnboxedPlainObject>();
-        const UnboxedLayout& layout = check == CheckGeneration::DoChecks
-                                      ? unboxed.layout()
-                                      : unboxed.layoutDontCheckGeneration();
-        if (layout.traceList()) {
-            VisitTraceList(f, layout.traceList(), unboxed.data(),
-                           mozilla::Forward<Args>(args)...);
-        }
-
-        return nullptr;
-    }
-
     clasp->doTrace(trc, obj);
 
     if (!clasp->isNative())
@@ -2293,18 +2261,6 @@ static inline void
 TraceWholeCell(TenuringTracer& mover, JSObject* object)
 {
     mover.traceObject(object);
-
-    // Additionally trace the expando object attached to any unboxed plain
-    // objects. Baseline and Ion can write properties to the expando while
-    // only adding a post barrier to the owning unboxed object. Note that
-    // it isn't possible for a nursery unboxed object to have a tenured
-    // expando, so that adding a post barrier on the original object will
-    // capture any tenured->nursery edges in the expando as well.
-
-    if (object->is<UnboxedPlainObject>()) {
-        if (UnboxedExpandoObject* expando = object->as<UnboxedPlainObject>().maybeExpando())
-            expando->traceChildren(&mover);
-    }
 }
 
 static inline void
diff --git a/js/src/gc/Tracer.cpp b/js/src/gc/Tracer.cpp
index 63cd9b08a4..3416464ddf 100644
--- a/js/src/gc/Tracer.cpp
+++ b/js/src/gc/Tracer.cpp
@@ -201,80 +201,15 @@ gc::TraceCycleCollectorChildren(JS::CallbackTracer* trc, Shape* shape)
     } while (shape);
 }
 
-// Object groups can point to other object groups via an UnboxedLayout or the
-// the original unboxed group link. There can potentially be deep or cyclic
-// chains of such groups to trace through without going through a thing that
-// participates in cycle collection. These need to be handled iteratively to
-// avoid blowing the stack when running the cycle collector's callback tracer.
-struct ObjectGroupCycleCollectorTracer : public JS::CallbackTracer
-{
-    explicit ObjectGroupCycleCollectorTracer(JS::CallbackTracer* innerTracer)
-        : JS::CallbackTracer(innerTracer->runtime(), DoNotTraceWeakMaps),
-          innerTracer(innerTracer)
-    {}
-
-    void onChild(const JS::GCCellPtr& thing) override;
-
-    JS::CallbackTracer* innerTracer;
-    Vector<ObjectGroup*, 4, SystemAllocPolicy> seen, worklist;
-};
-
-void
-ObjectGroupCycleCollectorTracer::onChild(const JS::GCCellPtr& thing)
-{
-    if (thing.is<BaseShape>()) {
-        // The CC does not care about BaseShapes, and no additional GC things
-        // will be reached by following this edge.
-        return;
-    }
-
-    if (thing.is<JSObject>() || thing.is<JSScript>()) {
-        // Invoke the inner cycle collector callback on this child. It will not
-        // recurse back into TraceChildren.
-        innerTracer->onChild(thing);
-        return;
-    }
-
-    if (thing.is<ObjectGroup>()) {
-        // If this group is required to be in an ObjectGroup chain, trace it
-        // via the provided worklist rather than continuing to recurse.
-        ObjectGroup& group = thing.as<ObjectGroup>();
-        if (group.maybeUnboxedLayout()) {
-            for (size_t i = 0; i < seen.length(); i++) {
-                if (seen[i] == &group)
-                    return;
-            }
-            if (seen.append(&group) && worklist.append(&group)) {
-                return;
-            } else {
-                // If append fails, keep tracing normally. The worst that will
-                // happen is we end up overrecursing.
-            }
-        }
-    }
-
-    TraceChildren(this, thing.asCell(), thing.kind());
-}
-
 void
 gc::TraceCycleCollectorChildren(JS::CallbackTracer* trc, ObjectGroup* group)
 {
     MOZ_ASSERT(trc->isCallbackTracer());
 
-    // Early return if this group is not required to be in an ObjectGroup chain.
-    if (!group->maybeUnboxedLayout())
-        return group->traceChildren(trc);
-
-    ObjectGroupCycleCollectorTracer groupTracer(trc->asCallbackTracer());
-    group->traceChildren(&groupTracer);
-
-    while (!groupTracer.worklist.empty()) {
-        ObjectGroup* innerGroup = groupTracer.worklist.popCopy();
-        innerGroup->traceChildren(&groupTracer);
-    }
+    group->traceChildren(trc);
 }
 
-
+
 /*** Traced Edge Printer *************************************************************************/
 
 static size_t