Revert #1091 Remove unboxed object code phase 1 + extras.

This should be the last code backout for this. merging this branch
should get us back to the way we were (+ additional code changes for
later changes) as fasr as the unused unboxed code is concerned.

1 files changed, 45 insertions, 1 deletions

diff --git a/js/src/gc/Marking.cpp b/js/src/gc/Marking.cpp
index a206a8762..43e325394 100644
--- a/js/src/gc/Marking.cpp
+++ b/js/src/gc/Marking.cpp
@@ -18,7 +18,6 @@
 #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"
@@ -29,6 +28,7 @@
 #include "vm/Shape.h"
 #include "vm/Symbol.h"
 #include "vm/TypedArrayObject.h"
+#include "vm/UnboxedObject.h"
 #include "wasm/WasmJS.h"
 
 #include "jscompartmentinlines.h"
@@ -37,6 +37,7 @@
 
 #include "gc/Nursery-inl.h"
 #include "vm/String-inl.h"
+#include "vm/UnboxedObject-inl.h"
 
 using namespace js;
 using namespace js::gc;
@@ -1394,6 +1395,14 @@ 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>());
@@ -1427,6 +1436,12 @@ 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));
 
@@ -1469,6 +1484,23 @@ 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())
@@ -2261,6 +2293,18 @@ 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