diff -r 000000000000 -r 6474c204b198 js/src/gc/GCInternals.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/gc/GCInternals.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,153 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef gc_GCInternals_h
+#define gc_GCInternals_h
+
+#include "jscntxt.h"
+#include "jsworkers.h"
+
+#include "gc/Zone.h"
+#include "vm/Runtime.h"
+
+namespace js {
+namespace gc {
+
+void
+MarkPersistentRootedChains(JSTracer *trc);
+
+void
+MarkRuntime(JSTracer *trc, bool useSavedRoots = false);
+
+void
+BufferGrayRoots(GCMarker *gcmarker);
+
+class AutoCopyFreeListToArenas
+{
+    JSRuntime *runtime;
+    ZoneSelector selector;
+
+  public:
+    AutoCopyFreeListToArenas(JSRuntime *rt, ZoneSelector selector);
+    ~AutoCopyFreeListToArenas();
+};
+
+struct AutoFinishGC
+{
+    AutoFinishGC(JSRuntime *rt);
+};
+
+/*
+ * This class should be used by any code that needs to exclusive access to the
+ * heap in order to trace through it...
+ */
+class AutoTraceSession
+{
+  public:
+    AutoTraceSession(JSRuntime *rt, HeapState state = Tracing);
+    ~AutoTraceSession();
+
+  protected:
+    AutoLockForExclusiveAccess lock;
+    JSRuntime *runtime;
+
+  private:
+    AutoTraceSession(const AutoTraceSession&) MOZ_DELETE;
+    void operator=(const AutoTraceSession&) MOZ_DELETE;
+
+    HeapState prevState;
+};
+
+struct AutoPrepareForTracing
+{
+    AutoFinishGC finish;
+    AutoTraceSession session;
+    AutoCopyFreeListToArenas copy;
+
+    AutoPrepareForTracing(JSRuntime *rt, ZoneSelector selector);
+};
+
+class IncrementalSafety
+{
+    const char *reason_;
+
+    IncrementalSafety(const char *reason) : reason_(reason) {}
+
+  public:
+    static IncrementalSafety Safe() { return IncrementalSafety(nullptr); }
+    static IncrementalSafety Unsafe(const char *reason) { return IncrementalSafety(reason); }
+
+    typedef void (IncrementalSafety::* ConvertibleToBool)();
+    void nonNull() {}
+
+    operator ConvertibleToBool() const {
+        return reason_ == nullptr ? &IncrementalSafety::nonNull : 0;
+    }
+
+    const char *reason() {
+        JS_ASSERT(reason_);
+        return reason_;
+    }
+};
+
+IncrementalSafety
+IsIncrementalGCSafe(JSRuntime *rt);
+
+#ifdef JS_GC_ZEAL
+void
+StartVerifyPreBarriers(JSRuntime *rt);
+
+void
+EndVerifyPreBarriers(JSRuntime *rt);
+
+void
+StartVerifyPostBarriers(JSRuntime *rt);
+
+void
+EndVerifyPostBarriers(JSRuntime *rt);
+
+void
+FinishVerifier(JSRuntime *rt);
+
+class AutoStopVerifyingBarriers
+{
+    JSRuntime *runtime;
+    bool restartPreVerifier;
+    bool restartPostVerifier;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+
+  public:
+    AutoStopVerifyingBarriers(JSRuntime *rt, bool isShutdown
+                              MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : runtime(rt)
+    {
+        restartPreVerifier = !isShutdown && rt->gcVerifyPreData;
+        restartPostVerifier = !isShutdown && rt->gcVerifyPostData && JS::IsGenerationalGCEnabled(rt);
+        if (rt->gcVerifyPreData)
+            EndVerifyPreBarriers(rt);
+        if (rt->gcVerifyPostData)
+            EndVerifyPostBarriers(rt);
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    }
+
+    ~AutoStopVerifyingBarriers() {
+        if (restartPreVerifier)
+            StartVerifyPreBarriers(runtime);
+        if (restartPostVerifier)
+            StartVerifyPostBarriers(runtime);
+    }
+};
+#else
+struct AutoStopVerifyingBarriers
+{
+    AutoStopVerifyingBarriers(JSRuntime *, bool) {}
+};
+#endif /* JS_GC_ZEAL */
+
+} /* namespace gc */
+} /* namespace js */
+
+#endif /* gc_GCInternals_h */