diff -r 000000000000 -r 6474c204b198 js/src/jit/CompilerRoot.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit/CompilerRoot.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,70 @@
+/* -*- 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 jit_CompilerRoot_h
+#define jit_CompilerRoot_h
+
+#ifdef JS_ION
+
+#include "jscntxt.h"
+
+#include "jit/Ion.h"
+#include "jit/IonAllocPolicy.h"
+#include "js/RootingAPI.h"
+
+namespace js {
+namespace jit {
+
+// Roots a read-only GCThing for the lifetime of a single compilation.
+// Each root is maintained in a linked list that is walked over during tracing.
+// The CompilerRoot must be heap-allocated and may not go out of scope.
+template <typename T>
+class CompilerRoot : public CompilerRootNode
+{
+  public:
+    CompilerRoot(T ptr)
+      : CompilerRootNode(nullptr)
+    {
+        if (ptr) {
+            JS_ASSERT(!GetIonContext()->runtime->isInsideNursery(ptr));
+            setRoot(ptr);
+        }
+    }
+
+  public:
+    // Sets the pointer and inserts into root list. The pointer becomes read-only.
+    void setRoot(T root) {
+        CompilerRootNode *&rootList = GetIonContext()->temp->rootList();
+
+        JS_ASSERT(!ptr_);
+        ptr_ = root;
+        next = rootList;
+        rootList = this;
+    }
+
+  public:
+    operator T () const { return static_cast<T>(ptr_); }
+    T operator ->() const { return static_cast<T>(ptr_); }
+
+  private:
+    CompilerRoot() MOZ_DELETE;
+    CompilerRoot(const CompilerRoot<T> &) MOZ_DELETE;
+    CompilerRoot<T> &operator =(const CompilerRoot<T> &) MOZ_DELETE;
+};
+
+typedef CompilerRoot<JSObject*> CompilerRootObject;
+typedef CompilerRoot<JSFunction*> CompilerRootFunction;
+typedef CompilerRoot<JSScript*> CompilerRootScript;
+typedef CompilerRoot<PropertyName*> CompilerRootPropertyName;
+typedef CompilerRoot<Shape*> CompilerRootShape;
+typedef CompilerRoot<Value> CompilerRootValue;
+
+} // namespace jit
+} // namespace js
+
+#endif // JS_ION
+
+#endif /* jit_CompilerRoot_h */