Bug 744192 - Assert that Vectors do not contain implicitly postbarriered types; r=luke

Since vectors move their memory around outside the control of the GC, it is not
valid to store an implicitly post-barriered item in a Vector.

--HG--
extra : rebase_source : 2cef4d855cc4e926cea872cda18e5cf29230f0a7

js/public/TemplateLib.h

@@ -174,6 +174,11 @@ template <typename T> struct IsPodType<T *>         { static const bool result =
 template <bool cond, typename T, T v1, T v2> struct If        { static const T result = v1; };
 template <typename T, T v1, T v2> struct If<false, T, v1, v2> { static const T result = v2; };
 
+/*
+ * Traits class for identifying types that are implicitly barriered.
+ */
+template <class T> struct IsPostBarrieredType { static const bool result = false; };
+
 } /* namespace tl */
 } /* namespace js */
 

js/public/Vector.h

@@ -213,6 +213,8 @@ struct VectorImpl<T, N, AP, true>
 template <class T, size_t N, class AllocPolicy>
 class Vector : private AllocPolicy
 {
+    typedef typename tl::StaticAssert<!tl::IsPostBarrieredType<T>::result>::result _;
+
     /* utilities */
 
     static const bool sElemIsPod = tl::IsPodType<T>::result;
@@ -505,7 +507,7 @@ class Vector : private AllocPolicy
      */
     size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const;
 
-    /* 
+    /*
      * Like sizeOfExcludingThis, but also measures the size of the Vector
      * object (which must be heap-allocated) itself.
      */

js/src/gc/Barrier.h

@@ -509,6 +509,15 @@ class ReadBarrieredValue
     inline JSObject &toObject() const;
 };
 
-}
+namespace tl {
+
+template <class T> struct IsPostBarrieredType<HeapPtr<T> > {
+                                                    static const bool result = true; };
+template <> struct IsPostBarrieredType<HeapSlot>  { static const bool result = true; };
+template <> struct IsPostBarrieredType<HeapValue> { static const bool result = true; };
+template <> struct IsPostBarrieredType<HeapId>    { static const bool result = true; };
+
+} /* namespace tl */
+} /* namespace js */
 
 #endif /* jsgc_barrier_h___ */