1 files changed, 10 insertions, 20 deletions
diff --git a/include/llvm/ADT/PointerUnion.h b/include/llvm/ADT/PointerUnion.h
index 2bcdf546c6e4..98c905775a77 100644
--- a/include/llvm/ADT/PointerUnion.h
+++ b/include/llvm/ADT/PointerUnion.h
@@ -54,21 +54,14 @@ struct PointerUnionTypeSelectorReturn<
 };
 
 namespace pointer_union_detail {
-  constexpr int constexprMin(int a, int b) { return a < b ? a : b; }
   /// Determine the number of bits required to store integers with values < n.
   /// This is ceil(log2(n)).
   constexpr int bitsRequired(unsigned n) {
     return n > 1 ? 1 + bitsRequired((n + 1) / 2) : 0;
   }
 
-  // FIXME: In C++14, replace this with
-  //   std::min({PointerLikeTypeTraits<Ts>::NumLowBitsAvailable...})
-  template <typename T> constexpr int lowBitsAvailable() {
-    return PointerLikeTypeTraits<T>::NumLowBitsAvailable;
-  }
-  template <typename T1, typename T2, typename... Ts>
-  constexpr int lowBitsAvailable() {
-    return constexprMin(lowBitsAvailable<T1>(), lowBitsAvailable<T2, Ts...>());
+  template <typename... Ts> constexpr int lowBitsAvailable() {
+    return std::min<int>({PointerLikeTypeTraits<Ts>::NumLowBitsAvailable...});
   }
 
   /// Find the index of a type in a list of types. TypeIndex<T, Us...>::Index
@@ -167,10 +160,11 @@ class PointerUnion
               void *, pointer_union_detail::bitsRequired(sizeof...(PTs)), int,
               pointer_union_detail::PointerUnionUIntTraits<PTs...>>,
           0, PTs...> {
-  // The first type is special in some ways, but we don't want PointerUnion to
-  // be a 'template <typename First, typename ...Rest>' because it's much more
-  // convenient to have a name for the whole pack. So split off the first type
-  // here.
+  // The first type is special because we want to directly cast a pointer to a
+  // default-initialized union to a pointer to the first type. But we don't
+  // want PointerUnion to be a 'template <typename First, typename ...Rest>'
+  // because it's much more convenient to have a name for the whole pack. So
+  // split off the first type here.
   using First = typename pointer_union_detail::GetFirstType<PTs...>::type;
   using Base = typename PointerUnion::PointerUnionMembers;
 
@@ -182,12 +176,7 @@ public:
 
   /// Test if the pointer held in the union is null, regardless of
   /// which type it is.
-  bool isNull() const {
-    // Convert from the void* to one of the pointer types, to make sure that
-    // we recursively strip off low bits if we have a nested PointerUnion.
-    return !PointerLikeTypeTraits<First>::getFromVoidPointer(
-        this->Val.getPointer());
-  }
+  bool isNull() const { return !this->Val.getPointer(); }
 
   explicit operator bool() const { return !isNull(); }
 
@@ -226,7 +215,8 @@ public:
   First *getAddrOfPtr1() {
     assert(is<First>() && "Val is not the first pointer");
     assert(
-        get<First>() == this->Val.getPointer() &&
+        PointerLikeTypeTraits<First>::getAsVoidPointer(get<First>()) ==
+            this->Val.getPointer() &&
         "Can't get the address because PointerLikeTypeTraits changes the ptr");
     return const_cast<First *>(
         reinterpret_cast<const First *>(this->Val.getAddrOfPointer()));