Cleanup the simplify_type implementation.

As far as simplify_type is concerned, there are 3 kinds of smart pointers:

* const correct: A 'const MyPtr<int> &' produces a 'const int*'. A
'MyPtr<int> &' produces a 'int *'.
* always const: Even a 'MyPtr<int> &' produces a 'const int*'.
* no const: Even a 'const MyPtr<int> &' produces a 'int*'.

This patch then does the following:

* Removes the unused specializations. Since they are unused, it is hard
to know which kind should be implemented.
* Make sure we don't drop const.
* Fix the default forwarding so that const correct pointer only need
one specialization.
* Simplifies the existing specializations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178147 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 4 insertions, 18 deletions

diff --git a/include/llvm/ADT/IntrusiveRefCntPtr.h b/include/llvm/ADT/IntrusiveRefCntPtr.h
index 9e5ab021a5..b8b8861995 100644
--- a/include/llvm/ADT/IntrusiveRefCntPtr.h
+++ b/include/llvm/ADT/IntrusiveRefCntPtr.h
@@ -226,13 +226,13 @@ namespace llvm {
 
   template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > {
     typedef T* SimpleType;
-    static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
+    static SimpleType getSimplifiedValue(IntrusiveRefCntPtr<T>& Val) {
       return Val.getPtr();
     }
   };
 
   template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > {
-    typedef T* SimpleType;
+    typedef /*const*/ T* SimpleType;
     static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
       return Val.getPtr();
     }
diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h
index 81d73ed8b9..194e53fac2 100644
--- a/include/llvm/ADT/Optional.h
+++ b/include/llvm/ADT/Optional.h
@@ -128,20 +128,6 @@ public:
 #endif
 };
 
-template<typename T> struct simplify_type;
-
-template <typename T>
-struct simplify_type<const Optional<T> > {
-  typedef const T* SimpleType;
-  static SimpleType getSimplifiedValue(const Optional<T> &Val) {
-    return Val.getPointer();
-  }
-};
-
-template <typename T>
-struct simplify_type<Optional<T> >
-  : public simplify_type<const Optional<T> > {};
-
 template <typename T> struct isPodLike;
 template <typename T> struct isPodLike<Optional<T> > {
   // An Optional<T> is pod-like if T is.
diff --git a/include/llvm/ADT/ilist.h b/include/llvm/ADT/ilist.h
index aeb78484c6..71dab2ef55 100644
--- a/include/llvm/ADT/ilist.h
+++ b/include/llvm/ADT/ilist.h
@@ -274,12 +274,12 @@ template<typename From> struct simplify_type;
 template<typename NodeTy> struct simplify_type<ilist_iterator<NodeTy> > {
   typedef NodeTy* SimpleType;
 
-  static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
+  static SimpleType getSimplifiedValue(ilist_iterator<NodeTy> &Node) {
     return &*Node;
   }
 };
 template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
-  typedef NodeTy* SimpleType;
+  typedef /*const*/ NodeTy* SimpleType;
 
   static SimpleType getSimplifiedValue(const ilist_iterator<NodeTy> &Node) {
     return &*Node;