give PATypeHolder an explicit copy ctor which initializes the type pointer,

and make PATypeHolder work with null pointers.

The implicitly generated one didn't work on numerous levels, but was still
accepted, allowing all sorts of bugs with default constructed pa type holders.

Previously, they "sort of" worked if they were default constructed and then
destructed.  Now they really work, and you can even default construct one,
then assign to it, amazing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107195 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 5 insertions, 4 deletions

diff --git a/include/llvm/AbstractTypeUser.h b/include/llvm/AbstractTypeUser.h
index b6cceb4011..81f5c5c768 100644
--- a/include/llvm/AbstractTypeUser.h
+++ b/include/llvm/AbstractTypeUser.h
@@ -146,6 +146,7 @@ class PATypeHolder {
   mutable const Type *Ty;
   void destroy();
 public:
+  PATypeHolder() : Ty(0) {}
   PATypeHolder(const Type *ty) : Ty(ty) {
     addRef();
   }
@@ -153,7 +154,7 @@ public:
     addRef();
   }
 
-  ~PATypeHolder() { if (Ty) dropRef(); }
+  ~PATypeHolder() { dropRef(); }
 
   operator Type *() const { return get(); }
   Type *get() const;
diff --git a/include/llvm/Type.h b/include/llvm/Type.h
index 52229acb32..617ef69de4 100644
--- a/include/llvm/Type.h
+++ b/include/llvm/Type.h
@@ -504,19 +504,19 @@ inline void PATypeHandle::removeUser() {
 /// reference to the type.
 ///
 inline Type* PATypeHolder::get() const {
+  if (Ty == 0) return 0;
   const Type *NewTy = Ty->getForwardedType();
   if (!NewTy) return const_cast<Type*>(Ty);
   return *const_cast<PATypeHolder*>(this) = NewTy;
 }
 
 inline void PATypeHolder::addRef() {
-  assert(Ty && "Type Holder has a null type!");
-  if (Ty->isAbstract())
+  if (Ty && Ty->isAbstract())
     Ty->addRef();
 }
 
 inline void PATypeHolder::dropRef() {
-  if (Ty->isAbstract())
+  if (Ty && Ty->isAbstract())
     Ty->dropRef();
 }