Remove the AugmentedUse struct.

I don't think the AugmentedUse struct buys us much, either in
correctness or in ease of use. Ditch it, and simplify Use::getUser() and
User::allocHungoffUses().


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133433 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Use.h

@@ -60,6 +60,10 @@ public:
   /// that also works with less standard-compliant compilers
   void swap(Use &RHS);
 
+  // A type for the word following an array of hung-off Uses in memory, which is
+  // a pointer back to their User with the bottom bit set.
+  typedef PointerIntPair<User*, 1, unsigned> UserRef;
+
 private:
   /// Copy ctor - do not implement
   Use(const Use &U);
@@ -208,15 +212,6 @@ public:
   unsigned getOperandNo() const;
 };
 
-//===----------------------------------------------------------------------===//
-//                         AugmentedUse layout struct
-//===----------------------------------------------------------------------===//
-
-struct AugmentedUse : public Use {
-  PointerIntPair<User*, 1, unsigned> ref;
-  AugmentedUse(); // not implemented
-};
-
 } // End llvm namespace
 
 #endif

lib/VMCore/Use.cpp

@@ -135,11 +135,9 @@ void Use::zap(Use *Start, const Use *Stop, bool del) {
 
 User *Use::getUser() const {
   const Use *End = getImpliedUser();
-  const PointerIntPair<User*, 1, unsigned>&
-    ref(static_cast<const AugmentedUse*>(End - 1)->ref);
-  User *She = ref.getPointer();
-  return ref.getInt()
-    ? She
+  const UserRef *ref = reinterpret_cast<const UserRef*>(End);
+  return ref->getInt()
+    ? ref->getPointer()
     : (User*)End;
 }
 

lib/VMCore/User.cpp

@@ -41,13 +41,9 @@ void User::replaceUsesOfWith(Value *From, Value *To) {
 
 Use *User::allocHungoffUses(unsigned N) const {
   Use *Begin = static_cast<Use*>(::operator new(sizeof(Use) * N
-                                                + sizeof(AugmentedUse)
-                                                - sizeof(Use)));
+                                                + sizeof(Use::UserRef)));
   Use *End = Begin + N;
-  PointerIntPair<User*, 1, unsigned>&
-    ref(static_cast<AugmentedUse&>(End[-1]).ref);
-  ref.setPointer(const_cast<User*>(this));
-  ref.setInt(1);
+  (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
   return Use::initTags(Begin, End);
 }