diff --git a/llvm/include/llvm/Transforms/Scalar/Float2Int.h b/llvm/include/llvm/Transforms/Scalar/Float2Int.h
--- a/llvm/include/llvm/Transforms/Scalar/Float2Int.h
+++ b/llvm/include/llvm/Transforms/Scalar/Float2Int.h
@@ -30,20 +30,22 @@
   bool runImpl(Function &F, const DominatorTree &DT);
 
 private:
+  using RootSet = SmallPtrSet<Instruction *, 8>;
+
   void findRoots(Function &F, const DominatorTree &DT,
-                 SmallPtrSet<Instruction *, 8> &Roots);
+                 RootSet &Roots);
   void seen(Instruction *I, ConstantRange R);
   ConstantRange badRange();
   ConstantRange unknownRange();
   ConstantRange validateRange(ConstantRange R);
-  void walkBackwards(const SmallPtrSetImpl<Instruction *> &Roots);
+  void walkBackwards(const RootSet &Roots);
   void walkForwards();
   bool validateAndTransform();
   Value *convert(Instruction *I, Type *ToTy);
   void cleanup();
 
   MapVector<Instruction *, ConstantRange> SeenInsts;
-  SmallPtrSet<Instruction *, 8> Roots;
+  RootSet Roots;
   EquivalenceClasses<Instruction *> ECs;
   MapVector<Instruction *, Value *> ConvertedInsts;
   LLVMContext *Ctx;
diff --git a/llvm/lib/Transforms/Scalar/Float2Int.cpp b/llvm/lib/Transforms/Scalar/Float2Int.cpp
--- a/llvm/lib/Transforms/Scalar/Float2Int.cpp
+++ b/llvm/lib/Transforms/Scalar/Float2Int.cpp
@@ -121,7 +121,7 @@
 // Find the roots - instructions that convert from the FP domain to
 // integer domain.
 void Float2IntPass::findRoots(Function &F, const DominatorTree &DT,
-                              SmallPtrSet<Instruction*,8> &Roots) {
+                              RootSet &Roots) {
   for (BasicBlock &BB : F) {
     // Unreachable code can take on strange forms that we are not prepared to
     // handle. For example, an instruction may have itself as an operand.
@@ -184,7 +184,7 @@
 
 // Breadth-first walk of the use-def graph; determine the set of nodes
 // we care about and eagerly determine if some of them are poisonous.
-void Float2IntPass::walkBackwards(const SmallPtrSetImpl<Instruction*> &Roots) {
+void Float2IntPass::walkBackwards(const RootSet &Roots) {
   std::deque<Instruction*> Worklist(Roots.begin(), Roots.end());
   while (!Worklist.empty()) {
     Instruction *I = Worklist.back();