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
@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
@@ -30,20 +31,19 @@
   bool runImpl(Function &F, const DominatorTree &DT);
 
 private:
-  void findRoots(Function &F, const DominatorTree &DT,
-                 SmallPtrSet<Instruction *, 8> &Roots);
+  void findRoots(Function &F, const DominatorTree &DT);
   void seen(Instruction *I, ConstantRange R);
   ConstantRange badRange();
   ConstantRange unknownRange();
   ConstantRange validateRange(ConstantRange R);
-  void walkBackwards(const SmallPtrSetImpl<Instruction *> &Roots);
+  void walkBackwards();
   void walkForwards();
   bool validateAndTransform();
   Value *convert(Instruction *I, Type *ToTy);
   void cleanup();
 
   MapVector<Instruction *, ConstantRange> SeenInsts;
-  SmallPtrSet<Instruction *, 8> Roots;
+  SmallSetVector<Instruction *, 8> 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
@@ -120,8 +120,7 @@
 
 // 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) {
+void Float2IntPass::findRoots(Function &F, const DominatorTree &DT) {
   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 +183,7 @@
 
 // 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() {
   std::deque<Instruction*> Worklist(Roots.begin(), Roots.end());
   while (!Worklist.empty()) {
     Instruction *I = Worklist.back();
@@ -525,9 +524,9 @@
 
   Ctx = &F.getParent()->getContext();
 
-  findRoots(F, DT, Roots);
+  findRoots(F, DT);
 
-  walkBackwards(Roots);
+  walkBackwards();
   walkForwards();
 
   bool Modified = validateAndTransform();