Index: llvm/trunk/include/llvm/Support/CheckedArithmetic.h
===================================================================
--- llvm/trunk/include/llvm/Support/CheckedArithmetic.h
+++ llvm/trunk/include/llvm/Support/CheckedArithmetic.h
@@ -16,66 +16,61 @@
 #define LLVM_SUPPORT_CHECKEDARITHMETIC_H
 
 #include "llvm/ADT/APInt.h"
+#include "llvm/ADT/Optional.h"
 
 #include <type_traits>
 
 namespace {
 
 /// Utility function to apply a given method of \c APInt \p F to \p LHS and
-/// \p RHS, and write the output into \p Res.
-/// \return Whether the operation overflows.
+/// \p RHS.
+/// \return Empty optional if the operation overflows, or result otherwise.
 template <typename T, typename F>
 typename std::enable_if<std::is_integral<T>::value && sizeof(T) * 8 <= 64,
-                        bool>::type
-checkedOp(T LHS, T RHS, F Op, T *Res = nullptr, bool Signed = true) {
+                        llvm::Optional<T>>::type
+checkedOp(T LHS, T RHS, F Op, bool Signed = true) {
   llvm::APInt ALHS(/*BitSize=*/sizeof(T) * 8, LHS, Signed);
   llvm::APInt ARHS(/*BitSize=*/sizeof(T) * 8, RHS, Signed);
   bool Overflow;
   llvm::APInt Out = (ALHS.*Op)(ARHS, Overflow);
-  if (Res)
-    *Res = Signed ? Out.getSExtValue() : Out.getZExtValue();
-  return Overflow;
+  if (Overflow)
+    return llvm::None;
+  return Signed ? Out.getSExtValue() : Out.getZExtValue();
 }
 }
 
 namespace llvm {
 
-/// Add two signed integers \p LHS and \p RHS, write into \p Res if non-null.
-/// Does not guarantee saturating arithmetic.
-/// \return Whether the result overflows.
+/// Add two signed integers \p LHS and \p RHS, return wrapped result if
+/// available.
 template <typename T>
-typename std::enable_if<std::is_signed<T>::value, bool>::type
-checkedAdd(T LHS, T RHS, T *Res = nullptr) {
-  return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov, Res);
+typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
+checkedAdd(T LHS, T RHS) {
+  return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov);
 }
 
-/// Multiply two signed integers \p LHS and \p RHS, write into \p Res if
-/// non-null.
-/// Does not guarantee saturating arithmetic.
-/// \return Whether the result overflows.
+/// Multiply two signed integers \p LHS and \p RHS, return wrapped result
+/// if available.
 template <typename T>
-typename std::enable_if<std::is_signed<T>::value, bool>::type
-checkedMul(T LHS, T RHS, T *Res = nullptr) {
-  return checkedOp(LHS, RHS, &llvm::APInt::smul_ov, Res);
+typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
+checkedMul(T LHS, T RHS) {
+  return checkedOp(LHS, RHS, &llvm::APInt::smul_ov);
 }
 
-/// Add two unsigned integers \p LHS and \p RHS, write into \p Res if non-null.
-/// Does not guarantee saturating arithmetic.
-/// \return Whether the result overflows.
+/// Add two unsigned integers \p LHS and \p RHS, return wrapped result
+/// if available.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, bool>::type
-checkedAddUnsigned(T LHS, T RHS, T *Res = nullptr) {
-  return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, Res, /*Signed=*/false);
+typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
+checkedAddUnsigned(T LHS, T RHS) {
+  return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, /*Signed=*/false);
 }
 
-/// Multiply two unsigned integers \p LHS and \p RHS, write into \p Res if
-/// non-null.
-/// Does not guarantee saturating arithmetic.
-/// \return Whether the result overflows.
+/// Multiply two unsigned integers \p LHS and \p RHS, return wrapped result
+/// if available.
 template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, bool>::type
-checkedMulUnsigned(T LHS, T RHS, T *Res = nullptr) {
-  return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, Res, /*Signed=*/false);
+typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
+checkedMulUnsigned(T LHS, T RHS) {
+  return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, /*Signed=*/false);
 }
 
 } // End llvm namespace
Index: llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
===================================================================
--- llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
+++ llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
@@ -6,65 +6,53 @@
 namespace {
 
 TEST(CheckedArithmetic, CheckedAdd) {
-  int64_t Out;
   const int64_t Max = std::numeric_limits<int64_t>::max();
   const int64_t Min = std::numeric_limits<int64_t>::min();
-  EXPECT_EQ(checkedAdd<int64_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedAdd<int64_t>(Min, -1, &Out), true);
-  EXPECT_EQ(checkedAdd<int64_t>(Max, 1, &Out), true);
-  EXPECT_EQ(checkedAdd<int64_t>(10, 1, &Out), false);
-  EXPECT_EQ(Out, 11);
+  EXPECT_EQ(checkedAdd<int64_t>(Max, Max), None);
+  EXPECT_EQ(checkedAdd<int64_t>(Min, -1), None);
+  EXPECT_EQ(checkedAdd<int64_t>(Max, 1), None);
+  EXPECT_EQ(checkedAdd<int64_t>(10, 1), Optional<int64_t>(11));
 }
 
 TEST(CheckedArithmetic, CheckedAddSmall) {
-  int16_t Out;
   const int16_t Max = std::numeric_limits<int16_t>::max();
   const int16_t Min = std::numeric_limits<int16_t>::min();
-  EXPECT_EQ(checkedAdd<int16_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedAdd<int16_t>(Min, -1, &Out), true);
-  EXPECT_EQ(checkedAdd<int16_t>(Max, 1, &Out), true);
-  EXPECT_EQ(checkedAdd<int16_t>(10, 1, &Out), false);
-  EXPECT_EQ(Out, 11);
+  EXPECT_EQ(checkedAdd<int16_t>(Max, Max), None);
+  EXPECT_EQ(checkedAdd<int16_t>(Min, -1), None);
+  EXPECT_EQ(checkedAdd<int16_t>(Max, 1), None);
+  EXPECT_EQ(checkedAdd<int16_t>(10, 1), Optional<int64_t>(11));
 }
 
 TEST(CheckedArithmetic, CheckedMul) {
-  int64_t Out;
   const int64_t Max = std::numeric_limits<int64_t>::max();
   const int64_t Min = std::numeric_limits<int64_t>::min();
-  EXPECT_EQ(checkedMul<int64_t>(Max, 2, &Out), true);
-  EXPECT_EQ(checkedMul<int64_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedMul<int64_t>(Min, 2, &Out), true);
-  EXPECT_EQ(checkedMul<int64_t>(10, 2, &Out), false);
-  EXPECT_EQ(Out, 20);
+  EXPECT_EQ(checkedMul<int64_t>(Max, 2), None);
+  EXPECT_EQ(checkedMul<int64_t>(Max, Max), None);
+  EXPECT_EQ(checkedMul<int64_t>(Min, 2), None);
+  EXPECT_EQ(checkedMul<int64_t>(10, 2), Optional<int64_t>(20));
 }
 
 TEST(CheckedArithmetic, CheckedMulSmall) {
-  int16_t Out;
   const int16_t Max = std::numeric_limits<int16_t>::max();
   const int16_t Min = std::numeric_limits<int16_t>::min();
-  EXPECT_EQ(checkedMul<int16_t>(Max, 2, &Out), true);
-  EXPECT_EQ(checkedMul<int16_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedMul<int16_t>(Min, 2, &Out), true);
-  EXPECT_EQ(checkedMul<int16_t>(10, 2, &Out), false);
-  EXPECT_EQ(Out, 20);
+  EXPECT_EQ(checkedMul<int16_t>(Max, 2), None);
+  EXPECT_EQ(checkedMul<int16_t>(Max, Max), None);
+  EXPECT_EQ(checkedMul<int16_t>(Min, 2), None);
+  EXPECT_EQ(checkedMul<int16_t>(10, 2), Optional<int16_t>(20));
 }
 
 TEST(CheckedArithmetic, CheckedAddUnsigned) {
-  uint64_t Out;
   const uint64_t Max = std::numeric_limits<uint64_t>::max();
-  EXPECT_EQ(checkedAddUnsigned<uint64_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedAddUnsigned<uint64_t>(Max, 1, &Out), true);
-  EXPECT_EQ(checkedAddUnsigned<uint64_t>(10, 1, &Out), false);
-  EXPECT_EQ(Out, uint64_t(11));
+  EXPECT_EQ(checkedAddUnsigned<uint64_t>(Max, Max), None);
+  EXPECT_EQ(checkedAddUnsigned<uint64_t>(Max, 1), None);
+  EXPECT_EQ(checkedAddUnsigned<uint64_t>(10, 1), Optional<uint64_t>(11));
 }
 
 TEST(CheckedArithmetic, CheckedMulUnsigned) {
-  uint64_t Out;
   const uint64_t Max = std::numeric_limits<uint64_t>::max();
-  EXPECT_EQ(checkedMulUnsigned<uint64_t>(Max, 2, &Out), true);
-  EXPECT_EQ(checkedMulUnsigned<uint64_t>(Max, Max, &Out), true);
-  EXPECT_EQ(checkedMulUnsigned<uint64_t>(10, 2, &Out), false);
-  EXPECT_EQ(Out, uint64_t(20));
+  EXPECT_EQ(checkedMulUnsigned<uint64_t>(Max, 2), llvm::None);
+  EXPECT_EQ(checkedMulUnsigned<uint64_t>(Max, Max), llvm::None);
+  EXPECT_EQ(checkedMulUnsigned<uint64_t>(10, 2), Optional<uint64_t>(20));
 }