1 files changed, 12 insertions, 15 deletions
diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 9d239101d8fd..0dbccaa1a66a 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -37,6 +37,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
+#include <optional>
 
 using namespace llvm;
 
@@ -85,7 +86,7 @@ KnownBits ConstantRange::toKnownBits() const {
   APInt Min = getUnsignedMin();
   APInt Max = getUnsignedMax();
   KnownBits Known = KnownBits::makeConstant(Min);
-  if (Optional<unsigned> DifferentBit =
+  if (std::optional<unsigned> DifferentBit =
           APIntOps::GetMostSignificantDifferentBit(Min, Max)) {
     Known.Zero.clearLowBits(*DifferentBit + 1);
     Known.One.clearLowBits(*DifferentBit + 1);
@@ -258,10 +259,9 @@ static ConstantRange makeExactMulNUWRegion(const APInt &V) {
 
 /// Exact mul nsw region for single element RHS.
 static ConstantRange makeExactMulNSWRegion(const APInt &V) {
-  // Handle special case for 0, -1 and 1. See the last for reason why we
-  // specialize -1 and 1.
+  // Handle 0 and -1 separately to avoid division by zero or overflow.
   unsigned BitWidth = V.getBitWidth();
-  if (V == 0 || V.isOne())
+  if (V == 0)
     return ConstantRange::getFull(BitWidth);
 
   APInt MinValue = APInt::getSignedMinValue(BitWidth);
@@ -278,10 +278,7 @@ static ConstantRange makeExactMulNSWRegion(const APInt &V) {
     Lower = APIntOps::RoundingSDiv(MinValue, V, APInt::Rounding::UP);
     Upper = APIntOps::RoundingSDiv(MaxValue, V, APInt::Rounding::DOWN);
   }
-  // ConstantRange ctor take a half inclusive interval [Lower, Upper + 1).
-  // Upper + 1 is guaranteed not to overflow, because |divisor| > 1. 0, -1,
-  // and 1 are already handled as special cases.
-  return ConstantRange(Lower, Upper + 1);
+  return ConstantRange::getNonEmpty(Lower, Upper + 1);
 }
 
 ConstantRange
@@ -699,22 +696,22 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR,
   return ConstantRange(std::move(L), std::move(U));
 }
 
-Optional<ConstantRange>
+std::optional<ConstantRange>
 ConstantRange::exactIntersectWith(const ConstantRange &CR) const {
   // TODO: This can be implemented more efficiently.
   ConstantRange Result = intersectWith(CR);
   if (Result == inverse().unionWith(CR.inverse()).inverse())
     return Result;
-  return None;
+  return std::nullopt;
 }
 
-Optional<ConstantRange>
+std::optional<ConstantRange>
 ConstantRange::exactUnionWith(const ConstantRange &CR) const {
   // TODO: This can be implemented more efficiently.
   ConstantRange Result = unionWith(CR);
   if (Result == inverse().intersectWith(CR.inverse()).inverse())
     return Result;
-  return None;
+  return std::nullopt;
 }
 
 ConstantRange ConstantRange::castOp(Instruction::CastOps CastOp,
@@ -1659,15 +1656,15 @@ ConstantRange ConstantRange::abs(bool IntMinIsPoison) const {
 
   // All non-negative.
   if (SMin.isNonNegative())
-    return *this;
+    return ConstantRange(SMin, SMax + 1);
 
   // All negative.
   if (SMax.isNegative())
     return ConstantRange(-SMax, -SMin + 1);
 
   // Range crosses zero.
-  return ConstantRange(APInt::getZero(getBitWidth()),
-                       APIntOps::umax(-SMin, SMax) + 1);
+  return ConstantRange::getNonEmpty(APInt::getZero(getBitWidth()),
+                                    APIntOps::umax(-SMin, SMax) + 1);
 }
 
 ConstantRange::OverflowResult ConstantRange::unsignedAddMayOverflow(