ValueTracking: Add computeKnownExponentRange

[arsenm]

Summary

Perform basic floating-point range analysis for the exponent.

I was looking into handling multiply by a constant to perform denorm
scaling to match the current ldexp handling in computeKnownFPClass,
and went a bit overboard on generalizing the helper function for it.

I also find these fltSemantics getters incredibly annoying and think
the struct definition should just be public (along with all the
definitions for it).

[arsenm]

ping

[goldstein.w.n]

llvm/lib/Analysis/ValueTracking.cpp

4271

Should this be intersectWith?

4343

On the note of TODOs, would also add one for bitcast as something like logicOp + bitcast isn't that uncommon.

[arsenm]

llvm/lib/Analysis/ValueTracking.cpp

4271

It can be either operand, so it's a union? The possible set needs to expand

4343

Casts that produces an FP value seems pretty uncommon?

[arsenm]

Rebase

[RKSimon]

LGTM with some style cleanup minors

llvm/include/llvm/Analysis/ValueTracking.h

253

(style) assertion messages

283

(style) assertion message

llvm/lib/Analysis/ValueTracking.cpp

4228

auto *

4251

auto*

4284

auto *

4324

auto *

llvm/include/llvm/ADT/APFloat.h

struct APFloatBase {
   /// Enumeration of \c ilogb error results.
   enum IlogbErrorKinds {
     IEK_Zero = INT_MIN + 1,
     IEK_NaN = INT_MIN,
     IEK_Inf = INT_MAX
   };
 
   static unsigned int semanticsPrecision(const fltSemantics &);
+
+  // Return the encoded, unbiased mininimum exponent.
   static ExponentType semanticsMinExponent(const fltSemantics &);
+
+  // Return the semantically meaningful mininimum exponent (i.e. the exponent of
+  // the smallest denormal).
+  static ExponentType semanticsMinExponentValue(const fltSemantics &);
+
+  // Return the semantic exponent range (i.e. the exponent of the smallest
+  // denormal, and the exponent of the largest normal.
+  static std::pair<ExponentType, ExponentType>
+  semanticsExponentRange(const fltSemantics &);
+
   static ExponentType semanticsMaxExponent(const fltSemantics &);
   static unsigned int semanticsSizeInBits(const fltSemantics &);
   static unsigned int semanticsIntSizeInBits(const fltSemantics&, bool);
 
   // Returns true if any number described by \p Src can be precisely represented
   // by a normal (not subnormal) value in \p Dst.
   static bool isRepresentableAsNormalIn(const fltSemantics &Src,
                                         const fltSemantics &Dst);

llvm/include/llvm/Analysis/ValueTracking.h

unsigned ComputeMaxSignificantBits(const Value *Op, const DataLayout &DL,
                                    const Instruction *CxtI = nullptr,
                                    const DominatorTree *DT = nullptr);
 
 /// Map a call instruction to an intrinsic ID.  Libcalls which have equivalent
 /// intrinsics are treated as-if they were intrinsics.
 Intrinsic::ID getIntrinsicForCallSite(const CallBase &CB,
                                       const TargetLibraryInfo *TLI);
 
+/// Track the known range for the exponent of a floating-point value.
+struct KnownExponentRange {
+  using ExponentType = APFloat::ExponentType;
+
+  /// The semantic minimimum exponent value (i.e. the most conservative choice
+  /// is the exponent of the smallest denormal)
+  ExponentType MinExp = APFloat::IEK_NaN;
+
+  /// The maximum exponent value, ignoring infinities and NaNs.
+  ExponentType MaxExpFiniteOnly = APFloat::IEK_Inf - 1;
+
+  /// The maximum exponent value, which include infinities and NaNs. This may
+  /// differ from MaxExpFiniteOnly in cases involving mixed fast math flag usage
+  /// and conversions.
+  ExponentType MaxExp = APFloat::IEK_Inf;
+
+  /// Construct an KnownExponentRange with no knowledge.
+  constexpr KnownExponentRange() = default;
+
+  /// Construct a KnownExponentRange with the provided finite range.
+  constexpr KnownExponentRange(std::pair<ExponentType, ExponentType> Pair)
+      : MinExp(Pair.first), MaxExpFiniteOnly(Pair.second) {}
+
+  /// Construct a KnownExponentRange with a finite range from \p Min to \p
+  /// MaxFiniteOnly. \p Max
+  constexpr KnownExponentRange(ExponentType Min, ExponentType MaxFiniteOnly,
+                               ExponentType Max = APFloat::IEK_Inf)
+      : MinExp(Min), MaxExpFiniteOnly(MaxFiniteOnly), MaxExp(Max) {
+    assert(MaxFiniteOnly <= Max);
+  }
+
+  /// Get an KnownexponentRange for a constant value.
+  KnownExponentRange(const APFloat &Val) {
+    ExponentType ExpVal = ilogb(Val);
+    if (ExpVal == APFloat::IEK_Zero)
+      ExpVal = 0;
+    else if (ExpVal == APFloat::IEK_NaN)
+      ExpVal = APFloat::IEK_Inf;
+    MinExp = MaxExp = MaxExpFiniteOnly = ExpVal;
+
+    if (ExpVal == APFloat::IEK_Inf) {
+      // If we encounter a constant infinity, keep tracking the possible finite
+      // only range. This value may still be used in an assume finite context.
+      // Use the minimum value so anything else we union with wins.
+      MaxExpFiniteOnly = APFloat::IEK_NaN;
+    }
+  }
+
+  /// Get a KnownExponentRange with the bounds for the floating-point type.
+  KnownExponentRange(const fltSemantics &Semantics) {
+    std::tie(MinExp, MaxExpFiniteOnly) =
+        APFloat::semanticsExponentRange(Semantics);
+  }
+
+  /// Get a KnownExponentRange from \p Min to \p Max that assumes the result
+  /// cannot be infinite or NaN.
+  static constexpr KnownExponentRange getFiniteOnly(ExponentType Min,
+                                                    ExponentType Max) {
+    assert(Max != APFloat::IEK_Inf);
+    return KnownExponentRange(Min, Max, Max);
+  }
+
+  /// Get an KnownExponentRange for a literal 0.
+  static KnownExponentRange getZero() {
+    return KnownExponentRange(0, 0, 0);
+  }
+
+  /// Get an KnownExponentRange for a literal infinity.
+  static KnownExponentRange getInf() {
+    return KnownExponentRange(APFloat::IEK_Inf, APFloat::IEK_NaN,
+                              APFloat::IEK_Inf);
+  }
+
+  /// Get an KnownExponentRange for a literal nan.
+  static KnownExponentRange getNaN() {
+    return getInf();
+  }
+
+  /// Get an KnownExponentRange for a value with an unknown exponent range, but
+  /// cannot be an infinity or NaN.
+  static KnownExponentRange getUnknownFinite() {
+    return KnownExponentRange(APFloat::IEK_NaN, APFloat::IEK_Inf - 1,
+                              APFloat::IEK_Inf - 1);
+  }
+
+  // Get a union identity value.
+  static KnownExponentRange getEmpty() {
+    return KnownExponentRange(APFloat::IEK_Inf, APFloat::IEK_NaN,
+                              APFloat::IEK_NaN);
+  }
+
+  /// Return true if this cannot be an infinity or NaN.
+  constexpr bool isFinite() const {
+    return MaxExp == MaxExpFiniteOnly && MaxExp != APFloat::IEK_Inf;
+  }
+
+  /// Return true if this has no usable knowledge.
+  constexpr bool isUnknown() const {
+    return MinExp == APFloat::IEK_NaN;
+  }
+
+  /// Return true if the range is unknown, but the value cannot be an infinity
+  /// or NaN.
+  constexpr bool isUnknownFinite() const {
+    return isUnknown() && isFinite();
+  }
+
+  ExponentType getMinExp() const {
+    return MinExp;
+  }
+
+  ExponentType getMaxExp(bool FiniteOnly) const {
+    return FiniteOnly ? MaxExpFiniteOnly : MaxExp;
+  }
+
+  /// Assume the range cannot include an infinity or NaN.
+  void knownFiniteOnly() {
+    // Even if we don't know the exponent we may find it can't be infinity.
+    if (MaxExpFiniteOnly == APFloat::IEK_Inf)
+      --MaxExpFiniteOnly;
+    MaxExp = MaxExpFiniteOnly;
+  }
+
+  /// Apply FastMathFlags from \p FMFSource and return this.
+  KnownExponentRange &applyFlags(const SimplifyQuery &Q,
+                                 const Instruction *FMFSource);
+
+  /// Perform range union.
+  KnownExponentRange &operator|=(KnownExponentRange RHS) {
+    MinExp = std::min(MinExp, RHS.MinExp);
+    MaxExpFiniteOnly = std::max(MaxExpFiniteOnly, RHS.MaxExpFiniteOnly);
+    MaxExp = std::max(std::max(MaxExp, MaxExpFiniteOnly), RHS.MaxExp);
+    return *this;
+  }
+
+  constexpr bool operator==(KnownExponentRange RHS) const {
+    return MinExp == RHS.MinExp && MaxExp == RHS.MaxExp &&
+           MaxExpFiniteOnly == RHS.MaxExpFiniteOnly;
+  }
+};
+
+constexpr KnownExponentRange operator|(KnownExponentRange LHS,
+                                       KnownExponentRange RHS) {
+  LHS |= RHS;
+  return LHS;
+}
+
+/// Compute the known exponent range for a floating-point value. If nothing
+/// useful could be determined for the value range,
+/// KnownExponentRange::isUnknown() will be true. The exponent range will be the
+/// full range implied by the the type's fltSemantics. If the finite range is
+/// unknown, but it's know this cannot be an infinity,
+/// KnownExponentRange::isFinite() and KnownExponentRange::isUnknown() will be
+/// true.
+KnownExponentRange computeKnownExponentRange(const Value *V,
+                                             const APInt &DemandedElts,
+                                             unsigned Depth,
+                                             const SimplifyQuery &Q);
+KnownExponentRange computeKnownExponentRange(const Value *V, unsigned Depth,
+                                             const SimplifyQuery &Q);
+
+KnownExponentRange computeKnownExponentRange(
+    const Value *V, const APInt &DemandedElts, const DataLayout &DL,
+    unsigned Depth = 0, const TargetLibraryInfo *TLI = nullptr,
+    AssumptionCache *AC = nullptr, const Instruction *CxtI = nullptr,
+    const DominatorTree *DT = nullptr, bool UseInstrInfo = true);
+KnownExponentRange computeKnownExponentRange(
+    const Value *V, const DataLayout &DL, unsigned Depth = 0,
+    const TargetLibraryInfo *TLI = nullptr, AssumptionCache *AC = nullptr,
+    const Instruction *CxtI = nullptr, const DominatorTree *DT = nullptr,
+    bool UseInstrInfo = true);
+
 /// Returns a pair of values, which if passed to llvm.is.fpclass, returns the
 /// same result as an fcmp with the given operands.
 ///
 /// If \p LookThroughSrc is true, consider the input value when computing the
 /// mask.
 ///
 /// If \p LookThroughSrc is false, ignore the source value (i.e. the first pair
 /// element will always be LHS.

llvm/lib/Analysis/ValueTracking.cpp

if (match(I->getArgOperand(0), m_FCmp(Pred, m_Value(LHS), m_Value(RHS)))) {
                          m_Value(LHS), m_ConstantInt(ClassVal)))) {
       KnownFromAssume &= static_cast<FPClassTest>(ClassVal);
     }
   }
 
   return KnownFromAssume;
 }
 
+KnownExponentRange &
+KnownExponentRange::applyFlags(const SimplifyQuery &Q,
+                               const Instruction *FMFSource) {
+  if (!Q.IIQ.UseInstrInfo)
+    return *this;
+
+  FastMathFlags FMF = cast<FPMathOperator>(FMFSource)->getFastMathFlags();
+  if (FMF.noNaNs() && FMF.noInfs())
+    knownFiniteOnly();
+  return *this;
+}
+
+/// Compute the known exponent range for a floating-point value.
+KnownExponentRange llvm::computeKnownExponentRange(const Value *V,
+                                                   const APInt &DemandedElts,
+                                                   unsigned Depth,
+                                                   const SimplifyQuery &Q) {
+  if (!DemandedElts) {
+    // No demanded elts, better to assume we don't know anything.
+    return KnownExponentRange();
+  }
+
+  if (auto *CFP = dyn_cast<ConstantFP>(V))
+    return KnownExponentRange(CFP->getValueAPF());
+
+  auto *VFVTy = dyn_cast<FixedVectorType>(V->getType());
+  const Constant *CV = dyn_cast<Constant>(V);
+  if (VFVTy && CV) {
+    KnownExponentRange Known = KnownExponentRange::getEmpty();
+    const unsigned NumElts = VFVTy->getNumElements();
+    for (unsigned i = 0; i != NumElts; ++i) {
+      if (!DemandedElts[i])
+        continue;
+      auto *CElt = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
+      if (!CElt)
+        return KnownExponentRange();
+      Known |= KnownExponentRange(CElt->getValueAPF());
+    }
+
+    return Known;
+  }
+
+  if (isa<ConstantAggregateZero>(V))
+    return KnownExponentRange::getZero();
+
+  // All recursive calls that increase depth must come after this.
+  if (Depth == MaxAnalysisRecursionDepth)
+    return KnownExponentRange();
+
+  const Instruction *Op = dyn_cast<Instruction>(V);
+  if (!Op)
+    return KnownExponentRange();
+
+  switch (Op->getOpcode()) {
+  case Instruction::FNeg:
+    return computeKnownExponentRange(Op->getOperand(0), DemandedElts, Depth + 1,
+                                     Q)
+        .applyFlags(Q, Op);
+  case Instruction::Freeze:
+    return computeKnownExponentRange(Op->getOperand(0), DemandedElts, Depth + 1,
+                                     Q);
+  case Instruction::Select: {
+    KnownExponentRange KnownRHS = computeKnownExponentRange(
+        Op->getOperand(2), DemandedElts, Depth + 1, Q);
+    if (KnownRHS.isUnknown())
+      return KnownRHS.applyFlags(Q, Op);
+
+    KnownExponentRange KnownLHS = computeKnownExponentRange(
+        Op->getOperand(1), DemandedElts, Depth + 1, Q);
+    KnownLHS |= KnownRHS;
+    return KnownLHS.applyFlags(Q, Op);
+  }
+  case Instruction::FPExt: {
+    const Value *Src = Op->getOperand(0);
+    KnownExponentRange KnownSrc =
+        computeKnownExponentRange(Src, DemandedElts, Depth + 1, Q);
+    if (KnownSrc.isUnknown())
+      return KnownExponentRange(
+          Src->getType()->getScalarType()->getFltSemantics());
+    return KnownSrc;
+  }
+  case Instruction::Call: {
+    const CallInst *CI = cast<CallInst>(Op);
+    const Intrinsic::ID IID = CI->getIntrinsicID();
+    switch (IID) {
+    case Intrinsic::fabs:
+    case Intrinsic::copysign:
+    case Intrinsic::arithmetic_fence:
+      return computeKnownExponentRange(CI->getArgOperand(0), DemandedElts,
+                                       Depth + 1, Q)
+          .applyFlags(Q, CI);
+    case Intrinsic::canonicalize:
+      // TODO: Can raise minimum exponent if denormals are flushed.
+      return computeKnownExponentRange(CI->getArgOperand(0), DemandedElts,
+                                       Depth + 1, Q)
+          .applyFlags(Q, CI);
+    case Intrinsic::ldexp:
+      // TODO: Known source range plus known exponent of second argument.
+    case Intrinsic::experimental_constrained_fpext:
+      // TODO: Same as fpext
+      break;
+    case Intrinsic::floor:
+    case Intrinsic::ceil:
+    case Intrinsic::trunc:
+    case Intrinsic::rint:
+    case Intrinsic::nearbyint:
+    case Intrinsic::round:
+    case Intrinsic::roundeven:
+      // TODO: Rounding-to-integer cases
+
+    case Intrinsic::minnum:
+    case Intrinsic::maxnum:
+    case Intrinsic::minimum:
+    case Intrinsic::maximum:
+      // TODO: Treat like select
+
+    default:
+      break;
+    }
+    break;
+  }
+  case Instruction::ExtractValue: {
+    const ExtractValueInst *Extract = cast<ExtractValueInst>(Op);
+    ArrayRef<unsigned> Indices = Extract->getIndices();
+    const Value *Src = Extract->getAggregateOperand();
+    if (isa<StructType>(Src->getType()) && Indices.size() == 1 &&
+        Indices[0] == 0) {
+      if (const auto *CI = dyn_cast<CallInst>(Src)) {
+        switch (CI->getIntrinsicID()) {
+        case Intrinsic::frexp:
+          return KnownExponentRange(-1, 1);
+        default:
+          break;
+        }
+      }
+    }
+
+    break;
+  }
+  case Instruction::SIToFP:
+  case Instruction::UIToFP:
+    // TODO: Check from known range of integer.
+    break;
+  case Instruction::ExtractElement:
+  case Instruction::InsertElement:
+  case Instruction::ShuffleVector:
+    // TODO: Handle vectors
+    break;
+  case Instruction::PHI:
+    // TODO:
+    break;
+  default:
+    break;
+  }
+
+  // TODO: Increase minimum exponent range if computeKnownFPClass says it can't
+  // be denormal.
+
+  return KnownExponentRange();
+}
+
+KnownExponentRange llvm::computeKnownExponentRange(
+    const Value *V, const APInt &DemandedElts, const DataLayout &DL,
+    unsigned Depth, const TargetLibraryInfo *TLI, AssumptionCache *AC,
+    const Instruction *CxtI, const DominatorTree *DT, bool UseInstrInfo) {
+  return computeKnownExponentRange(
+      V, DemandedElts, Depth,
+      SimplifyQuery(DL, TLI, DT, AC, safeCxtI(V, CxtI), UseInstrInfo));
+}
+
+KnownExponentRange
+llvm::computeKnownExponentRange(const Value *V, const DataLayout &DL,
+                                unsigned Depth, const TargetLibraryInfo *TLI,
+                                AssumptionCache *AC, const Instruction *CxtI,
+                                const DominatorTree *DT, bool UseInstrInfo) {
+  auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
+  APInt DemandedElts =
+      FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
+  return computeKnownExponentRange(
+      V, DemandedElts, Depth,
+      SimplifyQuery(DL, TLI, DT, AC, safeCxtI(V, CxtI), UseInstrInfo));
+}
+
 void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
                          FPClassTest InterestedClasses, KnownFPClass &Known,
                          unsigned Depth, const SimplifyQuery &Q);
 
 static void computeKnownFPClass(const Value *V, KnownFPClass &Known,
                                 FPClassTest InterestedClasses, unsigned Depth,
                                 const SimplifyQuery &Q) {
   auto *FVTy = dyn_cast<FixedVectorType>(V->getType());

llvm/lib/Support/APFloat.cpp

 APFloatBase::ExponentType
 APFloatBase::semanticsMaxExponent(const fltSemantics &semantics) {
   return semantics.maxExponent;
 }
 APFloatBase::ExponentType
 APFloatBase::semanticsMinExponent(const fltSemantics &semantics) {
   return semantics.minExponent;
 }
+
+APFloatBase::ExponentType
+APFloatBase::semanticsMinExponentValue(const fltSemantics &semantics) {
+  return semantics.minExponent - semantics.precision + 1;
+}
+
+std::pair<APFloatBase::ExponentType, APFloatBase::ExponentType>
+APFloatBase::semanticsExponentRange(const fltSemantics &semantics) {
+  return {semanticsMinExponentValue(semantics),
+          semanticsMaxExponent(semantics)};
+}
+
 unsigned int APFloatBase::semanticsSizeInBits(const fltSemantics &semantics) {
   return semantics.sizeInBits;
 }
 unsigned int APFloatBase::semanticsIntSizeInBits(const fltSemantics &semantics,
                                                  bool isSigned) {
   // The max FP value is pow(2, MaxExponent) * (1 + MaxFraction), so we need
   // at least one more bit than the MaxExponent to hold the max FP value.
   unsigned int MinBitWidth = semanticsMaxExponent(semantics) + 1;

llvm/unittests/Analysis/ValueTrackingTest.cpp

void expectKnownFPClass(unsigned KnownTrue, std::optional<bool> SignBitKnown,
     if (!TestVal)
       TestVal = A;
 
     KnownFPClass Known = computeKnownFPClass(TestVal, M->getDataLayout());
     EXPECT_EQ(KnownTrue, Known.KnownFPClasses);
     EXPECT_EQ(SignBitKnown, Known.SignBit);
   }
 };
+
+class ComputeKnownExponentRangeTest : public ValueTrackingTest {};
 }
 
 TEST_F(MatchSelectPatternTest, SimpleFMin) {
   parseAssembly(
       "define float @test(float %a) {\n"
       "  %1 = fcmp ult float %a, 5.0\n"
       "  %A = select i1 %1, float %a, float 5.0\n"
       "  ret float %A\n"
KnownFPClass NoUseInstrInfoNSZNoNan =
         computeKnownFPClass(A4, M->getDataLayout(), fcAllFlags, 0, nullptr,
                             nullptr, nullptr, nullptr, /*UseInstrInfo=*/false);
     EXPECT_EQ(fcPositive | fcNegZero | fcQNan,
               NoUseInstrInfoNSZNoNan.KnownFPClasses);
     EXPECT_EQ(std::nullopt, NoUseInstrInfoNSZNoNan.SignBit);
   }
 }
 
+TEST_F(ComputeKnownExponentRangeTest, SelectConstantFPScalar) {
+  parseAssembly("define float @test(i1 %cond) {\n"
+                "  %A = select i1 %cond, float 0.0, float -0.0\n"
+                "  %A2 = select i1 %cond, float 1.0, float 2.0\n"
+                "  %A3 = select i1 %cond, float -42.0, float 2.0\n"
+                "  %A4 = select i1 %cond, float 16.0, float 0.0\n"
+                "  %A5 = select i1 %cond, float 0.0, float 0.25\n"
+                "  %A6 = select i1 %cond, float poison, float 2.0\n"
+                "  %A7 = select i1 %cond, float 2.0, float poison\n"
+                "  ret float %A\n"
+                "}\n");
+
+  {
+    KnownExponentRange AResult =
+        computeKnownExponentRange(A, M->getDataLayout());
+    EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 0), AResult);
+    EXPECT_TRUE(AResult.isFinite());
+    EXPECT_FALSE(AResult.isUnknown());
+    EXPECT_FALSE(AResult.isUnknownFinite());
+    EXPECT_EQ(0, AResult.getMinExp());
+    EXPECT_EQ(0, AResult.getMaxExp(true));
+    EXPECT_EQ(0, AResult.getMaxExp(false));
+  }
+
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 1),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(1, 5),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 4),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-2, 0),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A7, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SelectFlags) {
+  parseAssembly(
+      "define float @test(i1 %cond, float %unknown0, float %unknown1) {\n"
+      "  %A = select i1 %cond, float %unknown0, float %unknown1\n"
+      "  %A2 = select nnan i1 %cond, float %unknown0, float %unknown1\n"
+      "  %A3 = select ninf i1 %cond, float %unknown0, float %unknown1\n"
+      "  %A4 = select nnan ninf i1 %cond, float %unknown0, float %unknown1\n"
+      "  %A5 = select nnan ninf i1 %cond, float %unknown0, float 1.0\n"
+      "  %A6 = select nnan ninf i1 %cond, float 1.0, float %unknown0\n"
+      "  ret float %A\n"
+      "}\n");
+  KnownExponentRange AResult = computeKnownExponentRange(A, M->getDataLayout());
+  EXPECT_TRUE(AResult.isUnknown());
+  EXPECT_FALSE(AResult.isUnknownFinite());
+  EXPECT_FALSE(AResult.isFinite());
+  EXPECT_EQ(KnownExponentRange(), AResult);
+
+  EXPECT_EQ(AResult, computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(AResult, computeKnownExponentRange(A3, M->getDataLayout()));
+
+  KnownExponentRange A4Result =
+      computeKnownExponentRange(A4, M->getDataLayout());
+  EXPECT_TRUE(A4Result.isFinite());
+  EXPECT_TRUE(A4Result.isUnknownFinite());
+  EXPECT_TRUE(A4Result.isUnknown());
+  EXPECT_EQ(KnownExponentRange::getUnknownFinite(), A4Result);
+
+  EXPECT_EQ(A4Result, computeKnownExponentRange(A5, M->getDataLayout()));
+  EXPECT_EQ(A4Result, computeKnownExponentRange(A6, M->getDataLayout()));
+
+  // Check UseInstrInfo=false ignores the flags
+
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A4, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A5, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A6, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SelectConstantFPScalarLimits) {
+  parseAssembly("define float @test(i1 %cond) {\n"
+                "  %A = select i1 %cond, float 0x36A0000000000000, float "
+                "0xB6A0000000000000\n"
+                "  %A2 = select i1 %cond, float 0x381FFFFFE0000000, float "
+                "0xB81FFFFFE0000000\n"
+                "  %A3 = select i1 %cond, float 0x3810000000000000, float "
+                "0xB810000000000000\n"
+                "  %A4 = select i1 %cond, float 0x47EFFFFFE0000000, float "
+                "0xC7EFFFFFE0000000\n"
+                "  %A5 = select i1 %cond, float 0x7FF0000000000000, float "
+                "0xFFF0000000000000\n"
+                "  %A6 = select i1 %cond, float 0x7FF8000000000000, float "
+                "0xFFF8000000000000\n"
+                "  %A7 = select i1 %cond, float 0x7FF4000000000000, float "
+                "0xFFF4000000000000\n"
+                "  ret float %A\n"
+                "}\n");
+
+  // Smallest denormal
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-149, -149),
+            computeKnownExponentRange(A, M->getDataLayout()));
+
+  // Largest denormal
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-126, -126),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+
+  // Smallest normal
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-126, -126),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+
+  // Largest normal
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(127, 127),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+
+  // Infinity
+  EXPECT_EQ(KnownExponentRange::getInf(),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+
+  // qnan
+  EXPECT_EQ(KnownExponentRange::getNaN(),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+
+  // snan
+  EXPECT_EQ(KnownExponentRange::getNaN(),
+            computeKnownExponentRange(A7, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SelectConstantFPVector) {
+  parseAssembly("define <2 x float> @test(i1 %cond) {\n"
+                "  %A = select i1 %cond, <2 x float> zeroinitializer, <2 x "
+                "float> <float -0.0, float -0.0>\n"
+                "  %A2 = select i1 %cond, <2 x float> <float 1.0, float 1.0>, "
+                "<2 x float> <float 2.0, float 3.0>\n"
+                "  %A3 = select i1 %cond, <2 x float> <float -42.0, float "
+                "-128.0>, <2 x float> <float 2.0, float 4.0>\n"
+                "  %A4 = select i1 %cond, <2 x float> <float -16.0, float "
+                "16.0>, <2 x float> zeroinitializer\n"
+                "  %A5 = select i1 %cond, <2 x float> zeroinitializer, <2 x "
+                "float> <float 0.25, float 0.25>\n"
+                "  %A6 = select i1 %cond, <2 x float> zeroinitializer, <2 x "
+                "float> <float 0.25, float poison>\n"
+                "  %A7 = select i1 %cond, <2 x float> <float poison, float "
+                "4.0>, <2 x float> <float 0.25, float 0.0>\n"
+                "  ret <2 x float> %A\n"
+                "}\n");
+
+  {
+    KnownExponentRange AResult =
+        computeKnownExponentRange(A, M->getDataLayout());
+    EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 0), AResult);
+    EXPECT_TRUE(AResult.isFinite());
+    EXPECT_FALSE(AResult.isUnknown());
+    EXPECT_FALSE(AResult.isUnknownFinite());
+  }
+
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 1),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+
+  {
+    KnownExponentRange A3Result =
+        computeKnownExponentRange(A3, M->getDataLayout());
+    EXPECT_EQ(KnownExponentRange::getFiniteOnly(1, 7), A3Result);
+    EXPECT_EQ(1, A3Result.getMinExp());
+    EXPECT_EQ(7, A3Result.getMaxExp(true));
+    EXPECT_EQ(7, A3Result.getMaxExp(false));
+  }
+
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 4),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-2, 0),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+  {
+    KnownExponentRange A6Result =
+        computeKnownExponentRange(A6, M->getDataLayout());
+    EXPECT_TRUE(A6Result.isUnknown());
+    EXPECT_FALSE(A6Result.isFinite());
+    EXPECT_FALSE(A6Result.isUnknownFinite());
+    EXPECT_EQ(KnownExponentRange(), A6Result);
+  }
+
+  {
+    KnownExponentRange A7Result =
+        computeKnownExponentRange(A7, M->getDataLayout());
+    EXPECT_TRUE(A7Result.isUnknown());
+    EXPECT_FALSE(A7Result.isFinite());
+    EXPECT_FALSE(A7Result.isUnknownFinite());
+    EXPECT_EQ(KnownExponentRange(), A7Result);
+  }
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SelectConstantFPVector2) {
+  parseAssembly(
+      "define <2 x float> @test(i1 %cond) {\n"
+      "  %A = select i1 %cond, <2 x float> <float 2.0, float 4.0>, <2 x float> "
+      "<float 0x7FF8000000000000, float 0.25>\n"
+      "  %A2 = select i1 %cond, <2 x float> <float 0x7FF8000000000000, float "
+      "8.0>, <2 x float> <float 16.0, float 8.0>\n"
+      "  %A3 = select i1 %cond, <2 x float> <float 0x7FF8000000000000, float "
+      "-0.0>, <2 x float> zeroinitializer\n"
+      "  %A4 = select i1 %cond, <2 x float> <float -2.0, float 4.0>, <2 x "
+      "float> <float 2.0, float 0x7FF8000000000000>\n"
+      "  ret <2 x float> %A\n"
+      "}\n");
+
+  KnownExponentRange AResult = computeKnownExponentRange(A, M->getDataLayout());
+  EXPECT_FALSE(AResult.isUnknown());
+  EXPECT_FALSE(AResult.isUnknownFinite());
+  EXPECT_FALSE(AResult.isFinite());
+
+  EXPECT_EQ(KnownExponentRange(-2, 2, APFloat::IEK_Inf), AResult);
+  EXPECT_EQ(KnownExponentRange(3, 4, APFloat::IEK_Inf),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(0, 0, APFloat::IEK_Inf),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(1, 2, APFloat::IEK_Inf),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SelectConstantFPScalableVector) {
+  parseAssembly("define <vscale x 2 x float> @test(i1 %cond, <vscale x 2 x "
+                "float> %arg) {\n"
+                "  %A = select i1 %cond, <vscale x 2 x float> zeroinitializer, "
+                "<vscale x 2 x float> %arg\n"
+                "  %A2 = select i1 %cond, <vscale x 2 x float> %arg, <vscale x "
+                "2 x float> zeroinitializer\n"
+                "  %A3 = select i1 %cond, <vscale x 2 x float> "
+                "zeroinitializer, <vscale x 2 x float> poison\n"
+                "  %A4 = select i1 %cond, <vscale x 2 x float> "
+                "zeroinitializer, <vscale x 2 x float> zeroinitializer\n"
+                "  %A5 = select nnan ninf i1 %cond, <vscale x 2 x float> %arg, "
+                "<vscale x 2 x float> zeroinitializer\n"
+                "  %A6 = select nnan i1 %cond, <vscale x 2 x float> %arg, "
+                "<vscale x 2 x float> zeroinitializer\n"
+                "  %A7 = select ninf i1 %cond, <vscale x 2 x float> %arg, "
+                "<vscale x 2 x float> zeroinitializer\n"
+                "  ret <vscale x 2 x float> %A\n"
+                "}\n");
+
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A, M->getDataLayout()));
+
+  KnownExponentRange A2Result =
+      computeKnownExponentRange(A2, M->getDataLayout());
+  EXPECT_FALSE(A2Result.isFinite());
+  EXPECT_TRUE(A2Result.isUnknown());
+
+  EXPECT_EQ(KnownExponentRange(), A2Result);
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(0, 0),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+
+  KnownExponentRange A5Result =
+      computeKnownExponentRange(A5, M->getDataLayout());
+  EXPECT_TRUE(A5Result.isFinite());
+  EXPECT_TRUE(A5Result.isUnknown());
+  EXPECT_TRUE(A5Result.isUnknownFinite());
+  EXPECT_EQ(KnownExponentRange::getUnknownFinite(), A5Result);
+
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A7, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, FPExt) {
+  parseAssembly(
+      "define float @test(half %src.f16, float %src.f32, bfloat %src.bf16, <2 "
+      "x half> %src.v2f16, half nofpclass(inf nan) %src.f16.finite) {\n"
+      "  %A = fpext half %src.f16 to float\n"
+      "  %A2 = fpext half %src.f16 to double\n"
+      "  %A3 = fpext float %src.f32 to double\n"
+      "  %A4 = fpext bfloat %src.bf16 to float\n"
+      "  %A5 = fpext bfloat %src.bf16 to double\n"
+      "  %A6 = fpext <2 x half> %src.v2f16 to <2 x float>\n"
+      "  %A7 = fpext half %src.f16.finite to float\n"
+      "  ret float %A\n"
+      "}\n");
+
+  {
+    KnownExponentRange AResult =
+        computeKnownExponentRange(A, M->getDataLayout());
+    EXPECT_EQ(KnownExponentRange(-24, 15), AResult);
+    EXPECT_EQ(-24, AResult.getMinExp());
+    EXPECT_EQ(15, AResult.getMaxExp(true));
+    EXPECT_EQ(APFloat::IEK_Inf, AResult.getMaxExp(false));
+  }
+
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-149, 127),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-133, 127),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-133, 127),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15), // TODO: Could detect finite only
+            computeKnownExponentRange(A7, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, SimpleIntrinsics) {
+  parseAssembly(
+      "declare float @llvm.fabs.f32(float)\n"
+      "declare float @llvm.arithmetic.fence.f32(float)\n"
+      "declare float @llvm.copysign.f32(float, float)\n"
+      "define float @test(half %src.f16, float %arg1) {\n"
+      "  %A = fpext half %src.f16 to float\n"
+      "  %A2 = call float @llvm.fabs.f32(float %A)\n"
+      "  %A3 = call float @llvm.arithmetic.fence.f32(float %A)\n"
+      "  %A4 = call float @llvm.copysign.f32(float %A, float %arg1)\n"
+      "  %A5 = call nnan ninf float @llvm.copysign.f32(float %A, float %arg1)\n"
+      "  %A6 = call nnan ninf float @llvm.fabs.f32(float %A)\n"
+      "  %A7 = call nnan ninf float @llvm.arithmetic.fence.f32(float %A)\n"
+      "  ret float %A\n"
+      "}\n");
+
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-24, 15),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-24, 15),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-24, 15),
+            computeKnownExponentRange(A7, M->getDataLayout()));
+
+  // Check UseInstrInfo=false ignores the flags
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A5, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A6, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A7, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, Canonicalize) {
+  parseAssembly(
+      "declare float @llvm.canonicalize.f32(float)\n"
+      "define float @test(half %src.f16, float %arg1) {\n"
+      "  %A = fpext half %src.f16 to float\n"
+      "  %A2 = call float @llvm.canonicalize.f32(float %A)\n"
+      "  %A3 = call nnan ninf float @llvm.canonicalize.f32(float %A)\n"
+      "  ret float %A\n"
+      "}\n");
+
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-24, 15),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A3, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, UnaryOps) {
+  parseAssembly("define float @test(half %src.f16, float %src.f32) {\n"
+                "  %A = fpext half %src.f16 to float\n"
+                "  %A2 = freeze float %A\n"
+                "  %A3 = freeze float %src.f32\n"
+                "  %A4 = fneg float %A\n"
+                "  %A5 = fneg float %src.f32\n"
+                "  %A6 = fneg nnan ninf float %src.f32\n"
+                "  %A7 = fneg nnan ninf float %A\n"
+                "  ret float %A\n"
+                "}\n");
+
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A5, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getUnknownFinite(),
+            computeKnownExponentRange(A6, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange::getFiniteOnly(-24, 15),
+            computeKnownExponentRange(A7, M->getDataLayout()));
+
+  EXPECT_EQ(KnownExponentRange(-24, 15),
+            computeKnownExponentRange(A7, M->getDataLayout(), 0, nullptr,
+                                      nullptr, nullptr, nullptr,
+                                      /*UseInstrInfo=*/false));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, Frexp) {
+  parseAssembly(
+      "declare { float, i32 } @llvm.frexp.f32.i32(float)\n"
+      "declare { double, i32 } @llvm.frexp.f64.i32(double)\n"
+      "declare { <2 x float>, <2 x i32> } @llvm.frexp.v2f32.v2i32(<2 x "
+      "float>)\n"
+      "declare { <2 x double>, <2 x i32> } @llvm.frexp.v2f64.v2i32(<2 x "
+      "double>)\n"
+      "define float @test(float %arg.f32, double %arg.f64, <2 x float> "
+      "%arg.v2f32, <2 x double> %arg.v2f64) {\n"
+      "  %frexp.f32.i32 = call { float, i32 } @llvm.frexp.f32.i32(float "
+      "%arg.f32)\n"
+      "  %A = extractvalue { float, i32 } %frexp.f32.i32, 0\n"
+      "  %frexp.f64.i32 = call { double, i32 } @llvm.frexp.f64.i32(double "
+      "%arg.f64)\n"
+      "  %A2 = extractvalue { double, i32 } %frexp.f64.i32, 0\n"
+      "  %frexp.v2f32.v2i32 = call { <2 x float>, <2 x i32> } "
+      "@llvm.frexp.v2f32.v2i32(<2 x float> %arg.v2f32)\n"
+      "  %A3 = extractvalue { <2 x float>, <2 x i32> } %frexp.v2f32.v2i32, 0\n"
+      "  %frexp.v2f64.v2i32 = call { <2 x double>, <2 x i32> } "
+      "@llvm.frexp.v2f64.v2i32(<2 x double> %arg.v2f64)\n"
+      "  %A4 = extractvalue { <2 x double>, <2 x i32> } %frexp.v2f64.v2i32, 0\n"
+      "  ret float %A\n"
+      "}\n");
+
+  EXPECT_EQ(KnownExponentRange(-1, 1),
+            computeKnownExponentRange(A, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-1, 1),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-1, 1),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(-1, 1),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+}
+
+TEST_F(ComputeKnownExponentRangeTest, ExtractValue) {
+  parseAssembly("define float @test({float, float} %arg0, [2 x float] %arg1, "
+                "i1 %cond) {\n"
+                "  %A = extractvalue { float, float } %arg0, 1\n"
+                "  %A2 = extractvalue [2 x float ] %arg1, 1\n"
+                "  %A3 = extractvalue { <2 x float>, i32 } zeroinitializer, 0\n"
+                "  %A4 = extractvalue [4 x float] zeroinitializer, 0\n"
+                "  ret float %A\n"
+                "}\n");
+
+  // TODO: Better handle arbitrary extracts.
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A2, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A3, M->getDataLayout()));
+  EXPECT_EQ(KnownExponentRange(),
+            computeKnownExponentRange(A4, M->getDataLayout()));
+}
+
 TEST_F(ValueTrackingTest, isNonZeroRecurrence) {
   parseAssembly(R"(
     define i1 @test(i8 %n, i8 %r) {
     entry:
       br label %loop
     loop:
       %p = phi i8 [ -1, %entry ], [ %next, %loop ]
       %next = add nsw i8 %p, -1