//===- llvm/unittest/Support/KnownBitsTest.cpp - KnownBits tests ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements unit tests for KnownBits functions.
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/ArrayRef.h"
#include "llvm/Support/KnownBits.h"
#include "KnownBitsTest.h"
#include "gtest/gtest.h"

using namespace llvm;

using UnaryBitsFn = llvm::function_ref<KnownBits(const KnownBits &)>;
using UnaryIntFn = llvm::function_ref<std::optional<APInt>(const APInt &)>;
using UnaryCheckFn = llvm::function_ref<bool(const KnownBits &)>;

using BinaryBitsFn =
    llvm::function_ref<KnownBits(const KnownBits &, const KnownBits &)>;
using BinaryIntFn =
    llvm::function_ref<std::optional<APInt>(const APInt &, const APInt &)>;
using BinaryCheckFn =
    llvm::function_ref<bool(const KnownBits &, const KnownBits &)>;

static bool checkOptimalityUnary(const KnownBits &) { return true; }
static bool checkCorrectnessOnlyUnary(const KnownBits &) { return false; }
static bool checkOptimalityBinary(const KnownBits &, const KnownBits &) {
  return true;
}
static bool checkCorrectnessOnlyBinary(const KnownBits &, const KnownBits &) {
  return false;
}

static testing::AssertionResult isCorrect(const KnownBits &Exact,
                                          const KnownBits &Computed,
                                          ArrayRef<KnownBits> Inputs) {
  if (Computed.Zero.isSubsetOf(Exact.Zero) &&
      Computed.One.isSubsetOf(Exact.One))
    return testing::AssertionSuccess();

  testing::AssertionResult Result = testing::AssertionFailure();
  Result << "Inputs = ";
  for (const KnownBits &Input : Inputs)
    Result << Input << ", ";
  Result << "Computed = " << Computed << ", Exact = " << Exact;
  return Result;
}

static testing::AssertionResult isOptimal(const KnownBits &Exact,
                                          const KnownBits &Computed,
                                          ArrayRef<KnownBits> Inputs) {
  if (Computed == Exact)
    return testing::AssertionSuccess();

  testing::AssertionResult Result = testing::AssertionFailure();
  Result << "Inputs = ";
  for (const KnownBits &Input : Inputs)
    Result << Input << ", ";
  Result << "Computed = " << Computed << ", Exact = " << Exact;
  return Result;
}

static void
testUnaryOpExhaustive(UnaryBitsFn BitsFn, UnaryIntFn IntFn,
                      UnaryCheckFn CheckOptimalityFn = checkOptimalityUnary) {
  for (unsigned Bits : {1, 4}) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known) {
      KnownBits Computed = BitsFn(Known);
      KnownBits Exact(Bits);
      Exact.Zero.setAllBits();
      Exact.One.setAllBits();

      ForeachNumInKnownBits(Known, [&](const APInt &N) {
        if (std::optional<APInt> Res = IntFn(N)) {
          Exact.One &= *Res;
          Exact.Zero &= ~*Res;
        }
      });

      EXPECT_TRUE(!Computed.hasConflict());
      EXPECT_TRUE(isCorrect(Exact, Computed, Known));
      // We generally don't want to return conflicting known bits, even if it is
      // legal for always poison results.
      if (CheckOptimalityFn(Known) && !Exact.hasConflict()) {
        EXPECT_TRUE(isOptimal(Exact, Computed, Known));
      }
    });
  }
}

static void
testBinaryOpExhaustive(BinaryBitsFn BitsFn, BinaryIntFn IntFn,
                       BinaryCheckFn CheckOptimalityFn = checkOptimalityBinary,
                       bool RefinePoisonToZero = false) {
  for (unsigned Bits : {1, 4}) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
      ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
        KnownBits Computed = BitsFn(Known1, Known2);
        KnownBits Exact(Bits);
        Exact.Zero.setAllBits();
        Exact.One.setAllBits();

        ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
          ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
            if (std::optional<APInt> Res = IntFn(N1, N2)) {
              Exact.One &= *Res;
              Exact.Zero &= ~*Res;
            }
          });
        });

        EXPECT_TRUE(!Computed.hasConflict());
        EXPECT_TRUE(isCorrect(Exact, Computed, {Known1, Known2}));
        // We generally don't want to return conflicting known bits, even if it
        // is legal for always poison results.
        if (CheckOptimalityFn(Known1, Known2) && !Exact.hasConflict()) {
          EXPECT_TRUE(isOptimal(Exact, Computed, {Known1, Known2}));
        }
        // In some cases we choose to return zero if the result is always
        // poison.
        if (RefinePoisonToZero && Exact.hasConflict()) {
          EXPECT_TRUE(Computed.isZero());
        }
      });
    });
  }
}

namespace {

TEST(KnownBitsTest, AddCarryExhaustive) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
      ForeachKnownBits(1, [&](const KnownBits &KnownCarry) {
        // Explicitly compute known bits of the addition by trying all
        // possibilities.
        KnownBits Known(Bits);
        Known.Zero.setAllBits();
        Known.One.setAllBits();
        ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
          ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
            ForeachNumInKnownBits(KnownCarry, [&](const APInt &Carry) {
              APInt Add = N1 + N2;
              if (Carry.getBoolValue())
                ++Add;

              Known.One &= Add;
              Known.Zero &= ~Add;
            });
          });
        });

        KnownBits KnownComputed =
            KnownBits::computeForAddCarry(Known1, Known2, KnownCarry);
        EXPECT_EQ(Known, KnownComputed);
      });
    });
  });
}

static void TestAddSubExhaustive(bool IsAdd) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
      KnownBits Known(Bits), KnownNSW(Bits);
      Known.Zero.setAllBits();
      Known.One.setAllBits();
      KnownNSW.Zero.setAllBits();
      KnownNSW.One.setAllBits();

      ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
        ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
          bool Overflow;
          APInt Res;
          if (IsAdd)
            Res = N1.sadd_ov(N2, Overflow);
          else
            Res = N1.ssub_ov(N2, Overflow);

          Known.One &= Res;
          Known.Zero &= ~Res;

          if (!Overflow) {
            KnownNSW.One &= Res;
            KnownNSW.Zero &= ~Res;
          }
        });
      });

      KnownBits KnownComputed =
          KnownBits::computeForAddSub(IsAdd, /*NSW*/ false, Known1, Known2);
      EXPECT_EQ(Known, KnownComputed);

      // The NSW calculation is not precise, only check that it's
      // conservatively correct.
      KnownBits KnownNSWComputed = KnownBits::computeForAddSub(
          IsAdd, /*NSW*/true, Known1, Known2);
      EXPECT_TRUE(KnownNSWComputed.Zero.isSubsetOf(KnownNSW.Zero));
      EXPECT_TRUE(KnownNSWComputed.One.isSubsetOf(KnownNSW.One));
    });
  });
}

TEST(KnownBitsTest, AddSubExhaustive) {
  TestAddSubExhaustive(true);
  TestAddSubExhaustive(false);
}

TEST(KnownBitsTest, BinaryExhaustive) {
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return Known1 & Known2;
      },
      [](const APInt &N1, const APInt &N2) { return N1 & N2; });
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return Known1 | Known2;
      },
      [](const APInt &N1, const APInt &N2) { return N1 | N2; });
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return Known1 ^ Known2;
      },
      [](const APInt &N1, const APInt &N2) { return N1 ^ N2; });

  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::umax(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) { return APIntOps::umax(N1, N2); });
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::umin(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) { return APIntOps::umin(N1, N2); });
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::smax(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) { return APIntOps::smax(N1, N2); });
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::smin(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) { return APIntOps::smin(N1, N2); });

  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::udiv(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero())
          return std::nullopt;
        return N1.udiv(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::udiv(Known1, Known2, /*Exact*/ true);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero() || !N1.urem(N2).isZero())
          return std::nullopt;
        return N1.udiv(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::sdiv(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero() || (N1.isMinSignedValue() && N2.isAllOnes()))
          return std::nullopt;
        return N1.sdiv(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::sdiv(Known1, Known2, /*Exact*/ true);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero() || (N1.isMinSignedValue() && N2.isAllOnes()) ||
            !N1.srem(N2).isZero())
          return std::nullopt;
        return N1.sdiv(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::urem(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero())
          return std::nullopt;
        return N1.urem(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::srem(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.isZero())
          return std::nullopt;
        return N1.srem(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::sadd_sat(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        return N1.sadd_sat(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::uadd_sat(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        return N1.uadd_sat(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::ssub_sat(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        return N1.ssub_sat(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::usub_sat(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        return N1.usub_sat(N2);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::shl(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.uge(N2.getBitWidth()))
          return std::nullopt;
        return N1.shl(N2);
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::shl(Known1, Known2, /* NUW */ true);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        bool Overflow;
        APInt Res = N1.ushl_ov(N2, Overflow);
        if (Overflow)
          return std::nullopt;
        return Res;
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::shl(Known1, Known2, /* NUW */ false, /* NSW */ true);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        bool Overflow;
        APInt Res = N1.sshl_ov(N2, Overflow);
        if (Overflow)
          return std::nullopt;
        return Res;
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::shl(Known1, Known2, /* NUW */ true, /* NSW */ true);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        bool OverflowUnsigned, OverflowSigned;
        APInt Res = N1.ushl_ov(N2, OverflowUnsigned);
        (void)N1.sshl_ov(N2, OverflowSigned);
        if (OverflowUnsigned || OverflowSigned)
          return std::nullopt;
        return Res;
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);

  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::lshr(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.uge(N2.getBitWidth()))
          return std::nullopt;
        return N1.lshr(N2);
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::ashr(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) -> std::optional<APInt> {
        if (N2.uge(N2.getBitWidth()))
          return std::nullopt;
        return N1.ashr(N2);
      },
      checkOptimalityBinary, /* RefinePoisonToZero */ true);

  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::mul(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) { return N1 * N2; },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::mulhs(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) {
        unsigned Bits = N1.getBitWidth();
        return (N1.sext(2 * Bits) * N2.sext(2 * Bits)).extractBits(Bits, Bits);
      },
      checkCorrectnessOnlyBinary);
  testBinaryOpExhaustive(
      [](const KnownBits &Known1, const KnownBits &Known2) {
        return KnownBits::mulhu(Known1, Known2);
      },
      [](const APInt &N1, const APInt &N2) {
        unsigned Bits = N1.getBitWidth();
        return (N1.zext(2 * Bits) * N2.zext(2 * Bits)).extractBits(Bits, Bits);
      },
      checkCorrectnessOnlyBinary);
}

TEST(KnownBitsTest, UnaryExhaustive) {
  testUnaryOpExhaustive([](const KnownBits &Known) { return Known.abs(); },
                        [](const APInt &N) { return N.abs(); });

  testUnaryOpExhaustive([](const KnownBits &Known) { return Known.abs(true); },
                        [](const APInt &N) -> std::optional<APInt> {
                          if (N.isMinSignedValue())
                            return std::nullopt;
                          return N.abs();
                        });

  testUnaryOpExhaustive([](const KnownBits &Known) { return Known.blsi(); },
                        [](const APInt &N) { return N & -N; });
  testUnaryOpExhaustive([](const KnownBits &Known) { return Known.blsmsk(); },
                        [](const APInt &N) { return N ^ (N - 1); });

  testUnaryOpExhaustive(
      [](const KnownBits &Known) {
        return KnownBits::mul(Known, Known, /*SelfMultiply*/ true);
      },
      [](const APInt &N) { return N * N; }, checkCorrectnessOnlyUnary);
}

TEST(KnownBitsTest, WideShifts) {
  unsigned BitWidth = 128;
  KnownBits Unknown(BitWidth);
  KnownBits AllOnes = KnownBits::makeConstant(APInt::getAllOnes(BitWidth));

  KnownBits ShlResult(BitWidth);
  ShlResult.makeNegative();
  EXPECT_EQ(KnownBits::shl(AllOnes, Unknown), ShlResult);
  KnownBits LShrResult(BitWidth);
  LShrResult.One.setBit(0);
  EXPECT_EQ(KnownBits::lshr(AllOnes, Unknown), LShrResult);
  EXPECT_EQ(KnownBits::ashr(AllOnes, Unknown), AllOnes);
}

TEST(KnownBitsTest, ICmpExhaustive) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
      bool AllEQ = true, NoneEQ = true;
      bool AllNE = true, NoneNE = true;
      bool AllUGT = true, NoneUGT = true;
      bool AllUGE = true, NoneUGE = true;
      bool AllULT = true, NoneULT = true;
      bool AllULE = true, NoneULE = true;
      bool AllSGT = true, NoneSGT = true;
      bool AllSGE = true, NoneSGE = true;
      bool AllSLT = true, NoneSLT = true;
      bool AllSLE = true, NoneSLE = true;

      ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
        ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
          AllEQ &= N1.eq(N2);
          AllNE &= N1.ne(N2);
          AllUGT &= N1.ugt(N2);
          AllUGE &= N1.uge(N2);
          AllULT &= N1.ult(N2);
          AllULE &= N1.ule(N2);
          AllSGT &= N1.sgt(N2);
          AllSGE &= N1.sge(N2);
          AllSLT &= N1.slt(N2);
          AllSLE &= N1.sle(N2);
          NoneEQ &= !N1.eq(N2);
          NoneNE &= !N1.ne(N2);
          NoneUGT &= !N1.ugt(N2);
          NoneUGE &= !N1.uge(N2);
          NoneULT &= !N1.ult(N2);
          NoneULE &= !N1.ule(N2);
          NoneSGT &= !N1.sgt(N2);
          NoneSGE &= !N1.sge(N2);
          NoneSLT &= !N1.slt(N2);
          NoneSLE &= !N1.sle(N2);
        });
      });

      std::optional<bool> KnownEQ = KnownBits::eq(Known1, Known2);
      std::optional<bool> KnownNE = KnownBits::ne(Known1, Known2);
      std::optional<bool> KnownUGT = KnownBits::ugt(Known1, Known2);
      std::optional<bool> KnownUGE = KnownBits::uge(Known1, Known2);
      std::optional<bool> KnownULT = KnownBits::ult(Known1, Known2);
      std::optional<bool> KnownULE = KnownBits::ule(Known1, Known2);
      std::optional<bool> KnownSGT = KnownBits::sgt(Known1, Known2);
      std::optional<bool> KnownSGE = KnownBits::sge(Known1, Known2);
      std::optional<bool> KnownSLT = KnownBits::slt(Known1, Known2);
      std::optional<bool> KnownSLE = KnownBits::sle(Known1, Known2);

      EXPECT_EQ(AllEQ || NoneEQ, KnownEQ.has_value());
      EXPECT_EQ(AllNE || NoneNE, KnownNE.has_value());
      EXPECT_EQ(AllUGT || NoneUGT, KnownUGT.has_value());
      EXPECT_EQ(AllUGE || NoneUGE, KnownUGE.has_value());
      EXPECT_EQ(AllULT || NoneULT, KnownULT.has_value());
      EXPECT_EQ(AllULE || NoneULE, KnownULE.has_value());
      EXPECT_EQ(AllSGT || NoneSGT, KnownSGT.has_value());
      EXPECT_EQ(AllSGE || NoneSGE, KnownSGE.has_value());
      EXPECT_EQ(AllSLT || NoneSLT, KnownSLT.has_value());
      EXPECT_EQ(AllSLE || NoneSLE, KnownSLE.has_value());

      EXPECT_EQ(AllEQ, KnownEQ.has_value() && *KnownEQ);
      EXPECT_EQ(AllNE, KnownNE.has_value() && *KnownNE);
      EXPECT_EQ(AllUGT, KnownUGT.has_value() && *KnownUGT);
      EXPECT_EQ(AllUGE, KnownUGE.has_value() && *KnownUGE);
      EXPECT_EQ(AllULT, KnownULT.has_value() && *KnownULT);
      EXPECT_EQ(AllULE, KnownULE.has_value() && *KnownULE);
      EXPECT_EQ(AllSGT, KnownSGT.has_value() && *KnownSGT);
      EXPECT_EQ(AllSGE, KnownSGE.has_value() && *KnownSGE);
      EXPECT_EQ(AllSLT, KnownSLT.has_value() && *KnownSLT);
      EXPECT_EQ(AllSLE, KnownSLE.has_value() && *KnownSLE);

      EXPECT_EQ(NoneEQ, KnownEQ.has_value() && !*KnownEQ);
      EXPECT_EQ(NoneNE, KnownNE.has_value() && !*KnownNE);
      EXPECT_EQ(NoneUGT, KnownUGT.has_value() && !*KnownUGT);
      EXPECT_EQ(NoneUGE, KnownUGE.has_value() && !*KnownUGE);
      EXPECT_EQ(NoneULT, KnownULT.has_value() && !*KnownULT);
      EXPECT_EQ(NoneULE, KnownULE.has_value() && !*KnownULE);
      EXPECT_EQ(NoneSGT, KnownSGT.has_value() && !*KnownSGT);
      EXPECT_EQ(NoneSGE, KnownSGE.has_value() && !*KnownSGE);
      EXPECT_EQ(NoneSLT, KnownSLT.has_value() && !*KnownSLT);
      EXPECT_EQ(NoneSLE, KnownSLE.has_value() && !*KnownSLE);
    });
  });
}

TEST(KnownBitsTest, GetMinMaxVal) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known) {
    APInt Min = APInt::getMaxValue(Bits);
    APInt Max = APInt::getMinValue(Bits);
    ForeachNumInKnownBits(Known, [&](const APInt &N) {
      Min = APIntOps::umin(Min, N);
      Max = APIntOps::umax(Max, N);
    });
    EXPECT_EQ(Min, Known.getMinValue());
    EXPECT_EQ(Max, Known.getMaxValue());
  });
}

TEST(KnownBitsTest, GetSignedMinMaxVal) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known) {
    APInt Min = APInt::getSignedMaxValue(Bits);
    APInt Max = APInt::getSignedMinValue(Bits);
    ForeachNumInKnownBits(Known, [&](const APInt &N) {
      Min = APIntOps::smin(Min, N);
      Max = APIntOps::smax(Max, N);
    });
    EXPECT_EQ(Min, Known.getSignedMinValue());
    EXPECT_EQ(Max, Known.getSignedMaxValue());
  });
}

TEST(KnownBitsTest, CountMaxActiveBits) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known) {
    unsigned Expected = 0;
    ForeachNumInKnownBits(Known, [&](const APInt &N) {
      Expected = std::max(Expected, N.getActiveBits());
    });
    EXPECT_EQ(Expected, Known.countMaxActiveBits());
  });
}

TEST(KnownBitsTest, CountMaxSignificantBits) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known) {
    unsigned Expected = 0;
    ForeachNumInKnownBits(Known, [&](const APInt &N) {
      Expected = std::max(Expected, N.getSignificantBits());
    });
    EXPECT_EQ(Expected, Known.countMaxSignificantBits());
  });
}

TEST(KnownBitsTest, SExtOrTrunc) {
  const unsigned NarrowerSize = 4;
  const unsigned BaseSize = 6;
  const unsigned WiderSize = 8;
  APInt NegativeFitsNarrower(BaseSize, -4, /*isSigned*/ true);
  APInt NegativeDoesntFitNarrower(BaseSize, -28, /*isSigned*/ true);
  APInt PositiveFitsNarrower(BaseSize, 14);
  APInt PositiveDoesntFitNarrower(BaseSize, 36);
  auto InitKnownBits = [&](KnownBits &Res, const APInt &Input) {
    Res = KnownBits(Input.getBitWidth());
    Res.One = Input;
    Res.Zero = ~Input;
  };

  for (unsigned Size : {NarrowerSize, BaseSize, WiderSize}) {
    for (const APInt &Input :
         {NegativeFitsNarrower, NegativeDoesntFitNarrower, PositiveFitsNarrower,
          PositiveDoesntFitNarrower}) {
      KnownBits Test;
      InitKnownBits(Test, Input);
      KnownBits Baseline;
      InitKnownBits(Baseline, Input.sextOrTrunc(Size));
      Test = Test.sextOrTrunc(Size);
      EXPECT_EQ(Test, Baseline);
    }
  }
}

TEST(KnownBitsTest, SExtInReg) {
  unsigned Bits = 4;
  for (unsigned FromBits = 1; FromBits <= Bits; ++FromBits) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known) {
      APInt CommonOne = APInt::getAllOnes(Bits);
      APInt CommonZero = APInt::getAllOnes(Bits);
      unsigned ExtBits = Bits - FromBits;
      ForeachNumInKnownBits(Known, [&](const APInt &N) {
        APInt Ext = N << ExtBits;
        Ext.ashrInPlace(ExtBits);
        CommonOne &= Ext;
        CommonZero &= ~Ext;
      });
      KnownBits KnownSExtInReg = Known.sextInReg(FromBits);
      EXPECT_EQ(CommonOne, KnownSExtInReg.One);
      EXPECT_EQ(CommonZero, KnownSExtInReg.Zero);
    });
  }
}

TEST(KnownBitsTest, CommonBitsSet) {
  unsigned Bits = 4;
  ForeachKnownBits(Bits, [&](const KnownBits &Known1) {
    ForeachKnownBits(Bits, [&](const KnownBits &Known2) {
      bool HasCommonBitsSet = false;
      ForeachNumInKnownBits(Known1, [&](const APInt &N1) {
        ForeachNumInKnownBits(Known2, [&](const APInt &N2) {
          HasCommonBitsSet |= N1.intersects(N2);
        });
      });
      EXPECT_EQ(!HasCommonBitsSet,
                KnownBits::haveNoCommonBitsSet(Known1, Known2));
    });
  });
}

TEST(KnownBitsTest, ConcatBits) {
  unsigned Bits = 4;
  for (unsigned LoBits = 1; LoBits < Bits; ++LoBits) {
    unsigned HiBits = Bits - LoBits;
    ForeachKnownBits(LoBits, [&](const KnownBits &KnownLo) {
      ForeachKnownBits(HiBits, [&](const KnownBits &KnownHi) {
        KnownBits KnownAll = KnownHi.concat(KnownLo);

        EXPECT_EQ(KnownLo.countMinPopulation() + KnownHi.countMinPopulation(),
                  KnownAll.countMinPopulation());
        EXPECT_EQ(KnownLo.countMaxPopulation() + KnownHi.countMaxPopulation(),
                  KnownAll.countMaxPopulation());

        KnownBits ExtractLo = KnownAll.extractBits(LoBits, 0);
        KnownBits ExtractHi = KnownAll.extractBits(HiBits, LoBits);

        EXPECT_EQ(KnownLo.One.getZExtValue(), ExtractLo.One.getZExtValue());
        EXPECT_EQ(KnownHi.One.getZExtValue(), ExtractHi.One.getZExtValue());
        EXPECT_EQ(KnownLo.Zero.getZExtValue(), ExtractLo.Zero.getZExtValue());
        EXPECT_EQ(KnownHi.Zero.getZExtValue(), ExtractHi.Zero.getZExtValue());
      });
    });
  }
}

} // end anonymous namespace