C++ ConstantRange::getLower方法代码示例

ConstantRange
ConstantRange::udiv(const ConstantRange &RHS) const {
  if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax() == 0)
    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
  if (RHS.isFullSet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());

  APInt RHS_umin = RHS.getUnsignedMin();
  if (RHS_umin == 0) {
    // We want the lowest value in RHS excluding zero. Usually that would be 1
    // except for a range in the form of [X, 1) in which case it would be X.
    if (RHS.getUpper() == 1)
      RHS_umin = RHS.getLower();
    else
      RHS_umin = APInt(getBitWidth(), 1);
  }

  APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;

  // If the LHS is Full and the RHS is a wrapped interval containing 1 then
  // this could occur.
  if (Lower == Upper)
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  return ConstantRange(Lower, Upper);
}

/// contains - Return true if the argument is a subset of this range.
/// Two equal sets contain each other. The empty set contained by all other
/// sets.
///
bool ConstantRange::contains(const ConstantRange &Other) const {
  if (isFullSet() || Other.isEmptySet()) return true;
  if (isEmptySet() || Other.isFullSet()) return false;

  if (!isWrappedSet()) {
    if (Other.isWrappedSet())
      return false;

    return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
  }

  if (!Other.isWrappedSet())
    return Other.getUpper().ule(Upper) ||
           Lower.ule(Other.getLower());

  return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
}

ConstantRange
ConstantRange::multiply(const ConstantRange &Other) const {
  // TODO: If either operand is a single element and the multiply is known to
  // be non-wrapping, round the result min and max value to the appropriate
  // multiple of that element. If wrapping is possible, at least adjust the
  // range according to the greatest power-of-two factor of the single element.

  if (isEmptySet() || Other.isEmptySet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/false);

  // Multiplication is signedness-independent. However different ranges can be
  // obtained depending on how the input ranges are treated. These different
  // ranges are all conservatively correct, but one might be better than the
  // other. We calculate two ranges; one treating the inputs as unsigned
  // and the other signed, then return the smallest of these ranges.

  // Unsigned range first.
  APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
  APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
  APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
  APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);

  ConstantRange Result_zext = ConstantRange(this_min * Other_min,
                                            this_max * Other_max + 1);
  ConstantRange UR = Result_zext.truncate(getBitWidth());

  // If the unsigned range doesn't wrap, and isn't negative then it's a range
  // from one positive number to another which is as good as we can generate.
  // In this case, skip the extra work of generating signed ranges which aren't
  // going to be better than this range.
  if (!UR.isWrappedSet() && UR.getLower().isNonNegative())
    return UR;

  // Now the signed range. Because we could be dealing with negative numbers
  // here, the lower bound is the smallest of the cartesian product of the
  // lower and upper ranges; for example:
  //   [-1,4) * [-2,3) = min(-1*-2, -1*2, 3*-2, 3*2) = -6.
  // Similarly for the upper bound, swapping min for max.

  this_min = getSignedMin().sext(getBitWidth() * 2);
  this_max = getSignedMax().sext(getBitWidth() * 2);
  Other_min = Other.getSignedMin().sext(getBitWidth() * 2);
  Other_max = Other.getSignedMax().sext(getBitWidth() * 2);
  
  auto L = {this_min * Other_min, this_min * Other_max,
            this_max * Other_min, this_max * Other_max};
  auto Compare = [](const APInt &A, const APInt &B) { return A.slt(B); };
  ConstantRange Result_sext(std::min(L, Compare), std::max(L, Compare) + 1);
  ConstantRange SR = Result_sext.truncate(getBitWidth());

  return UR.getSetSize().ult(SR.getSetSize()) ? UR : SR;
}

MyConstantRange binaryAnd(const ConstantRange &Other) const {
  if (isEmptySet() || Other.isEmptySet())
    return MyConstantRange(getBitWidth(), /*isFullSet=*/false);

  if (!isWrappedSet() && !Other.isWrappedSet() && !isFullSet() && !Other.isFullSet()) {
    unsigned width1 = ((getUpper() - 1) ^ getLower()).logBase2() + 1;
    unsigned width2 = ((Other.getUpper() - 1) ^ Other.getLower()).logBase2() + 1;
    APInt res1 = getLower().lshr(width1) << width1;
    APInt res2 = Other.getLower().lshr(width2) << width2;
    APInt res_high1 = getLower();
    APInt res_high2 = Other.getLower();
    res_high1.setLowBits(width1);
    res_high2.setLowBits(width2);
    if ((res1 & res2).isNullValue() && (res_high1 & res_high2).isAllOnesValue()) {
        return MyConstantRange(getBitWidth(), /*isFullSet=*/true);
    }
    return MyConstantRange(res1 & res2, (res_high1 & res_high2) + 1);
  }

  APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
  if (umin.isAllOnesValue())
    return MyConstantRange(getBitWidth(), /*isFullSet=*/true);
  return MyConstantRange(APInt::getNullValue(getBitWidth()), std::move(umin) + 1);
}

static bool tryMergeRange(SmallVectorImpl<Value *> &EndPoints, ConstantInt *Low,
                          ConstantInt *High) {
  ConstantRange NewRange(Low->getValue(), High->getValue());
  unsigned Size = EndPoints.size();
  APInt LB = cast<ConstantInt>(EndPoints[Size - 2])->getValue();
  APInt LE = cast<ConstantInt>(EndPoints[Size - 1])->getValue();
  ConstantRange LastRange(LB, LE);
  if (canBeMerged(NewRange, LastRange)) {
    ConstantRange Union = LastRange.unionWith(NewRange);
    Type *Ty = High->getType();
    EndPoints[Size - 2] = ConstantInt::get(Ty, Union.getLower());
    EndPoints[Size - 1] = ConstantInt::get(Ty, Union.getUpper());
    return true;
  }
  return false;
}

ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
                                            const ConstantRange &CR) {
  uint32_t W = CR.getBitWidth();
  switch (Pred) {
    default: assert(!"Invalid ICmp predicate to makeICmpRegion()");
    case ICmpInst::ICMP_EQ:
      return CR;
    case ICmpInst::ICMP_NE:
      if (CR.isSingleElement())
        return ConstantRange(CR.getUpper(), CR.getLower());
      return ConstantRange(W);
    case ICmpInst::ICMP_ULT:
      return ConstantRange(APInt::getMinValue(W), CR.getUnsignedMax());
    case ICmpInst::ICMP_SLT:
      return ConstantRange(APInt::getSignedMinValue(W), CR.getSignedMax());
    case ICmpInst::ICMP_ULE: {
      APInt UMax(CR.getUnsignedMax());
      if (UMax.isMaxValue())
        return ConstantRange(W);
      return ConstantRange(APInt::getMinValue(W), UMax + 1);
    }
    case ICmpInst::ICMP_SLE: {
      APInt SMax(CR.getSignedMax());
      if (SMax.isMaxSignedValue() || (SMax+1).isMaxSignedValue())
        return ConstantRange(W);
      return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
    }
    case ICmpInst::ICMP_UGT:
      return ConstantRange(CR.getUnsignedMin() + 1, APInt::getNullValue(W));
    case ICmpInst::ICMP_SGT:
      return ConstantRange(CR.getSignedMin() + 1,
                           APInt::getSignedMinValue(W));
    case ICmpInst::ICMP_UGE: {
      APInt UMin(CR.getUnsignedMin());
      if (UMin.isMinValue())
        return ConstantRange(W);
      return ConstantRange(UMin, APInt::getNullValue(W));
    }
    case ICmpInst::ICMP_SGE: {
      APInt SMin(CR.getSignedMin());
      if (SMin.isMinSignedValue())
        return ConstantRange(W);
      return ConstantRange(SMin, APInt::getSignedMinValue(W));
    }
  }
}

ConstantRange
ConstantRange::sub(const ConstantRange &Other) const {
  if (isEmptySet() || Other.isEmptySet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
  if (isFullSet() || Other.isFullSet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  APInt NewLower = getLower() - Other.getUpper() + 1;
  APInt NewUpper = getUpper() - Other.getLower();
  if (NewLower == NewUpper)
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  ConstantRange X = ConstantRange(std::move(NewLower), std::move(NewUpper));
  if (X.isSizeStrictlySmallerThan(*this) ||
      X.isSizeStrictlySmallerThan(Other))
    // We've wrapped, therefore, full set.
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
  return X;
}

ConstantRange
ConstantRange::sub(const ConstantRange &Other) const {
  if (isEmptySet() || Other.isEmptySet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
  if (isFullSet() || Other.isFullSet())
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
  APInt NewLower = getLower() - Other.getUpper() + 1;
  APInt NewUpper = getUpper() - Other.getLower();
  if (NewLower == NewUpper)
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  ConstantRange X = ConstantRange(NewLower, NewUpper);
  if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
    // We've wrapped, therefore, full set.
    return ConstantRange(getBitWidth(), /*isFullSet=*/true);

  return X;
}

ConstantRange ConstantRange::makeAllowedICmpRegion(CmpInst::Predicate Pred,
                                                   const ConstantRange &CR) {
  if (CR.isEmptySet())
    return CR;

  uint32_t W = CR.getBitWidth();
  switch (Pred) {
  default:
    llvm_unreachable("Invalid ICmp predicate to makeAllowedICmpRegion()");
    case CmpInst::ICMP_EQ:
      return CR;
    case CmpInst::ICMP_NE:
      if (CR.isSingleElement())
        return ConstantRange(CR.getUpper(), CR.getLower());
      return ConstantRange(W);
    case CmpInst::ICMP_ULT: {
      APInt UMax(CR.getUnsignedMax());
      if (UMax.isMinValue())
        return ConstantRange(W, /* empty */ false);
      return ConstantRange(APInt::getMinValue(W), UMax);
    }
    case CmpInst::ICMP_SLT: {
      APInt SMax(CR.getSignedMax());
      if (SMax.isMinSignedValue())
        return ConstantRange(W, /* empty */ false);
      return ConstantRange(APInt::getSignedMinValue(W), SMax);
    }
    case CmpInst::ICMP_ULE: {
      APInt UMax(CR.getUnsignedMax());
      if (UMax.isMaxValue())
        return ConstantRange(W);
      return ConstantRange(APInt::getMinValue(W), UMax + 1);
    }
    case CmpInst::ICMP_SLE: {
      APInt SMax(CR.getSignedMax());
      if (SMax.isMaxSignedValue())
        return ConstantRange(W);
      return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
    }
    case CmpInst::ICMP_UGT: {
      APInt UMin(CR.getUnsignedMin());
      if (UMin.isMaxValue())
        return ConstantRange(W, /* empty */ false);
      return ConstantRange(UMin + 1, APInt::getNullValue(W));
    }
    case CmpInst::ICMP_SGT: {
      APInt SMin(CR.getSignedMin());
      if (SMin.isMaxSignedValue())
        return ConstantRange(W, /* empty */ false);
      return ConstantRange(SMin + 1, APInt::getSignedMinValue(W));
    }
    case CmpInst::ICMP_UGE: {
      APInt UMin(CR.getUnsignedMin());
      if (UMin.isMinValue())
        return ConstantRange(W);
      return ConstantRange(UMin, APInt::getNullValue(W));
    }
    case CmpInst::ICMP_SGE: {
      APInt SMin(CR.getSignedMin());
      if (SMin.isMinSignedValue())
        return ConstantRange(W);
      return ConstantRange(SMin, APInt::getSignedMinValue(W));
    }
  }
}

static bool isContiguous(const ConstantRange &A, const ConstantRange &B) {
  return A.getUpper() == B.getLower() || A.getLower() == B.getUpper();
}