C++ APInt::ugt方法代码示例

int FunctionComparator::cmpAPInts(const APInt &L, const APInt &R) const {
  if (int Res = cmpNumbers(L.getBitWidth(), R.getBitWidth()))
    return Res;
  if (L.ugt(R)) return 1;
  if (R.ugt(L)) return -1;
  return 0;
}

/// Extract all of the characters from the number \p Num one by one and
/// insert them into the string builder \p SB.
static void DecodeFixedWidth(APInt &Num, std::string &SB) {
  uint64_t CL = Huffman::CharsetLength;

  // NL is the number of characters that we can hold in a 64bit number.
  // Each letter takes Log2(CL) bits. Doing this computation in floating-
  // point arithmetic could give a slightly better (more optimistic) result,
  // but the computation may not be constant at compile time.
  uint64_t NumLetters = 64 / Log2_64_Ceil(CL);

  assert(Num.getBitWidth() > 8 &&
         "Not enough bits for arithmetic on this alphabet");

  // Try to decode eight numbers at once. It is much faster to work with
  // local 64bit numbers than working with APInt. In this loop we try to
  // extract NL characters at once and process them using a local 64-bit
  // number.

  // Calculate CharsetLength**NumLetters (CL to the power of NL), which is the
  // highest numeric value that can hold NumLetters characters in a 64bit
  // number. Notice: this loop is optimized away and CLX is computed to a
  // constant integer at compile time.
  uint64_t CLX = 1;
  for (unsigned  i = 0; i < NumLetters; i++) { CLX *= CL; }

  while (Num.ugt(CLX)) {
    unsigned BW = Num.getBitWidth();
    APInt C = APInt(BW, CLX);
    APInt Quotient(1, 0), Remainder(1, 0);
    APInt::udivrem(Num, C, Quotient, Remainder);

    // Try to reduce the bitwidth of the API after the division. This can
    // accelerate the division operation in future iterations because the
    // number becomes smaller (fewer bits) with each iteration. However,
    // We can't reduce the number to something too small because we still
    // need to be able to perform the "mod charset_length" operation.
    Num = Quotient.zextOrTrunc(std::max(Quotient.getActiveBits(), 64u));
    uint64_t Tail = Remainder.getZExtValue();
    for (unsigned i = 0; i < NumLetters; i++) {
      SB += Huffman::Charset[Tail % CL];
      Tail = Tail / CL;
    }
  }

  // Pop characters out of the APInt one by one.
  while (Num.getBoolValue()) {
    unsigned BW = Num.getBitWidth();

    APInt C = APInt(BW, CL);
    APInt Quotient(1, 0), Remainder(1, 0);
    APInt::udivrem(Num, C, Quotient, Remainder);
    Num = Quotient;
    SB += Huffman::Charset[Remainder.getZExtValue()];
  }
}

/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
///   SPF2(SPF1(A, B), C)
Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
                                        SelectPatternFlavor SPF1,
                                        Value *A, Value *B,
                                        Instruction &Outer,
                                        SelectPatternFlavor SPF2, Value *C) {
  if (C == A || C == B) {
    // MAX(MAX(A, B), B) -> MAX(A, B)
    // MIN(MIN(a, b), a) -> MIN(a, b)
    if (SPF1 == SPF2)
      return ReplaceInstUsesWith(Outer, Inner);

    // MAX(MIN(a, b), a) -> a
    // MIN(MAX(a, b), a) -> a
    if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
        (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
        (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
        (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
      return ReplaceInstUsesWith(Outer, C);
  }

  if (SPF1 == SPF2) {
    if (ConstantInt *CB = dyn_cast<ConstantInt>(B)) {
      if (ConstantInt *CC = dyn_cast<ConstantInt>(C)) {
        APInt ACB = CB->getValue();
        APInt ACC = CC->getValue();

        // MIN(MIN(A, 23), 97) -> MIN(A, 23)
        // MAX(MAX(A, 97), 23) -> MAX(A, 97)
        if ((SPF1 == SPF_UMIN && ACB.ule(ACC)) ||
            (SPF1 == SPF_SMIN && ACB.sle(ACC)) ||
            (SPF1 == SPF_UMAX && ACB.uge(ACC)) ||
            (SPF1 == SPF_SMAX && ACB.sge(ACC)))
          return ReplaceInstUsesWith(Outer, Inner);

        // MIN(MIN(A, 97), 23) -> MIN(A, 23)
        // MAX(MAX(A, 23), 97) -> MAX(A, 97)
        if ((SPF1 == SPF_UMIN && ACB.ugt(ACC)) ||
            (SPF1 == SPF_SMIN && ACB.sgt(ACC)) ||
            (SPF1 == SPF_UMAX && ACB.ult(ACC)) ||
            (SPF1 == SPF_SMAX && ACB.slt(ACC))) {
          Outer.replaceUsesOfWith(Inner, A);
          return &Outer;
        }
      }
    }
  }
  return nullptr;
}

APInt swift::constantFoldComparison(APInt lhs, APInt rhs, BuiltinValueKind ID) {
  bool result;
  switch (ID) {
    default: llvm_unreachable("Invalid integer compare kind");
    case BuiltinValueKind::ICMP_EQ:  result = lhs == rhs; break;
    case BuiltinValueKind::ICMP_NE:  result = lhs != rhs; break;
    case BuiltinValueKind::ICMP_SLT: result = lhs.slt(rhs); break;
    case BuiltinValueKind::ICMP_SGT: result = lhs.sgt(rhs); break;
    case BuiltinValueKind::ICMP_SLE: result = lhs.sle(rhs); break;
    case BuiltinValueKind::ICMP_SGE: result = lhs.sge(rhs); break;
    case BuiltinValueKind::ICMP_ULT: result = lhs.ult(rhs); break;
    case BuiltinValueKind::ICMP_UGT: result = lhs.ugt(rhs); break;
    case BuiltinValueKind::ICMP_ULE: result = lhs.ule(rhs); break;
    case BuiltinValueKind::ICMP_UGE: result = lhs.uge(rhs); break;
  }
  return APInt(1, result);
}

std::string swift::Compress::DecodeStringFromNumber(const APInt &In,
                                                    EncodingKind Kind) {
  APInt num = In;
  std::string sb;

  if (Kind == EncodingKind::Variable) {
    // Keep decoding until we reach our sentinel value.
    // See the encoder implementation for more details.
    while (num.ugt(1)) {
      sb += Huffman::variable_decode(num);
    }
  } else {
    // Decode this number as a regular fixed-width sequence of characters.
    DecodeFixedWidth(num, sb);
 }

  return sb;
}

/// Extract all of the characters from the number \p Num one by one and
/// insert them into the string builder \p SB.
static void DecodeFixedWidth(APInt &Num, std::string &SB) {
  uint64_t CL = Huffman::CharsetLength;
  assert(Num.getBitWidth() > 8 &&
         "Not enough bits for arithmetic on this alphabet");

  // Try to decode eight numbers at once. It is much faster to work with
  // local 64bit numbers than working with APInt. In this loop we try to
  // extract 8 characters at one and process them using a local 64bit number.
  // In this code we assume a worse case scenario where our alphabet is a full
  // 8-bit ascii. It is possible to improve this code by packing one or two
  // more characters into the 64bit local variable.
  uint64_t CL8 = CL * CL * CL * CL * CL * CL * CL * CL;
  while (Num.ugt(CL8)) {
    unsigned BW = Num.getBitWidth();
    APInt C = APInt(BW, CL8);
    APInt Quotient(1, 0), Remainder(1, 0);
    APInt::udivrem(Num, C, Quotient, Remainder);

    // Try to reduce the bitwidth of the API after the division. This can
    // accelerate the division operation in future iterations because the
    // number becomes smaller (fewer bits) with each iteration. However,
    // We can't reduce the number to something too small because we still
    // need to be able to perform the "mod charset_length" operation.
    Num = Quotient.zextOrTrunc(std::max(Quotient.getActiveBits(), 64u));
    uint64_t Tail = Remainder.getZExtValue();
    for (int i=0; i < 8; i++) {
      SB += Huffman::Charset[Tail % CL];
      Tail = Tail / CL;
    }
  }

  // Pop characters out of the APInt one by one.
  while (Num.getBoolValue()) {
    unsigned BW = Num.getBitWidth();

    APInt C = APInt(BW, CL);
    APInt Quotient(1, 0), Remainder(1, 0);
    APInt::udivrem(Num, C, Quotient, Remainder);
    Num = Quotient;
    SB += Huffman::Charset[Remainder.getZExtValue()];
  }
}

/// MultiplyOverflows - True if the multiply can not be expressed in an int
/// this size.
static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
  uint32_t W = C1->getBitWidth();
  APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
  if (sign) {
    LHSExt = LHSExt.sext(W * 2);
    RHSExt = RHSExt.sext(W * 2);
  } else {
    LHSExt = LHSExt.zext(W * 2);
    RHSExt = RHSExt.zext(W * 2);
  }
  
  APInt MulExt = LHSExt * RHSExt;
  
  if (!sign)
    return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
  
  APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
  APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
  return MulExt.slt(Min) || MulExt.sgt(Max);
}

/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
///   SPF2(SPF1(A, B), C)
Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
                                        SelectPatternFlavor SPF1,
                                        Value *A, Value *B,
                                        Instruction &Outer,
                                        SelectPatternFlavor SPF2, Value *C) {
  if (C == A || C == B) {
    // MAX(MAX(A, B), B) -> MAX(A, B)
    // MIN(MIN(a, b), a) -> MIN(a, b)
    if (SPF1 == SPF2)
      return ReplaceInstUsesWith(Outer, Inner);

    // MAX(MIN(a, b), a) -> a
    // MIN(MAX(a, b), a) -> a
    if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
        (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
        (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
        (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
      return ReplaceInstUsesWith(Outer, C);
  }

  if (SPF1 == SPF2) {
    if (ConstantInt *CB = dyn_cast<ConstantInt>(B)) {
      if (ConstantInt *CC = dyn_cast<ConstantInt>(C)) {
        APInt ACB = CB->getValue();
        APInt ACC = CC->getValue();

        // MIN(MIN(A, 23), 97) -> MIN(A, 23)
        // MAX(MAX(A, 97), 23) -> MAX(A, 97)
        if ((SPF1 == SPF_UMIN && ACB.ule(ACC)) ||
            (SPF1 == SPF_SMIN && ACB.sle(ACC)) ||
            (SPF1 == SPF_UMAX && ACB.uge(ACC)) ||
            (SPF1 == SPF_SMAX && ACB.sge(ACC)))
          return ReplaceInstUsesWith(Outer, Inner);

        // MIN(MIN(A, 97), 23) -> MIN(A, 23)
        // MAX(MAX(A, 23), 97) -> MAX(A, 97)
        if ((SPF1 == SPF_UMIN && ACB.ugt(ACC)) ||
            (SPF1 == SPF_SMIN && ACB.sgt(ACC)) ||
            (SPF1 == SPF_UMAX && ACB.ult(ACC)) ||
            (SPF1 == SPF_SMAX && ACB.slt(ACC))) {
          Outer.replaceUsesOfWith(Inner, A);
          return &Outer;
        }
      }
    }
  }

  // ABS(ABS(X)) -> ABS(X)
  // NABS(NABS(X)) -> NABS(X)
  if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) {
    return ReplaceInstUsesWith(Outer, Inner);
  }

  // ABS(NABS(X)) -> ABS(X)
  // NABS(ABS(X)) -> NABS(X)
  if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) ||
      (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) {
    SelectInst *SI = cast<SelectInst>(Inner);
    Value *NewSI = Builder->CreateSelect(
        SI->getCondition(), SI->getFalseValue(), SI->getTrueValue());
    return ReplaceInstUsesWith(Outer, NewSI);
  }
  return nullptr;
}