C++ APInt::isIntN方法代码示例

/// Check if a checked trunc instruction can overflow.
/// Returns false if it can be proven that no overflow can happen.
/// Otherwise returns true.
static bool checkTruncOverflow(BuiltinInst *BI) {
  SILValue Left, Right;
  if (match(BI, m_CheckedTrunc(m_And(m_SILValue(Left),
                               m_SILValue(Right))))) {
    // [US]ToSCheckedTrunc(And(x, mask)) cannot overflow
    // if mask has the following properties:
    // Only the first (N-1) bits are allowed to be set, where N is the width
    // of the trunc result type.
    //
    // [US]ToUCheckedTrunc(And(x, mask)) cannot overflow
    // if mask has the following properties:
    // Only the first N bits are allowed to be set, where N is the width
    // of the trunc result type.
    if (auto BITy = BI->getType().
                        getTupleElementType(0).
                        getAs<BuiltinIntegerType>()) {
      unsigned Width = BITy->getFixedWidth();

      switch (BI->getBuiltinInfo().ID) {
      case BuiltinValueKind::SToSCheckedTrunc:
      case BuiltinValueKind::UToSCheckedTrunc:
        // If it is a trunc to a signed value
        // then sign bit should not be set to avoid overflows.
        --Width;
        break;
      default:
        break;
      }

      if (auto *ILLeft = dyn_cast<IntegerLiteralInst>(Left)) {
        APInt Value = ILLeft->getValue();
        if (Value.isIntN(Width)) {
          return false;
        }
      }

      if (auto *ILRight = dyn_cast<IntegerLiteralInst>(Right)) {
        APInt Value = ILRight->getValue();
        if (Value.isIntN(Width)) {
          return false;
        }
      }
    }
  }
  return true;
}

/// We do not support symbolic projections yet, only 32-bit unsigned integers.
bool swift::getIntegerIndex(SILValue IndexVal, unsigned &IndexConst) {
    if (auto *IndexLiteral = dyn_cast<IntegerLiteralInst>(IndexVal)) {
        APInt ConstInt = IndexLiteral->getValue();
        // IntegerLiterals are signed.
        if (ConstInt.isIntN(32) && ConstInt.isNonNegative()) {
            IndexConst = (unsigned)ConstInt.getSExtValue();
            return true;
        }
    }
    return false;
}

// Select constant vector splats.
//
// In addition to the requirements of selectVSplat(), this function returns
// true and sets Imm if:
// * The splat value is the same width as the elements of the vector
// * The splat value fits in an integer with the specified signed-ness and
//   width.
//
// This function looks through ISD::BITCAST nodes.
// TODO: This might not be appropriate for big-endian MSA since BITCAST is
//       sometimes a shuffle in big-endian mode.
//
// It's worth noting that this function is not used as part of the selection
// of ldi.[bhwd] since it does not permit using the wrong-typed ldi.[bhwd]
// instruction to achieve the desired bit pattern. ldi.[bhwd] is selected in
// MipsSEDAGToDAGISel::selectNode.
bool MipsSEDAGToDAGISel::
selectVSplatCommon(SDValue N, SDValue &Imm, bool Signed,
                   unsigned ImmBitSize) const {
  APInt ImmValue;
  EVT EltTy = N->getValueType(0).getVectorElementType();

  if (N->getOpcode() == ISD::BITCAST)
    N = N->getOperand(0);

  if (selectVSplat (N.getNode(), ImmValue) &&
      ImmValue.getBitWidth() == EltTy.getSizeInBits()) {
    if (( Signed && ImmValue.isSignedIntN(ImmBitSize)) ||
        (!Signed && ImmValue.isIntN(ImmBitSize))) {
      Imm = CurDAG->getTargetConstant(ImmValue, EltTy);
      return true;
    }
  }

  return false;
}

static AsmToken intToken(StringRef Ref, APInt &Value)
{
  if (Value.isIntN(64))
    return AsmToken(AsmToken::Integer, Ref, Value);
  return AsmToken(AsmToken::BigNum, Ref, Value);
}