C++ APInt::sext方法代码示例

/// signExtend - Return a new range in the specified integer type, which must
/// be strictly larger than the current type.  The returned range will
/// correspond to the possible range of values as if the source range had been
/// sign extended.
ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
  unsigned SrcTySize = getBitWidth();
  assert(SrcTySize < DstTySize && "Not a value extension");
  if (isFullSet()) {
    return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
                         APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
  }

  APInt L = Lower; L.sext(DstTySize);
  APInt U = Upper; U.sext(DstTySize);
  return ConstantRange(L, U);
}

int X86TTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
  assert(Ty->isIntegerTy());

  unsigned BitSize = Ty->getPrimitiveSizeInBits();
  if (BitSize == 0)
    return ~0U;

  // Never hoist constants larger than 128bit, because this might lead to
  // incorrect code generation or assertions in codegen.
  // Fixme: Create a cost model for types larger than i128 once the codegen
  // issues have been fixed.
  if (BitSize > 128)
    return TTI::TCC_Free;

  if (Imm == 0)
    return TTI::TCC_Free;

  // Sign-extend all constants to a multiple of 64-bit.
  APInt ImmVal = Imm;
  if (BitSize & 0x3f)
    ImmVal = Imm.sext((BitSize + 63) & ~0x3fU);

  // Split the constant into 64-bit chunks and calculate the cost for each
  // chunk.
  int Cost = 0;
  for (unsigned ShiftVal = 0; ShiftVal < BitSize; ShiftVal += 64) {
    APInt Tmp = ImmVal.ashr(ShiftVal).sextOrTrunc(64);
    int64_t Val = Tmp.getSExtValue();
    Cost += getIntImmCost(Val);
  }
  // We need at least one instruction to materialze the constant.
  return std::max(1, Cost);
}

APInt swift::constantFoldCast(APInt val, const BuiltinInfo &BI) {
  // Get the cast result.
  Type SrcTy = BI.Types[0];
  Type DestTy = BI.Types.size() == 2 ? BI.Types[1] : Type();
  uint32_t SrcBitWidth =
  SrcTy->castTo<BuiltinIntegerType>()->getGreatestWidth();
  uint32_t DestBitWidth =
  DestTy->castTo<BuiltinIntegerType>()->getGreatestWidth();
  
  APInt CastResV;
  if (SrcBitWidth == DestBitWidth) {
    return val;
  } else switch (BI.ID) {
    default : llvm_unreachable("Invalid case.");
    case BuiltinValueKind::Trunc:
    case BuiltinValueKind::TruncOrBitCast:
      return val.trunc(DestBitWidth);
    case BuiltinValueKind::ZExt:
    case BuiltinValueKind::ZExtOrBitCast:
      return val.zext(DestBitWidth);
      break;
    case BuiltinValueKind::SExt:
    case BuiltinValueKind::SExtOrBitCast:
      return val.sext(DestBitWidth);
  }
}

/// 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);
}

/// \brief Calculate the cost of materializing the given constant.
int AArch64TTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
  assert(Ty->isIntegerTy());

  unsigned BitSize = Ty->getPrimitiveSizeInBits();
  if (BitSize == 0)
    return ~0U;

  // Sign-extend all constants to a multiple of 64-bit.
  APInt ImmVal = Imm;
  if (BitSize & 0x3f)
    ImmVal = Imm.sext((BitSize + 63) & ~0x3fU);

  // Split the constant into 64-bit chunks and calculate the cost for each
  // chunk.
  int Cost = 0;
  for (unsigned ShiftVal = 0; ShiftVal < BitSize; ShiftVal += 64) {
    APInt Tmp = ImmVal.ashr(ShiftVal).sextOrTrunc(64);
    int64_t Val = Tmp.getSExtValue();
    Cost += getIntImmCost(Val);
  }
  // We need at least one instruction to materialze the constant.
  return std::max(1, Cost);
}

SymbolicValue
ConstExprFunctionState::computeConstantValueBuiltin(BuiltinInst *inst) {
  const BuiltinInfo &builtin = inst->getBuiltinInfo();

  // Handle various cases in groups.
  auto unknownResult = [&]() -> SymbolicValue {
    return evaluator.getUnknown(SILValue(inst), UnknownReason::Default);
  };

  // Unary operations.
  if (inst->getNumOperands() == 1) {
    auto operand = getConstantValue(inst->getOperand(0));
    // TODO: Could add a "value used here" sort of diagnostic.
    if (!operand.isConstant())
      return operand;

    // TODO: SUCheckedConversion/USCheckedConversion

    // Implement support for s_to_s_checked_trunc_Int2048_Int64 and other
    // checking integer truncates.  These produce a tuple of the result value
    // and an overflow bit.
    //
    // TODO: We can/should diagnose statically detectable integer overflow
    // errors and subsume the ConstantFolding.cpp mandatory SIL pass.
    auto IntCheckedTruncFn = [&](bool srcSigned,
                                 bool dstSigned) -> SymbolicValue {
      if (operand.getKind() != SymbolicValue::Integer)
        return unknownResult();

      auto operandVal = operand.getIntegerValue();
      uint32_t srcBitWidth = operandVal.getBitWidth();
      auto dstBitWidth =
          builtin.Types[1]->castTo<BuiltinIntegerType>()->getGreatestWidth();

      APInt result = operandVal.trunc(dstBitWidth);

      // Compute the overflow by re-extending the value back to its source and
      // checking for loss of value.
      APInt reextended =
          dstSigned ? result.sext(srcBitWidth) : result.zext(srcBitWidth);
      bool overflowed = (operandVal != reextended);

      if (!srcSigned && dstSigned)
        overflowed |= result.isSignBitSet();

      if (overflowed)
        return evaluator.getUnknown(SILValue(inst), UnknownReason::Overflow);

      auto &astContext = evaluator.getASTContext();
      // Build the Symbolic value result for our truncated value.
      return SymbolicValue::getAggregate(
          {SymbolicValue::getInteger(result, astContext),
           SymbolicValue::getInteger(APInt(1, overflowed), astContext)},
          astContext);
    };

    switch (builtin.ID) {
    default:
      break;
    case BuiltinValueKind::SToSCheckedTrunc:
      return IntCheckedTruncFn(true, true);
    case BuiltinValueKind::UToSCheckedTrunc:
      return IntCheckedTruncFn(false, true);
    case BuiltinValueKind::SToUCheckedTrunc:
      return IntCheckedTruncFn(true, false);
    case BuiltinValueKind::UToUCheckedTrunc:
      return IntCheckedTruncFn(false, false);

    case BuiltinValueKind::Trunc:
    case BuiltinValueKind::TruncOrBitCast:
    case BuiltinValueKind::ZExt:
    case BuiltinValueKind::ZExtOrBitCast:
    case BuiltinValueKind::SExt:
    case BuiltinValueKind::SExtOrBitCast: {
      if (operand.getKind() != SymbolicValue::Integer)
        return unknownResult();

      unsigned destBitWidth =
          inst->getType().castTo<BuiltinIntegerType>()->getGreatestWidth();

      APInt result = operand.getIntegerValue();
      if (result.getBitWidth() != destBitWidth) {
        switch (builtin.ID) {
        default:
          assert(0 && "Unknown case");
        case BuiltinValueKind::Trunc:
        case BuiltinValueKind::TruncOrBitCast:
          result = result.trunc(destBitWidth);
          break;
        case BuiltinValueKind::ZExt:
        case BuiltinValueKind::ZExtOrBitCast:
          result = result.zext(destBitWidth);
          break;
        case BuiltinValueKind::SExt:
        case BuiltinValueKind::SExtOrBitCast:
          result = result.sext(destBitWidth);
          break;
        }
      }
      return SymbolicValue::getInteger(result, evaluator.getASTContext());
//.........这里部分代码省略.........

// A helper function that unifies the bitwidth of A and B.
static void unifyBitWidth(APInt &A, APInt &B) {
  if (A.getBitWidth() < B.getBitWidth())
    A = A.sext(B.getBitWidth());
  else if (A.getBitWidth() > B.getBitWidth())
    B = B.sext(A.getBitWidth());
}

static SILInstruction *
constantFoldAndCheckIntegerConversions(BuiltinInst *BI,
                                       const BuiltinInfo &Builtin,
                                       Optional<bool> &ResultsInError) {
  assert(Builtin.ID == BuiltinValueKind::SToSCheckedTrunc ||
         Builtin.ID == BuiltinValueKind::UToUCheckedTrunc ||
         Builtin.ID == BuiltinValueKind::SToUCheckedTrunc ||
         Builtin.ID == BuiltinValueKind::UToSCheckedTrunc ||
         Builtin.ID == BuiltinValueKind::SUCheckedConversion ||
         Builtin.ID == BuiltinValueKind::USCheckedConversion);

  // Check if we are converting a constant integer.
  OperandValueArrayRef Args = BI->getArguments();
  auto *V = dyn_cast<IntegerLiteralInst>(Args[0]);
  if (!V)
    return nullptr;
  APInt SrcVal = V->getValue();

  // Get source type and bit width.
  Type SrcTy = Builtin.Types[0];
  uint32_t SrcBitWidth =
    Builtin.Types[0]->castTo<BuiltinIntegerType>()->getGreatestWidth();

  // Compute the destination (for SrcBitWidth < DestBitWidth) and enough info
  // to check for overflow.
  APInt Result;
  bool OverflowError;
  Type DstTy;

  // Process conversions signed <-> unsigned for same size integers.
  if (Builtin.ID == BuiltinValueKind::SUCheckedConversion ||
      Builtin.ID == BuiltinValueKind::USCheckedConversion) {
    DstTy = SrcTy;
    Result = SrcVal;
    // Report an error if the sign bit is set.
    OverflowError = SrcVal.isNegative();

  // Process truncation from unsigned to signed.
  } else if (Builtin.ID != BuiltinValueKind::UToSCheckedTrunc) {
    assert(Builtin.Types.size() == 2);
    DstTy = Builtin.Types[1];
    uint32_t DstBitWidth =
      DstTy->castTo<BuiltinIntegerType>()->getGreatestWidth();
    //     Result = trunc_IntFrom_IntTo(Val)
    //   For signed destination:
    //     sext_IntFrom(Result) == Val ? Result : overflow_error
    //   For signed destination:
    //     zext_IntFrom(Result) == Val ? Result : overflow_error
    Result = SrcVal.trunc(DstBitWidth);
    // Get the signedness of the destination.
    bool Signed = (Builtin.ID == BuiltinValueKind::SToSCheckedTrunc);
    APInt Ext = Signed ? Result.sext(SrcBitWidth) : Result.zext(SrcBitWidth);
    OverflowError = (SrcVal != Ext);

  // Process the rest of truncations.
  } else {
    assert(Builtin.Types.size() == 2);
    DstTy = Builtin.Types[1];
    uint32_t DstBitWidth =
      Builtin.Types[1]->castTo<BuiltinIntegerType>()->getGreatestWidth();
    // Compute the destination (for SrcBitWidth < DestBitWidth):
    //   Result = trunc_IntTo(Val)
    //   Trunc  = trunc_'IntTo-1bit'(Val)
    //   zext_IntFrom(Trunc) == Val ? Result : overflow_error
    Result = SrcVal.trunc(DstBitWidth);
    APInt TruncVal = SrcVal.trunc(DstBitWidth - 1);
    OverflowError = (SrcVal != TruncVal.zext(SrcBitWidth));
  }

  // Check for overflow.
  if (OverflowError) {
    // If we are not asked to emit overflow diagnostics, just return nullptr on
    // overflow.
    if (!ResultsInError.hasValue())
      return nullptr;

    SILLocation Loc = BI->getLoc();
    SILModule &M = BI->getModule();
    const ApplyExpr *CE = Loc.getAsASTNode<ApplyExpr>();
    Type UserSrcTy;
    Type UserDstTy;
    // Primitive heuristics to get the user-written type.
    // Eventually we might be able to use SILLocation (when it contains info
    // about inlined call chains).
    if (CE) {
      if (const TupleType *RTy = CE->getArg()->getType()->getAs<TupleType>()) {
        if (RTy->getNumElements() == 1) {
          UserSrcTy = RTy->getElementType(0);
          UserDstTy = CE->getType();
        }
      } else {
        UserSrcTy = CE->getArg()->getType();
        UserDstTy = CE->getType();
      }
    }
    
 
    // Assume that we are converting from a literal if the Source size is
    // 2048. Is there a better way to identify conversions from literals?
    bool Literal = (SrcBitWidth == 2048);
//.........这里部分代码省略.........