C++ APSInt::getBitWidth方法代码示例

ProgramStateRef SimpleConstraintManager::assumeInclusiveRange(
    ProgramStateRef State, NonLoc Value, const llvm::APSInt &From,
    const llvm::APSInt &To, bool InRange) {

  assert(From.isUnsigned() == To.isUnsigned() &&
         From.getBitWidth() == To.getBitWidth() &&
         "Values should have same types!");

  if (!canReasonAbout(Value)) {
    // Just add the constraint to the expression without trying to simplify.
    SymbolRef Sym = Value.getAsSymExpr();
    assert(Sym);
    return assumeSymWithinInclusiveRange(State, Sym, From, To, InRange);
  }

  switch (Value.getSubKind()) {
  default:
    llvm_unreachable("'assumeInclusiveRange' is not implemented"
                     "for this NonLoc");

  case nonloc::LocAsIntegerKind:
  case nonloc::SymbolValKind: {
    if (SymbolRef Sym = Value.getAsSymbol())
      return assumeSymWithinInclusiveRange(State, Sym, From, To, InRange);
    return State;
  } // end switch

  case nonloc::ConcreteIntKind: {
    const llvm::APSInt &IntVal = Value.castAs<nonloc::ConcreteInt>().getValue();
    bool IsInRange = IntVal >= From && IntVal <= To;
    bool isFeasible = (IsInRange == InRange);
    return isFeasible ? State : nullptr;
  }
  } // end switch
}

ProgramStateRef 
BasicConstraintManager::assumeSymLE(ProgramStateRef state,
                                    SymbolRef sym,
                                    const llvm::APSInt &V,
                                    const llvm::APSInt &Adjustment) {
  // Reject a path if the value of sym is a constant X and !(X+Adj <= V).
  if (const llvm::APSInt* X = getSymVal(state, sym)) {
    bool isFeasible = (*X <= V-Adjustment);
    return isFeasible ? state : NULL;
  }

  // Sym is not a constant, but it is worth looking to see if V is the
  // minimum integer value.
  if (V == llvm::APSInt::getMinValue(V.getBitWidth(), V.isUnsigned())) {
    llvm::APSInt Adjusted = V-Adjustment;

    // If we know that sym != V (after adjustment), then this condition
    // is infeasible since there is no other value less than V.
    bool isFeasible = !isNotEqual(state, sym, Adjusted);

    // If the path is still feasible then as a consequence we know that
    // 'sym+Adjustment == V' because there are no smaller values.
    // Add this constraint.
    return isFeasible ? AddEQ(state, sym, Adjusted) : NULL;
  }

  return state;
}

ProgramStateRef 
BasicConstraintManager::assumeSymGT(ProgramStateRef state,
                                    SymbolRef sym,
                                    const llvm::APSInt &V,
                                    const llvm::APSInt &Adjustment) {
  // Is 'V' the largest possible value?
  if (V == llvm::APSInt::getMaxValue(V.getBitWidth(), V.isUnsigned())) {
    // sym cannot be any value greater than 'V'.  This path is infeasible.
    return NULL;
  }

  // FIXME: For now have assuming x > y be the same as assuming sym != V;
  return assumeSymNE(state, sym, V, Adjustment);
}

TemplateArgument::TemplateArgument(ASTContext &Ctx, const llvm::APSInt &Value,
                                   QualType Type) {
  Integer.Kind = Integral;
  // Copy the APSInt value into our decomposed form.
  Integer.BitWidth = Value.getBitWidth();
  Integer.IsUnsigned = Value.isUnsigned();
  // If the value is large, we have to get additional memory from the ASTContext
  unsigned NumWords = Value.getNumWords();
  if (NumWords > 1) {
    void *Mem = Ctx.Allocate(NumWords * sizeof(uint64_t));
    std::memcpy(Mem, Value.getRawData(), NumWords * sizeof(uint64_t));
    Integer.pVal = static_cast<uint64_t *>(Mem);
  } else {
    Integer.VAL = Value.getZExtValue();
  }

  Integer.Type = Type.getAsOpaquePtr();
}

/// \brief Determine if two APSInts have the same value, zero- or sign-extending
/// as needed.
static bool IsSameValue(const llvm::APSInt &I1, const llvm::APSInt &I2) {
  if (I1.getBitWidth() == I2.getBitWidth() && I1.isSigned() == I2.isSigned())
    return I1 == I2;
  
  // Check for a bit-width mismatch.
  if (I1.getBitWidth() > I2.getBitWidth())
    return IsSameValue(I1, I2.extend(I1.getBitWidth()));
  else if (I2.getBitWidth() > I1.getBitWidth())
    return IsSameValue(I1.extend(I2.getBitWidth()), I2);
  
  // We have a signedness mismatch. Turn the signed value into an unsigned 
  // value.
  if (I1.isSigned()) {
    if (I1.isNegative())
      return false;
    
    return llvm::APSInt(I1, true) == I2;
  }
 
  if (I2.isNegative())
    return false;
  
  return I1 == llvm::APSInt(I2, true);
}

SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
                                    BinaryOperator::Opcode op,
                                    const llvm::APSInt &RHS,
                                    QualType resultTy) {
  bool isIdempotent = false;

  // Check for a few special cases with known reductions first.
  switch (op) {
  default:
    // We can't reduce this case; just treat it normally.
    break;
  case BO_Mul:
    // a*0 and a*1
    if (RHS == 0)
      return makeIntVal(0, resultTy);
    else if (RHS == 1)
      isIdempotent = true;
    break;
  case BO_Div:
    // a/0 and a/1
    if (RHS == 0)
      // This is also handled elsewhere.
      return UndefinedVal();
    else if (RHS == 1)
      isIdempotent = true;
    break;
  case BO_Rem:
    // a%0 and a%1
    if (RHS == 0)
      // This is also handled elsewhere.
      return UndefinedVal();
    else if (RHS == 1)
      return makeIntVal(0, resultTy);
    break;
  case BO_Add:
  case BO_Sub:
  case BO_Shl:
  case BO_Shr:
  case BO_Xor:
    // a+0, a-0, a<<0, a>>0, a^0
    if (RHS == 0)
      isIdempotent = true;
    break;
  case BO_And:
    // a&0 and a&(~0)
    if (RHS == 0)
      return makeIntVal(0, resultTy);
    else if (RHS.isAllOnesValue())
      isIdempotent = true;
    break;
  case BO_Or:
    // a|0 and a|(~0)
    if (RHS == 0)
      isIdempotent = true;
    else if (RHS.isAllOnesValue()) {
      const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
      return nonloc::ConcreteInt(Result);
    }
    break;
  }

  // Idempotent ops (like a*1) can still change the type of an expression.
  // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
  // dirty work.
  if (isIdempotent)
      return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);

  // If we reach this point, the expression cannot be simplified.
  // Make a SymbolVal for the entire expression, after converting the RHS.
  const llvm::APSInt *ConvertedRHS = &RHS;
  if (BinaryOperator::isComparisonOp(op)) {
    // We're looking for a type big enough to compare the symbolic value
    // with the given constant.
    // FIXME: This is an approximation of Sema::UsualArithmeticConversions.
    ASTContext &Ctx = getContext();
    QualType SymbolType = LHS->getType();
    uint64_t ValWidth = RHS.getBitWidth();
    uint64_t TypeWidth = Ctx.getTypeSize(SymbolType);

    if (ValWidth < TypeWidth) {
      // If the value is too small, extend it.
      ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
    } else if (ValWidth == TypeWidth) {
      // If the value is signed but the symbol is unsigned, do the comparison
      // in unsigned space. [C99 6.3.1.8]
      // (For the opposite case, the value is already unsigned.)
      if (RHS.isSigned() && !SymbolType->isSignedIntegerOrEnumerationType())
        ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
    }
  } else
    ConvertedRHS = &BasicVals.Convert(resultTy, RHS);

  return makeNonLoc(LHS, op, *ConvertedRHS, resultTy);
}

 unsigned getBitWidth() const { return Val.getBitWidth(); }