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//
// ExpressionAssertDischarger.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2011 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using Mono.CodeContracts.Static.AST;
using Mono.CodeContracts.Static.AST.Visitors;
using Mono.CodeContracts.Static.ControlFlow;
using Mono.CodeContracts.Static.Lattices;
namespace Mono.CodeContracts.Static.Analysis.NonNull {
struct ExpressionAssertDischarger<E, V>
: ISymbolicExpressionVisitor<E, E, V, bool, FlatDomain<bool>>
where E : IEquatable<E>
where V : IEquatable<V> {
private readonly Analysis<E, V> analysis;
private readonly APC pc;
public ExpressionAssertDischarger(Analysis<E, V> analysis, APC pc)
{
this.analysis = analysis;
this.pc = pc;
}
private IExpressionContextProvider<E, V> ContextProvider
{
get { return this.analysis.ContextProvider; }
}
#region Implementation of IExpressionILVisitor<Expression,Expression,Variable,bool,ProofOutcome>
private FlatDomain<bool> Recurse(bool polarity, E expr)
{
return this.ContextProvider.ExpressionContext.Decode<bool, FlatDomain<bool>, ExpressionAssertDischarger<E, V>>(expr, this, polarity);
}
public FlatDomain<bool> Binary(E orig, BinaryOperator op, V dest, E operand1, E operand2, bool polarity)
{
switch (op) {
case BinaryOperator.Ceq:
case BinaryOperator.Cobjeq:
if (this.ContextProvider.ExpressionContext.IsZero (operand2) || this.ContextProvider.ExpressionContext.IsZero (operand1))
return this.Recurse (!polarity, operand1);
return ProofOutcome.Top;
case BinaryOperator.Cne_Un:
if (this.ContextProvider.ExpressionContext.IsZero(operand2) || this.ContextProvider.ExpressionContext.IsZero(operand1))
return this.Recurse (polarity, operand1);
return ProofOutcome.Top;
default:
return this.SymbolicConstant (orig, this.ContextProvider.ExpressionContext.Unrefine (orig), polarity);
}
}
public FlatDomain<bool> Isinst(E orig, TypeNode type, V dest, E obj, bool polarity)
{
if (!polarity)
return this.analysis.IsNull (this.pc, dest);
FlatDomain<bool> outcome = this.analysis.IsNonNull(this.pc, dest);
return outcome.IsTrue() ? outcome : this.Recurse (true, obj);
}
public FlatDomain<bool> LoadNull(E orig, V dest, bool polarity)
{
return polarity ? ProofOutcome.False : ProofOutcome.True;
}
public FlatDomain<bool> LoadConst(E orig, TypeNode type, object constant, V dest, bool polarity)
{
var isConstantEqualZero = constant is int && (int) constant == 0;
return (isConstantEqualZero != polarity) ? ProofOutcome.True : ProofOutcome.False;
}
public FlatDomain<bool> Sizeof(E pc, TypeNode type, V dest, bool polarity)
{
return polarity ? ProofOutcome.True : ProofOutcome.False;
}
public FlatDomain<bool> Unary(E orig, UnaryOperator op, bool unsigned, V dest, E source, bool polarity)
{
switch (op) {
case UnaryOperator.Conv_i:
case UnaryOperator.Conv_i1:
case UnaryOperator.Conv_i2:
case UnaryOperator.Conv_i4:
case UnaryOperator.Conv_i8:
case UnaryOperator.Conv_u:
case UnaryOperator.Conv_u1:
case UnaryOperator.Conv_u2:
case UnaryOperator.Conv_u4:
case UnaryOperator.Conv_u8:
return this.Recurse (polarity, source);
case UnaryOperator.Neg:
return this.Recurse(polarity, source);
case UnaryOperator.Not:
return this.Recurse(!polarity, source);
default:
return this.SymbolicConstant (orig, this.ContextProvider.ExpressionContext.Unrefine (orig), polarity);
}
}
#endregion
#region Implementation of ISymbolicExpressionVisitor<Expression,Expression,Variable,bool,ProofOutcome>
public FlatDomain<bool> SymbolicConstant(E pc, V variable, bool polarity)
{
return polarity ? this.analysis.IsNonNull (this.pc, variable) : this.analysis.IsNull(this.pc, variable);
}
#endregion
}
}
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