1 // 2 // ExpressionAssertDischarger.cs 3 // 4 // Authors: 5 // Alexander Chebaturkin (chebaturkin@gmail.com) 6 // 7 // Copyright (C) 2011 Alexander Chebaturkin 8 // 9 // Permission is hereby granted, free of charge, to any person obtaining 10 // a copy of this software and associated documentation files (the 11 // "Software"), to deal in the Software without restriction, including 12 // without limitation the rights to use, copy, modify, merge, publish, 13 // distribute, sublicense, and/or sell copies of the Software, and to 14 // permit persons to whom the Software is furnished to do so, subject to 15 // the following conditions: 16 // 17 // The above copyright notice and this permission notice shall be 18 // included in all copies or substantial portions of the Software. 19 // 20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 27 // 28 29 using System; 30 using Mono.CodeContracts.Static.AST; 31 using Mono.CodeContracts.Static.AST.Visitors; 32 using Mono.CodeContracts.Static.ControlFlow; 33 using Mono.CodeContracts.Static.Lattices; 34 35 namespace Mono.CodeContracts.Static.Analysis.NonNull { 36 struct ExpressionAssertDischarger<E, V> 37 : ISymbolicExpressionVisitor<E, E, V, bool, FlatDomain<bool>> 38 where E : IEquatable<E> 39 where V : IEquatable<V> { 40 private readonly Analysis<E, V> analysis; 41 private readonly APC pc; 42 ExpressionAssertDischargerMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger43 public ExpressionAssertDischarger(Analysis<E, V> analysis, APC pc) 44 { 45 this.analysis = analysis; 46 this.pc = pc; 47 } 48 49 private IExpressionContextProvider<E, V> ContextProvider 50 { 51 get { return this.analysis.ContextProvider; } 52 } 53 54 #region Implementation of IExpressionILVisitor<Expression,Expression,Variable,bool,ProofOutcome> RecurseMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger55 private FlatDomain<bool> Recurse(bool polarity, E expr) 56 { 57 return this.ContextProvider.ExpressionContext.Decode<bool, FlatDomain<bool>, ExpressionAssertDischarger<E, V>>(expr, this, polarity); 58 } 59 BinaryMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger60 public FlatDomain<bool> Binary(E orig, BinaryOperator op, V dest, E operand1, E operand2, bool polarity) 61 { 62 switch (op) { 63 case BinaryOperator.Ceq: 64 case BinaryOperator.Cobjeq: 65 if (this.ContextProvider.ExpressionContext.IsZero (operand2) || this.ContextProvider.ExpressionContext.IsZero (operand1)) 66 return this.Recurse (!polarity, operand1); 67 return ProofOutcome.Top; 68 case BinaryOperator.Cne_Un: 69 if (this.ContextProvider.ExpressionContext.IsZero(operand2) || this.ContextProvider.ExpressionContext.IsZero(operand1)) 70 return this.Recurse (polarity, operand1); 71 return ProofOutcome.Top; 72 default: 73 return this.SymbolicConstant (orig, this.ContextProvider.ExpressionContext.Unrefine (orig), polarity); 74 } 75 } 76 IsinstMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger77 public FlatDomain<bool> Isinst(E orig, TypeNode type, V dest, E obj, bool polarity) 78 { 79 if (!polarity) 80 return this.analysis.IsNull (this.pc, dest); 81 FlatDomain<bool> outcome = this.analysis.IsNonNull(this.pc, dest); 82 83 return outcome.IsTrue() ? outcome : this.Recurse (true, obj); 84 } 85 LoadNullMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger86 public FlatDomain<bool> LoadNull(E orig, V dest, bool polarity) 87 { 88 return polarity ? ProofOutcome.False : ProofOutcome.True; 89 } 90 LoadConstMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger91 public FlatDomain<bool> LoadConst(E orig, TypeNode type, object constant, V dest, bool polarity) 92 { 93 var isConstantEqualZero = constant is int && (int) constant == 0; 94 95 return (isConstantEqualZero != polarity) ? ProofOutcome.True : ProofOutcome.False; 96 } 97 SizeofMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger98 public FlatDomain<bool> Sizeof(E pc, TypeNode type, V dest, bool polarity) 99 { 100 return polarity ? ProofOutcome.True : ProofOutcome.False; 101 } 102 UnaryMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger103 public FlatDomain<bool> Unary(E orig, UnaryOperator op, bool unsigned, V dest, E source, bool polarity) 104 { 105 switch (op) { 106 case UnaryOperator.Conv_i: 107 case UnaryOperator.Conv_i1: 108 case UnaryOperator.Conv_i2: 109 case UnaryOperator.Conv_i4: 110 case UnaryOperator.Conv_i8: 111 case UnaryOperator.Conv_u: 112 case UnaryOperator.Conv_u1: 113 case UnaryOperator.Conv_u2: 114 case UnaryOperator.Conv_u4: 115 case UnaryOperator.Conv_u8: 116 return this.Recurse (polarity, source); 117 case UnaryOperator.Neg: 118 return this.Recurse(polarity, source); 119 case UnaryOperator.Not: 120 return this.Recurse(!polarity, source); 121 default: 122 return this.SymbolicConstant (orig, this.ContextProvider.ExpressionContext.Unrefine (orig), polarity); 123 } 124 } 125 #endregion 126 127 #region Implementation of ISymbolicExpressionVisitor<Expression,Expression,Variable,bool,ProofOutcome> SymbolicConstantMono.CodeContracts.Static.Analysis.NonNull.ExpressionAssertDischarger128 public FlatDomain<bool> SymbolicConstant(E pc, V variable, bool polarity) 129 { 130 return polarity ? this.analysis.IsNonNull (this.pc, variable) : this.analysis.IsNull(this.pc, variable); 131 } 132 #endregion 133 } 134 }