mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.Analysis.ExpressionAnalysis/ExpressionDecoder.cs

   1 //
   2 // ExpressionDecoder.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.Analysis.ExpressionAnalysis.Expressions;
  33 using Mono.CodeContracts.Static.Analysis.HeapAnalysis;
  34 using Mono.CodeContracts.Static.ControlFlow;
  35 using Mono.CodeContracts.Static.DataStructures;
  36 using Mono.CodeContracts.Static.Lattices;
  37 using Mono.CodeContracts.Static.Providers;
  38
  39 namespace Mono.CodeContracts.Static.Analysis.ExpressionAnalysis {
  40         class ExpressionDecoder<TSymbolicValue, TContext, TEdgeData> :
  41                 IILDecoder<APC, LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue, IExpressionContextProvider<LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue>, TEdgeData>,
  42                 IExpressionContextProvider<LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue>,
  43                 IExpressionContext<LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue>
  44                 where TSymbolicValue : IEquatable<TSymbolicValue>
  45                 where TContext : IValueContextProvider<TSymbolicValue>
  46                 where TEdgeData : IImmutableMap<TSymbolicValue, Sequence<TSymbolicValue>> {
  47                 private readonly IILDecoder<APC, TSymbolicValue, TSymbolicValue, IValueContextProvider<TSymbolicValue>, TEdgeData> value_decoder;
  48                 private readonly ExpressionAnalysisFacade<TSymbolicValue, TContext, TEdgeData> parent;
  49                 private readonly IValueContextProvider<TSymbolicValue> underlying;
  50
  51                 public ExpressionDecoder (IILDecoder<APC, TSymbolicValue, TSymbolicValue, IValueContextProvider<TSymbolicValue>, TEdgeData> valueDecoder,
  52                                           ExpressionAnalysisFacade<TSymbolicValue, TContext, TEdgeData> parent)
  53                 {
  54                         this.value_decoder = valueDecoder;
  55                         this.parent = parent;
  56                         this.underlying = valueDecoder.ContextProvider;
  57                 }
  58
  59                 #region IExpressionContext<LabeledSymbol<APC,SymbolicValue>,SymbolicValue> Members
  60                 public LabeledSymbol<APC, TSymbolicValue> Refine (APC pc, TSymbolicValue variable)
  61                 {
  62                         return new LabeledSymbol<APC, TSymbolicValue> (pc, variable);
  63                 }
  64
  65                 public TSymbolicValue Unrefine (LabeledSymbol<APC, TSymbolicValue> expression)
  66                 {
  67                         return expression.Symbol;
  68                 }
  69
  70                 public Result Decode<Data, Result, Visitor> (LabeledSymbol<APC, TSymbolicValue> expr, Visitor visitor, Data data)
  71                         where Visitor : ISymbolicExpressionVisitor<LabeledSymbol<APC, TSymbolicValue>, LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue, Data, Result>
  72                 {
  73                         ExprDomain<TSymbolicValue> ifFound;
  74                         if (!this.parent.PreStateLookup (expr.ReadAt, out ifFound) || ifFound.IsBottom)
  75                                 return visitor.SymbolicConstant (expr, expr.Symbol, data);
  76
  77                         FlatDomain<Expr<TSymbolicValue>> aExpr = ifFound [expr.Symbol];
  78                         if (aExpr.IsNormal()) {
  79                                 return aExpr.Value.Decode<Data, Result, ExpressionDecoderAdapter<TSymbolicValue, Data, Result, Visitor>>
  80                                         (expr.ReadAt, expr.Symbol, new ExpressionDecoderAdapter<TSymbolicValue, Data, Result, Visitor> (visitor), data);
  81                         }
  82
  83                         TypeNode type;
  84                         object constant;
  85                         if (this.parent.ValueLayer.ILDecoder.ContextProvider.ValueContext.IsConstant (expr.ReadAt, expr.Symbol, out type, out constant))
  86                                 return visitor.LoadConst (expr, type, constant, expr.Symbol, data);
  87
  88                         return visitor.SymbolicConstant (expr, expr.Symbol, data);
  89                 }
  90
  91                 public FlatDomain<TypeNode> GetType (LabeledSymbol<APC, TSymbolicValue> expr)
  92                 {
  93                         return this.underlying.ValueContext.GetType (expr.ReadAt, expr.Symbol);
  94                 }
  95
  96                 public APC GetPC (LabeledSymbol<APC, TSymbolicValue> pc)
  97                 {
  98                         return pc.ReadAt;
  99                 }
 100
 101                 public LabeledSymbol<APC, TSymbolicValue> For (TSymbolicValue variable)
 102                 {
 103                         return new LabeledSymbol<APC, TSymbolicValue> (MethodContext.CFG.Entry, variable);
 104                 }
 105
 106                 public bool IsZero (LabeledSymbol<APC, TSymbolicValue> expression)
 107                 {
 108                         return ValueContext.IsZero (expression.ReadAt, expression.Symbol);
 109                 }
 110                 #endregion
 111
 112                 #region IILDecoder<APC,LabeledSymbol<APC,SymbolicValue>,SymbolicValue,IExpressionContextProvider<LabeledSymbol<APC,SymbolicValue>,SymbolicValue>,EdgeData> Members
 113                 public IExpressionContextProvider<LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue> ContextProvider
 114                 {
 115                         get { return this; }
 116                 }
 117
 118                 public Result ForwardDecode<Data, Result, Visitor> (APC pc, Visitor visitor, Data state)
 119                         where Visitor : IILVisitor<APC, LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue, Data, Result>
 120                 {
 121                         return this.value_decoder.ForwardDecode<Data, Result, ILDecoderAdapter<TSymbolicValue, Data, Result, Visitor>>
 122                                 (pc, new ILDecoderAdapter<TSymbolicValue, Data, Result, Visitor> (visitor), state);
 123                 }
 124
 125                 public bool IsUnreachable (APC pc)
 126                 {
 127                         return this.parent.IsUnreachable (pc);
 128                 }
 129
 130                 public TEdgeData EdgeData (APC from, APC to)
 131                 {
 132                         return this.parent.ValueLayer.ILDecoder.EdgeData (from, to);
 133                 }
 134                 #endregion
 135
 136                 #region Implementation of IMethodContextProvider<Field,Method>
 137                 public IMethodContext MethodContext
 138                 {
 139                         get { return this.underlying.MethodContext; }
 140                 }
 141                 #endregion
 142
 143                 #region Implementation of IStackContextProvider<Field,Method>
 144                 public IStackContext StackContext
 145                 {
 146                         get { return this.underlying.StackContext; }
 147                 }
 148                 #endregion
 149
 150                 #region Implementation of IValueContextProvider<Local,Parameter,Method,Field,Type,SymbolicValue>
 151                 public IValueContext<TSymbolicValue> ValueContext
 152                 {
 153                         get { return this.underlying.ValueContext; }
 154                 }
 155                 #endregion
 156
 157                 #region Implementation of IExpressionContextProvider<Local,Parameter,Method,Field,Type,ExternalExpression<APC,SymbolicValue>,SymbolicValue>
 158                 public IExpressionContext<LabeledSymbol<APC, TSymbolicValue>, TSymbolicValue> ExpressionContext
 159                 {
 160                         get { return this; }
 161                 }
 162                 #endregion
 163         }
 164 }