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//
// ForwardDataFlowAnalysisBase.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.Collections.Generic;
using Mono.CodeContracts.Static.ControlFlow;
using Mono.CodeContracts.Static.DataStructures;
namespace Mono.CodeContracts.Static.DataFlowAnalysis {
abstract class ForwardDataFlowAnalysisBase<AState> : DataFlowAnalysisBase<AState> {
private readonly Dictionary<APC, AState> post_state = new Dictionary<APC, AState> ();
protected ForwardDataFlowAnalysisBase (ICFG cfg) : base (cfg)
{
}
public bool GetPreState (APC pc, out AState state)
{
bool noInfo;
state = GetPreState (pc, default(AState), out noInfo);
return !noInfo;
}
public AState GetPreStateWithDefault (APC apc, AState ifMissing)
{
bool noInfo;
AState preState = GetPreState (apc, default(AState), out noInfo);
return noInfo ? ifMissing : preState;
}
private AState GetPreState (APC apc, AState ifMissing, out bool noInfo)
{
Sequence<APC> rest = null;
APC tmp = apc;
APC singlePredecessor;
AState state;
bool weHaveState;
while (!(weHaveState = this.JoinState.TryGetValue (tmp, out state)) &&
!RequiresJoining (tmp) && this.CFG.HasSinglePredecessor (tmp, out singlePredecessor)) {
tmp = singlePredecessor;
rest = rest.Cons (tmp);
}
if (!weHaveState) {
noInfo = true;
return ifMissing;
}
bool listWasNotEmpty = rest != null;
while (rest != null) {
if (IsBottom (rest.Head, state)) {
noInfo = false;
return state;
}
state = MutableVersion (state, rest.Head);
state = Transfer (rest.Head, state);
if (IsBottom (rest.Head, state)) {
noInfo = false;
return state;
}
rest = rest.Tail;
if (rest != null)
this.JoinState.Add (rest.Head, ImmutableVersion (state, rest.Head));
}
if (listWasNotEmpty)
this.JoinState.Add (apc, ImmutableVersion (state, apc));
noInfo = false;
return state;
}
public bool GetPostState (APC apc, out AState result)
{
if (this.post_state.TryGetValue (apc, out result))
return true;
APC singleSuccessor;
if (apc.Block.Count <= apc.Index)
return GetPreState (apc, out result);
if (this.CFG.HasSingleSuccessor (apc, out singleSuccessor) && !RequiresJoining (singleSuccessor))
return GetPreState (singleSuccessor, out result);
AState ifFound;
if (!GetPreState (apc, out ifFound))
return false;
result = MutableVersion (ifFound, apc);
result = Transfer (apc, result);
this.post_state.Add (apc, result);
return true;
}
public void Run (AState startState)
{
Initialize (this.CFG.Entry, startState);
ComputeFixPoint ();
}
protected override int WorkingListComparer (APC a, APC b)
{
return b.Block.ReversePostOrderIndex - a.Block.ReversePostOrderIndex;
}
protected override bool RequiresJoining (APC pc)
{
return this.CFG.IsJoinPoint (pc);
}
protected override bool HasSingleSuccessor (APC pc, out APC next)
{
return this.CFG.HasSingleSuccessor (pc, out next);
}
protected override IEnumerable<APC> Successors (APC pc)
{
return this.CFG.Successors (pc);
}
protected override bool IsBackEdge (APC from, APC to)
{
return CFG.IsForwardBackEdge (from, to);
}
}
}
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