private static bool ExtractLastIf(DoStatement stat)
{
// search for an if condition at the end of the loop
Statement last = stat.GetFirst();
while (last.type == Statement.Type_Sequence)
{
last = last.GetStats().GetLast();
}
if (last.type == Statement.Type_If)
{
IfStatement lastif = (IfStatement)last;
if (lastif.iftype == IfStatement.Iftype_If && lastif.GetIfstat() != null)
{
Statement ifstat = lastif.GetIfstat();
StatEdge elseedge = lastif.GetAllSuccessorEdges()[0];
if (elseedge.GetType() == StatEdge.Type_Continue && elseedge.closure == stat)
{
HashSet <Statement> set = stat.GetNeighboursSet(StatEdge.Type_Continue, Statement.
Direction_Backward);
set.Remove(last);
if ((set.Count == 0))
{
// no direct continues in a do{}while loop
if (IsExternStatement(stat, ifstat, ifstat))
{
ExtractIfBlock(stat, lastif);
return(true);
}
}
}
}
}
return(false);
}
private static bool ExtractFirstIf(DoStatement stat)
{
// search for an if condition at the entrance of the loop
Statement first = stat.GetFirst();
while (first.type == Statement.Type_Sequence)
{
first = first.GetFirst();
}
// found an if statement
if (first.type == Statement.Type_If)
{
IfStatement firstif = (IfStatement)first;
if ((firstif.GetFirst().GetExprents().Count == 0))
{
if (firstif.iftype == IfStatement.Iftype_If && firstif.GetIfstat() != null)
{
Statement ifstat = firstif.GetIfstat();
if (IsExternStatement(stat, ifstat, ifstat))
{
ExtractIfBlock(stat, firstif);
return(true);
}
}
}
}
return(false);
}
private static void RemoveLastEmptyStatement(DoStatement dostat, Statement stat)
{
if (stat == dostat.GetFirst())
{
BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(DecompilerContext
.GetCounterContainer().GetCounterAndIncrement(CounterContainer.Statement_Counter
)));
bstat.SetExprents(new List <Exprent>());
dostat.ReplaceStatement(stat, bstat);
}
else
{
foreach (StatEdge edge in stat.GetAllPredecessorEdges())
{
edge.GetSource().ChangeEdgeType(Statement.Direction_Forward, edge, StatEdge.Type_Continue
);
stat.RemovePredecessor(edge);
edge.GetSource().ChangeEdgeNode(Statement.Direction_Forward, edge, dostat);
dostat.AddPredecessor(edge);
dostat.AddLabeledEdge(edge);
}
// parent is a sequence statement
stat.GetParent().GetStats().RemoveWithKey(stat.id);
}
}
private static void MatchDoWhile(DoStatement stat)
{
// search for an if condition at the end of the loop
Statement last = stat.GetFirst();
while (last.type == Statement.Type_Sequence)
{
last = last.GetStats().GetLast();
}
if (last.type == Statement.Type_If)
{
IfStatement lastif = (IfStatement)last;
if (lastif.iftype == IfStatement.Iftype_If && lastif.GetIfstat() == null)
{
StatEdge ifedge = lastif.GetIfEdge();
StatEdge elseedge = lastif.GetAllSuccessorEdges()[0];
if ((ifedge.GetType() == StatEdge.Type_Break && elseedge.GetType() == StatEdge.Type_Continue &&
elseedge.closure == stat && IsDirectPath(stat, ifedge.GetDestination())) ||
(ifedge.GetType() == StatEdge.Type_Continue && elseedge.GetType() == StatEdge.Type_Break &&
ifedge.closure == stat && IsDirectPath(stat, elseedge.GetDestination())))
{
HashSet <Statement> set = stat.GetNeighboursSet(StatEdge.Type_Continue, Statement.
Direction_Backward);
set.Remove(last);
if (!(set.Count == 0))
{
return;
}
stat.SetLooptype(DoStatement.Loop_Dowhile);
IfExprent ifexpr = (IfExprent)lastif.GetHeadexprent().Copy();
if (ifedge.GetType() == StatEdge.Type_Break)
{
ifexpr.NegateIf();
}
stat.SetConditionExprent(ifexpr.GetCondition());
lastif.GetFirst().RemoveSuccessor(ifedge);
lastif.RemoveSuccessor(elseedge);
// remove empty if
if ((lastif.GetFirst().GetExprents().Count == 0))
{
RemoveLastEmptyStatement(stat, lastif);
}
else
{
lastif.SetExprents(lastif.GetFirst().GetExprents());
StatEdge newedge = new StatEdge(StatEdge.Type_Continue, lastif, stat);
lastif.AddSuccessor(newedge);
stat.AddLabeledEdge(newedge);
}
if ((stat.GetAllSuccessorEdges().Count == 0))
{
StatEdge edge = elseedge.GetType() == StatEdge.Type_Continue ? ifedge : elseedge;
edge.SetSource(stat);
if (edge.closure == stat)
{
edge.closure = stat.GetParent();
}
stat.AddSuccessor(edge);
}
}
}
}
}
private static void MatchFor(DoStatement stat)
{
Exprent lastDoExprent;
Exprent initDoExprent;
Statement lastData;
Statement preData = null;
// get last exprent
lastData = GetLastDirectData(stat.GetFirst());
if (lastData == null || (lastData.GetExprents().Count == 0))
{
return;
}
List <Exprent> lstExpr = lastData.GetExprents();
lastDoExprent = lstExpr[lstExpr.Count - 1];
bool issingle = false;
if (lstExpr.Count == 1)
{
// single exprent
if (lastData.GetAllPredecessorEdges().Count > 1)
{
// break edges
issingle = true;
}
}
bool haslast = issingle || lastDoExprent.type == Exprent.Exprent_Assignment || lastDoExprent
.type == Exprent.Exprent_Function;
if (!haslast)
{
return;
}
bool hasinit = false;
// search for an initializing exprent
Statement current = stat;
while (true)
{
Statement parent = current.GetParent();
if (parent == null)
{
break;
}
if (parent.type == Statement.Type_Sequence)
{
if (current == parent.GetFirst())
{
current = parent;
}
else
{
preData = current.GetNeighbours(StatEdge.Type_Regular, Statement.Direction_Backward
)[0];
preData = GetLastDirectData(preData);
if (preData != null && !(preData.GetExprents().Count == 0))
{
initDoExprent = preData.GetExprents()[preData.GetExprents().Count - 1];
if (initDoExprent.type == Exprent.Exprent_Assignment)
{
hasinit = true;
}
}
break;
}
}
else
{
break;
}
}
if (hasinit || issingle)
{
// FIXME: issingle sufficient?
HashSet <Statement> set = stat.GetNeighboursSet(StatEdge.Type_Continue, Statement.
Direction_Backward);
set.Remove(lastData);
if (!(set.Count == 0))
{
return;
}
stat.SetLooptype(DoStatement.Loop_For);
if (hasinit)
{
stat.SetInitExprent(preData.GetExprents().RemoveAtReturningValue(preData.GetExprents
().Count - 1));
}
stat.SetIncExprent(lastData.GetExprents().RemoveAtReturningValue(lastData.GetExprents
().Count - 1));
}
if ((lastData.GetExprents().Count == 0))
{
List <StatEdge> lst = lastData.GetAllSuccessorEdges();
if (!(lst.Count == 0))
{
lastData.RemoveSuccessor(lst[0]);
}
RemoveLastEmptyStatement(stat, lastData);
}
}
private static bool MatchWhile(DoStatement stat)
{
// search for an if condition at the entrance of the loop
Statement first = stat.GetFirst();
while (first.type == Statement.Type_Sequence)
{
first = first.GetFirst();
}
// found an if statement
if (first.type == Statement.Type_If)
{
IfStatement firstif = (IfStatement)first;
if ((firstif.GetFirst().GetExprents().Count == 0))
{
if (firstif.iftype == IfStatement.Iftype_If)
{
if (firstif.GetIfstat() == null)
{
StatEdge ifedge = firstif.GetIfEdge();
if (IsDirectPath(stat, ifedge.GetDestination()))
{
// exit condition identified
stat.SetLooptype(DoStatement.Loop_While);
// negate condition (while header)
IfExprent ifexpr = (IfExprent)firstif.GetHeadexprent().Copy();
ifexpr.NegateIf();
stat.SetConditionExprent(ifexpr.GetCondition());
// remove edges
firstif.GetFirst().RemoveSuccessor(ifedge);
firstif.RemoveSuccessor(firstif.GetAllSuccessorEdges()[0]);
if ((stat.GetAllSuccessorEdges().Count == 0))
{
ifedge.SetSource(stat);
if (ifedge.closure == stat)
{
ifedge.closure = stat.GetParent();
}
stat.AddSuccessor(ifedge);
}
// remove empty if statement as it is now part of the loop
if (firstif == stat.GetFirst())
{
BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(DecompilerContext
.GetCounterContainer().GetCounterAndIncrement(CounterContainer.Statement_Counter
)));
bstat.SetExprents(new List <Exprent>());
stat.ReplaceStatement(firstif, bstat);
}
else
{
// precondition: sequence must contain more than one statement!
Statement sequence = firstif.GetParent();
sequence.GetStats().RemoveWithKey(firstif.id);
sequence.SetFirst(sequence.GetStats()[0]);
}
return(true);
}
}
else
{
StatEdge elseedge = firstif.GetAllSuccessorEdges()[0];
if (IsDirectPath(stat, elseedge.GetDestination()))
{
// exit condition identified
stat.SetLooptype(DoStatement.Loop_While);
// no need to negate the while condition
stat.SetConditionExprent(((IfExprent)firstif.GetHeadexprent().Copy()).GetCondition
());
// remove edges
StatEdge ifedge = firstif.GetIfEdge();
firstif.GetFirst().RemoveSuccessor(ifedge);
firstif.RemoveSuccessor(elseedge);
if ((stat.GetAllSuccessorEdges().Count == 0))
{
elseedge.SetSource(stat);
if (elseedge.closure == stat)
{
elseedge.closure = stat.GetParent();
}
stat.AddSuccessor(elseedge);
}
if (firstif.GetIfstat() == null)
{
BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(DecompilerContext
.GetCounterContainer().GetCounterAndIncrement(CounterContainer.Statement_Counter
)));
bstat.SetExprents(new List <Exprent>());
ifedge.SetSource(bstat);
bstat.AddSuccessor(ifedge);
stat.ReplaceStatement(firstif, bstat);
}
else
{
// replace the if statement with its content
first.GetParent().ReplaceStatement(first, firstif.GetIfstat());
// lift closures
foreach (StatEdge prededge in elseedge.GetDestination().GetPredecessorEdges(StatEdge
.Type_Break))
{
if (stat.ContainsStatementStrict(prededge.closure))
{
stat.AddLabeledEdge(prededge);
}
}
LabelHelper.LowClosures(stat);
}
return(true);
}
}
}
}
}
return(false);
}
