public static void RemoveRedundantReturns(RootStatement root)
{
DummyExitStatement dummyExit = root.GetDummyExit();
foreach (StatEdge edge in dummyExit.GetAllPredecessorEdges())
{
if (!edge.@explicit)
{
Statement source = edge.GetSource();
List <Exprent> lstExpr = source.GetExprents();
if (lstExpr != null && !(lstExpr.Count == 0))
{
Exprent expr = lstExpr[lstExpr.Count - 1];
if (expr.type == Exprent.Exprent_Exit)
{
ExitExprent ex = (ExitExprent)expr;
if (ex.GetExitType() == ExitExprent.Exit_Return && ex.GetValue() == null)
{
// remove redundant return
dummyExit.AddBytecodeOffsets(ex.bytecode);
lstExpr.RemoveAtReturningValue(lstExpr.Count - 1);
}
}
}
}
}
}
private static RootStatement GraphToStatement(ControlFlowGraph graph)
{
VBStyleCollection <Statement, int> stats = new VBStyleCollection <Statement, int>();
VBStyleCollection <BasicBlock, int> blocks = graph.GetBlocks();
foreach (BasicBlock block in blocks)
{
stats.AddWithKey(new BasicBlockStatement(block), block.id);
}
BasicBlock firstblock = graph.GetFirst();
// head statement
Statement firstst = stats.GetWithKey(firstblock.id);
// dummy exit statement
DummyExitStatement dummyexit = new DummyExitStatement();
Statement general;
if (stats.Count > 1 || firstblock.IsSuccessor(firstblock))
{
// multiple basic blocks or an infinite loop of one block
general = new GeneralStatement(firstst, stats, null);
}
else
{
// one straightforward basic block
RootStatement root = new RootStatement(firstst, dummyexit);
firstst.AddSuccessor(new StatEdge(StatEdge.Type_Break, firstst, dummyexit, root));
return(root);
}
foreach (BasicBlock block in blocks)
{
Statement stat = stats.GetWithKey(block.id);
foreach (BasicBlock succ in block.GetSuccs())
{
Statement stsucc = stats.GetWithKey(succ.id);
int type;
if (stsucc == firstst)
{
type = StatEdge.Type_Continue;
}
else if (graph.GetFinallyExits().Contains(block))
{
type = StatEdge.Type_Finallyexit;
stsucc = dummyexit;
}
else if (succ.id == graph.GetLast().id)
{
type = StatEdge.Type_Break;
stsucc = dummyexit;
}
else
{
type = StatEdge.Type_Regular;
}
stat.AddSuccessor(new StatEdge(type, stat, (type == StatEdge.Type_Continue) ? general
: stsucc, (type == StatEdge.Type_Regular) ? null : general));
}
// exceptions edges
foreach (BasicBlock succex in block.GetSuccExceptions())
{
Statement stsuccex = stats.GetWithKey(succex.id);
ExceptionRangeCFG range = graph.GetExceptionRange(succex, block);
if (!range.IsCircular())
{
stat.AddSuccessor(new StatEdge(stat, stsuccex, range.GetExceptionTypes()));
}
}
}
general.BuildContinueSet();
general.BuildMonitorFlags();
return(new RootStatement(general, dummyexit));
}
