public static (ControlFlowGraph, string) Decompile(ControlFlowGraph graph)
{
if (graph == null)
{
throw new ArgumentNullException(nameof(graph));
}
foreach (var index in graph.GetDfsPostOrder())
{
var children = graph.Children(index);
if (children.Length != 1 || children[0] == index)
{
continue;
}
// If the node is the target of a back-edge then leave it alone: it's probably an empty loop-header node
if (graph.GetBackEdges().Any(x => x.end == index))
{
continue;
}
int child = children[0];
// Func<string> vis = () => graph.ToVis().AddPointer("index", index).AddPointer("child", child).ToString(); // For VS Code debug visualisation
var childsParents = graph.Parents(child);
var grandChildren = graph.Children(child);
if (childsParents.Length != 1 || grandChildren.Length > 1)
{
continue; // Is a jump target from somewhere else as well - can't combine
}
if (grandChildren.Length == 1 && (grandChildren[0] == index || grandChildren[0] == child))
{
continue; // Loops around, not a sequence
}
var node = graph.Nodes[index];
var childNode = graph.Nodes[child];
var updated = graph
.RemoveNode(child)
.ReplaceNode(index, Emit.Seq(node, childNode));
foreach (var grandChild in grandChildren)
{
updated = updated.AddEdge(index, grandChild, graph.GetEdgeLabel(child, grandChild));
}
return(updated, $"Reduce sequence (node {index}, child {child})");
}
return(graph, null);
}
public static (ControlFlowGraph, string) Decompile(ControlFlowGraph graph /*, RecordFunc recordFunc = null*/)
{
if (graph == null)
{
throw new ArgumentNullException(nameof(graph));
}
var regions = graph.GetAllSeseRegions();
// Do smallest regions first, as they may be nested in a larger one
foreach (var(region, regionEntry, regionExit) in regions.OrderBy(x => x.nodes.Count))
{
if (regionEntry == graph.EntryIndex)
{
continue; // Don't try and reduce the 'sequence' of start node -> actual entry point nodes when there's only one entry
}
/* Func<string> vis = () => // For VS Code debug visualisation
* {
* var d = graph.ToVis();
* foreach(var n in d.Nodes)
* if (region.Contains(int.Parse(n.Id, CultureInfo.InvariantCulture)))
* n.Color = "#4040b0";
* return d.ToString();
* }; */
bool containsOther = regions.Any(x => x.nodes != region && !x.nodes.Except(region).Any());
if (containsOther)
{
continue;
}
// If either end is a loop header then leave it alone and let the loop rule handle it.
if (graph.GetBackEdges().Any(x => x.end == regionEntry || x.end == regionExit))
{
continue;
}
var cut = graph.Cut(region, regionEntry, regionExit);
if (cut.Cut.IsCyclic()) // Loop reduction comes later
{
continue;
}
return(cut.Merge(ReduceSese(cut.Cut)), Description);
}
return(graph, null);
}
public static (ControlFlowGraph, string) Decompile(ControlFlowGraph graph)
{
var(reachability, reachableCount) = graph.Reverse().GetReachability(graph.ExitIndex);
if (reachableCount == graph.ActiveNodeCount)
{
return(graph, null);
}
var acyclic = graph.RemoveBackEdges();
var distances = acyclic.GetLongestPaths(acyclic.EntryIndex);
int longestDistance = 0;
int winner = -1;
for (int i = 0; i < graph.NodeCount; i++)
{
if (graph.Nodes[i] == null || reachability[i]) // Only consider nodes that can't reach the exit
{
continue;
}
if (distances[i] <= longestDistance)
{
continue;
}
longestDistance = distances[i];
winner = i;
}
if (winner == -1)
{
return(graph, null);
}
foreach (var backEdge in graph.GetBackEdges().Where(x => x.start == winner))
{
return(graph.AddEdge(backEdge.end, graph.ExitIndex, CfgEdge.LoopSuccessor), Description);
}
return(graph.AddEdge(winner, graph.ExitIndex, CfgEdge.DisjointGraphFixup), Description);
}
internal static string GetGraphInformation(ControlFlowGraph cfg)
{
var str = new StringBuilder();
str.AppendLine("Доминаторы:");
var domTree = new DominatorTree().GetDominators(cfg);
foreach (var pair in domTree)
{
foreach (var x in pair.Value)
{
str.AppendLine($"{cfg.VertexOf(x)} dom {cfg.VertexOf(pair.Key)}");
}
str.AppendLine("----------------");
}
str.AppendLine("\r\nКлассификация ребер:");
foreach (var pair in cfg.ClassifiedEdges)
{
str.AppendLine($"{ pair }");
}
str.AppendLine("\r\nОбходы графа:");
str.AppendLine($"Прямой: { string.Join(" -> ", cfg.PreOrderNumeration) }");
str.AppendLine($"Обратный: { string.Join(" -> ", cfg.PostOrderNumeration) }");
str.AppendLine($"\r\nГлубинное остовное дерево:");
foreach (var x in cfg.DepthFirstSpanningTree)
{
str.AppendLine($"({x.from} - > {x.to})");
}
var backEdges = cfg.GetBackEdges();
if (backEdges.Count > 0)
{
str.AppendLine("\r\nОбратные ребра:");
foreach (var x in backEdges)
{
str.AppendLine($"({cfg.VertexOf(x.Item1)}, {cfg.VertexOf(x.Item2)})");
}
}
else
{
str.AppendLine("\r\nОбратных ребер нет");
}
var answ = cfg.IsReducibleGraph() ? "Граф приводим" : "Граф неприводим";
str.AppendLine($"\r\n{answ}");
if (cfg.IsReducibleGraph())
{
var natLoops = NaturalLoop.GetAllNaturalLoops(cfg);
if (natLoops.Count > 0)
{
str.AppendLine($"\r\nЕстественные циклы:");
foreach (var x in natLoops)
{
if (x.Count == 0)
{
continue;
}
for (var i = 0; i < x.Count; i++)
{
str.AppendLine($"Номер блока: {i}");
foreach (var xfrom in x[i].GetInstructions())
{
str.AppendLine(xfrom.ToString());
}
}
str.AppendLine();
str.AppendLine("-------------");
}
}
else
{
str.AppendLine($"\r\nЕстественных циклов нет");
}
}
else
{
str.AppendLine($"\r\nНевозможно определить естественные циклы, т.к. граф неприводим");
}
return(str.ToString());
}
