// findPrim locates a control flow primitive in the provided control flow graph
// and merges its nodes into a single node.
func findPrim(graph *dot.Graph, subs []*graphs.SubGraph, step int) (*primitive.Primitive, error) {
for _, sub := range subs {
// Locate an isomorphism of sub in graph.
m, ok := iso.Search(graph, sub)
if !ok {
// No match, try next control flow primitive.
continue
}
if flagVerbose && !flagQuiet {
printMapping(graph, sub, m)
}
// Output pre-merge intermediate control flow graphs.
if flagSteps {
// Highlight nodes to be replaced in red.
for _, preNodeName := range m {
preNode, ok := graph.Nodes.Lookup[preNodeName]
if !ok {
return nil, errutil.Newf("unable to locate pre-merge node %q", preNodeName)
}
if preNode.Attrs == nil {
preNode.Attrs = dot.NewAttrs()
}
preNode.Attrs["fillcolor"] = "red"
preNode.Attrs["style"] = "filled"
}
// Store pre-merge DOT graph.
stepName := fmt.Sprintf("%s_%da", graph.Name, step)
if err := createDOT(stepName, graph); err != nil {
return nil, errutil.Err(err)
}
// Restore node colour.
for _, preNodeName := range m {
preNode, ok := graph.Nodes.Lookup[preNodeName]
if !ok {
return nil, errutil.Newf("unable to locate pre-merge node %q", preNodeName)
}
delete(preNode.Attrs, "fillcolor")
delete(preNode.Attrs, "style")
}
}
// Check if one of the nodes to be merged has the label "entry".
hasEntry := false
for _, preNodeName := range m {
preNode, ok := graph.Nodes.Lookup[preNodeName]
if !ok {
return nil, errutil.Newf("unable to locate pre-merge node %q", preNodeName)
}
if preNode.Attrs != nil && preNode.Attrs["label"] == "entry" {
hasEntry = true
break
}
}
// Merge the nodes of the subgraph isomorphism into a single node.
postNodeName, err := merge.Merge(graph, m, sub)
if err != nil {
return nil, errutil.Err(err)
}
// Add "entry" label to new node if present in the pre-merge nodes.
if hasEntry {
postNode, ok := graph.Nodes.Lookup[postNodeName]
if !ok {
return nil, errutil.Newf("unable to locate post-merge node %q", postNodeName)
}
if postNode.Attrs == nil {
postNode.Attrs = dot.NewAttrs()
}
postNode.Attrs["label"] = "entry"
index := postNode.Index
graph.Nodes.Nodes[0], graph.Nodes.Nodes[index] = postNode, graph.Nodes.Nodes[0]
}
// Output post-merge intermediate control flow graphs.
if flagSteps {
// Highlight node to be replaced in red.
postNode, ok := graph.Nodes.Lookup[postNodeName]
if !ok {
return nil, errutil.Newf("unable to locate post-merge node %q", postNodeName)
}
if postNode.Attrs == nil {
postNode.Attrs = dot.NewAttrs()
}
postNode.Attrs["fillcolor"] = "red"
postNode.Attrs["style"] = "filled"
// Store post-merge DOT graph.
stepName := fmt.Sprintf("%s_%db", graph.Name, step)
if err := createDOT(stepName, graph); err != nil {
return nil, errutil.Err(err)
}
// Restore node colour.
delete(postNode.Attrs, "fillcolor")
delete(postNode.Attrs, "style")
}
// Create a new control flow primitive.
prim := &primitive.Primitive{
Node: postNodeName,
Prim: sub.Name,
Nodes: m,
}
return prim, nil
}
return nil, errutil.New("unable to locate control flow primitive")
}
// locateAndMerge parses the provided graphs and tries to merge isomorphisms of
// the subgraph in the graph into single nodes.
func locateAndMerge(graphPath, subPath string) error {
// Parse graph.
graph, err := dot.ParseFile(graphPath)
if err != nil {
return errutil.Err(err)
}
// Search for subgraph in GOPATH if not found.
if ok, _ := osutil.Exists(subPath); !ok {
dir, err := goutil.SrcDir("decomp.org/decomp/graphs/testdata/primitives")
if err != nil {
return errutil.Err(err)
}
subPath = filepath.Join(dir, subPath)
}
sub, err := graphs.ParseSubGraph(subPath)
if err != nil {
return errutil.Err(err)
}
// Merge isomorphisms.
found := false
if len(flagStart) > 0 {
// Merge an isomorphism of sub in graph which starts at the node
// specified by the "-start" flag.
m, ok := iso.Isomorphism(graph, flagStart, sub)
if ok {
found = true
printMapping(graph, sub, m)
_, err := merge.Merge(graph, m, sub)
if err != nil {
return errutil.Err(err)
}
}
} else {
// Merge all isomorphisms of sub in graph.
for {
m, ok := iso.Search(graph, sub)
if !ok {
break
}
found = true
printMapping(graph, sub, m)
_, err := merge.Merge(graph, m, sub)
if err != nil {
return errutil.Err(err)
}
}
}
// Store DOT and PNG representation of graph.
if found {
err = dump(graph)
if err != nil {
return errutil.Err(err)
}
} else {
fmt.Println("not found.")
}
return nil
}