Add support for VTA algorithm

README.md

@@ -129,7 +129,7 @@ Usage of go-callvis:
   -tests
     	Include test code.
   -algo string
-        Use specific algorithm for package analyzer: static, cha or rta (default "static")
+        Use specific algorithm for package analyzer: static, cha, rta or vta (default "static")
   -version
     	Show version and exit.
 ```

analysis.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/tools/go/callgraph"
 	"golang.org/x/tools/go/callgraph/cha"
 	"golang.org/x/tools/go/callgraph/rta"
+	"golang.org/x/tools/go/callgraph/vta"
 	"golang.org/x/tools/go/callgraph/static"
 
 	"golang.org/x/tools/go/packages"
@@ -29,6 +30,7 @@ const (
 	CallGraphTypeStatic CallGraphType = "static"
 	CallGraphTypeCha    CallGraphType = "cha"
 	CallGraphTypeRta    CallGraphType = "rta"
+	CallGraphTypeVta    CallGraphType = "vta"
 )
 
 // ==[ type def/func: analysis   ]===============================================
@@ -134,6 +136,8 @@ func (a *analysis) DoAnalysis(
 		graph = static.CallGraph(prog)
 	case CallGraphTypeCha:
 		graph = cha.CallGraph(prog)
+	case CallGraphTypeVta:
+		fallthrough
 	case CallGraphTypeRta:
 		mains, err := mainPackages(prog.AllPackages())
 		if err != nil {
@@ -152,8 +156,15 @@ func (a *analysis) DoAnalysis(
 		for _, init := range inits {
 			roots = append(roots, init)
 		}
-
 		graph = rta.Analyze(roots, true).CallGraph
+
+		if algo == CallGraphTypeVta {
+			funcs := make(map[*ssa.Function]bool)
+			for fun := range graph.Nodes {
+				funcs[fun] = true
+			}
+			graph = vta.CallGraph(funcs, graph)
+		}
 	default:
 		return fmt.Errorf("invalid call graph type: %s", a.opts.algo)
 	}

main.go

@@ -43,8 +43,8 @@ var (
 	outputFile    = flag.String("file", "", "output filename - omit to use server mode")
 	outputFormat  = flag.String("format", "svg", "output file format [svg | png | jpg | ...]")
 	cacheDir      = flag.String("cacheDir", "", "Enable caching to avoid unnecessary re-rendering, you can force rendering by adding 'refresh=true' to the URL query or emptying the cache directory")
-	callgraphAlgo = flag.String("algo", string(CallGraphTypeStatic), fmt.Sprintf("The algorithm used to construct the call graph. Possible values inlcude: %q, %q, %q",
-		CallGraphTypeStatic, CallGraphTypeCha, CallGraphTypeRta))
+	callgraphAlgo = flag.String("algo", string(CallGraphTypeStatic), fmt.Sprintf("The algorithm used to construct the call graph. Possible values inlcude: %q, %q, %q, %q",
+		CallGraphTypeStatic, CallGraphTypeCha, CallGraphTypeRta, CallGraphTypeVta))
 
 	debugFlag   = flag.Bool("debug", false, "Enable verbose log.")
 	versionFlag = flag.Bool("version", false, "Show version and exit.")