// pointer runs the pointer analysis.
func (a *analysis) pointer(mainPkgs []*ssa.Package) {
// Run the pointer analysis and build the complete callgraph.
a.ptaConfig.Mains = mainPkgs
a.ptaConfig.BuildCallGraph = true
a.ptaConfig.Reflection = false // (for now)
a.result.setStatusf("Pointer analysis running...")
ptares, err := pointer.Analyze(&a.ptaConfig)
if err != nil {
// If this happens, it indicates a bug.
a.result.setStatusf("Pointer analysis failed: %s.", err)
return
}
log.Print("Pointer analysis complete.")
// Add the results of pointer analysis.
a.result.setStatusf("Computing channel peers...")
a.doChannelPeers(ptares.Queries)
a.result.setStatusf("Computing dynamic call graph edges...")
a.doCallgraph(ptares.CallGraph)
a.result.setStatusf("Analysis complete.")
}
// This program demonstrates how to use the pointer analysis to
// obtain a conservative call-graph of a Go program.
// It also shows how to compute the points-to set of a variable,
// in this case, (C).f's ch parameter.
//
func Example() {
const myprog = `
package main
import "fmt"
type I interface {
f(map[string]int)
}
type C struct{}
func (C) f(m map[string]int) {
fmt.Println("C.f()")
}
func main() {
var i I = C{}
x := map[string]int{"one":1}
i.f(x) // dynamic method call
}
`
// Construct a loader.
conf := loader.Config{SourceImports: true}
// Parse the input file.
file, err := conf.ParseFile("myprog.go", myprog)
if err != nil {
fmt.Print(err) // parse error
return
}
// Create single-file main package and import its dependencies.
conf.CreateFromFiles("main", file)
iprog, err := conf.Load()
if err != nil {
fmt.Print(err) // type error in some package
return
}
// Create SSA-form program representation.
prog := ssa.Create(iprog, 0)
mainPkg := prog.Package(iprog.Created[0].Pkg)
// Build SSA code for bodies of all functions in the whole program.
prog.BuildAll()
// Configure the pointer analysis to build a call-graph.
config := &pointer.Config{
Mains: []*ssa.Package{mainPkg},
BuildCallGraph: true,
}
// Query points-to set of (C).f's parameter m, a map.
C := mainPkg.Type("C").Type()
Cfm := prog.LookupMethod(C, mainPkg.Object, "f").Params[1]
config.AddQuery(Cfm)
// Run the pointer analysis.
result, err := pointer.Analyze(config)
if err != nil {
panic(err) // internal error in pointer analysis
}
// Find edges originating from the main package.
// By converting to strings, we de-duplicate nodes
// representing the same function due to context sensitivity.
var edges []string
callgraph.GraphVisitEdges(result.CallGraph, func(edge *callgraph.Edge) error {
caller := edge.Caller.Func
if caller.Pkg == mainPkg {
edges = append(edges, fmt.Sprint(caller, " --> ", edge.Callee.Func))
}
return nil
})
// Print the edges in sorted order.
sort.Strings(edges)
for _, edge := range edges {
fmt.Println(edge)
}
fmt.Println()
// Print the labels of (C).f(m)'s points-to set.
fmt.Println("m may point to:")
var labels []string
for _, l := range result.Queries[Cfm].PointsTo().Labels() {
label := fmt.Sprintf(" %s: %s", prog.Fset.Position(l.Pos()), l)
labels = append(labels, label)
}
sort.Strings(labels)
for _, label := range labels {
fmt.Println(label)
}
// Output:
// (main.C).f --> fmt.Println
// main.init --> fmt.init
// main.main --> (main.C).f
//
// m may point to:
// myprog.go:18:21: makemap
}
func doOneInput(input, filename string) bool {
conf := loader.Config{SourceImports: true}
// Parsing.
f, err := conf.ParseFile(filename, input)
if err != nil {
fmt.Println(err)
return false
}
// Create single-file main package and import its dependencies.
conf.CreateFromFiles("main", f)
iprog, err := conf.Load()
if err != nil {
fmt.Println(err)
return false
}
mainPkgInfo := iprog.Created[0].Pkg
// SSA creation + building.
prog := ssa.Create(iprog, ssa.SanityCheckFunctions)
prog.BuildAll()
mainpkg := prog.Package(mainPkgInfo)
ptrmain := mainpkg // main package for the pointer analysis
if mainpkg.Func("main") == nil {
// No main function; assume it's a test.
ptrmain = prog.CreateTestMainPackage(mainpkg)
}
// Find all calls to the built-in print(x). Analytically,
// print is a no-op, but it's a convenient hook for testing
// the PTS of an expression, so our tests use it.
probes := make(map[*ssa.CallCommon]bool)
for fn := range ssautil.AllFunctions(prog) {
if fn.Pkg == mainpkg {
for _, b := range fn.Blocks {
for _, instr := range b.Instrs {
if instr, ok := instr.(ssa.CallInstruction); ok {
if b, ok := instr.Common().Value.(*ssa.Builtin); ok && b.Name() == "print" {
probes[instr.Common()] = true
}
}
}
}
}
}
ok := true
lineMapping := make(map[string]string) // maps "file:line" to @line tag
// Parse expectations in this input.
var exps []*expectation
re := regexp.MustCompile("// *@([a-z]*) *(.*)$")
lines := strings.Split(input, "\n")
for linenum, line := range lines {
linenum++ // make it 1-based
if matches := re.FindAllStringSubmatch(line, -1); matches != nil {
match := matches[0]
kind, rest := match[1], match[2]
e := &expectation{kind: kind, filename: filename, linenum: linenum}
if kind == "line" {
if rest == "" {
ok = false
e.errorf("@%s expectation requires identifier", kind)
} else {
lineMapping[fmt.Sprintf("%s:%d", filename, linenum)] = rest
}
continue
}
if e.needsProbe() && !strings.Contains(line, "print(") {
ok = false
e.errorf("@%s expectation must follow call to print(x)", kind)
continue
}
switch kind {
case "pointsto":
e.args = split(rest, "|")
case "types":
for _, typstr := range split(rest, "|") {
var t types.Type = types.Typ[types.Invalid] // means "..."
if typstr != "..." {
texpr, err := parser.ParseExpr(typstr)
if err != nil {
ok = false
// Don't print err since its location is bad.
e.errorf("'%s' is not a valid type", typstr)
continue
}
mainFileScope := mainpkg.Object.Scope().Child(0)
t, _, err = types.EvalNode(prog.Fset, texpr, mainpkg.Object, mainFileScope)
if err != nil {
ok = false
// Don't print err since its location is bad.
e.errorf("'%s' is not a valid type: %s", typstr, err)
continue
}
}
e.types = append(e.types, t)
}
case "calls":
e.args = split(rest, "->")
// TODO(adonovan): eagerly reject the
// expectation if fn doesn't denote
// existing function, rather than fail
// the expectation after analysis.
if len(e.args) != 2 {
ok = false
e.errorf("@calls expectation wants 'caller -> callee' arguments")
continue
}
case "warning":
lit, err := strconv.Unquote(strings.TrimSpace(rest))
if err != nil {
ok = false
e.errorf("couldn't parse @warning operand: %s", err.Error())
continue
}
e.args = append(e.args, lit)
default:
ok = false
e.errorf("unknown expectation kind: %s", e)
continue
}
exps = append(exps, e)
}
}
var log bytes.Buffer
fmt.Fprintf(&log, "Input: %s\n", filename)
// Run the analysis.
config := &pointer.Config{
Reflection: true,
BuildCallGraph: true,
Mains: []*ssa.Package{ptrmain},
Log: &log,
}
for probe := range probes {
v := probe.Args[0]
if pointer.CanPoint(v.Type()) {
config.AddQuery(v)
}
}
// Print the log is there was an error or a panic.
complete := false
defer func() {
if !complete || !ok {
log.WriteTo(os.Stderr)
}
}()
result, err := pointer.Analyze(config)
if err != nil {
panic(err) // internal error in pointer analysis
}
// Check the expectations.
for _, e := range exps {
var call *ssa.CallCommon
var pts pointer.PointsToSet
var tProbe types.Type
if e.needsProbe() {
if call, pts = findProbe(prog, probes, result.Queries, e); call == nil {
ok = false
e.errorf("unreachable print() statement has expectation %s", e)
continue
}
tProbe = call.Args[0].Type()
if !pointer.CanPoint(tProbe) {
ok = false
e.errorf("expectation on non-pointerlike operand: %s", tProbe)
continue
}
}
switch e.kind {
case "pointsto":
if !checkPointsToExpectation(e, pts, lineMapping, prog) {
ok = false
}
case "types":
if !checkTypesExpectation(e, pts, tProbe) {
ok = false
}
case "calls":
if !checkCallsExpectation(prog, e, result.CallGraph) {
ok = false
}
case "warning":
if !checkWarningExpectation(prog, e, result.Warnings) {
ok = false
}
}
}
complete = true
// ok = false // debugging: uncomment to always see log
return ok
}