// Callstack displays an arbitrary path from a root of the callgraph
// to the function at the current position.
//
// The information may be misleading in a context-insensitive
// analysis. e.g. the call path X->Y->Z might be infeasible if Y never
// calls Z when it is called from X. TODO(adonovan): think about UI.
//
// TODO(adonovan): permit user to specify a starting point other than
// the analysis root.
//
func callstack(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis and build the complete call graph.
o.ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(o).CallGraph
cg.DeleteSyntheticNodes()
// Search for an arbitrary path from a root to the target function.
isEnd := func(n *callgraph.Node) bool { return n.Func == target }
callpath := callgraph.PathSearch(cg.Root, isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
return &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
}, nil
}
// Callers reports the possible callers of the function
// immediately enclosing the specified source location.
//
func callers(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis, recording each
// call found to originate from target.
o.ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(o).CallGraph
cg.DeleteSyntheticNodes()
edges := cg.CreateNode(target).In
// TODO(adonovan): sort + dedup calls to ensure test determinism.
return &callersResult{
target: target,
callgraph: cg,
edges: edges,
}, nil
}
// Callees reports the possible callees of the function call site
// identified by the specified source location.
func callees(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
// Determine the enclosing call for the specified position.
var e *ast.CallExpr
for _, n := range qpos.path {
if e, _ = n.(*ast.CallExpr); e != nil {
break
}
}
if e == nil {
return nil, fmt.Errorf("there is no function call here")
}
// TODO(adonovan): issue an error if the call is "too far
// away" from the current selection, as this most likely is
// not what the user intended.
// Reject type conversions.
if qpos.info.Types[e.Fun].IsType() {
return nil, fmt.Errorf("this is a type conversion, not a function call")
}
// Reject calls to built-ins.
if id, ok := unparen(e.Fun).(*ast.Ident); ok {
if b, ok := qpos.info.Uses[id].(*types.Builtin); ok {
return nil, fmt.Errorf("this is a call to the built-in '%s' operator", b.Name())
}
}
buildSSA(o)
// Ascertain calling function and call site.
callerFn := ssa.EnclosingFunction(pkg, qpos.path)
if callerFn == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Find the call site.
site, err := findCallSite(callerFn, e.Lparen)
if err != nil {
return nil, err
}
funcs, err := findCallees(o, site)
if err != nil {
return nil, err
}
return &calleesResult{
site: site,
funcs: funcs,
}, nil
}
// ssaValueForExpr returns the ssa.Value of the non-ast.Ident
// expression whose path to the root of the AST is path.
//
func ssaValueForExpr(prog *ssa.Program, qinfo *loader.PackageInfo, path []ast.Node) (value ssa.Value, isAddr bool, err error) {
pkg := prog.Package(qinfo.Pkg)
pkg.SetDebugMode(true)
pkg.Build()
fn := ssa.EnclosingFunction(pkg, path)
if fn == nil {
return nil, false, fmt.Errorf("no SSA function built for this location (dead code?)")
}
if v, addr := fn.ValueForExpr(path[0].(ast.Expr)); v != nil {
return v, addr, nil
}
return nil, false, fmt.Errorf("can't locate SSA Value for expression in %s", fn)
}
func (l langType) FuncName(fnx *ssa.Function) string {
pn := ""
if fnx.Signature.Recv() != nil {
pn = fnx.Signature.Recv().Type().String() // NOTE no use of underlying here
} else {
pn, _ = pogo.FuncPathName(fnx) //fmt.Sprintf("fn%d", fnx.Pos())
fn := ssa.EnclosingFunction(fnx.Package(), []ast.Node{fnx.Syntax()})
if fn == nil {
fn = fnx
}
if fn.Pkg != nil {
if fn.Pkg.Object != nil {
pn = fn.Pkg.Object.Path() // was .Name()
}
} else {
if fn.Object() != nil {
if fn.Object().Pkg() != nil {
pn = fn.Object().Pkg().Path() // was .Name()
}
}
}
}
return l.LangName(pn, fnx.Name())
}
func TestEnclosingFunction(t *testing.T) {
tests := []struct {
input string // the input file
substr string // first occurrence of this string denotes interval
fn string // name of expected containing function
}{
// We use distinctive numbers as syntactic landmarks.
// Ordinary function:
{`package main
func f() { println(1003) }`,
"100", "main.f"},
// Methods:
{`package main
type T int
func (t T) f() { println(200) }`,
"200", "(main.T).f"},
// Function literal:
{`package main
func f() { println(func() { print(300) }) }`,
"300", "main.f$1"},
// Doubly nested
{`package main
func f() { println(func() { print(func() { print(350) })})}`,
"350", "main.f$1$1"},
// Implicit init for package-level var initializer.
{"package main; var a = 400", "400", "main.init"},
// No code for constants:
{"package main; const a = 500", "500", "(none)"},
// Explicit init()
{"package main; func init() { println(600) }", "600", "main.init#1"},
// Multiple explicit init functions:
{`package main
func init() { println("foo") }
func init() { println(800) }`,
"800", "main.init#2"},
// init() containing FuncLit.
{`package main
func init() { println(func(){print(900)}) }`,
"900", "main.init#1$1"},
}
for _, test := range tests {
conf := loader.Config{Fset: token.NewFileSet()}
f, start, end := findInterval(t, conf.Fset, test.input, test.substr)
if f == nil {
continue
}
path, exact := astutil.PathEnclosingInterval(f, start, end)
if !exact {
t.Errorf("EnclosingFunction(%q) not exact", test.substr)
continue
}
conf.CreateFromFiles("main", f)
iprog, err := conf.Load()
if err != nil {
t.Error(err)
continue
}
prog := ssautil.CreateProgram(iprog, 0)
pkg := prog.Package(iprog.Created[0].Pkg)
pkg.Build()
name := "(none)"
fn := ssa.EnclosingFunction(pkg, path)
if fn != nil {
name = fn.String()
}
if name != test.fn {
t.Errorf("EnclosingFunction(%q in %q) got %s, want %s",
test.substr, test.input, name, test.fn)
continue
}
// While we're here: test HasEnclosingFunction.
if has := ssa.HasEnclosingFunction(pkg, path); has != (fn != nil) {
t.Errorf("HasEnclosingFunction(%q in %q) got %v, want %v",
test.substr, test.input, has, fn != nil)
continue
}
}
}
// Ensure that, in debug mode, we can determine the ssa.Value
// corresponding to every ast.Expr.
func TestValueForExpr(t *testing.T) {
if runtime.GOOS == "android" {
t.Skipf("no testdata dir on %s", runtime.GOOS)
}
conf := loader.Config{ParserMode: parser.ParseComments}
f, err := conf.ParseFile("testdata/valueforexpr.go", nil)
if err != nil {
t.Error(err)
return
}
conf.CreateFromFiles("main", f)
iprog, err := conf.Load()
if err != nil {
t.Error(err)
return
}
mainInfo := iprog.Created[0]
prog := ssautil.CreateProgram(iprog, 0)
mainPkg := prog.Package(mainInfo.Pkg)
mainPkg.SetDebugMode(true)
mainPkg.Build()
if false {
// debugging
for _, mem := range mainPkg.Members {
if fn, ok := mem.(*ssa.Function); ok {
fn.WriteTo(os.Stderr)
}
}
}
// Find the actual AST node for each canonical position.
parenExprByPos := make(map[token.Pos]*ast.ParenExpr)
ast.Inspect(f, func(n ast.Node) bool {
if n != nil {
if e, ok := n.(*ast.ParenExpr); ok {
parenExprByPos[e.Pos()] = e
}
}
return true
})
// Find all annotations of form /*@kind*/.
for _, c := range f.Comments {
text := strings.TrimSpace(c.Text())
if text == "" || text[0] != '@' {
continue
}
text = text[1:]
pos := c.End() + 1
position := prog.Fset.Position(pos)
var e ast.Expr
if target := parenExprByPos[pos]; target == nil {
t.Errorf("%s: annotation doesn't precede ParenExpr: %q", position, text)
continue
} else {
e = target.X
}
path, _ := astutil.PathEnclosingInterval(f, pos, pos)
if path == nil {
t.Errorf("%s: can't find AST path from root to comment: %s", position, text)
continue
}
fn := ssa.EnclosingFunction(mainPkg, path)
if fn == nil {
t.Errorf("%s: can't find enclosing function", position)
continue
}
v, gotAddr := fn.ValueForExpr(e) // (may be nil)
got := strings.TrimPrefix(fmt.Sprintf("%T", v), "*ssa.")
if want := text; got != want {
t.Errorf("%s: got value %q, want %q", position, got, want)
}
if v != nil {
T := v.Type()
if gotAddr {
T = T.Underlying().(*types.Pointer).Elem() // deref
}
if !types.Identical(T, mainInfo.TypeOf(e)) {
t.Errorf("%s: got type %s, want %s", position, mainInfo.TypeOf(e), T)
}
}
}
}
// Callstack displays an arbitrary path from a root of the callgraph
// to the function at the current position.
//
// The information may be misleading in a context-insensitive
// analysis. e.g. the call path X->Y->Z might be infeasible if Y never
// calls Z when it is called from X. TODO(adonovan): think about UI.
//
// TODO(adonovan): permit user to specify a starting point other than
// the analysis root.
//
func callstack(q *Query) error {
fset := token.NewFileSet()
lconf := loader.Config{Fset: fset, Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := loadWithSoftErrors(&lconf)
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
prog := ssautil.CreateProgram(lprog, 0)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return fmt.Errorf("this position is not inside a function")
}
// Defer SSA construction till after errors are reported.
prog.Build()
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
var callpath []*callgraph.Edge
isEnd := func(n *callgraph.Node) bool { return n.Func == target }
// First, build a callgraph containing only static call edges,
// and search for an arbitrary path from a root to the target function.
// This is quick, and the user wants a static path if one exists.
cg := static.CallGraph(prog)
cg.DeleteSyntheticNodes()
for _, ep := range entryPoints(ptaConfig.Mains) {
callpath = callgraph.PathSearch(cg.CreateNode(ep), isEnd)
if callpath != nil {
break
}
}
// No fully static path found.
// Run the pointer analysis and build a complete call graph.
if callpath == nil {
ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(ptaConfig).CallGraph
cg.DeleteSyntheticNodes()
callpath = callgraph.PathSearch(cg.Root, isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
}
q.Output(fset, &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
})
return nil
}
// Callstack displays an arbitrary path from a root of the callgraph
// to the function at the current position.
//
// The information may be misleading in a context-insensitive
// analysis. e.g. the call path X->Y->Z might be infeasible if Y never
// calls Z when it is called from X. TODO(adonovan): think about UI.
//
// TODO(adonovan): permit user to specify a starting point other than
// the analysis root.
//
func callstack(q *Query) error {
fset := token.NewFileSet()
lconf := loader.Config{Fset: fset, Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
prog := ssautil.CreateProgram(lprog, 0)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return fmt.Errorf("this position is not inside a function")
}
// Defer SSA construction till after errors are reported.
prog.BuildAll()
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis and build the complete call graph.
ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(ptaConfig).CallGraph
cg.DeleteSyntheticNodes()
// Search for an arbitrary path from a root to the target function.
isEnd := func(n *callgraph.Node) bool { return n.Func == target }
callpath := callgraph.PathSearch(cg.Root, isEnd)
if callpath != nil {
callpath = callpath[1:] // remove synthetic edge from <root>
}
q.Fset = fset
q.result = &callstackResult{
qpos: qpos,
target: target,
callpath: callpath,
}
return nil
}
// Callees reports the possible callees of the function call site
// identified by the specified source location.
func callees(q *Query) error {
lconf := loader.Config{Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
q.Fset = lprog.Fset
qpos, err := parseQueryPos(lprog, q.Pos, true) // needs exact pos
if err != nil {
return err
}
// Determine the enclosing call for the specified position.
var e *ast.CallExpr
for _, n := range qpos.path {
if e, _ = n.(*ast.CallExpr); e != nil {
break
}
}
if e == nil {
return fmt.Errorf("there is no function call here")
}
// TODO(adonovan): issue an error if the call is "too far
// away" from the current selection, as this most likely is
// not what the user intended.
// Reject type conversions.
if qpos.info.Types[e.Fun].IsType() {
return fmt.Errorf("this is a type conversion, not a function call")
}
// Deal with obviously static calls before constructing SSA form.
// Some static calls may yet require SSA construction,
// e.g. f := func(){}; f().
switch funexpr := unparen(e.Fun).(type) {
case *ast.Ident:
switch obj := qpos.info.Uses[funexpr].(type) {
case *types.Builtin:
// Reject calls to built-ins.
return fmt.Errorf("this is a call to the built-in '%s' operator", obj.Name())
case *types.Func:
// This is a static function call
q.result = &calleesTypesResult{
site: e,
callee: obj,
}
return nil
}
case *ast.SelectorExpr:
sel := qpos.info.Selections[funexpr]
if sel == nil {
// qualified identifier.
// May refer to top level function variable
// or to top level function.
callee := qpos.info.Uses[funexpr.Sel]
if obj, ok := callee.(*types.Func); ok {
q.result = &calleesTypesResult{
site: e,
callee: obj,
}
return nil
}
} else if sel.Kind() == types.MethodVal {
// Inspect the receiver type of the selected method.
// If it is concrete, the call is statically dispatched.
// (Due to implicit field selections, it is not enough to look
// at sel.Recv(), the type of the actual receiver expression.)
method := sel.Obj().(*types.Func)
recvtype := method.Type().(*types.Signature).Recv().Type()
if !types.IsInterface(recvtype) {
// static method call
q.result = &calleesTypesResult{
site: e,
callee: method,
}
return nil
}
}
}
prog := ssautil.CreateProgram(lprog, ssa.GlobalDebug)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
// Defer SSA construction till after errors are reported.
prog.Build()
// Ascertain calling function and call site.
callerFn := ssa.EnclosingFunction(pkg, qpos.path)
if callerFn == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Find the call site.
site, err := findCallSite(callerFn, e)
if err != nil {
return err
}
funcs, err := findCallees(ptaConfig, site)
if err != nil {
return err
}
q.result = &calleesSSAResult{
site: site,
funcs: funcs,
}
return nil
}
// Callers reports the possible callers of the function
// immediately enclosing the specified source location.
//
func callers(q *Query) error {
lconf := loader.Config{Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
q.Fset = lprog.Fset
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
prog := ssautil.CreateProgram(lprog, 0)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return fmt.Errorf("this position is not inside a function")
}
// Defer SSA construction till after errors are reported.
prog.Build()
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
// If the function is never address-taken, all calls are direct
// and can be found quickly by inspecting the whole SSA program.
cg := directCallsTo(target, entryPoints(ptaConfig.Mains))
if cg == nil {
// Run the pointer analysis, recording each
// call found to originate from target.
// (Pointer analysis may return fewer results than
// directCallsTo because it ignores dead code.)
ptaConfig.BuildCallGraph = true
cg = ptrAnalysis(ptaConfig).CallGraph
}
cg.DeleteSyntheticNodes()
edges := cg.CreateNode(target).In
// TODO(adonovan): sort + dedup calls to ensure test determinism.
q.result = &callersResult{
target: target,
callgraph: cg,
edges: edges,
}
return nil
}
// Returns true if unused
func checkObj(expr *ast.Ident, object types.Object, prog *loader.Program, ssaprog *ssa.Program, fset *token.FileSet) (unused bool) {
if _, ok := object.(*types.Var); !ok {
if debug {
fmt.Println("Skipping object", object)
}
return false
}
pkg, node, _ := prog.PathEnclosingInterval(expr.Pos(), expr.End())
spkg := ssaprog.Package(pkg.Pkg)
f := ssa.EnclosingFunction(spkg, node)
if f == nil {
if debug {
fmt.Printf("Unknown function %v %v %v %v\n", fset.Position(expr.Pos()), object, pkg, prog)
}
return false
}
value, _ := f.ValueForExpr(expr)
// Unwrap unops and grab the value inside
if v, ok := value.(*ssa.UnOp); ok {
if debug {
fmt.Println("Unwrapping unop")
}
value = v.X
}
if debug {
fmt.Printf("%v %v: %v %#v\n", fset.Position(expr.Pos()), expr, object, value)
}
if _, ok := value.(*ssa.Global); ok {
if debug {
fmt.Printf(" is global\n")
}
return false
}
if value == nil {
if debug {
fmt.Println("Value is nil", object)
}
return false
}
refs := value.Referrers()
if refs == nil {
if debug {
fmt.Println("Referrers is nil", object)
}
return false
}
if debug {
fmt.Printf(" (refs) %v\n", refs)
}
hasRef := false
for _, r := range *refs {
_, ok := r.(*ssa.DebugRef)
hasRef = hasRef || !ok
if debug && !ok {
fmt.Printf("%v %v: %v %v\n", fset.Position(expr.Pos()), expr, object, r)
}
}
if !hasRef {
unused = true
}
return unused
}
// Callers reports the possible callers of the function
// immediately enclosing the specified source location.
//
func callers(q *Query) error {
lconf := loader.Config{Build: q.Build}
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
q.Fset = lprog.Fset
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
prog := ssautil.CreateProgram(lprog, 0)
ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
if err != nil {
return err
}
pkg := prog.Package(qpos.info.Pkg)
if pkg == nil {
return fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return fmt.Errorf("this position is not inside a function")
}
// Defer SSA construction till after errors are reported.
prog.Build()
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return fmt.Errorf("no SSA function built for this location (dead code?)")
}
// TODO(adonovan): opt: if function is never address-taken, skip
// the pointer analysis. Just look for direct calls. This can
// be done in a single pass over the SSA.
// Run the pointer analysis, recording each
// call found to originate from target.
ptaConfig.BuildCallGraph = true
cg := ptrAnalysis(ptaConfig).CallGraph
cg.DeleteSyntheticNodes()
edges := cg.CreateNode(target).In
// TODO(adonovan): sort + dedup calls to ensure test determinism.
q.result = &callersResult{
target: target,
callgraph: cg,
edges: edges,
}
return nil
}
