Golang ssa.EnclosingFunction函數代碼示例

// 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
}

//.........這裏部分代碼省略.........
	}
	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
}