Exemple #1
0
// find all panic instructions in program
// TODO: handle go panic() and defer panic(). They're handled
// as builtin calls, but unlikely to show up in real code.
func findPanics(prog *ssa.Program) []*ssa.Panic {
	var panics []*ssa.Panic
	for f := range ssautil.AllFunctions(prog) {
		for _, b := range f.Blocks {
			for _, i := range b.Instrs {
				p, ok := i.(*ssa.Panic)
				if ok {
					panics = append(panics, p)
				}
			}
		}
	}
	return panics
}
Exemple #2
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// translatePackage translates an *ssa.Package into an LLVM module, and returns
// the translation unit information.
func (u *unit) translatePackage(pkg *ssa.Package) {
	ms := make([]ssa.Member, len(pkg.Members))
	i := 0
	for _, m := range pkg.Members {
		ms[i] = m
		i++
	}

	sort.Sort(byMemberName(ms))

	// Initialize global storage and type descriptors for this package.
	// We must create globals regardless of whether they're referenced,
	// hence the duplication in frame.value.
	for _, m := range ms {
		switch v := m.(type) {
		case *ssa.Global:
			elemtyp := deref(v.Type())
			llelemtyp := u.llvmtypes.ToLLVM(elemtyp)
			vname := u.types.mc.mangleGlobalName(v)
			global := llvm.AddGlobal(u.module.Module, llelemtyp, vname)
			if !v.Object().Exported() {
				global.SetLinkage(llvm.InternalLinkage)
			}
			u.addGlobal(global, elemtyp)
			global = llvm.ConstBitCast(global, u.llvmtypes.ToLLVM(v.Type()))
			u.globals[v] = global
		case *ssa.Type:
			u.types.getTypeDescriptorPointer(v.Type())
		}
	}

	// Define functions.
	u.defineFunctionsInOrder(ssautil.AllFunctions(pkg.Prog))

	// Emit initializers for type descriptors, which may trigger
	// the resolution of additional functions.
	u.types.emitTypeDescInitializers()

	// Define remaining functions that were resolved during
	// runtime type mapping, but not defined.
	u.defineFunctionsInOrder(u.undefinedFuncs)

	// Set initializers for globals.
	for global, init := range u.globalInits {
		initval := init.build(global.Type().ElementType())
		global.SetInitializer(initval)
	}
}
Exemple #3
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// progChanOps extract all channels from a program.
func progChanOps(prog *ssa.Program) []ChanOp {
	var ops []ChanOp // all sends/receives of opposite direction

	// Look at all channel operations in the whole ssa.Program.
	allFuncs := ssautil.AllFunctions(prog)
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				for _, op := range chanOps(instr) {
					ops = append(ops, op)
				}
			}
		}
	}
	return ops
}
Exemple #4
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// visitInstrs visits all SSA instructions in the program.
func (a *analysis) visitInstrs(pta bool) {
	log.Print("Visit instructions...")
	for fn := range ssautil.AllFunctions(a.prog) {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				// CALLEES (static)
				// (Dynamic calls require pointer analysis.)
				//
				// We use the SSA representation to find the static callee,
				// since in many cases it does better than the
				// types.Info.{Refs,Selection} information.  For example:
				//
				//   defer func(){}()      // static call to anon function
				//   f := func(){}; f()    // static call to anon function
				//   f := fmt.Println; f() // static call to named function
				//
				// The downside is that we get no static callee information
				// for packages that (transitively) contain errors.
				if site, ok := instr.(ssa.CallInstruction); ok {
					if callee := site.Common().StaticCallee(); callee != nil {
						// TODO(adonovan): callgraph: elide wrappers.
						// (Do static calls ever go to wrappers?)
						if site.Common().Pos() != token.NoPos {
							a.addCallees(site, []*ssa.Function{callee})
						}
					}
				}

				if !pta {
					continue
				}

				// CHANNEL PEERS
				// Collect send/receive/close instructions in the whole ssa.Program.
				for _, op := range chanOps(instr) {
					a.ops = append(a.ops, op)
					a.ptaConfig.AddQuery(op.ch) // add channel ssa.Value to PTA query
				}
			}
		}
	}
	log.Print("Visit instructions complete")
}
Exemple #5
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// CallGraph computes the call graph of the specified program
// considering only static calls.
//
func CallGraph(prog *ssa.Program) *callgraph.Graph {
	cg := callgraph.New(nil) // TODO(adonovan) eliminate concept of rooted callgraph

	// TODO(adonovan): opt: use only a single pass over the ssa.Program.
	for f := range ssautil.AllFunctions(prog) {
		fnode := cg.CreateNode(f)
		for _, b := range f.Blocks {
			for _, instr := range b.Instrs {
				if site, ok := instr.(ssa.CallInstruction); ok {
					if g := site.Common().StaticCallee(); g != nil {
						gnode := cg.CreateNode(g)
						callgraph.AddEdge(fnode, site, gnode)
					}
				}
			}
		}
	}

	return cg
}
Exemple #6
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func TestStdlib(t *testing.T) {
	// Load, parse and type-check the program.
	t0 := time.Now()
	alloc0 := bytesAllocated()

	// Load, parse and type-check the program.
	ctxt := build.Default // copy
	ctxt.GOPATH = ""      // disable GOPATH
	conf := loader.Config{Build: &ctxt}
	for _, path := range buildutil.AllPackages(conf.Build) {
		if skip[path] {
			continue
		}
		conf.ImportWithTests(path)
	}

	iprog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load failed: %v", err)
	}

	t1 := time.Now()
	alloc1 := bytesAllocated()

	// Create SSA packages.
	var mode ssa.BuilderMode
	// Comment out these lines during benchmarking.  Approx SSA build costs are noted.
	mode |= ssa.SanityCheckFunctions // + 2% space, + 4% time
	mode |= ssa.GlobalDebug          // +30% space, +18% time
	prog := ssautil.CreateProgram(iprog, mode)

	t2 := time.Now()

	// Build SSA.
	prog.Build()

	t3 := time.Now()
	alloc3 := bytesAllocated()

	numPkgs := len(prog.AllPackages())
	if want := 140; numPkgs < want {
		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, want)
	}

	// Keep iprog reachable until after we've measured memory usage.
	if len(iprog.AllPackages) == 0 {
		print() // unreachable
	}

	allFuncs := ssautil.AllFunctions(prog)

	// Check that all non-synthetic functions have distinct names.
	// Synthetic wrappers for exported methods should be distinct too,
	// except for unexported ones (explained at (*Function).RelString).
	byName := make(map[string]*ssa.Function)
	for fn := range allFuncs {
		if fn.Synthetic == "" || ast.IsExported(fn.Name()) {
			str := fn.String()
			prev := byName[str]
			byName[str] = fn
			if prev != nil {
				t.Errorf("%s: duplicate function named %s",
					prog.Fset.Position(fn.Pos()), str)
				t.Errorf("%s:   (previously defined here)",
					prog.Fset.Position(prev.Pos()))
			}
		}
	}

	// Dump some statistics.
	var numInstrs int
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			numInstrs += len(b.Instrs)
		}
	}

	// determine line count
	var lineCount int
	prog.Fset.Iterate(func(f *token.File) bool {
		lineCount += f.LineCount()
		return true
	})

	// NB: when benchmarking, don't forget to clear the debug +
	// sanity builder flags for better performance.

	t.Log("GOMAXPROCS:           ", runtime.GOMAXPROCS(0))
	t.Log("#Source lines:        ", lineCount)
	t.Log("Load/parse/typecheck: ", t1.Sub(t0))
	t.Log("SSA create:           ", t2.Sub(t1))
	t.Log("SSA build:            ", t3.Sub(t2))

	// SSA stats:
	t.Log("#Packages:            ", numPkgs)
	t.Log("#Functions:           ", len(allFuncs))
	t.Log("#Instructions:        ", numInstrs)
	t.Log("#MB AST+types:        ", int64(alloc1-alloc0)/1e6)
	t.Log("#MB SSA:              ", int64(alloc3-alloc1)/1e6)
}
Exemple #7
0
// CallGraph computes the call graph of the specified program using the
// Class Hierarchy Analysis algorithm.
//
func CallGraph(prog *ssa.Program) *callgraph.Graph {
	cg := callgraph.New(nil) // TODO(adonovan) eliminate concept of rooted callgraph

	allFuncs := ssautil.AllFunctions(prog)

	// funcsBySig contains all functions, keyed by signature.  It is
	// the effective set of address-taken functions used to resolve
	// a dynamic call of a particular signature.
	var funcsBySig typeutil.Map // value is []*ssa.Function

	// methodsByName contains all methods,
	// grouped by name for efficient lookup.
	methodsByName := make(map[string][]*ssa.Function)

	// methodsMemo records, for every abstract method call call I.f on
	// interface type I, the set of concrete methods C.f of all
	// types C that satisfy interface I.
	methodsMemo := make(map[*types.Func][]*ssa.Function)
	lookupMethods := func(m *types.Func) []*ssa.Function {
		methods, ok := methodsMemo[m]
		if !ok {
			I := m.Type().(*types.Signature).Recv().Type().Underlying().(*types.Interface)
			for _, f := range methodsByName[m.Name()] {
				C := f.Signature.Recv().Type() // named or *named
				if types.Implements(C, I) {
					methods = append(methods, f)
				}
			}
			methodsMemo[m] = methods
		}
		return methods
	}

	for f := range allFuncs {
		if f.Signature.Recv() == nil {
			// Package initializers can never be address-taken.
			if f.Name() == "init" && f.Synthetic == "package initializer" {
				continue
			}
			funcs, _ := funcsBySig.At(f.Signature).([]*ssa.Function)
			funcs = append(funcs, f)
			funcsBySig.Set(f.Signature, funcs)
		} else {
			methodsByName[f.Name()] = append(methodsByName[f.Name()], f)
		}
	}

	addEdge := func(fnode *callgraph.Node, site ssa.CallInstruction, g *ssa.Function) {
		gnode := cg.CreateNode(g)
		callgraph.AddEdge(fnode, site, gnode)
	}

	addEdges := func(fnode *callgraph.Node, site ssa.CallInstruction, callees []*ssa.Function) {
		// Because every call to a highly polymorphic and
		// frequently used abstract method such as
		// (io.Writer).Write is assumed to call every concrete
		// Write method in the program, the call graph can
		// contain a lot of duplication.
		//
		// TODO(adonovan): opt: consider factoring the callgraph
		// API so that the Callers component of each edge is a
		// slice of nodes, not a singleton.
		for _, g := range callees {
			addEdge(fnode, site, g)
		}
	}

	for f := range allFuncs {
		fnode := cg.CreateNode(f)
		for _, b := range f.Blocks {
			for _, instr := range b.Instrs {
				if site, ok := instr.(ssa.CallInstruction); ok {
					call := site.Common()
					if call.IsInvoke() {
						addEdges(fnode, site, lookupMethods(call.Method))
					} else if g := call.StaticCallee(); g != nil {
						addEdge(fnode, site, g)
					} else if _, ok := call.Value.(*ssa.Builtin); !ok {
						callees, _ := funcsBySig.At(call.Signature()).([]*ssa.Function)
						addEdges(fnode, site, callees)
					}
				}
			}
		}
	}

	return cg
}
Exemple #8
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func TestStdlib(t *testing.T) {
	if !*runStdlibTest {
		t.Skip("skipping (slow) stdlib test (use --stdlib)")
	}

	// Load, parse and type-check the program.
	ctxt := build.Default // copy
	ctxt.GOPATH = ""      // disable GOPATH
	conf := loader.Config{Build: &ctxt}
	if _, err := conf.FromArgs(buildutil.AllPackages(conf.Build), true); err != nil {
		t.Errorf("FromArgs failed: %v", err)
		return
	}

	iprog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load failed: %v", err)
	}

	// Create SSA packages.
	prog := ssautil.CreateProgram(iprog, 0)
	prog.BuildAll()

	numPkgs := len(prog.AllPackages())
	if want := 240; numPkgs < want {
		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, want)
	}

	// Determine the set of packages/tests to analyze.
	var testPkgs []*ssa.Package
	for _, info := range iprog.InitialPackages() {
		testPkgs = append(testPkgs, prog.Package(info.Pkg))
	}
	testmain := prog.CreateTestMainPackage(testPkgs...)
	if testmain == nil {
		t.Fatal("analysis scope has tests")
	}

	// Run the analysis.
	config := &Config{
		Reflection:     false, // TODO(adonovan): fix remaining bug in rVCallConstraint, then enable.
		BuildCallGraph: true,
		Mains:          []*ssa.Package{testmain},
	}
	// TODO(adonovan): add some query values (affects track bits).

	t0 := time.Now()

	result, err := Analyze(config)
	if err != nil {
		t.Fatal(err) // internal error in pointer analysis
	}
	_ = result // TODO(adonovan): measure something

	t1 := time.Now()

	// Dump some statistics.
	allFuncs := ssautil.AllFunctions(prog)
	var numInstrs int
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			numInstrs += len(b.Instrs)
		}
	}

	// determine line count
	var lineCount int
	prog.Fset.Iterate(func(f *token.File) bool {
		lineCount += f.LineCount()
		return true
	})

	t.Log("#Source lines:          ", lineCount)
	t.Log("#Instructions:          ", numInstrs)
	t.Log("Pointer analysis:       ", t1.Sub(t0))
}
Exemple #9
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// peers enumerates, for a given channel send (or receive) operation,
// the set of possible receives (or sends) that correspond to it.
//
// TODO(adonovan): support reflect.{Select,Recv,Send,Close}.
// TODO(adonovan): permit the user to query based on a MakeChan (not send/recv),
// or the implicit receive in "for v := range ch".
func peers(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, ssa.GlobalDebug)

	ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
	if err != nil {
		return err
	}

	opPos := findOp(qpos)
	if opPos == token.NoPos {
		return fmt.Errorf("there is no channel operation here")
	}

	// Defer SSA construction till after errors are reported.
	prog.BuildAll()

	var queryOp chanOp // the originating send or receive operation
	var ops []chanOp   // all sends/receives of opposite direction

	// Look at all channel operations in the whole ssa.Program.
	// Build a list of those of same type as the query.
	allFuncs := ssautil.AllFunctions(prog)
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				for _, op := range chanOps(instr) {
					ops = append(ops, op)
					if op.pos == opPos {
						queryOp = op // we found the query op
					}
				}
			}
		}
	}
	if queryOp.ch == nil {
		return fmt.Errorf("ssa.Instruction for send/receive not found")
	}

	// Discard operations of wrong channel element type.
	// Build set of channel ssa.Values as query to pointer analysis.
	// We compare channels by element types, not channel types, to
	// ignore both directionality and type names.
	queryType := queryOp.ch.Type()
	queryElemType := queryType.Underlying().(*types.Chan).Elem()
	ptaConfig.AddQuery(queryOp.ch)
	i := 0
	for _, op := range ops {
		if types.Identical(op.ch.Type().Underlying().(*types.Chan).Elem(), queryElemType) {
			ptaConfig.AddQuery(op.ch)
			ops[i] = op
			i++
		}
	}
	ops = ops[:i]

	// Run the pointer analysis.
	ptares := ptrAnalysis(ptaConfig)

	// Find the points-to set.
	queryChanPtr := ptares.Queries[queryOp.ch]

	// Ascertain which make(chan) labels the query's channel can alias.
	var makes []token.Pos
	for _, label := range queryChanPtr.PointsTo().Labels() {
		makes = append(makes, label.Pos())
	}
	sort.Sort(byPos(makes))

	// Ascertain which channel operations can alias the same make(chan) labels.
	var sends, receives, closes []token.Pos
	for _, op := range ops {
		if ptr, ok := ptares.Queries[op.ch]; ok && ptr.MayAlias(queryChanPtr) {
			switch op.dir {
			case types.SendOnly:
				sends = append(sends, op.pos)
			case types.RecvOnly:
				receives = append(receives, op.pos)
			case types.SendRecv:
				closes = append(closes, op.pos)
			}
		}
	}
	sort.Sort(byPos(sends))
	sort.Sort(byPos(receives))
	sort.Sort(byPos(closes))

	q.result = &peersResult{
		queryPos:  opPos,
		queryType: queryType,
		makes:     makes,
		sends:     sends,
		receives:  receives,
		closes:    closes,
	}
	return nil
}
// TestSyntheticFuncs checks that the expected synthetic functions are
// created, reachable, and not duplicated.
func TestSyntheticFuncs(t *testing.T) {
	const input = `package P
type T int
func (T) f() int
func (*T) g() int
var (
	// thunks
	a = T.f
	b = T.f
	c = (struct{T}).f
	d = (struct{T}).f
	e = (*T).g
	f = (*T).g
	g = (struct{*T}).g
	h = (struct{*T}).g

	// bounds
	i = T(0).f
	j = T(0).f
	k = new(T).g
	l = new(T).g

	// wrappers
	m interface{} = struct{T}{}
	n interface{} = struct{T}{}
	o interface{} = struct{*T}{}
	p interface{} = struct{*T}{}
	q interface{} = new(struct{T})
	r interface{} = new(struct{T})
	s interface{} = new(struct{*T})
	t interface{} = new(struct{*T})
)
`
	// Parse
	var conf loader.Config
	f, err := conf.ParseFile("<input>", input)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	conf.CreateFromFiles(f.Name.Name, f)

	// Load
	lprog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	// Create and build SSA
	prog := ssautil.CreateProgram(lprog, 0)
	prog.Build()

	// Enumerate reachable synthetic functions
	want := map[string]string{
		"(*P.T).g$bound": "bound method wrapper for func (*P.T).g() int",
		"(P.T).f$bound":  "bound method wrapper for func (P.T).f() int",

		"(*P.T).g$thunk":         "thunk for func (*P.T).g() int",
		"(P.T).f$thunk":          "thunk for func (P.T).f() int",
		"(struct{*P.T}).g$thunk": "thunk for func (*P.T).g() int",
		"(struct{P.T}).f$thunk":  "thunk for func (P.T).f() int",

		"(*P.T).f":          "wrapper for func (P.T).f() int",
		"(*struct{*P.T}).f": "wrapper for func (P.T).f() int",
		"(*struct{*P.T}).g": "wrapper for func (*P.T).g() int",
		"(*struct{P.T}).f":  "wrapper for func (P.T).f() int",
		"(*struct{P.T}).g":  "wrapper for func (*P.T).g() int",
		"(struct{*P.T}).f":  "wrapper for func (P.T).f() int",
		"(struct{*P.T}).g":  "wrapper for func (*P.T).g() int",
		"(struct{P.T}).f":   "wrapper for func (P.T).f() int",

		"P.init": "package initializer",
	}
	for fn := range ssautil.AllFunctions(prog) {
		if fn.Synthetic == "" {
			continue
		}
		name := fn.String()
		wantDescr, ok := want[name]
		if !ok {
			t.Errorf("got unexpected/duplicate func: %q: %q", name, fn.Synthetic)
			continue
		}
		delete(want, name)

		if wantDescr != fn.Synthetic {
			t.Errorf("(%s).Synthetic = %q, want %q", name, fn.Synthetic, wantDescr)
		}
	}
	for fn, descr := range want {
		t.Errorf("want func: %q: %q", fn, descr)
	}
}
Exemple #11
0
// whicherrs takes an position to an error and tries to find all types, constants
// and global value which a given error can point to and which can be checked from the
// scope where the error lives.
// In short, it returns a list of things that can be checked against in order to handle
// an error properly.
//
// TODO(dmorsing): figure out if fields in errors like *os.PathError.Err
// can be queried recursively somehow.
func whicherrs(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
	}

	prog := ssautil.CreateProgram(lprog, ssa.GlobalDebug)

	ptaConfig, err := setupPTA(prog, lprog, q.PTALog, q.Reflection)
	if err != nil {
		return err
	}

	path, action := findInterestingNode(qpos.info, qpos.path)
	if action != actionExpr {
		return fmt.Errorf("whicherrs wants an expression; got %s",
			astutil.NodeDescription(qpos.path[0]))
	}
	var expr ast.Expr
	var obj types.Object
	switch n := path[0].(type) {
	case *ast.ValueSpec:
		// ambiguous ValueSpec containing multiple names
		return fmt.Errorf("multiple value specification")
	case *ast.Ident:
		obj = qpos.info.ObjectOf(n)
		expr = n
	case ast.Expr:
		expr = n
	default:
		return fmt.Errorf("unexpected AST for expr: %T", n)
	}

	typ := qpos.info.TypeOf(expr)
	if !types.Identical(typ, builtinErrorType) {
		return fmt.Errorf("selection is not an expression of type 'error'")
	}
	// Determine the ssa.Value for the expression.
	var value ssa.Value
	if obj != nil {
		// def/ref of func/var object
		value, _, err = ssaValueForIdent(prog, qpos.info, obj, path)
	} else {
		value, _, err = ssaValueForExpr(prog, qpos.info, path)
	}
	if err != nil {
		return err // e.g. trivially dead code
	}

	// Defer SSA construction till after errors are reported.
	prog.Build()

	globals := findVisibleErrs(prog, qpos)
	constants := findVisibleConsts(prog, qpos)

	res := &whicherrsResult{
		qpos:   qpos,
		errpos: expr.Pos(),
	}

	// TODO(adonovan): the following code is heavily duplicated
	// w.r.t.  "pointsto".  Refactor?

	// Find the instruction which initialized the
	// global error. If more than one instruction has stored to the global
	// remove the global from the set of values that we want to query.
	allFuncs := ssautil.AllFunctions(prog)
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				store, ok := instr.(*ssa.Store)
				if !ok {
					continue
				}
				gval, ok := store.Addr.(*ssa.Global)
				if !ok {
					continue
				}
				gbl, ok := globals[gval]
				if !ok {
					continue
				}
				// we already found a store to this global
				// The normal error define is just one store in the init
				// so we just remove this global from the set we want to query
				if gbl != nil {
					delete(globals, gval)
				}
				globals[gval] = store.Val
			}
		}
	}

	ptaConfig.AddQuery(value)
	for _, v := range globals {
		ptaConfig.AddQuery(v)
	}

	ptares := ptrAnalysis(ptaConfig)
	valueptr := ptares.Queries[value]
	for g, v := range globals {
		ptr, ok := ptares.Queries[v]
		if !ok {
			continue
		}
		if !ptr.MayAlias(valueptr) {
			continue
		}
		res.globals = append(res.globals, g)
	}
	pts := valueptr.PointsTo()
	dedup := make(map[*ssa.NamedConst]bool)
	for _, label := range pts.Labels() {
		// These values are either MakeInterfaces or reflect
		// generated interfaces. For the purposes of this
		// analysis, we don't care about reflect generated ones
		makeiface, ok := label.Value().(*ssa.MakeInterface)
		if !ok {
			continue
		}
		constval, ok := makeiface.X.(*ssa.Const)
		if !ok {
			continue
		}
		c := constants[*constval]
		if c != nil && !dedup[c] {
			dedup[c] = true
			res.consts = append(res.consts, c)
		}
	}
	concs := pts.DynamicTypes()
	concs.Iterate(func(conc types.Type, _ interface{}) {
		// go/types is a bit annoying here.
		// We want to find all the types that we can
		// typeswitch or assert to. This means finding out
		// if the type pointed to can be seen by us.
		//
		// For the purposes of this analysis, the type is always
		// either a Named type or a pointer to one.
		// There are cases where error can be implemented
		// by unnamed types, but in that case, we can't assert to
		// it, so we don't care about it for this analysis.
		var name *types.TypeName
		switch t := conc.(type) {
		case *types.Pointer:
			named, ok := t.Elem().(*types.Named)
			if !ok {
				return
			}
			name = named.Obj()
		case *types.Named:
			name = t.Obj()
		default:
			return
		}
		if !isAccessibleFrom(name, qpos.info.Pkg) {
			return
		}
		res.types = append(res.types, &errorType{conc, name})
	})
	sort.Sort(membersByPosAndString(res.globals))
	sort.Sort(membersByPosAndString(res.consts))
	sort.Sort(sorterrorType(res.types))

	q.result = res
	return nil
}
// directCallsTo inspects the whole program and returns a callgraph
// containing edges for all direct calls to the target function.
// directCallsTo returns nil if the function is ever address-taken.
func directCallsTo(target *ssa.Function, entrypoints []*ssa.Function) *callgraph.Graph {
	cg := callgraph.New(nil) // use nil as root *Function
	targetNode := cg.CreateNode(target)

	// Is the function a program entry point?
	// If so, add edge from callgraph root.
	for _, f := range entrypoints {
		if f == target {
			callgraph.AddEdge(cg.Root, nil, targetNode)
		}
	}

	// Find receiver type (for methods).
	var recvType types.Type
	if recv := target.Signature.Recv(); recv != nil {
		recvType = recv.Type()
	}

	// Find all direct calls to function,
	// or a place where its address is taken.
	var space [32]*ssa.Value // preallocate
	for fn := range ssautil.AllFunctions(target.Prog) {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				// Is this a method (T).f of a concrete type T
				// whose runtime type descriptor is address-taken?
				// (To be fully sound, we would have to check that
				// the type doesn't make it to reflection as a
				// subelement of some other address-taken type.)
				if recvType != nil {
					if mi, ok := instr.(*ssa.MakeInterface); ok {
						if types.Identical(mi.X.Type(), recvType) {
							return nil // T is address-taken
						}
						if ptr, ok := mi.X.Type().(*types.Pointer); ok &&
							types.Identical(ptr.Elem(), recvType) {
							return nil // *T is address-taken
						}
					}
				}

				// Direct call to target?
				rands := instr.Operands(space[:0])
				if site, ok := instr.(ssa.CallInstruction); ok &&
					site.Common().Value == target {
					callgraph.AddEdge(cg.CreateNode(fn), site, targetNode)
					rands = rands[1:] // skip .Value (rands[0])
				}

				// Address-taken?
				for _, rand := range rands {
					if rand != nil && *rand == target {
						return nil
					}
				}
			}
		}
	}

	return cg
}
Exemple #13
0
func doOneInput(input, filename string) bool {
	var conf loader.Config

	// 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 {
						call := instr.Common()
						if b, ok := call.Value.(*ssa.Builtin); ok && b.Name() == "print" && len(call.Args) == 1 {
							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)
						tv, 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
						}
						t = tv.Type
					}
					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
}
Exemple #14
0
// peers enumerates, for a given channel send (or receive) operation,
// the set of possible receives (or sends) that correspond to it.
//
// TODO(adonovan): support reflect.{Select,Recv,Send,Close}.
// TODO(adonovan): permit the user to query based on a MakeChan (not send/recv),
// or the implicit receive in "for v := range ch".
func peers(o *Oracle, qpos *QueryPos) (queryResult, error) {
	opPos := findOp(qpos)
	if opPos == token.NoPos {
		return nil, fmt.Errorf("there is no channel operation here")
	}

	buildSSA(o)

	var queryOp chanOp // the originating send or receive operation
	var ops []chanOp   // all sends/receives of opposite direction

	// Look at all channel operations in the whole ssa.Program.
	// Build a list of those of same type as the query.
	allFuncs := ssautil.AllFunctions(o.prog)
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				for _, op := range chanOps(instr) {
					ops = append(ops, op)
					if op.pos == opPos {
						queryOp = op // we found the query op
					}
				}
			}
		}
	}
	if queryOp.ch == nil {
		return nil, fmt.Errorf("ssa.Instruction for send/receive not found")
	}

	// Discard operations of wrong channel element type.
	// Build set of channel ssa.Values as query to pointer analysis.
	// We compare channels by element types, not channel types, to
	// ignore both directionality and type names.
	queryType := queryOp.ch.Type()
	queryElemType := queryType.Underlying().(*types.Chan).Elem()
	o.ptaConfig.AddQuery(queryOp.ch)
	i := 0
	for _, op := range ops {
		if types.Identical(op.ch.Type().Underlying().(*types.Chan).Elem(), queryElemType) {
			o.ptaConfig.AddQuery(op.ch)
			ops[i] = op
			i++
		}
	}
	ops = ops[:i]

	// Run the pointer analysis.
	ptares := ptrAnalysis(o)

	// Find the points-to set.
	queryChanPtr := ptares.Queries[queryOp.ch]

	// Ascertain which make(chan) labels the query's channel can alias.
	var makes []token.Pos
	for _, label := range queryChanPtr.PointsTo().Labels() {
		makes = append(makes, label.Pos())
	}
	sort.Sort(byPos(makes))

	// Ascertain which channel operations can alias the same make(chan) labels.
	var sends, receives, closes []token.Pos
	for _, op := range ops {
		if ptr, ok := ptares.Queries[op.ch]; ok && ptr.MayAlias(queryChanPtr) {
			switch op.dir {
			case types.SendOnly:
				sends = append(sends, op.pos)
			case types.RecvOnly:
				receives = append(receives, op.pos)
			case types.SendRecv:
				closes = append(closes, op.pos)
			}
		}
	}
	sort.Sort(byPos(sends))
	sort.Sort(byPos(receives))
	sort.Sort(byPos(closes))

	return &peersResult{
		queryPos:  opPos,
		queryType: queryType,
		makes:     makes,
		sends:     sends,
		receives:  receives,
		closes:    closes,
	}, nil
}