Add generated file

This PR adds generated files under pkg/client and vendor folder.

vendor/golang.org/x/tools/go/callgraph/callgraph.go

@@ -0,0 +1,129 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+
+Package callgraph defines the call graph and various algorithms
+and utilities to operate on it.
+
+A call graph is a labelled directed graph whose nodes represent
+functions and whose edge labels represent syntactic function call
+sites.  The presence of a labelled edge (caller, site, callee)
+indicates that caller may call callee at the specified call site.
+
+A call graph is a multigraph: it may contain multiple edges (caller,
+*, callee) connecting the same pair of nodes, so long as the edges
+differ by label; this occurs when one function calls another function
+from multiple call sites.  Also, it may contain multiple edges
+(caller, site, *) that differ only by callee; this indicates a
+polymorphic call.
+
+A SOUND call graph is one that overapproximates the dynamic calling
+behaviors of the program in all possible executions.  One call graph
+is more PRECISE than another if it is a smaller overapproximation of
+the dynamic behavior.
+
+All call graphs have a synthetic root node which is responsible for
+calling main() and init().
+
+Calls to built-in functions (e.g. panic, println) are not represented
+in the call graph; they are treated like built-in operators of the
+language.
+
+*/
+package callgraph // import "golang.org/x/tools/go/callgraph"
+
+// TODO(adonovan): add a function to eliminate wrappers from the
+// callgraph, preserving topology.
+// More generally, we could eliminate "uninteresting" nodes such as
+// nodes from packages we don't care about.
+
+import (
+	"fmt"
+	"go/token"
+
+	"golang.org/x/tools/go/ssa"
+)
+
+// A Graph represents a call graph.
+//
+// A graph may contain nodes that are not reachable from the root.
+// If the call graph is sound, such nodes indicate unreachable
+// functions.
+//
+type Graph struct {
+	Root  *Node                   // the distinguished root node
+	Nodes map[*ssa.Function]*Node // all nodes by function
+}
+
+// New returns a new Graph with the specified root node.
+func New(root *ssa.Function) *Graph {
+	g := &Graph{Nodes: make(map[*ssa.Function]*Node)}
+	g.Root = g.CreateNode(root)
+	return g
+}
+
+// CreateNode returns the Node for fn, creating it if not present.
+func (g *Graph) CreateNode(fn *ssa.Function) *Node {
+	n, ok := g.Nodes[fn]
+	if !ok {
+		n = &Node{Func: fn, ID: len(g.Nodes)}
+		g.Nodes[fn] = n
+	}
+	return n
+}
+
+// A Node represents a node in a call graph.
+type Node struct {
+	Func *ssa.Function // the function this node represents
+	ID   int           // 0-based sequence number
+	In   []*Edge       // unordered set of incoming call edges (n.In[*].Callee == n)
+	Out  []*Edge       // unordered set of outgoing call edges (n.Out[*].Caller == n)
+}
+
+func (n *Node) String() string {
+	return fmt.Sprintf("n%d:%s", n.ID, n.Func)
+}
+
+// A Edge represents an edge in the call graph.
+//
+// Site is nil for edges originating in synthetic or intrinsic
+// functions, e.g. reflect.Call or the root of the call graph.
+type Edge struct {
+	Caller *Node
+	Site   ssa.CallInstruction
+	Callee *Node
+}
+
+func (e Edge) String() string {
+	return fmt.Sprintf("%s --> %s", e.Caller, e.Callee)
+}
+
+func (e Edge) Description() string {
+	var prefix string
+	switch e.Site.(type) {
+	case nil:
+		return "synthetic call"
+	case *ssa.Go:
+		prefix = "concurrent "
+	case *ssa.Defer:
+		prefix = "deferred "
+	}
+	return prefix + e.Site.Common().Description()
+}
+
+func (e Edge) Pos() token.Pos {
+	if e.Site == nil {
+		return token.NoPos
+	}
+	return e.Site.Pos()
+}
+
+// AddEdge adds the edge (caller, site, callee) to the call graph.
+// Elimination of duplicate edges is the caller's responsibility.
+func AddEdge(caller *Node, site ssa.CallInstruction, callee *Node) {
+	e := &Edge{caller, site, callee}
+	callee.In = append(callee.In, e)
+	caller.Out = append(caller.Out, e)
+}

vendor/golang.org/x/tools/go/callgraph/cha/cha.go

@@ -0,0 +1,139 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cha computes the call graph of a Go program using the Class
+// Hierarchy Analysis (CHA) algorithm.
+//
+// CHA was first described in "Optimization of Object-Oriented Programs
+// Using Static Class Hierarchy Analysis", Jeffrey Dean, David Grove,
+// and Craig Chambers, ECOOP'95.
+//
+// CHA is related to RTA (see go/callgraph/rta); the difference is that
+// CHA conservatively computes the entire "implements" relation between
+// interfaces and concrete types ahead of time, whereas RTA uses dynamic
+// programming to construct it on the fly as it encounters new functions
+// reachable from main.  CHA may thus include spurious call edges for
+// types that haven't been instantiated yet, or types that are never
+// instantiated.
+//
+// Since CHA conservatively assumes that all functions are address-taken
+// and all concrete types are put into interfaces, it is sound to run on
+// partial programs, such as libraries without a main or test function.
+//
+package cha // import "golang.org/x/tools/go/callgraph/cha"
+
+import (
+	"go/types"
+
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/ssa"
+	"golang.org/x/tools/go/ssa/ssautil"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// 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.
+	// (methodsById would be better but not every SSA method has a go/types ID.)
+	methodsByName := make(map[string][]*ssa.Function)
+
+	// An imethod represents an interface method I.m.
+	// (There's no go/types object for it;
+	// a *types.Func may be shared by many interfaces due to interface embedding.)
+	type imethod struct {
+		I  *types.Interface
+		id string
+	}
+	// methodsMemo records, for every abstract method call I.m on
+	// interface type I, the set of concrete methods C.m of all
+	// types C that satisfy interface I.
+	//
+	// Abstract methods may be shared by several interfaces,
+	// hence we must pass I explicitly, not guess from m.
+	//
+	// methodsMemo is just a cache, so it needn't be a typeutil.Map.
+	methodsMemo := make(map[imethod][]*ssa.Function)
+	lookupMethods := func(I *types.Interface, m *types.Func) []*ssa.Function {
+		id := m.Id()
+		methods, ok := methodsMemo[imethod{I, id}]
+		if !ok {
+			for _, f := range methodsByName[m.Name()] {
+				C := f.Signature.Recv().Type() // named or *named
+				if types.Implements(C, I) {
+					methods = append(methods, f)
+				}
+			}
+			methodsMemo[imethod{I, id}] = 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() {
+						tiface := call.Value.Type().Underlying().(*types.Interface)
+						addEdges(fnode, site, lookupMethods(tiface, 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
+}

vendor/golang.org/x/tools/go/callgraph/cha/cha_test.go

@@ -0,0 +1,111 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// No testdata on Android.
+
+// +build !android
+
+package cha_test
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io/ioutil"
+	"sort"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/callgraph/cha"
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/ssa/ssautil"
+)
+
+var inputs = []string{
+	"testdata/func.go",
+	"testdata/iface.go",
+	"testdata/recv.go",
+	"testdata/issue23925.go",
+}
+
+func expectation(f *ast.File) (string, token.Pos) {
+	for _, c := range f.Comments {
+		text := strings.TrimSpace(c.Text())
+		if t := strings.TrimPrefix(text, "WANT:\n"); t != text {
+			return t, c.Pos()
+		}
+	}
+	return "", token.NoPos
+}
+
+// TestCHA runs CHA on each file in inputs, prints the dynamic edges of
+// the call graph, and compares it with the golden results embedded in
+// the WANT comment at the end of the file.
+//
+func TestCHA(t *testing.T) {
+	for _, filename := range inputs {
+		content, err := ioutil.ReadFile(filename)
+		if err != nil {
+			t.Errorf("couldn't read file '%s': %s", filename, err)
+			continue
+		}
+
+		conf := loader.Config{
+			ParserMode: parser.ParseComments,
+		}
+		f, err := conf.ParseFile(filename, content)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		want, pos := expectation(f)
+		if pos == token.NoPos {
+			t.Errorf("No WANT: comment in %s", filename)
+			continue
+		}
+
+		conf.CreateFromFiles("main", f)
+		iprog, err := conf.Load()
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		prog := ssautil.CreateProgram(iprog, 0)
+		mainPkg := prog.Package(iprog.Created[0].Pkg)
+		prog.Build()
+
+		cg := cha.CallGraph(prog)
+
+		if got := printGraph(cg, mainPkg.Pkg); got != want {
+			t.Errorf("%s: got:\n%s\nwant:\n%s",
+				prog.Fset.Position(pos), got, want)
+		}
+	}
+}
+
+func printGraph(cg *callgraph.Graph, from *types.Package) string {
+	var edges []string
+	callgraph.GraphVisitEdges(cg, func(e *callgraph.Edge) error {
+		if strings.Contains(e.Description(), "dynamic") {
+			edges = append(edges, fmt.Sprintf("%s --> %s",
+				e.Caller.Func.RelString(from),
+				e.Callee.Func.RelString(from)))
+		}
+		return nil
+	})
+	sort.Strings(edges)
+
+	var buf bytes.Buffer
+	buf.WriteString("Dynamic calls\n")
+	for _, edge := range edges {
+		fmt.Fprintf(&buf, "  %s\n", edge)
+	}
+	return strings.TrimSpace(buf.String())
+}

vendor/golang.org/x/tools/go/callgraph/cha/testdata/func.go

@@ -0,0 +1,23 @@
+//+build ignore
+
+package main
+
+// Test of dynamic function calls; no interfaces.
+
+func A(int) {}
+
+var (
+	B = func(int) {}
+	C = func(int) {}
+)
+
+func f() {
+	pfn := B
+	pfn(0) // calls A, B, C, even though A is not even address-taken
+}
+
+// WANT:
+// Dynamic calls
+//   f --> A
+//   f --> init$1
+//   f --> init$2

vendor/golang.org/x/tools/go/callgraph/cha/testdata/iface.go

@@ -0,0 +1,65 @@
+//+build ignore
+
+package main
+
+// Test of interface calls.  None of the concrete types are ever
+// instantiated or converted to interfaces.
+
+type I interface {
+	f()
+}
+
+type J interface {
+	f()
+	g()
+}
+
+type C int // implements I
+
+func (*C) f()
+
+type D int // implements I and J
+
+func (*D) f()
+func (*D) g()
+
+func one(i I, j J) {
+	i.f() // calls *C and *D
+}
+
+func two(i I, j J) {
+	j.f() // calls *D (but not *C, even though it defines method f)
+}
+
+func three(i I, j J) {
+	j.g() // calls *D
+}
+
+func four(i I, j J) {
+	Jf := J.f
+	if unknown {
+		Jf = nil // suppress SSA constant propagation
+	}
+	Jf(nil) // calls *D
+}
+
+func five(i I, j J) {
+	jf := j.f
+	if unknown {
+		jf = nil // suppress SSA constant propagation
+	}
+	jf() // calls *D
+}
+
+var unknown bool
+
+// WANT:
+// Dynamic calls
+//   (J).f$bound --> (*D).f
+//   (J).f$thunk --> (*D).f
+//   five --> (J).f$bound
+//   four --> (J).f$thunk
+//   one --> (*C).f
+//   one --> (*D).f
+//   three --> (*D).g
+//   two --> (*D).f

vendor/golang.org/x/tools/go/callgraph/cha/testdata/issue23925.go

@@ -0,0 +1,38 @@
+package main
+
+// Regression test for https://github.com/golang/go/issues/23925
+
+type stringFlagImpl string
+
+func (*stringFlagImpl) Set(s string) error { return nil }
+
+type boolFlagImpl bool
+
+func (*boolFlagImpl) Set(s string) error { return nil }
+func (*boolFlagImpl) extra()             {}
+
+// A copy of flag.boolFlag interface, without a dependency.
+// Must appear first, so that it becomes the owner of the Set methods.
+type boolFlag interface {
+	flagValue
+	extra()
+}
+
+// A copy of flag.Value, without adding a dependency.
+type flagValue interface {
+	Set(string) error
+}
+
+func main() {
+	var x flagValue = new(stringFlagImpl)
+	x.Set("")
+
+	var y boolFlag = new(boolFlagImpl)
+	y.Set("")
+}
+
+// WANT:
+// Dynamic calls
+//   main --> (*boolFlagImpl).Set
+//   main --> (*boolFlagImpl).Set
+//   main --> (*stringFlagImpl).Set

vendor/golang.org/x/tools/go/callgraph/cha/testdata/recv.go

@@ -0,0 +1,37 @@
+//+build ignore
+
+package main
+
+type I interface {
+	f()
+}
+
+type J interface {
+	g()
+}
+
+type C int // C and *C implement I; *C implements J
+
+func (C) f()
+func (*C) g()
+
+type D int // *D implements I and J
+
+func (*D) f()
+func (*D) g()
+
+func f(i I) {
+	i.f() // calls C, *C, *D
+}
+
+func g(j J) {
+	j.g() // calls *C, *D
+}
+
+// WANT:
+// Dynamic calls
+//   f --> (*C).f
+//   f --> (*D).f
+//   f --> (C).f
+//   g --> (*C).g
+//   g --> (*D).g

vendor/golang.org/x/tools/go/callgraph/rta/rta.go

@@ -0,0 +1,459 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This package provides Rapid Type Analysis (RTA) for Go, a fast
+// algorithm for call graph construction and discovery of reachable code
+// (and hence dead code) and runtime types.  The algorithm was first
+// described in:
+//
+// David F. Bacon and Peter F. Sweeney. 1996.
+// Fast static analysis of C++ virtual function calls. (OOPSLA '96)
+// http://doi.acm.org/10.1145/236337.236371
+//
+// The algorithm uses dynamic programming to tabulate the cross-product
+// of the set of known "address taken" functions with the set of known
+// dynamic calls of the same type.  As each new address-taken function
+// is discovered, call graph edges are added from each known callsite,
+// and as each new call site is discovered, call graph edges are added
+// from it to each known address-taken function.
+//
+// A similar approach is used for dynamic calls via interfaces: it
+// tabulates the cross-product of the set of known "runtime types",
+// i.e. types that may appear in an interface value, or be derived from
+// one via reflection, with the set of known "invoke"-mode dynamic
+// calls.  As each new "runtime type" is discovered, call edges are
+// added from the known call sites, and as each new call site is
+// discovered, call graph edges are added to each compatible
+// method.
+//
+// In addition, we must consider all exported methods of any runtime type
+// as reachable, since they may be called via reflection.
+//
+// Each time a newly added call edge causes a new function to become
+// reachable, the code of that function is analyzed for more call sites,
+// address-taken functions, and runtime types.  The process continues
+// until a fixed point is achieved.
+//
+// The resulting call graph is less precise than one produced by pointer
+// analysis, but the algorithm is much faster.  For example, running the
+// cmd/callgraph tool on its own source takes ~2.1s for RTA and ~5.4s
+// for points-to analysis.
+//
+package rta // import "golang.org/x/tools/go/callgraph/rta"
+
+// TODO(adonovan): test it by connecting it to the interpreter and
+// replacing all "unreachable" functions by a special intrinsic, and
+// ensure that that intrinsic is never called.
+
+import (
+	"fmt"
+	"go/types"
+
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/ssa"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// A Result holds the results of Rapid Type Analysis, which includes the
+// set of reachable functions/methods, runtime types, and the call graph.
+//
+type Result struct {
+	// CallGraph is the discovered callgraph.
+	// It does not include edges for calls made via reflection.
+	CallGraph *callgraph.Graph
+
+	// Reachable contains the set of reachable functions and methods.
+	// This includes exported methods of runtime types, since
+	// they may be accessed via reflection.
+	// The value indicates whether the function is address-taken.
+	//
+	// (We wrap the bool in a struct to avoid inadvertent use of
+	// "if Reachable[f] {" to test for set membership.)
+	Reachable map[*ssa.Function]struct{ AddrTaken bool }
+
+	// RuntimeTypes contains the set of types that are needed at
+	// runtime, for interfaces or reflection.
+	//
+	// The value indicates whether the type is inaccessible to reflection.
+	// Consider:
+	// 	type A struct{B}
+	// 	fmt.Println(new(A))
+	// Types *A, A and B are accessible to reflection, but the unnamed
+	// type struct{B} is not.
+	RuntimeTypes typeutil.Map
+}
+
+// Working state of the RTA algorithm.
+type rta struct {
+	result *Result
+
+	prog *ssa.Program
+
+	worklist []*ssa.Function // list of functions to visit
+
+	// addrTakenFuncsBySig contains all address-taken *Functions, grouped by signature.
+	// Keys are *types.Signature, values are map[*ssa.Function]bool sets.
+	addrTakenFuncsBySig typeutil.Map
+
+	// dynCallSites contains all dynamic "call"-mode call sites, grouped by signature.
+	// Keys are *types.Signature, values are unordered []ssa.CallInstruction.
+	dynCallSites typeutil.Map
+
+	// invokeSites contains all "invoke"-mode call sites, grouped by interface.
+	// Keys are *types.Interface (never *types.Named),
+	// Values are unordered []ssa.CallInstruction sets.
+	invokeSites typeutil.Map
+
+	// The following two maps together define the subset of the
+	// m:n "implements" relation needed by the algorithm.
+
+	// concreteTypes maps each concrete type to the set of interfaces that it implements.
+	// Keys are types.Type, values are unordered []*types.Interface.
+	// Only concrete types used as MakeInterface operands are included.
+	concreteTypes typeutil.Map
+
+	// interfaceTypes maps each interface type to
+	// the set of concrete types that implement it.
+	// Keys are *types.Interface, values are unordered []types.Type.
+	// Only interfaces used in "invoke"-mode CallInstructions are included.
+	interfaceTypes typeutil.Map
+}
+
+// addReachable marks a function as potentially callable at run-time,
+// and ensures that it gets processed.
+func (r *rta) addReachable(f *ssa.Function, addrTaken bool) {
+	reachable := r.result.Reachable
+	n := len(reachable)
+	v := reachable[f]
+	if addrTaken {
+		v.AddrTaken = true
+	}
+	reachable[f] = v
+	if len(reachable) > n {
+		// First time seeing f.  Add it to the worklist.
+		r.worklist = append(r.worklist, f)
+	}
+}
+
+// addEdge adds the specified call graph edge, and marks it reachable.
+// addrTaken indicates whether to mark the callee as "address-taken".
+func (r *rta) addEdge(site ssa.CallInstruction, callee *ssa.Function, addrTaken bool) {
+	r.addReachable(callee, addrTaken)
+
+	if g := r.result.CallGraph; g != nil {
+		if site.Parent() == nil {
+			panic(site)
+		}
+		from := g.CreateNode(site.Parent())
+		to := g.CreateNode(callee)
+		callgraph.AddEdge(from, site, to)
+	}
+}
+
+// ---------- addrTakenFuncs × dynCallSites ----------
+
+// visitAddrTakenFunc is called each time we encounter an address-taken function f.
+func (r *rta) visitAddrTakenFunc(f *ssa.Function) {
+	// Create two-level map (Signature -> Function -> bool).
+	S := f.Signature
+	funcs, _ := r.addrTakenFuncsBySig.At(S).(map[*ssa.Function]bool)
+	if funcs == nil {
+		funcs = make(map[*ssa.Function]bool)
+		r.addrTakenFuncsBySig.Set(S, funcs)
+	}
+	if !funcs[f] {
+		// First time seeing f.
+		funcs[f] = true
+
+		// If we've seen any dyncalls of this type, mark it reachable,
+		// and add call graph edges.
+		sites, _ := r.dynCallSites.At(S).([]ssa.CallInstruction)
+		for _, site := range sites {
+			r.addEdge(site, f, true)
+		}
+	}
+}
+
+// visitDynCall is called each time we encounter a dynamic "call"-mode call.
+func (r *rta) visitDynCall(site ssa.CallInstruction) {
+	S := site.Common().Signature()
+
+	// Record the call site.
+	sites, _ := r.dynCallSites.At(S).([]ssa.CallInstruction)
+	r.dynCallSites.Set(S, append(sites, site))
+
+	// For each function of signature S that we know is address-taken,
+	// mark it reachable.  We'll add the callgraph edges later.
+	funcs, _ := r.addrTakenFuncsBySig.At(S).(map[*ssa.Function]bool)
+	for g := range funcs {
+		r.addEdge(site, g, true)
+	}
+}
+
+// ---------- concrete types × invoke sites ----------
+
+// addInvokeEdge is called for each new pair (site, C) in the matrix.
+func (r *rta) addInvokeEdge(site ssa.CallInstruction, C types.Type) {
+	// Ascertain the concrete method of C to be called.
+	imethod := site.Common().Method
+	cmethod := r.prog.MethodValue(r.prog.MethodSets.MethodSet(C).Lookup(imethod.Pkg(), imethod.Name()))
+	r.addEdge(site, cmethod, true)
+}
+
+// visitInvoke is called each time the algorithm encounters an "invoke"-mode call.
+func (r *rta) visitInvoke(site ssa.CallInstruction) {
+	I := site.Common().Value.Type().Underlying().(*types.Interface)
+
+	// Record the invoke site.
+	sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
+	r.invokeSites.Set(I, append(sites, site))
+
+	// Add callgraph edge for each existing
+	// address-taken concrete type implementing I.
+	for _, C := range r.implementations(I) {
+		r.addInvokeEdge(site, C)
+	}
+}
+
+// ---------- main algorithm ----------
+
+// visitFunc processes function f.
+func (r *rta) visitFunc(f *ssa.Function) {
+	var space [32]*ssa.Value // preallocate space for common case
+
+	for _, b := range f.Blocks {
+		for _, instr := range b.Instrs {
+			rands := instr.Operands(space[:0])
+
+			switch instr := instr.(type) {
+			case ssa.CallInstruction:
+				call := instr.Common()
+				if call.IsInvoke() {
+					r.visitInvoke(instr)
+				} else if g := call.StaticCallee(); g != nil {
+					r.addEdge(instr, g, false)
+				} else if _, ok := call.Value.(*ssa.Builtin); !ok {
+					r.visitDynCall(instr)
+				}
+
+				// Ignore the call-position operand when
+				// looking for address-taken Functions.
+				// Hack: assume this is rands[0].
+				rands = rands[1:]
+
+			case *ssa.MakeInterface:
+				r.addRuntimeType(instr.X.Type(), false)
+			}
+
+			// Process all address-taken functions.
+			for _, op := range rands {
+				if g, ok := (*op).(*ssa.Function); ok {
+					r.visitAddrTakenFunc(g)
+				}
+			}
+		}
+	}
+}
+
+// Analyze performs Rapid Type Analysis, starting at the specified root
+// functions.  It returns nil if no roots were specified.
+//
+// If buildCallGraph is true, Result.CallGraph will contain a call
+// graph; otherwise, only the other fields (reachable functions) are
+// populated.
+//
+func Analyze(roots []*ssa.Function, buildCallGraph bool) *Result {
+	if len(roots) == 0 {
+		return nil
+	}
+
+	r := &rta{
+		result: &Result{Reachable: make(map[*ssa.Function]struct{ AddrTaken bool })},
+		prog:   roots[0].Prog,
+	}
+
+	if buildCallGraph {
+		// TODO(adonovan): change callgraph API to eliminate the
+		// notion of a distinguished root node.  Some callgraphs
+		// have many roots, or none.
+		r.result.CallGraph = callgraph.New(roots[0])
+	}
+
+	hasher := typeutil.MakeHasher()
+	r.result.RuntimeTypes.SetHasher(hasher)
+	r.addrTakenFuncsBySig.SetHasher(hasher)
+	r.dynCallSites.SetHasher(hasher)
+	r.invokeSites.SetHasher(hasher)
+	r.concreteTypes.SetHasher(hasher)
+	r.interfaceTypes.SetHasher(hasher)
+
+	// Visit functions, processing their instructions, and adding
+	// new functions to the worklist, until a fixed point is
+	// reached.
+	var shadow []*ssa.Function // for efficiency, we double-buffer the worklist
+	r.worklist = append(r.worklist, roots...)
+	for len(r.worklist) > 0 {
+		shadow, r.worklist = r.worklist, shadow[:0]
+		for _, f := range shadow {
+			r.visitFunc(f)
+		}
+	}
+	return r.result
+}
+
+// interfaces(C) returns all currently known interfaces implemented by C.
+func (r *rta) interfaces(C types.Type) []*types.Interface {
+	// Ascertain set of interfaces C implements
+	// and update 'implements' relation.
+	var ifaces []*types.Interface
+	r.interfaceTypes.Iterate(func(I types.Type, concs interface{}) {
+		if I := I.(*types.Interface); types.Implements(C, I) {
+			concs, _ := concs.([]types.Type)
+			r.interfaceTypes.Set(I, append(concs, C))
+			ifaces = append(ifaces, I)
+		}
+	})
+	r.concreteTypes.Set(C, ifaces)
+	return ifaces
+}
+
+// implementations(I) returns all currently known concrete types that implement I.
+func (r *rta) implementations(I *types.Interface) []types.Type {
+	var concs []types.Type
+	if v := r.interfaceTypes.At(I); v != nil {
+		concs = v.([]types.Type)
+	} else {
+		// First time seeing this interface.
+		// Update the 'implements' relation.
+		r.concreteTypes.Iterate(func(C types.Type, ifaces interface{}) {
+			if types.Implements(C, I) {
+				ifaces, _ := ifaces.([]*types.Interface)
+				r.concreteTypes.Set(C, append(ifaces, I))
+				concs = append(concs, C)
+			}
+		})
+		r.interfaceTypes.Set(I, concs)
+	}
+	return concs
+}
+
+// addRuntimeType is called for each concrete type that can be the
+// dynamic type of some interface or reflect.Value.
+// Adapted from needMethods in go/ssa/builder.go
+//
+func (r *rta) addRuntimeType(T types.Type, skip bool) {
+	if prev, ok := r.result.RuntimeTypes.At(T).(bool); ok {
+		if skip && !prev {
+			r.result.RuntimeTypes.Set(T, skip)
+		}
+		return
+	}
+	r.result.RuntimeTypes.Set(T, skip)
+
+	mset := r.prog.MethodSets.MethodSet(T)
+
+	if _, ok := T.Underlying().(*types.Interface); !ok {
+		// T is a new concrete type.
+		for i, n := 0, mset.Len(); i < n; i++ {
+			sel := mset.At(i)
+			m := sel.Obj()
+
+			if m.Exported() {
+				// Exported methods are always potentially callable via reflection.
+				r.addReachable(r.prog.MethodValue(sel), true)
+			}
+		}
+
+		// Add callgraph edge for each existing dynamic
+		// "invoke"-mode call via that interface.
+		for _, I := range r.interfaces(T) {
+			sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
+			for _, site := range sites {
+				r.addInvokeEdge(site, T)
+			}
+		}
+	}
+
+	// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+	// Recursive case: skip => don't call makeMethods(T).
+	// Each package maintains its own set of types it has visited.
+
+	var n *types.Named
+	switch T := T.(type) {
+	case *types.Named:
+		n = T
+	case *types.Pointer:
+		n, _ = T.Elem().(*types.Named)
+	}
+	if n != nil {
+		owner := n.Obj().Pkg()
+		if owner == nil {
+			return // built-in error type
+		}
+	}
+
+	// Recursion over signatures of each exported method.
+	for i := 0; i < mset.Len(); i++ {
+		if mset.At(i).Obj().Exported() {
+			sig := mset.At(i).Type().(*types.Signature)
+			r.addRuntimeType(sig.Params(), true)  // skip the Tuple itself
+			r.addRuntimeType(sig.Results(), true) // skip the Tuple itself
+		}
+	}
+
+	switch t := T.(type) {
+	case *types.Basic:
+		// nop
+
+	case *types.Interface:
+		// nop---handled by recursion over method set.
+
+	case *types.Pointer:
+		r.addRuntimeType(t.Elem(), false)
+
+	case *types.Slice:
+		r.addRuntimeType(t.Elem(), false)
+
+	case *types.Chan:
+		r.addRuntimeType(t.Elem(), false)
+
+	case *types.Map:
+		r.addRuntimeType(t.Key(), false)
+		r.addRuntimeType(t.Elem(), false)
+
+	case *types.Signature:
+		if t.Recv() != nil {
+			panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
+		}
+		r.addRuntimeType(t.Params(), true)  // skip the Tuple itself
+		r.addRuntimeType(t.Results(), true) // skip the Tuple itself
+
+	case *types.Named:
+		// A pointer-to-named type can be derived from a named
+		// type via reflection.  It may have methods too.
+		r.addRuntimeType(types.NewPointer(T), false)
+
+		// Consider 'type T struct{S}' where S has methods.
+		// Reflection provides no way to get from T to struct{S},
+		// only to S, so the method set of struct{S} is unwanted,
+		// so set 'skip' flag during recursion.
+		r.addRuntimeType(t.Underlying(), true)
+
+	case *types.Array:
+		r.addRuntimeType(t.Elem(), false)
+
+	case *types.Struct:
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			r.addRuntimeType(t.Field(i).Type(), false)
+		}
+
+	case *types.Tuple:
+		for i, n := 0, t.Len(); i < n; i++ {
+			r.addRuntimeType(t.At(i).Type(), false)
+		}
+
+	default:
+		panic(T)
+	}
+}

vendor/golang.org/x/tools/go/callgraph/rta/rta_test.go

@@ -0,0 +1,139 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// No testdata on Android.
+
+// +build !android
+
+package rta_test
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io/ioutil"
+	"sort"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/callgraph/rta"
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/ssa"
+	"golang.org/x/tools/go/ssa/ssautil"
+)
+
+var inputs = []string{
+	"testdata/func.go",
+	"testdata/rtype.go",
+	"testdata/iface.go",
+}
+
+func expectation(f *ast.File) (string, token.Pos) {
+	for _, c := range f.Comments {
+		text := strings.TrimSpace(c.Text())
+		if t := strings.TrimPrefix(text, "WANT:\n"); t != text {
+			return t, c.Pos()
+		}
+	}
+	return "", token.NoPos
+}
+
+// TestRTA runs RTA on each file in inputs, prints the results, and
+// compares it with the golden results embedded in the WANT comment at
+// the end of the file.
+//
+// The results string consists of two parts: the set of dynamic call
+// edges, "f --> g", one per line, and the set of reachable functions,
+// one per line.  Each set is sorted.
+//
+func TestRTA(t *testing.T) {
+	for _, filename := range inputs {
+		content, err := ioutil.ReadFile(filename)
+		if err != nil {
+			t.Errorf("couldn't read file '%s': %s", filename, err)
+			continue
+		}
+
+		conf := loader.Config{
+			ParserMode: parser.ParseComments,
+		}
+		f, err := conf.ParseFile(filename, content)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		want, pos := expectation(f)
+		if pos == token.NoPos {
+			t.Errorf("No WANT: comment in %s", filename)
+			continue
+		}
+
+		conf.CreateFromFiles("main", f)
+		iprog, err := conf.Load()
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		prog := ssautil.CreateProgram(iprog, 0)
+		mainPkg := prog.Package(iprog.Created[0].Pkg)
+		prog.Build()
+
+		res := rta.Analyze([]*ssa.Function{
+			mainPkg.Func("main"),
+			mainPkg.Func("init"),
+		}, true)
+
+		if got := printResult(res, mainPkg.Pkg); got != want {
+			t.Errorf("%s: got:\n%s\nwant:\n%s",
+				prog.Fset.Position(pos), got, want)
+		}
+	}
+}
+
+func printResult(res *rta.Result, from *types.Package) string {
+	var buf bytes.Buffer
+
+	writeSorted := func(ss []string) {
+		sort.Strings(ss)
+		for _, s := range ss {
+			fmt.Fprintf(&buf, "  %s\n", s)
+		}
+	}
+
+	buf.WriteString("Dynamic calls\n")
+	var edges []string
+	callgraph.GraphVisitEdges(res.CallGraph, func(e *callgraph.Edge) error {
+		if strings.Contains(e.Description(), "dynamic") {
+			edges = append(edges, fmt.Sprintf("%s --> %s",
+				e.Caller.Func.RelString(from),
+				e.Callee.Func.RelString(from)))
+		}
+		return nil
+	})
+	writeSorted(edges)
+
+	buf.WriteString("Reachable functions\n")
+	var reachable []string
+	for f := range res.Reachable {
+		reachable = append(reachable, f.RelString(from))
+	}
+	writeSorted(reachable)
+
+	buf.WriteString("Reflect types\n")
+	var rtypes []string
+	res.RuntimeTypes.Iterate(func(key types.Type, value interface{}) {
+		if value == false { // accessible to reflection
+			rtypes = append(rtypes, types.TypeString(key, types.RelativeTo(from)))
+		}
+	})
+	writeSorted(rtypes)
+
+	return strings.TrimSpace(buf.String())
+}

vendor/golang.org/x/tools/go/callgraph/rta/testdata/func.go

@@ -0,0 +1,37 @@
+//+build ignore
+
+package main
+
+// Test of dynamic function calls.
+// No interfaces, so no runtime/reflect types.
+
+func A1() {
+	A2(0)
+}
+
+func A2(int) {} // not address-taken
+
+func B() {} // unreachable
+
+var (
+	C = func(int) {}
+	D = func(int) {}
+)
+
+func main() {
+	A1()
+
+	pfn := C
+	pfn(0) // calls C and D but not A2 (same sig but not address-taken)
+}
+
+// WANT:
+// Dynamic calls
+//   main --> init$1
+//   main --> init$2
+// Reachable functions
+//   A1
+//   A2
+//   init$1
+//   init$2
+// Reflect types

vendor/golang.org/x/tools/go/callgraph/rta/testdata/iface.go

@@ -0,0 +1,79 @@
+//+build ignore
+
+package main
+
+// Test of interface calls.
+
+func use(interface{})
+
+type A byte // instantiated but not a reflect type
+
+func (A) f() {} // called directly
+func (A) F() {} // unreachable
+
+type B int // a reflect type
+
+func (*B) f() {} // reachable via interface invoke
+func (*B) F() {} // reachable: exported method of reflect type
+
+type B2 int // a reflect type, and *B2 also
+
+func (B2) f() {} // reachable via interface invoke
+func (B2) g() {} // reachable: exported method of reflect type
+
+type C string // not instantiated
+
+func (C) f() {} // unreachable
+func (C) F() {} // unreachable
+
+type D uint // instantiated only in dead code
+
+func (D) f() {} // unreachable
+func (D) F() {} // unreachable
+
+func main() {
+	A(0).f()
+
+	use(new(B))
+	use(B2(0))
+
+	var i interface {
+		f()
+	}
+	i.f() // calls (*B).f, (*B2).f and (B2.f)
+
+	live()
+}
+
+func live() {
+	var j interface {
+		f()
+		g()
+	}
+	j.f() // calls (B2).f and (*B2).f but not (*B).f (no g method).
+}
+
+func dead() {
+	use(D(0))
+}
+
+// WANT:
+// Dynamic calls
+//   live --> (*B2).f
+//   live --> (B2).f
+//   main --> (*B).f
+//   main --> (*B2).f
+//   main --> (B2).f
+// Reachable functions
+//   (*B).F
+//   (*B).f
+//   (*B2).f
+//   (A).f
+//   (B2).f
+//   live
+//   use
+// Reflect types
+//   *B
+//   *B2
+//   B
+//   B2

vendor/golang.org/x/tools/go/callgraph/rta/testdata/rtype.go

@@ -0,0 +1,35 @@
+//+build ignore
+
+package main
+
+// Test of runtime types (types for which descriptors are needed).
+
+func use(interface{})
+
+type A byte // neither A nor byte are runtime types
+
+type B struct{ x uint } // B and uint are runtime types, but not the struct
+
+func main() {
+	var x int // not a runtime type
+	print(x)
+
+	var y string // runtime type due to interface conversion
+	use(y)
+
+	use(struct{ uint64 }{}) // struct is a runtime type
+
+	use(new(B)) // *B is a runtime type
+}
+
+// WANT:
+// Dynamic calls
+// Reachable functions
+//   use
+// Reflect types
+//   *B
+//   B
+//   string
+//   struct{uint64}
+//   uint
+//   uint64

vendor/golang.org/x/tools/go/callgraph/static/static.go

@@ -0,0 +1,35 @@
+// Package static computes the call graph of a Go program containing
+// only static call edges.
+package static // import "golang.org/x/tools/go/callgraph/static"
+
+import (
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/ssa"
+	"golang.org/x/tools/go/ssa/ssautil"
+)
+
+// 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.
+	// TODO(adonovan): opt: this is slower than RTA (perhaps because
+	// the lower precision means so many edges are allocated)!
+	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
+}

vendor/golang.org/x/tools/go/callgraph/static/static_test.go

@@ -0,0 +1,88 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package static_test
+
+import (
+	"fmt"
+	"go/parser"
+	"reflect"
+	"sort"
+	"testing"
+
+	"golang.org/x/tools/go/callgraph"
+	"golang.org/x/tools/go/callgraph/static"
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/ssa/ssautil"
+)
+
+const input = `package P
+
+type C int
+func (C) f()
+
+type I interface{f()}
+
+func f() {
+	p := func() {}
+	g()
+	p() // SSA constant propagation => static
+
+	if unknown {
+		p = h
+	}
+	p() // dynamic
+
+	C(0).f()
+}
+
+func g() {
+	var i I = C(0)
+	i.f()
+}
+
+func h()
+
+var unknown bool
+`
+
+func TestStatic(t *testing.T) {
+	conf := loader.Config{ParserMode: parser.ParseComments}
+	f, err := conf.ParseFile("P.go", input)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	conf.CreateFromFiles("P", f)
+	iprog, err := conf.Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	P := iprog.Created[0].Pkg
+
+	prog := ssautil.CreateProgram(iprog, 0)
+	prog.Build()
+
+	cg := static.CallGraph(prog)
+
+	var edges []string
+	callgraph.GraphVisitEdges(cg, func(e *callgraph.Edge) error {
+		edges = append(edges, fmt.Sprintf("%s -> %s",
+			e.Caller.Func.RelString(P),
+			e.Callee.Func.RelString(P)))
+		return nil
+	})
+	sort.Strings(edges)
+
+	want := []string{
+		"(*C).f -> (C).f",
+		"f -> (C).f",
+		"f -> f$1",
+		"f -> g",
+	}
+	if !reflect.DeepEqual(edges, want) {
+		t.Errorf("Got edges %v, want %v", edges, want)
+	}
+}

vendor/golang.org/x/tools/go/callgraph/util.go

@@ -0,0 +1,181 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package callgraph
+
+import "golang.org/x/tools/go/ssa"
+
+// This file provides various utilities over call graphs, such as
+// visitation and path search.
+
+// CalleesOf returns a new set containing all direct callees of the
+// caller node.
+//
+func CalleesOf(caller *Node) map[*Node]bool {
+	callees := make(map[*Node]bool)
+	for _, e := range caller.Out {
+		callees[e.Callee] = true
+	}
+	return callees
+}
+
+// GraphVisitEdges visits all the edges in graph g in depth-first order.
+// The edge function is called for each edge in postorder.  If it
+// returns non-nil, visitation stops and GraphVisitEdges returns that
+// value.
+//
+func GraphVisitEdges(g *Graph, edge func(*Edge) error) error {
+	seen := make(map[*Node]bool)
+	var visit func(n *Node) error
+	visit = func(n *Node) error {
+		if !seen[n] {
+			seen[n] = true
+			for _, e := range n.Out {
+				if err := visit(e.Callee); err != nil {
+					return err
+				}
+				if err := edge(e); err != nil {
+					return err
+				}
+			}
+		}
+		return nil
+	}
+	for _, n := range g.Nodes {
+		if err := visit(n); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// PathSearch finds an arbitrary path starting at node start and
+// ending at some node for which isEnd() returns true.  On success,
+// PathSearch returns the path as an ordered list of edges; on
+// failure, it returns nil.
+//
+func PathSearch(start *Node, isEnd func(*Node) bool) []*Edge {
+	stack := make([]*Edge, 0, 32)
+	seen := make(map[*Node]bool)
+	var search func(n *Node) []*Edge
+	search = func(n *Node) []*Edge {
+		if !seen[n] {
+			seen[n] = true
+			if isEnd(n) {
+				return stack
+			}
+			for _, e := range n.Out {
+				stack = append(stack, e) // push
+				if found := search(e.Callee); found != nil {
+					return found
+				}
+				stack = stack[:len(stack)-1] // pop
+			}
+		}
+		return nil
+	}
+	return search(start)
+}
+
+// DeleteSyntheticNodes removes from call graph g all nodes for
+// synthetic functions (except g.Root and package initializers),
+// preserving the topology.  In effect, calls to synthetic wrappers
+// are "inlined".
+//
+func (g *Graph) DeleteSyntheticNodes() {
+	// Measurements on the standard library and go.tools show that
+	// resulting graph has ~15% fewer nodes and 4-8% fewer edges
+	// than the input.
+	//
+	// Inlining a wrapper of in-degree m, out-degree n adds m*n
+	// and removes m+n edges.  Since most wrappers are monomorphic
+	// (n=1) this results in a slight reduction.  Polymorphic
+	// wrappers (n>1), e.g. from embedding an interface value
+	// inside a struct to satisfy some interface, cause an
+	// increase in the graph, but they seem to be uncommon.
+
+	// Hash all existing edges to avoid creating duplicates.
+	edges := make(map[Edge]bool)
+	for _, cgn := range g.Nodes {
+		for _, e := range cgn.Out {
+			edges[*e] = true
+		}
+	}
+	for fn, cgn := range g.Nodes {
+		if cgn == g.Root || fn.Synthetic == "" || isInit(cgn.Func) {
+			continue // keep
+		}
+		for _, eIn := range cgn.In {
+			for _, eOut := range cgn.Out {
+				newEdge := Edge{eIn.Caller, eIn.Site, eOut.Callee}
+				if edges[newEdge] {
+					continue // don't add duplicate
+				}
+				AddEdge(eIn.Caller, eIn.Site, eOut.Callee)
+				edges[newEdge] = true
+			}
+		}
+		g.DeleteNode(cgn)
+	}
+}
+
+func isInit(fn *ssa.Function) bool {
+	return fn.Pkg != nil && fn.Pkg.Func("init") == fn
+}
+
+// DeleteNode removes node n and its edges from the graph g.
+// (NB: not efficient for batch deletion.)
+func (g *Graph) DeleteNode(n *Node) {
+	n.deleteIns()
+	n.deleteOuts()
+	delete(g.Nodes, n.Func)
+}
+
+// deleteIns deletes all incoming edges to n.
+func (n *Node) deleteIns() {
+	for _, e := range n.In {
+		removeOutEdge(e)
+	}
+	n.In = nil
+}
+
+// deleteOuts deletes all outgoing edges from n.
+func (n *Node) deleteOuts() {
+	for _, e := range n.Out {
+		removeInEdge(e)
+	}
+	n.Out = nil
+}
+
+// removeOutEdge removes edge.Caller's outgoing edge 'edge'.
+func removeOutEdge(edge *Edge) {
+	caller := edge.Caller
+	n := len(caller.Out)
+	for i, e := range caller.Out {
+		if e == edge {
+			// Replace it with the final element and shrink the slice.
+			caller.Out[i] = caller.Out[n-1]
+			caller.Out[n-1] = nil // aid GC
+			caller.Out = caller.Out[:n-1]
+			return
+		}
+	}
+	panic("edge not found: " + edge.String())
+}
+
+// removeInEdge removes edge.Callee's incoming edge 'edge'.
+func removeInEdge(edge *Edge) {
+	caller := edge.Callee
+	n := len(caller.In)
+	for i, e := range caller.In {
+		if e == edge {
+			// Replace it with the final element and shrink the slice.
+			caller.In[i] = caller.In[n-1]
+			caller.In[n-1] = nil // aid GC
+			caller.In = caller.In[:n-1]
+			return
+		}
+	}
+	panic("edge not found: " + edge.String())
+}