go/ssa/builder_test.go - tools - Git at Google

 // 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 ssa_test

 import (
 	"bytes"
 	"go/ast"
 	"go/importer"
 	"go/parser"
 	"go/token"
 	"go/types"
 	"os"
 	"reflect"
 	"sort"
 	"strings"
 	"testing"

 	"golang.org/x/tools/go/loader"
 	"golang.org/x/tools/go/ssa"
 	"golang.org/x/tools/go/ssa/ssautil"
 )

 func isEmpty(f *ssa.Function) bool { return f.Blocks == nil }

 // Tests that programs partially loaded from gc object files contain
 // functions with no code for the external portions, but are otherwise ok.
 func TestBuildPackage(t *testing.T) {
 	input := `
 package main

 import (
 	"bytes"
 	"io"
 	"testing"
 )

 func main() {
         var t testing.T
 	t.Parallel()    // static call to external declared method
         t.Fail()        // static call to promoted external declared method
         testing.Short() // static call to external package-level function

         var w io.Writer = new(bytes.Buffer)
         w.Write(nil)    // interface invoke of external declared method
 }
 `

 	// Parse the file.
 	fset := token.NewFileSet()
 	f, err := parser.ParseFile(fset, "input.go", input, 0)
 	if err != nil {
 		t.Error(err)
 		return
 	}

 	// Build an SSA program from the parsed file.
 	// Load its dependencies from gc binary export data.
 	mainPkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
 		types.NewPackage("main", ""), []*ast.File{f}, ssa.SanityCheckFunctions)
 	if err != nil {
 		t.Error(err)
 		return
 	}

 	// The main package, its direct and indirect dependencies are loaded.
 	deps := []string{
 		// directly imported dependencies:
 		"bytes", "io", "testing",
 		// indirect dependencies mentioned by
 		// the direct imports' export data
 		"sync", "unicode", "time",
 	}

 	prog := mainPkg.Prog
 	all := prog.AllPackages()
 	if len(all) <= len(deps) {
 		t.Errorf("unexpected set of loaded packages: %q", all)
 	}
 	for _, path := range deps {
 		pkg := prog.ImportedPackage(path)
 		if pkg == nil {
 			t.Errorf("package not loaded: %q", path)
 			continue
 		}

 		// External packages should have no function bodies (except for wrappers).
 		isExt := pkg != mainPkg

 		// init()
 		if isExt && !isEmpty(pkg.Func("init")) {
 			t.Errorf("external package %s has non-empty init", pkg)
 		} else if !isExt && isEmpty(pkg.Func("init")) {
 			t.Errorf("main package %s has empty init", pkg)
 		}

 		for _, mem := range pkg.Members {
 			switch mem := mem.(type) {
 			case *ssa.Function:
 				// Functions at package level.
 				if isExt && !isEmpty(mem) {
 					t.Errorf("external function %s is non-empty", mem)
 				} else if !isExt && isEmpty(mem) {
 					t.Errorf("function %s is empty", mem)
 				}

 			case *ssa.Type:
 				// Methods of named types T.
 				// (In this test, all exported methods belong to *T not T.)
 				if !isExt {
 					t.Fatalf("unexpected name type in main package: %s", mem)
 				}
 				mset := prog.MethodSets.MethodSet(types.NewPointer(mem.Type()))
 				for i, n := 0, mset.Len(); i < n; i++ {
 					m := prog.MethodValue(mset.At(i))
 					// For external types, only synthetic wrappers have code.
 					expExt := !strings.Contains(m.Synthetic, "wrapper")
 					if expExt && !isEmpty(m) {
 						t.Errorf("external method %s is non-empty: %s",
 							m, m.Synthetic)
 					} else if !expExt && isEmpty(m) {
 						t.Errorf("method function %s is empty: %s",
 							m, m.Synthetic)
 					}
 				}
 			}
 		}
 	}

 	expectedCallee := []string{
 		"(*testing.T).Parallel",
 		"(*testing.common).Fail",
 		"testing.Short",
 		"N/A",
 	}
 	callNum := 0
 	for _, b := range mainPkg.Func("main").Blocks {
 		for _, instr := range b.Instrs {
 			switch instr := instr.(type) {
 			case ssa.CallInstruction:
 				call := instr.Common()
 				if want := expectedCallee[callNum]; want != "N/A" {
 					got := call.StaticCallee().String()
 					if want != got {
 						t.Errorf("call #%d from main.main: got callee %s, want %s",
 							callNum, got, want)
 					}
 				}
 				callNum++
 			}
 		}
 	}
 	if callNum != 4 {
 		t.Errorf("in main.main: got %d calls, want %d", callNum, 4)
 	}
 }

 // TestRuntimeTypes tests that (*Program).RuntimeTypes() includes all necessary types.
 func TestRuntimeTypes(t *testing.T) {
 	tests := []struct {
 		input string
 		want  []string
 	}{
 		// An exported package-level type is needed.
 		{`package A; type T struct{}; func (T) f() {}`,
 			[]string{"*p.T", "p.T"},
 		},
 		// An unexported package-level type is not needed.
 		{`package B; type t struct{}; func (t) f() {}`,
 			nil,
 		},
 		// Subcomponents of type of exported package-level var are needed.
 		{`package C; import "bytes"; var V struct {*bytes.Buffer}`,
 			[]string{"*bytes.Buffer", "*struct{*bytes.Buffer}", "struct{*bytes.Buffer}"},
 		},
 		// Subcomponents of type of unexported package-level var are not needed.
 		{`package D; import "bytes"; var v struct {*bytes.Buffer}`,
 			nil,
 		},
 		// Subcomponents of type of exported package-level function are needed.
 		{`package E; import "bytes"; func F(struct {*bytes.Buffer}) {}`,
 			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
 		},
 		// Subcomponents of type of unexported package-level function are not needed.
 		{`package F; import "bytes"; func f(struct {*bytes.Buffer}) {}`,
 			nil,
 		},
 		// Subcomponents of type of exported method of uninstantiated unexported type are not needed.
 		{`package G; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v x`,
 			nil,
 		},
 		// ...unless used by MakeInterface.
 		{`package G2; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v interface{} = x{}`,
 			[]string{"*bytes.Buffer", "*p.x", "p.x", "struct{*bytes.Buffer}"},
 		},
 		// Subcomponents of type of unexported method are not needed.
 		{`package I; import "bytes"; type X struct{}; func (X) G(struct {*bytes.Buffer}) {}`,
 			[]string{"*bytes.Buffer", "*p.X", "p.X", "struct{*bytes.Buffer}"},
 		},
 		// Local types aren't needed.
 		{`package J; import "bytes"; func f() { type T struct {*bytes.Buffer}; var t T; _ = t }`,
 			nil,
 		},
 		// ...unless used by MakeInterface.
 		{`package K; import "bytes"; func f() { type T struct {*bytes.Buffer}; _ = interface{}(T{}) }`,
 			[]string{"*bytes.Buffer", "*p.T", "p.T"},
 		},
 		// Types used as operand of MakeInterface are needed.
 		{`package L; import "bytes"; func f() { _ = interface{}(struct{*bytes.Buffer}{}) }`,
 			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
 		},
 		// MakeInterface is optimized away when storing to a blank.
 		{`package M; import "bytes"; var _ interface{} = struct{*bytes.Buffer}{}`,
 			nil,
 		},
 	}
 	for _, test := range tests {
 		// Parse the file.
 		fset := token.NewFileSet()
 		f, err := parser.ParseFile(fset, "input.go", test.input, 0)
 		if err != nil {
 			t.Errorf("test %q: %s", test.input[:15], err)
 			continue
 		}

 		// Create a single-file main package.
 		// Load dependencies from gc binary export data.
 		ssapkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
 			types.NewPackage("p", ""), []*ast.File{f}, ssa.SanityCheckFunctions)
 		if err != nil {
 			t.Errorf("test %q: %s", test.input[:15], err)
 			continue
 		}

 		var typstrs []string
 		for _, T := range ssapkg.Prog.RuntimeTypes() {
 			typstrs = append(typstrs, T.String())
 		}
 		sort.Strings(typstrs)

 		if !reflect.DeepEqual(typstrs, test.want) {
 			t.Errorf("test 'package %s': got %q, want %q",
 				f.Name.Name, typstrs, test.want)
 		}
 	}
 }

 // TestInit tests that synthesized init functions are correctly formed.
 // Bare init functions omit calls to dependent init functions and the use of
 // an init guard. They are useful in cases where the client uses a different
 // calling convention for init functions, or cases where it is easier for a
 // client to analyze bare init functions. Both of these aspects are used by
 // the llgo compiler for simpler integration with gccgo's runtime library,
 // and to simplify the analysis whereby it deduces which stores to globals
 // can be lowered to global initializers.
 func TestInit(t *testing.T) {
 	tests := []struct {
 		mode        ssa.BuilderMode
 		input, want string
 	}{
 		{0, `package A; import _ "errors"; var i int = 42`,
 			`# Name: A.init
 # Package: A
 # Synthetic: package initializer
 func init():
 0:                                                                entry P:0 S:2
 	t0 = *init$guard                                                   bool
 	if t0 goto 2 else 1
 1:                                                           init.start P:1 S:1
 	*init$guard = true:bool
 	t1 = errors.init()                                                   ()
 	*i = 42:int
 	jump 2
 2:                                                            init.done P:2 S:0
 	return

 `},
 		{ssa.BareInits, `package B; import _ "errors"; var i int = 42`,
 			`# Name: B.init
 # Package: B
 # Synthetic: package initializer
 func init():
 0:                                                                entry P:0 S:0
 	*i = 42:int
 	return

 `},
 	}
 	for _, test := range tests {
 		// Create a single-file main package.
 		var conf loader.Config
 		f, err := conf.ParseFile("<input>", test.input)
 		if err != nil {
 			t.Errorf("test %q: %s", test.input[:15], err)
 			continue
 		}
 		conf.CreateFromFiles(f.Name.Name, f)

 		lprog, err := conf.Load()
 		if err != nil {
 			t.Errorf("test 'package %s': Load: %s", f.Name.Name, err)
 			continue
 		}
 		prog := ssautil.CreateProgram(lprog, test.mode)
 		mainPkg := prog.Package(lprog.Created[0].Pkg)
 		prog.Build()
 		initFunc := mainPkg.Func("init")
 		if initFunc == nil {
 			t.Errorf("test 'package %s': no init function", f.Name.Name)
 			continue
 		}

 		var initbuf bytes.Buffer
 		_, err = initFunc.WriteTo(&initbuf)
 		if err != nil {
 			t.Errorf("test 'package %s': WriteTo: %s", f.Name.Name, err)
 			continue
 		}

 		if initbuf.String() != test.want {
 			t.Errorf("test 'package %s': got %s, want %s", f.Name.Name, initbuf.String(), test.want)
 		}
 	}
 }

 // 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)
 	}
 }

 // TestPhiElimination ensures that dead phis, including those that
 // participate in a cycle, are properly eliminated.
 func TestPhiElimination(t *testing.T) {
 	const input = `
 package p

 func f() error

 func g(slice []int) {
 	for {
 		for range slice {
 			// e should not be lifted to a dead φ-node.
 			e := f()
 			h(e)
 		}
 	}
 }

 func h(error)
 `
 	// The SSA code for this function should look something like this:
 	// 0:
 	//         jump 1
 	// 1:
 	//         t0 = len(slice)
 	//         jump 2
 	// 2:
 	//         t1 = phi [1: -1:int, 3: t2]
 	//         t2 = t1 + 1:int
 	//         t3 = t2 < t0
 	//         if t3 goto 3 else 1
 	// 3:
 	//         t4 = f()
 	//         t5 = h(t4)
 	//         jump 2
 	//
 	// But earlier versions of the SSA construction algorithm would
 	// additionally generate this cycle of dead phis:
 	//
 	// 1:
 	//         t7 = phi [0: nil:error, 2: t8] #e
 	//         ...
 	// 2:
 	//         t8 = phi [1: t7, 3: t4] #e
 	//         ...

 	// Parse
 	var conf loader.Config
 	f, err := conf.ParseFile("<input>", input)
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
 	conf.CreateFromFiles("p", f)

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

 	// Create and build SSA
 	prog := ssautil.CreateProgram(lprog, 0)
 	p := prog.Package(lprog.Package("p").Pkg)
 	p.Build()
 	g := p.Func("g")

 	phis := 0
 	for _, b := range g.Blocks {
 		for _, instr := range b.Instrs {
 			if _, ok := instr.(*ssa.Phi); ok {
 				phis++
 			}
 		}
 	}
 	if phis != 1 {
 		g.WriteTo(os.Stderr)
 		t.Errorf("expected a single Phi (for the range index), got %d", phis)
 	}
 }
	// 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 ssa_test

	import (
	"bytes"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"reflect"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	)

	func isEmpty(f *ssa.Function) bool { return f.Blocks == nil }

	// Tests that programs partially loaded from gc object files contain
	// functions with no code for the external portions, but are otherwise ok.
	func TestBuildPackage(t *testing.T) {
	input := `
	package main

	import (
	"bytes"
	"io"
	"testing"
	)

	func main() {
	var t testing.T
	t.Parallel() // static call to external declared method
	t.Fail() // static call to promoted external declared method
	testing.Short() // static call to external package-level function

	var w io.Writer = new(bytes.Buffer)
	w.Write(nil) // interface invoke of external declared method
	}
	`

	// Parse the file.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "input.go", input, 0)
	if err != nil {
	t.Error(err)
	return
	}

	// Build an SSA program from the parsed file.
	// Load its dependencies from gc binary export data.
	mainPkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
	types.NewPackage("main", ""), []*ast.File{f}, ssa.SanityCheckFunctions)
	if err != nil {
	t.Error(err)
	return
	}

	// The main package, its direct and indirect dependencies are loaded.
	deps := []string{
	// directly imported dependencies:
	"bytes", "io", "testing",
	// indirect dependencies mentioned by
	// the direct imports' export data
	"sync", "unicode", "time",
	}

	prog := mainPkg.Prog
	all := prog.AllPackages()
	if len(all) <= len(deps) {
	t.Errorf("unexpected set of loaded packages: %q", all)
	}
	for _, path := range deps {
	pkg := prog.ImportedPackage(path)
	if pkg == nil {
	t.Errorf("package not loaded: %q", path)
	continue
	}

	// External packages should have no function bodies (except for wrappers).
	isExt := pkg != mainPkg

	// init()
	if isExt && !isEmpty(pkg.Func("init")) {
	t.Errorf("external package %s has non-empty init", pkg)
	} else if !isExt && isEmpty(pkg.Func("init")) {
	t.Errorf("main package %s has empty init", pkg)
	}

	for _, mem := range pkg.Members {
	switch mem := mem.(type) {
	case *ssa.Function:
	// Functions at package level.
	if isExt && !isEmpty(mem) {
	t.Errorf("external function %s is non-empty", mem)
	} else if !isExt && isEmpty(mem) {
	t.Errorf("function %s is empty", mem)
	}

	case *ssa.Type:
	// Methods of named types T.
	// (In this test, all exported methods belong to *T not T.)
	if !isExt {
	t.Fatalf("unexpected name type in main package: %s", mem)
	}
	mset := prog.MethodSets.MethodSet(types.NewPointer(mem.Type()))
	for i, n := 0, mset.Len(); i < n; i++ {
	m := prog.MethodValue(mset.At(i))
	// For external types, only synthetic wrappers have code.
	expExt := !strings.Contains(m.Synthetic, "wrapper")
	if expExt && !isEmpty(m) {
	t.Errorf("external method %s is non-empty: %s",
	m, m.Synthetic)
	} else if !expExt && isEmpty(m) {
	t.Errorf("method function %s is empty: %s",
	m, m.Synthetic)
	}
	}
	}
	}
	}

	expectedCallee := []string{
	"(*testing.T).Parallel",
	"(*testing.common).Fail",
	"testing.Short",
	"N/A",
	}
	callNum := 0
	for _, b := range mainPkg.Func("main").Blocks {
	for _, instr := range b.Instrs {
	switch instr := instr.(type) {
	case ssa.CallInstruction:
	call := instr.Common()
	if want := expectedCallee[callNum]; want != "N/A" {
	got := call.StaticCallee().String()
	if want != got {
	t.Errorf("call #%d from main.main: got callee %s, want %s",
	callNum, got, want)
	}
	}
	callNum++
	}
	}
	}
	if callNum != 4 {
	t.Errorf("in main.main: got %d calls, want %d", callNum, 4)
	}
	}

	// TestRuntimeTypes tests that (*Program).RuntimeTypes() includes all necessary types.
	func TestRuntimeTypes(t *testing.T) {
	tests := []struct {
	input string
	want []string
	}{
	// An exported package-level type is needed.
	{`package A; type T struct{}; func (T) f() {}`,
	[]string{"*p.T", "p.T"},
	},
	// An unexported package-level type is not needed.
	{`package B; type t struct{}; func (t) f() {}`,
	nil,
	},
	// Subcomponents of type of exported package-level var are needed.
	{`package C; import "bytes"; var V struct {*bytes.Buffer}`,
	[]string{"bytes.Buffer", "struct{bytes.Buffer}", "struct{bytes.Buffer}"},
	},
	// Subcomponents of type of unexported package-level var are not needed.
	{`package D; import "bytes"; var v struct {*bytes.Buffer}`,
	nil,
	},
	// Subcomponents of type of exported package-level function are needed.
	{`package E; import "bytes"; func F(struct {*bytes.Buffer}) {}`,
	[]string{"bytes.Buffer", "struct{bytes.Buffer}"},
	},
	// Subcomponents of type of unexported package-level function are not needed.
	{`package F; import "bytes"; func f(struct {*bytes.Buffer}) {}`,
	nil,
	},
	// Subcomponents of type of exported method of uninstantiated unexported type are not needed.
	{`package G; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v x`,
	nil,
	},
	// ...unless used by MakeInterface.
	{`package G2; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v interface{} = x{}`,
	[]string{"bytes.Buffer", "p.x", "p.x", "struct{*bytes.Buffer}"},
	},
	// Subcomponents of type of unexported method are not needed.
	{`package I; import "bytes"; type X struct{}; func (X) G(struct {*bytes.Buffer}) {}`,
	[]string{"bytes.Buffer", "p.X", "p.X", "struct{*bytes.Buffer}"},
	},
	// Local types aren't needed.
	{`package J; import "bytes"; func f() { type T struct {*bytes.Buffer}; var t T; _ = t }`,
	nil,
	},
	// ...unless used by MakeInterface.
	{`package K; import "bytes"; func f() { type T struct {*bytes.Buffer}; _ = interface{}(T{}) }`,
	[]string{"bytes.Buffer", "p.T", "p.T"},
	},
	// Types used as operand of MakeInterface are needed.
	{`package L; import "bytes"; func f() { _ = interface{}(struct{*bytes.Buffer}{}) }`,
	[]string{"bytes.Buffer", "struct{bytes.Buffer}"},
	},
	// MakeInterface is optimized away when storing to a blank.
	{`package M; import "bytes"; var _ interface{} = struct{*bytes.Buffer}{}`,
	nil,
	},
	}
	for _, test := range tests {
	// Parse the file.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "input.go", test.input, 0)
	if err != nil {
	t.Errorf("test %q: %s", test.input[:15], err)
	continue
	}

	// Create a single-file main package.
	// Load dependencies from gc binary export data.
	ssapkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
	types.NewPackage("p", ""), []*ast.File{f}, ssa.SanityCheckFunctions)
	if err != nil {
	t.Errorf("test %q: %s", test.input[:15], err)
	continue
	}

	var typstrs []string
	for _, T := range ssapkg.Prog.RuntimeTypes() {
	typstrs = append(typstrs, T.String())
	}
	sort.Strings(typstrs)

	if !reflect.DeepEqual(typstrs, test.want) {
	t.Errorf("test 'package %s': got %q, want %q",
	f.Name.Name, typstrs, test.want)
	}
	}
	}

	// TestInit tests that synthesized init functions are correctly formed.
	// Bare init functions omit calls to dependent init functions and the use of
	// an init guard. They are useful in cases where the client uses a different
	// calling convention for init functions, or cases where it is easier for a
	// client to analyze bare init functions. Both of these aspects are used by
	// the llgo compiler for simpler integration with gccgo's runtime library,
	// and to simplify the analysis whereby it deduces which stores to globals
	// can be lowered to global initializers.
	func TestInit(t *testing.T) {
	tests := []struct {
	mode ssa.BuilderMode
	input, want string
	}{
	{0, `package A; import _ "errors"; var i int = 42`,
	`# Name: A.init
	# Package: A
	# Synthetic: package initializer
	func init():
	0: entry P:0 S:2
	t0 = *init$guard bool
	if t0 goto 2 else 1
	1: init.start P:1 S:1
	*init$guard = true:bool
	t1 = errors.init() ()
	*i = 42:int
	jump 2
	2: init.done P:2 S:0
	return

	`},
	{ssa.BareInits, `package B; import _ "errors"; var i int = 42`,
	`# Name: B.init
	# Package: B
	# Synthetic: package initializer
	func init():
	0: entry P:0 S:0
	*i = 42:int
	return

	`},
	}
	for _, test := range tests {
	// Create a single-file main package.
	var conf loader.Config
	f, err := conf.ParseFile("<input>", test.input)
	if err != nil {
	t.Errorf("test %q: %s", test.input[:15], err)
	continue
	}
	conf.CreateFromFiles(f.Name.Name, f)

	lprog, err := conf.Load()
	if err != nil {
	t.Errorf("test 'package %s': Load: %s", f.Name.Name, err)
	continue
	}
	prog := ssautil.CreateProgram(lprog, test.mode)
	mainPkg := prog.Package(lprog.Created[0].Pkg)
	prog.Build()
	initFunc := mainPkg.Func("init")
	if initFunc == nil {
	t.Errorf("test 'package %s': no init function", f.Name.Name)
	continue
	}

	var initbuf bytes.Buffer
	_, err = initFunc.WriteTo(&initbuf)
	if err != nil {
	t.Errorf("test 'package %s': WriteTo: %s", f.Name.Name, err)
	continue
	}

	if initbuf.String() != test.want {
	t.Errorf("test 'package %s': got %s, want %s", f.Name.Name, initbuf.String(), test.want)
	}
	}
	}

	// 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)
	}
	}

	// TestPhiElimination ensures that dead phis, including those that
	// participate in a cycle, are properly eliminated.
	func TestPhiElimination(t *testing.T) {
	const input = `
	package p

	func f() error

	func g(slice []int) {
	for {
	for range slice {
	// e should not be lifted to a dead φ-node.
	e := f()
	h(e)
	}
	}
	}

	func h(error)
	`
	// The SSA code for this function should look something like this:
	// 0:
	// jump 1
	// 1:
	// t0 = len(slice)
	// jump 2
	// 2:
	// t1 = phi [1: -1:int, 3: t2]
	// t2 = t1 + 1:int
	// t3 = t2 < t0
	// if t3 goto 3 else 1
	// 3:
	// t4 = f()
	// t5 = h(t4)
	// jump 2
	//
	// But earlier versions of the SSA construction algorithm would
	// additionally generate this cycle of dead phis:
	//
	// 1:
	// t7 = phi [0: nil:error, 2: t8] #e
	// ...
	// 2:
	// t8 = phi [1: t7, 3: t4] #e
	// ...

	// Parse
	var conf loader.Config
	f, err := conf.ParseFile("<input>", input)
	if err != nil {
	t.Fatalf("parse: %v", err)
	}
	conf.CreateFromFiles("p", f)

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

	// Create and build SSA
	prog := ssautil.CreateProgram(lprog, 0)
	p := prog.Package(lprog.Package("p").Pkg)
	p.Build()
	g := p.Func("g")

	phis := 0
	for _, b := range g.Blocks {
	for _, instr := range b.Instrs {
	if _, ok := instr.(*ssa.Phi); ok {
	phis++
	}
	}
	}
	if phis != 1 {
	g.WriteTo(os.Stderr)
	t.Errorf("expected a single Phi (for the range index), got %d", phis)
	}
	}