func (v *Variable) readFunctionPtr() {
	val, err := v.mem.readMemory(v.Addr, v.dbp.arch.PtrSize())
	if err != nil {
		v.Unreadable = err
		return
	}

	// dereference pointer to find function pc
	fnaddr := uintptr(binary.LittleEndian.Uint64(val))
	if fnaddr == 0 {
		v.Base = 0
		v.Value = constant.MakeString("")
		return
	}

	val, err = v.mem.readMemory(fnaddr, v.dbp.arch.PtrSize())
	if err != nil {
		v.Unreadable = err
		return
	}

	v.Base = uintptr(binary.LittleEndian.Uint64(val))
	fn := v.dbp.goSymTable.PCToFunc(uint64(v.Base))
	if fn == nil {
		v.Unreadable = fmt.Errorf("could not find function for %#v", v.Base)
		return
	}

	v.Value = constant.MakeString(fn.Name)
}

// zeroConst returns a new "zero" constant of the specified type,
// which must not be an array or struct type: the zero values of
// aggregates are well-defined but cannot be represented by Const.
//
func zeroConst(t types.Type) *Const {
	switch t := t.(type) {
	case *types.Basic:
		switch {
		case t.Info()&types.IsBoolean != 0:
			return NewConst(exact.MakeBool(false), t)
		case t.Info()&types.IsNumeric != 0:
			return NewConst(exact.MakeInt64(0), t)
		case t.Info()&types.IsString != 0:
			return NewConst(exact.MakeString(""), t)
		case t.Kind() == types.UnsafePointer:
			fallthrough
		case t.Kind() == types.UntypedNil:
			return nilConst(t)
		default:
			panic(fmt.Sprint("zeroConst for unexpected type:", t))
		}
	case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature:
		return nilConst(t)
	case *types.Named:
		return NewConst(zeroConst(t.Underlying()).Value, t)
	case *types.Array, *types.Struct, *types.Tuple:
		panic(fmt.Sprint("zeroConst applied to aggregate:", t))
	}
	panic(fmt.Sprint("zeroConst: unexpected ", t))
}

func (c *funcContext) zeroValue(ty types.Type) ast.Expr {
	switch t := ty.Underlying().(type) {
	case *types.Basic:
		switch {
		case isBoolean(t):
			return c.newConst(ty, constant.MakeBool(false))
		case isNumeric(t):
			return c.newConst(ty, constant.MakeInt64(0))
		case isString(t):
			return c.newConst(ty, constant.MakeString(""))
		case t.Kind() == types.UnsafePointer:
			// fall through to "nil"
		case t.Kind() == types.UntypedNil:
			panic("Zero value for untyped nil.")
		default:
			panic(fmt.Sprintf("Unhandled basic type: %v\n", t))
		}
	case *types.Array, *types.Struct:
		return c.setType(&ast.CompositeLit{}, ty)
	case *types.Chan, *types.Interface, *types.Map, *types.Signature, *types.Slice, *types.Pointer:
		// fall through to "nil"
	default:
		panic(fmt.Sprintf("Unhandled type: %T\n", t))
	}
	id := c.newIdent("nil", ty)
	c.p.Uses[id] = nilObj
	return id
}

// Conversion type-checks the conversion T(x).
// The result is in x.
func (check *Checker) conversion(x *operand, T Type) {
	constArg := x.mode == constant_

	var ok bool
	switch {
	case constArg && isConstType(T):
		// constant conversion
		switch t := T.Underlying().(*Basic); {
		case representableConst(x.val, check.conf, t.kind, &x.val):
			ok = true
		case isInteger(x.typ) && isString(t):
			codepoint := int64(-1)
			if i, ok := constant.Int64Val(x.val); ok {
				codepoint = i
			}
			// If codepoint < 0 the absolute value is too large (or unknown) for
			// conversion. This is the same as converting any other out-of-range
			// value - let string(codepoint) do the work.
			x.val = constant.MakeString(string(codepoint))
			ok = true
		}
	case x.convertibleTo(check.conf, T):
		// non-constant conversion
		x.mode = value
		ok = true
	}

	if !ok {
		check.errorf(x.pos(), "cannot convert %s to %s", x, T)
		x.mode = invalid
		return
	}

	// The conversion argument types are final. For untyped values the
	// conversion provides the type, per the spec: "A constant may be
	// given a type explicitly by a constant declaration or conversion,...".
	final := x.typ
	if isUntyped(x.typ) {
		final = T
		// - For conversions to interfaces, use the argument's default type.
		// - For conversions of untyped constants to non-constant types, also
		//   use the default type (e.g., []byte("foo") should report string
		//   not []byte as type for the constant "foo").
		// - Keep untyped nil for untyped nil arguments.
		if IsInterface(T) || constArg && !isConstType(T) {
			final = defaultType(x.typ)
		}
		check.updateExprType(x.expr, final, true)
	}

	x.typ = T
}

func (p *importer) value() constant.Value {
	switch tag := p.tagOrIndex(); tag {
	case falseTag:
		return constant.MakeBool(false)
	case trueTag:
		return constant.MakeBool(true)
	case int64Tag:
		return constant.MakeInt64(p.int64())
	case floatTag:
		return p.float()
	case complexTag:
		re := p.float()
		im := p.float()
		return constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
	case stringTag:
		return constant.MakeString(p.string())
	default:
		panic(fmt.Sprintf("unexpected value tag %d", tag))
	}
}

func (p *importer) value() constant.Value {
	switch kind := constant.Kind(p.int()); kind {
	case falseTag:
		return constant.MakeBool(false)
	case trueTag:
		return constant.MakeBool(true)
	case int64Tag:
		return constant.MakeInt64(p.int64())
	case floatTag:
		return p.float()
	case complexTag:
		re := p.float()
		im := p.float()
		return constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
	case stringTag:
		return constant.MakeString(p.string())
	default:
		panic(fmt.Sprintf("unexpected value kind %d", kind))
	}
}

// ConstValue     = string | "false" | "true" | ["-"] (int ["'"] | FloatOrComplex) .
// FloatOrComplex = float ["i" | ("+"|"-") float "i"] .
func (p *parser) parseConstValue() (val constant.Value, typ types.Type) {
	switch p.tok {
	case scanner.String:
		str := p.parseString()
		val = constant.MakeString(str)
		typ = types.Typ[types.UntypedString]
		return

	case scanner.Ident:
		b := false
		switch p.lit {
		case "false":
		case "true":
			b = true

		default:
			p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
		}

		p.next()
		val = constant.MakeBool(b)
		typ = types.Typ[types.UntypedBool]
		return
	}

	sign := ""
	if p.tok == '-' {
		p.next()
		sign = "-"
	}

	switch p.tok {
	case scanner.Int:
		val = constant.MakeFromLiteral(sign+p.lit, token.INT, 0)
		if val == nil {
			p.error("could not parse integer literal")
		}

		p.next()
		if p.tok == '\'' {
			p.next()
			typ = types.Typ[types.UntypedRune]
		} else {
			typ = types.Typ[types.UntypedInt]
		}

	case scanner.Float:
		re := sign + p.lit
		p.next()

		var im string
		switch p.tok {
		case '+':
			p.next()
			im = p.expect(scanner.Float)

		case '-':
			p.next()
			im = "-" + p.expect(scanner.Float)

		case scanner.Ident:
			// re is in fact the imaginary component. Expect "i" below.
			im = re
			re = "0"

		default:
			val = constant.MakeFromLiteral(re, token.FLOAT, 0)
			if val == nil {
				p.error("could not parse float literal")
			}
			typ = types.Typ[types.UntypedFloat]
			return
		}

		p.expectKeyword("i")
		reval := constant.MakeFromLiteral(re, token.FLOAT, 0)
		if reval == nil {
			p.error("could not parse real component of complex literal")
		}
		imval := constant.MakeFromLiteral(im+"i", token.IMAG, 0)
		if imval == nil {
			p.error("could not parse imag component of complex literal")
		}
		val = constant.BinaryOp(reval, token.ADD, imval)
		typ = types.Typ[types.UntypedComplex]

	default:
		p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
	}

	return
}

func compare(a, b interface{}, tok token.Token) bool {
	vala := reflect.ValueOf(a)
	valb := reflect.ValueOf(b)

	ak := vala.Kind()
	bk := valb.Kind()
	switch {
	case ak >= reflect.Int && ak <= reflect.Int64:
		if bk >= reflect.Int && bk <= reflect.Int64 {
			return constant.Compare(constant.MakeInt64(vala.Int()), tok, constant.MakeInt64(valb.Int()))
		}

		if bk == reflect.Float32 || bk == reflect.Float64 {
			return constant.Compare(constant.MakeFloat64(float64(vala.Int())), tok, constant.MakeFloat64(valb.Float()))
		}

		if bk == reflect.String {
			bla, err := strconv.ParseFloat(valb.String(), 64)
			if err != nil {
				return false
			}

			return constant.Compare(constant.MakeFloat64(float64(vala.Int())), tok, constant.MakeFloat64(bla))
		}
	case ak == reflect.Float32 || ak == reflect.Float64:
		if bk == reflect.Float32 || bk == reflect.Float64 {
			return constant.Compare(constant.MakeFloat64(vala.Float()), tok, constant.MakeFloat64(valb.Float()))
		}

		if bk >= reflect.Int && bk <= reflect.Int64 {
			return constant.Compare(constant.MakeFloat64(vala.Float()), tok, constant.MakeFloat64(float64(valb.Int())))
		}

		if bk == reflect.String {
			bla, err := strconv.ParseFloat(valb.String(), 64)
			if err != nil {
				return false
			}

			return constant.Compare(constant.MakeFloat64(vala.Float()), tok, constant.MakeFloat64(bla))
		}
	case ak == reflect.String:
		if bk == reflect.String {
			return constant.Compare(constant.MakeString(vala.String()), tok, constant.MakeString(valb.String()))
		}
	}

	if reflect.TypeOf(a).String() == "time.Time" && reflect.TypeOf(b).String() == "time.Time" {
		var x, y int64
		x = 1
		if vala.MethodByName("Equal").Call([]reflect.Value{valb})[0].Bool() {
			y = 1
		} else if vala.MethodByName("Before").Call([]reflect.Value{valb})[0].Bool() {
			y = 2
		}
		return constant.Compare(constant.MakeInt64(x), tok, constant.MakeInt64(y))
	}

	if tok == token.EQL {
		return reflect.DeepEqual(a, b)
	}

	return false
}

// stringConst returns a 'string' constant that evaluates to s.
func stringConst(s string) *Const {
	return NewConst(exact.MakeString(s), tString)
}

func (v *Variable) loadValueInternal(recurseLevel int, cfg LoadConfig) {
	if v.Unreadable != nil || v.loaded || (v.Addr == 0 && v.Base == 0) {
		return
	}

	v.loaded = true
	switch v.Kind {
	case reflect.Ptr, reflect.UnsafePointer:
		v.Len = 1
		v.Children = []Variable{*v.maybeDereference()}
		if cfg.FollowPointers {
			// Don't increase the recursion level when dereferencing pointers
			v.Children[0].loadValueInternal(recurseLevel, cfg)
		} else {
			v.Children[0].OnlyAddr = true
		}

	case reflect.Chan:
		sv := v.clone()
		sv.RealType = resolveTypedef(&(sv.RealType.(*dwarf.ChanType).TypedefType))
		sv = sv.maybeDereference()
		sv.loadValueInternal(0, loadFullValue)
		v.Children = sv.Children
		v.Len = sv.Len
		v.Base = sv.Addr

	case reflect.Map:
		if recurseLevel <= cfg.MaxVariableRecurse {
			v.loadMap(recurseLevel, cfg)
		}

	case reflect.String:
		var val string
		val, v.Unreadable = readStringValue(v.mem, v.Base, v.Len, cfg)
		v.Value = constant.MakeString(val)

	case reflect.Slice, reflect.Array:
		v.loadArrayValues(recurseLevel, cfg)

	case reflect.Struct:
		v.mem = cacheMemory(v.mem, v.Addr, int(v.RealType.Size()))
		t := v.RealType.(*dwarf.StructType)
		v.Len = int64(len(t.Field))
		// Recursively call extractValue to grab
		// the value of all the members of the struct.
		if recurseLevel <= cfg.MaxVariableRecurse {
			v.Children = make([]Variable, 0, len(t.Field))
			for i, field := range t.Field {
				if cfg.MaxStructFields >= 0 && len(v.Children) >= cfg.MaxStructFields {
					break
				}
				f, _ := v.toField(field)
				v.Children = append(v.Children, *f)
				v.Children[i].Name = field.Name
				v.Children[i].loadValueInternal(recurseLevel+1, cfg)
			}
		}

	case reflect.Interface:
		v.loadInterface(recurseLevel, true, cfg)

	case reflect.Complex64, reflect.Complex128:
		v.readComplex(v.RealType.(*dwarf.ComplexType).ByteSize)
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		var val int64
		val, v.Unreadable = readIntRaw(v.mem, v.Addr, v.RealType.(*dwarf.IntType).ByteSize)
		v.Value = constant.MakeInt64(val)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		var val uint64
		val, v.Unreadable = readUintRaw(v.mem, v.Addr, v.RealType.(*dwarf.UintType).ByteSize)
		v.Value = constant.MakeUint64(val)

	case reflect.Bool:
		val, err := v.mem.readMemory(v.Addr, 1)
		v.Unreadable = err
		if err == nil {
			v.Value = constant.MakeBool(val[0] != 0)
		}
	case reflect.Float32, reflect.Float64:
		var val float64
		val, v.Unreadable = v.readFloatRaw(v.RealType.(*dwarf.FloatType).ByteSize)
		v.Value = constant.MakeFloat64(val)
	case reflect.Func:
		v.readFunctionPtr()
	default:
		v.Unreadable = fmt.Errorf("unknown or unsupported kind: \"%s\"", v.Kind.String())
	}
}

func (v *Variable) loadValueInternal(recurseLevel int) {
	if v.Unreadable != nil || v.loaded || (v.Addr == 0 && v.base == 0) {
		return
	}
	v.loaded = true
	switch v.Kind {
	case reflect.Ptr, reflect.UnsafePointer:
		v.Len = 1
		v.Children = []Variable{*v.maybeDereference()}
		// Don't increase the recursion level when dereferencing pointers
		v.Children[0].loadValueInternal(recurseLevel)

	case reflect.Chan:
		sv := v.maybeDereference()
		sv.loadValueInternal(recurseLevel)
		v.Children = sv.Children
		v.Len = sv.Len
		v.base = sv.Addr

	case reflect.Map:
		v.loadMap(recurseLevel)

	case reflect.String:
		var val string
		val, v.Unreadable = v.thread.readStringValue(v.base, v.Len)
		v.Value = constant.MakeString(val)

	case reflect.Slice, reflect.Array:
		v.loadArrayValues(recurseLevel)

	case reflect.Struct:
		t := v.RealType.(*dwarf.StructType)
		v.Len = int64(len(t.Field))
		// Recursively call extractValue to grab
		// the value of all the members of the struct.
		if recurseLevel <= maxVariableRecurse {
			v.Children = make([]Variable, 0, len(t.Field))
			for i, field := range t.Field {
				f, _ := v.toField(field)
				v.Children = append(v.Children, *f)
				v.Children[i].Name = field.Name
				v.Children[i].loadValueInternal(recurseLevel + 1)
			}
		}

	case reflect.Complex64, reflect.Complex128:
		v.readComplex(v.RealType.(*dwarf.ComplexType).ByteSize)
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		var val int64
		val, v.Unreadable = v.thread.readIntRaw(v.Addr, v.RealType.(*dwarf.IntType).ByteSize)
		v.Value = constant.MakeInt64(val)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		var val uint64
		val, v.Unreadable = v.thread.readUintRaw(v.Addr, v.RealType.(*dwarf.UintType).ByteSize)
		v.Value = constant.MakeUint64(val)

	case reflect.Bool:
		val, err := v.thread.readMemory(v.Addr, 1)
		v.Unreadable = err
		if err == nil {
			v.Value = constant.MakeBool(val[0] != 0)
		}
	case reflect.Float32, reflect.Float64:
		var val float64
		val, v.Unreadable = v.readFloatRaw(v.RealType.(*dwarf.FloatType).ByteSize)
		v.Value = constant.MakeFloat64(val)
	case reflect.Func:
		v.readFunctionPtr()
	default:
		v.Unreadable = fmt.Errorf("unknown or unsupported kind: \"%s\"", v.Kind.String())
	}
}

// CreateTestMainPackage creates and returns a synthetic "main"
// package that runs all the tests of the supplied packages, similar
// to the one that would be created by the 'go test' tool.
//
// It returns nil if the program contains no tests.
//
func (prog *Program) CreateTestMainPackage(pkgs ...*Package) *Package {
	pkgs, tests, benchmarks, examples := FindTests(pkgs)
	if len(pkgs) == 0 {
		return nil
	}

	testmain := &Package{
		Prog:    prog,
		Members: make(map[string]Member),
		values:  make(map[types.Object]Value),
		Pkg:     types.NewPackage("test$main", "main"),
	}

	// Build package's init function.
	init := &Function{
		name:      "init",
		Signature: new(types.Signature),
		Synthetic: "package initializer",
		Pkg:       testmain,
		Prog:      prog,
	}
	init.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(init)
	}

	// Initialize packages to test.
	var pkgpaths []string
	for _, pkg := range pkgs {
		var v Call
		v.Call.Value = pkg.init
		v.setType(types.NewTuple())
		init.emit(&v)

		pkgpaths = append(pkgpaths, pkg.Pkg.Path())
	}
	sort.Strings(pkgpaths)
	init.emit(new(Return))
	init.finishBody()
	testmain.init = init
	testmain.Pkg.MarkComplete()
	testmain.Members[init.name] = init

	// For debugging convenience, define an unexported const
	// that enumerates the packages.
	packagesConst := types.NewConst(token.NoPos, testmain.Pkg, "packages", tString,
		exact.MakeString(strings.Join(pkgpaths, " ")))
	memberFromObject(testmain, packagesConst, nil)

	// Create main *types.Func and *ssa.Function
	mainFunc := types.NewFunc(token.NoPos, testmain.Pkg, "main", new(types.Signature))
	memberFromObject(testmain, mainFunc, nil)
	main := testmain.Func("main")
	main.Synthetic = "test main function"

	main.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(main)
	}

	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
		testingMain := testingPkg.Func("Main")
		testingMainParams := testingMain.Signature.Params()

		// The generated code is as if compiled from this:
		//
		// func main() {
		//      match      := func(_, _ string) (bool, error) { return true, nil }
		//      tests      := []testing.InternalTest{{"TestFoo", TestFoo}, ...}
		//      benchmarks := []testing.InternalBenchmark{...}
		//      examples   := []testing.InternalExample{...}
		// 	testing.Main(match, tests, benchmarks, examples)
		// }

		matcher := &Function{
			name:      "matcher",
			Signature: testingMainParams.At(0).Type().(*types.Signature),
			Synthetic: "test matcher predicate",
			parent:    main,
			Pkg:       testmain,
			Prog:      prog,
		}
		main.AnonFuncs = append(main.AnonFuncs, matcher)
		matcher.startBody()
		matcher.emit(&Return{Results: []Value{vTrue, nilConst(types.Universe.Lookup("error").Type())}})
		matcher.finishBody()

		// Emit call: testing.Main(matcher, tests, benchmarks, examples).
		var c Call
		c.Call.Value = testingMain
		c.Call.Args = []Value{
			matcher,
//.........这里部分代码省略.........