func (loc *AddrLocationSpec) Find(d *Debugger, scope *proc.EvalScope, locStr string) ([]api.Location, error) {
	if scope == nil {
		addr, err := strconv.ParseInt(loc.AddrExpr, 0, 64)
		if err != nil {
			return nil, fmt.Errorf("could not determine current location (scope is nil)")
		}
		return []api.Location{{PC: uint64(addr)}}, nil
	} else {
		v, err := scope.EvalExpression(loc.AddrExpr)
		if err != nil {
			return nil, err
		}
		if v.Unreadable != nil {
			return nil, v.Unreadable
		}
		switch v.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
			addr, _ := constant.Uint64Val(v.Value)
			return []api.Location{{PC: addr}}, nil
		case reflect.Func:
			pc, err := d.process.FunctionEntryToFirstLine(uint64(v.Base))
			if err != nil {
				return nil, err
			}
			return []api.Location{{PC: uint64(pc)}}, nil
		default:
			return nil, fmt.Errorf("wrong expression kind: %v", v.Kind)
		}
	}
}

// goVal returns the Go value for val, or nil.
func goVal(val constant.Value) interface{} {
	// val should exist, but be conservative and check
	if val == nil {
		return nil
	}
	// Match implementation restriction of other compilers.
	// gc only checks duplicates for integer, floating-point
	// and string values, so only create Go values for these
	// types.
	switch val.Kind() {
	case constant.Int:
		if x, ok := constant.Int64Val(val); ok {
			return x
		}
		if x, ok := constant.Uint64Val(val); ok {
			return x
		}
	case constant.Float:
		if x, ok := constant.Float64Val(val); ok {
			return x
		}
	case constant.String:
		return constant.StringVal(val)
	}
	return nil
}

func (v *Variable) setValue(y *Variable) error {
	var err error
	switch v.Kind {
	case reflect.Float32, reflect.Float64:
		f, _ := constant.Float64Val(y.Value)
		err = v.writeFloatRaw(f, v.RealType.Size())
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		n, _ := constant.Int64Val(y.Value)
		err = v.writeUint(uint64(n), v.RealType.Size())
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		n, _ := constant.Uint64Val(y.Value)
		err = v.writeUint(n, v.RealType.Size())
	case reflect.Bool:
		err = v.writeBool(constant.BoolVal(y.Value))
	case reflect.Complex64, reflect.Complex128:
		real, _ := constant.Float64Val(constant.Real(y.Value))
		imag, _ := constant.Float64Val(constant.Imag(y.Value))
		err = v.writeComplex(real, imag, v.RealType.Size())
	default:
		fmt.Printf("default\n")
		if t, isptr := v.RealType.(*dwarf.PtrType); isptr {
			err = v.writeUint(uint64(y.Children[0].Addr), int64(t.ByteSize))
		} else {
			return fmt.Errorf("can not set variables of type %s (not implemented)", v.Kind.String())
		}
	}

	return err
}

// Uint64 returns the numeric value of this constant truncated to fit
// an unsigned 64-bit integer.
//
func (c *Const) Uint64() uint64 {
	switch x := c.Value; x.Kind() {
	case exact.Int:
		if u, ok := exact.Uint64Val(x); ok {
			return u
		}
		return 0
	case exact.Float:
		f, _ := exact.Float64Val(x)
		return uint64(f)
	}
	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}

func constantBinaryOp(op token.Token, x, y constant.Value) (r constant.Value, err error) {
	defer func() {
		if ierr := recover(); ierr != nil {
			err = fmt.Errorf("%v", ierr)
		}
	}()
	switch op {
	case token.SHL, token.SHR:
		n, _ := constant.Uint64Val(y)
		r = constant.Shift(x, op, uint(n))
	default:
		r = constant.BinaryOp(x, op, y)
	}
	return
}

func (v *Variable) asUint() (uint64, error) {
	if v.DwarfType == nil {
		if v.Value.Kind() != constant.Int {
			return 0, fmt.Errorf("can not convert constant %s to uint", v.Value)
		}
	} else {
		v.loadValue()
		if v.Unreadable != nil {
			return 0, v.Unreadable
		}
		if _, ok := v.DwarfType.(*dwarf.UintType); !ok {
			return 0, fmt.Errorf("can not convert value of type %s to uint", v.DwarfType.String())
		}
	}
	n, _ := constant.Uint64Val(v.Value)
	return n, nil
}

func (filter *ScenarioFilterBasedOnTags) evaluateExp(tagExpression string) (bool, error) {
	tre := regexp.MustCompile("true")
	fre := regexp.MustCompile("false")

	s := fre.ReplaceAllString(tre.ReplaceAllString(tagExpression, "1"), "0")

	val, err := types.Eval(token.NewFileSet(), nil, 0, s)
	if err != nil {
		return false, errors.New("Invalid Expression.\n" + err.Error())
	}
	res, _ := constant.Uint64Val(val.Value)

	var final bool
	if res == 1 {
		final = true
	} else {
		final = false
	}

	return final, nil
}

// genDecl processes one declaration clause.
func (f *File) genDecl(node ast.Node) bool {
	decl, ok := node.(*ast.GenDecl)
	if !ok || decl.Tok != token.CONST {
		// We only care about const declarations.
		return true
	}
	// The name of the type of the constants we are declaring.
	// Can change if this is a multi-element declaration.
	typ := ""
	// Loop over the elements of the declaration. Each element is a ValueSpec:
	// a list of names possibly followed by a type, possibly followed by values.
	// If the type and value are both missing, we carry down the type (and value,
	// but the "go/types" package takes care of that).
	for _, spec := range decl.Specs {
		vspec := spec.(*ast.ValueSpec) // Guaranteed to succeed as this is CONST.
		if vspec.Type == nil && len(vspec.Values) > 0 {
			// "X = 1". With no type but a value, the constant is untyped.
			// Skip this vspec and reset the remembered type.
			typ = ""
			continue
		}
		if vspec.Type != nil {
			// "X T". We have a type. Remember it.
			ident, ok := vspec.Type.(*ast.Ident)
			if !ok {
				continue
			}
			typ = ident.Name
		}
		if typ != f.typeName {
			// This is not the type we're looking for.
			continue
		}
		// We now have a list of names (from one line of source code) all being
		// declared with the desired type.
		// Grab their names and actual values and store them in f.values.
		for _, name := range vspec.Names {
			if name.Name == "_" {
				continue
			}
			// This dance lets the type checker find the values for us. It's a
			// bit tricky: look up the object declared by the name, find its
			// types.Const, and extract its value.
			obj, ok := f.pkg.defs[name]
			if !ok {
				log.Fatalf("no value for constant %s", name)
			}
			info := obj.Type().Underlying().(*types.Basic).Info()
			if info&types.IsInteger == 0 {
				log.Fatalf("can't handle non-integer constant type %s", typ)
			}
			value := obj.(*types.Const).Val() // Guaranteed to succeed as this is CONST.
			if value.Kind() != exact.Int {
				log.Fatalf("can't happen: constant is not an integer %s", name)
			}
			i64, isInt := exact.Int64Val(value)
			u64, isUint := exact.Uint64Val(value)
			if !isInt && !isUint {
				log.Fatalf("internal error: value of %s is not an integer: %s", name, value.String())
			}
			if !isInt {
				u64 = uint64(i64)
			}
			v := Value{
				name:   name.Name,
				value:  u64,
				signed: info&types.IsUnsigned == 0,
				str:    value.String(),
			}
			f.values = append(f.values, v)
		}
	}
	return false
}

func (c *funcContext) translateExpr(expr ast.Expr) *expression {
	exprType := c.p.TypeOf(expr)
	if value := c.p.Types[expr].Value; value != nil {
		basic := exprType.Underlying().(*types.Basic)
		switch {
		case isBoolean(basic):
			return c.formatExpr("%s", strconv.FormatBool(constant.BoolVal(value)))
		case isInteger(basic):
			if is64Bit(basic) {
				if basic.Kind() == types.Int64 {
					d, ok := constant.Int64Val(constant.ToInt(value))
					if !ok {
						panic("could not get exact uint")
					}
					return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatInt(d>>32, 10), strconv.FormatUint(uint64(d)&(1<<32-1), 10))
				}
				d, ok := constant.Uint64Val(constant.ToInt(value))
				if !ok {
					panic("could not get exact uint")
				}
				return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatUint(d>>32, 10), strconv.FormatUint(d&(1<<32-1), 10))
			}
			d, ok := constant.Int64Val(constant.ToInt(value))
			if !ok {
				panic("could not get exact int")
			}
			return c.formatExpr("%s", strconv.FormatInt(d, 10))
		case isFloat(basic):
			f, _ := constant.Float64Val(value)
			return c.formatExpr("%s", strconv.FormatFloat(f, 'g', -1, 64))
		case isComplex(basic):
			r, _ := constant.Float64Val(constant.Real(value))
			i, _ := constant.Float64Val(constant.Imag(value))
			if basic.Kind() == types.UntypedComplex {
				exprType = types.Typ[types.Complex128]
			}
			return c.formatExpr("new %s(%s, %s)", c.typeName(exprType), strconv.FormatFloat(r, 'g', -1, 64), strconv.FormatFloat(i, 'g', -1, 64))
		case isString(basic):
			return c.formatExpr("%s", encodeString(constant.StringVal(value)))
		default:
			panic("Unhandled constant type: " + basic.String())
		}
	}

	var obj types.Object
	switch e := expr.(type) {
	case *ast.SelectorExpr:
		obj = c.p.Uses[e.Sel]
	case *ast.Ident:
		obj = c.p.Defs[e]
		if obj == nil {
			obj = c.p.Uses[e]
		}
	}

	if obj != nil && typesutil.IsJsPackage(obj.Pkg()) {
		switch obj.Name() {
		case "Global":
			return c.formatExpr("$global")
		case "Module":
			return c.formatExpr("$module")
		case "Undefined":
			return c.formatExpr("undefined")
		}
	}

	switch e := expr.(type) {
	case *ast.CompositeLit:
		if ptrType, isPointer := exprType.(*types.Pointer); isPointer {
			exprType = ptrType.Elem()
		}

		collectIndexedElements := func(elementType types.Type) []string {
			var elements []string
			i := 0
			zero := c.translateExpr(c.zeroValue(elementType)).String()
			for _, element := range e.Elts {
				if kve, isKve := element.(*ast.KeyValueExpr); isKve {
					key, ok := constant.Int64Val(constant.ToInt(c.p.Types[kve.Key].Value))
					if !ok {
						panic("could not get exact int")
					}
					i = int(key)
					element = kve.Value
				}
				for len(elements) <= i {
					elements = append(elements, zero)
				}
				elements[i] = c.translateImplicitConversionWithCloning(element, elementType).String()
				i++
			}
			return elements
		}

		switch t := exprType.Underlying().(type) {
		case *types.Array:
			elements := collectIndexedElements(t.Elem())
			if len(elements) == 0 {
				return c.formatExpr("%s.zero()", c.typeName(t))
			}
//.........这里部分代码省略.........

func (c *funcContext) formatExprInternal(format string, a []interface{}, parens bool) *expression {
	processFormat := func(f func(uint8, uint8, int)) {
		n := 0
		for i := 0; i < len(format); i++ {
			b := format[i]
			if b == '%' {
				i++
				k := format[i]
				if k >= '0' && k <= '9' {
					n = int(k - '0' - 1)
					i++
					k = format[i]
				}
				f(0, k, n)
				n++
				continue
			}
			f(b, 0, 0)
		}
	}

	counts := make([]int, len(a))
	processFormat(func(b, k uint8, n int) {
		switch k {
		case 'e', 'f', 'h', 'l', 'r', 'i':
			counts[n]++
		}
	})

	out := bytes.NewBuffer(nil)
	vars := make([]string, len(a))
	hasAssignments := false
	for i, e := range a {
		if counts[i] <= 1 {
			continue
		}
		if _, isIdent := e.(*ast.Ident); isIdent {
			continue
		}
		if val := c.p.Types[e.(ast.Expr)].Value; val != nil {
			continue
		}
		if !hasAssignments {
			hasAssignments = true
			out.WriteByte('(')
			parens = false
		}
		v := c.newVariable("x")
		out.WriteString(v + " = " + c.translateExpr(e.(ast.Expr)).String() + ", ")
		vars[i] = v
	}

	processFormat(func(b, k uint8, n int) {
		writeExpr := func(suffix string) {
			if vars[n] != "" {
				out.WriteString(vars[n] + suffix)
				return
			}
			out.WriteString(c.translateExpr(a[n].(ast.Expr)).StringWithParens() + suffix)
		}
		switch k {
		case 0:
			out.WriteByte(b)
		case 's':
			if e, ok := a[n].(*expression); ok {
				out.WriteString(e.StringWithParens())
				return
			}
			out.WriteString(a[n].(string))
		case 'd':
			out.WriteString(strconv.Itoa(a[n].(int)))
		case 't':
			out.WriteString(a[n].(token.Token).String())
		case 'e':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				out.WriteString(c.translateExpr(e).String())
				return
			}
			writeExpr("")
		case 'f':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				d, _ := constant.Int64Val(constant.ToInt(val))
				out.WriteString(strconv.FormatInt(d, 10))
				return
			}
			if is64Bit(c.p.TypeOf(e).Underlying().(*types.Basic)) {
				out.WriteString("$flatten64(")
				writeExpr("")
				out.WriteString(")")
				return
			}
			writeExpr("")
		case 'h':
			e := a[n].(ast.Expr)
			if val := c.p.Types[e].Value; val != nil {
				d, _ := constant.Uint64Val(constant.ToInt(val))
				if c.p.TypeOf(e).Underlying().(*types.Basic).Kind() == types.Int64 {
					out.WriteString(strconv.FormatInt(int64(d)>>32, 10))
//.........这里部分代码省略.........

func (check *Checker) shift(x, y *operand, e *ast.BinaryExpr, op token.Token) {
	untypedx := isUntyped(x.typ)

	var xval constant.Value
	if x.mode == constant_ {
		xval = constant.ToInt(x.val)
	}

	if isInteger(x.typ) || untypedx && xval != nil && xval.Kind() == constant.Int {
		// The lhs is of integer type or an untyped constant representable
		// as an integer. Nothing to do.
	} else {
		// shift has no chance
		check.invalidOp(x.pos(), "shifted operand %s must be integer", x)
		x.mode = invalid
		return
	}

	// spec: "The right operand in a shift expression must have unsigned
	// integer type or be an untyped constant that can be converted to
	// unsigned integer type."
	switch {
	case isUnsigned(y.typ):
		// nothing to do
	case isUntyped(y.typ):
		check.convertUntyped(y, Typ[UntypedInt])
		if y.mode == invalid {
			x.mode = invalid
			return
		}
	default:
		check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
		x.mode = invalid
		return
	}

	if x.mode == constant_ {
		if y.mode == constant_ {
			// rhs must be an integer value
			yval := constant.ToInt(y.val)
			if yval.Kind() != constant.Int {
				check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
				x.mode = invalid
				return
			}
			// rhs must be within reasonable bounds
			const shiftBound = 1023 - 1 + 52 // so we can express smallestFloat64
			s, ok := constant.Uint64Val(yval)
			if !ok || s > shiftBound {
				check.invalidOp(y.pos(), "invalid shift count %s", y)
				x.mode = invalid
				return
			}
			// The lhs is representable as an integer but may not be an integer
			// (e.g., 2.0, an untyped float) - this can only happen for untyped
			// non-integer numeric constants. Correct the type so that the shift
			// result is of integer type.
			if !isInteger(x.typ) {
				x.typ = Typ[UntypedInt]
			}
			// x is a constant so xval != nil and it must be of Int kind.
			x.val = constant.Shift(xval, op, uint(s))
			// Typed constants must be representable in
			// their type after each constant operation.
			if isTyped(x.typ) {
				if e != nil {
					x.expr = e // for better error message
				}
				check.representable(x, x.typ.Underlying().(*Basic))
			}
			return
		}

		// non-constant shift with constant lhs
		if untypedx {
			// spec: "If the left operand of a non-constant shift
			// expression is an untyped constant, the type of the
			// constant is what it would be if the shift expression
			// were replaced by its left operand alone.".
			//
			// Delay operand checking until we know the final type
			// by marking the lhs expression as lhs shift operand.
			//
			// Usually (in correct programs), the lhs expression
			// is in the untyped map. However, it is possible to
			// create incorrect programs where the same expression
			// is evaluated twice (via a declaration cycle) such
			// that the lhs expression type is determined in the
			// first round and thus deleted from the map, and then
			// not found in the second round (double insertion of
			// the same expr node still just leads to one entry for
			// that node, and it can only be deleted once).
			// Be cautious and check for presence of entry.
			// Example: var e, f = int(1<<""[f]) // issue 11347
			if info, found := check.untyped[x.expr]; found {
				info.isLhs = true
				check.untyped[x.expr] = info
			}
			// keep x's type
			x.mode = value
//.........这里部分代码省略.........

// Eval type cast expressions
func (scope *EvalScope) evalTypeCast(node *ast.CallExpr) (*Variable, error) {
	argv, err := scope.evalAST(node.Args[0])
	if err != nil {
		return nil, err
	}
	argv.loadValue()
	if argv.Unreadable != nil {
		return nil, argv.Unreadable
	}

	fnnode := node.Fun

	// remove all enclosing parenthesis from the type name
	for {
		p, ok := fnnode.(*ast.ParenExpr)
		if !ok {
			break
		}
		fnnode = p.X
	}

	styp, err := scope.Thread.dbp.findTypeExpr(fnnode)
	if err != nil {
		return nil, err
	}
	typ := resolveTypedef(styp)

	converr := fmt.Errorf("can not convert %q to %s", exprToString(node.Args[0]), typ.String())

	v := newVariable("", 0, styp, scope.Thread.dbp, scope.Thread)
	v.loaded = true

	switch ttyp := typ.(type) {
	case *dwarf.PtrType:
		switch argv.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			// ok
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			// ok
		default:
			return nil, converr
		}

		n, _ := constant.Int64Val(argv.Value)

		v.Children = []Variable{*(scope.newVariable("", uintptr(n), ttyp.Type))}
		return v, nil

	case *dwarf.UintType:
		switch argv.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			n, _ := constant.Int64Val(argv.Value)
			v.Value = constant.MakeUint64(convertInt(uint64(n), false, ttyp.Size()))
			return v, nil
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			n, _ := constant.Uint64Val(argv.Value)
			v.Value = constant.MakeUint64(convertInt(n, false, ttyp.Size()))
			return v, nil
		case reflect.Float32, reflect.Float64:
			x, _ := constant.Float64Val(argv.Value)
			v.Value = constant.MakeUint64(uint64(x))
			return v, nil
		}
	case *dwarf.IntType:
		switch argv.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			n, _ := constant.Int64Val(argv.Value)
			v.Value = constant.MakeInt64(int64(convertInt(uint64(n), true, ttyp.Size())))
			return v, nil
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			n, _ := constant.Uint64Val(argv.Value)
			v.Value = constant.MakeInt64(int64(convertInt(n, true, ttyp.Size())))
			return v, nil
		case reflect.Float32, reflect.Float64:
			x, _ := constant.Float64Val(argv.Value)
			v.Value = constant.MakeInt64(int64(x))
			return v, nil
		}
	case *dwarf.FloatType:
		switch argv.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			fallthrough
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			fallthrough
		case reflect.Float32, reflect.Float64:
			v.Value = argv.Value
			return v, nil
		}
	case *dwarf.ComplexType:
		switch argv.Kind {
		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
			fallthrough
		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			fallthrough
		case reflect.Float32, reflect.Float64:
			v.Value = argv.Value
			return v, nil
		}
	}
//.........这里部分代码省略.........

func (check *Checker) shift(x, y *operand, op token.Token) {
	untypedx := isUntyped(x.typ)

	// The lhs must be of integer type or be representable
	// as an integer; otherwise the shift has no chance.
	if !x.isInteger() {
		check.invalidOp(x.pos(), "shifted operand %s must be integer", x)
		x.mode = invalid
		return
	}

	// spec: "The right operand in a shift expression must have unsigned
	// integer type or be an untyped constant that can be converted to
	// unsigned integer type."
	switch {
	case isInteger(y.typ) && isUnsigned(y.typ):
		// nothing to do
	case isUntyped(y.typ):
		check.convertUntyped(y, Typ[UntypedInt])
		if y.mode == invalid {
			x.mode = invalid
			return
		}
	default:
		check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
		x.mode = invalid
		return
	}

	if x.mode == constant {
		if y.mode == constant {
			// rhs must be an integer value
			if !y.isInteger() {
				check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
				x.mode = invalid
				return
			}
			// rhs must be within reasonable bounds
			const stupidShift = 1023 - 1 + 52 // so we can express smallestFloat64
			s, ok := exact.Uint64Val(y.val)
			if !ok || s > stupidShift {
				check.invalidOp(y.pos(), "stupid shift count %s", y)
				x.mode = invalid
				return
			}
			// The lhs is representable as an integer but may not be an integer
			// (e.g., 2.0, an untyped float) - this can only happen for untyped
			// non-integer numeric constants. Correct the type so that the shift
			// result is of integer type.
			if !isInteger(x.typ) {
				x.typ = Typ[UntypedInt]
			}
			x.val = exact.Shift(x.val, op, uint(s))
			return
		}

		// non-constant shift with constant lhs
		if untypedx {
			// spec: "If the left operand of a non-constant shift
			// expression is an untyped constant, the type of the
			// constant is what it would be if the shift expression
			// were replaced by its left operand alone.".
			//
			// Delay operand checking until we know the final type:
			// The lhs expression must be in the untyped map, mark
			// the entry as lhs shift operand.
			info, found := check.untyped[x.expr]
			assert(found)
			info.isLhs = true
			check.untyped[x.expr] = info
			// keep x's type
			x.mode = value
			return
		}
	}

	// constant rhs must be >= 0
	if y.mode == constant && exact.Sign(y.val) < 0 {
		check.invalidOp(y.pos(), "shift count %s must not be negative", y)
	}

	// non-constant shift - lhs must be an integer
	if !isInteger(x.typ) {
		check.invalidOp(x.pos(), "shifted operand %s must be integer", x)
		x.mode = invalid
		return
	}

	x.mode = value
}