Пример #1
0
func (constantFolderVisitor) VisitPost(expr Expr) (retExpr Expr) {
	defer func() {
		// go/constant operations can panic for a number of reasons (like division
		// by zero), but it's difficult to preemptively detect when they will. It's
		// safest to just recover here without folding the expression and let
		// normalization or evaluation deal with error handling.
		if r := recover(); r != nil {
			retExpr = expr
		}
	}()
	switch t := expr.(type) {
	case *ParenExpr:
		if cv, ok := t.Expr.(*NumVal); ok {
			return cv
		}
	case *UnaryExpr:
		if cv, ok := t.Expr.(*NumVal); ok {
			if token, ok := unaryOpToToken[t.Operator]; ok {
				return &NumVal{Value: constant.UnaryOp(token, cv.Value, 0)}
			}
			if token, ok := unaryOpToTokenIntOnly[t.Operator]; ok {
				if intVal, ok := cv.asConstantInt(); ok {
					return &NumVal{Value: constant.UnaryOp(token, intVal, 0)}
				}
			}
		}
	case *BinaryExpr:
		l, okL := t.Left.(*NumVal)
		r, okR := t.Right.(*NumVal)
		if okL && okR {
			if token, ok := binaryOpToToken[t.Operator]; ok {
				return &NumVal{Value: constant.BinaryOp(l.Value, token, r.Value)}
			}
			if token, ok := binaryOpToTokenIntOnly[t.Operator]; ok {
				if lInt, ok := l.asConstantInt(); ok {
					if rInt, ok := r.asConstantInt(); ok {
						return &NumVal{Value: constant.BinaryOp(lInt, token, rInt)}
					}
				}
			}
			if token, ok := binaryShiftOpToToken[t.Operator]; ok {
				if lInt, ok := l.asConstantInt(); ok {
					if rInt64, err := r.asInt64(); err == nil && rInt64 >= 0 {
						return &NumVal{Value: constant.Shift(lInt, token, uint(rInt64))}
					}
				}
			}
		}
	case *ComparisonExpr:
		l, okL := t.Left.(*NumVal)
		r, okR := t.Right.(*NumVal)
		if okL && okR {
			if token, ok := comparisonOpToToken[t.Operator]; ok {
				return MakeDBool(DBool(constant.Compare(l.Value, token, r.Value)))
			}
		}
	}
	return expr
}
Пример #2
0
// number = int_lit [ "p" int_lit ] .
//
func (p *parser) parseNumber() (typ *types.Basic, val exact.Value) {
	// mantissa
	mant := exact.MakeFromLiteral(p.parseInt(), token.INT, 0)
	if mant == nil {
		panic("invalid mantissa")
	}

	if p.lit == "p" {
		// exponent (base 2)
		p.next()
		exp, err := strconv.ParseInt(p.parseInt(), 10, 0)
		if err != nil {
			p.error(err)
		}
		if exp < 0 {
			denom := exact.MakeInt64(1)
			denom = exact.Shift(denom, token.SHL, uint(-exp))
			typ = types.Typ[types.UntypedFloat]
			val = exact.BinaryOp(mant, token.QUO, denom)
			return
		}
		if exp > 0 {
			mant = exact.Shift(mant, token.SHL, uint(exp))
		}
		typ = types.Typ[types.UntypedFloat]
		val = mant
		return
	}

	typ = types.Typ[types.UntypedInt]
	val = mant
	return
}
Пример #3
0
func (p *importer) ufloat() constant.Value {
	exp := p.int()
	x := constant.MakeFromBytes(p.bytes())
	switch {
	case exp < 0:
		d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
		x = constant.BinaryOp(x, token.QUO, d)
	case exp > 0:
		x = constant.Shift(x, token.SHL, uint(exp))
	}
	return x
}
Пример #4
0
func (p *importer) fraction() constant.Value {
	sign := p.int()
	if sign == 0 {
		return constant.MakeInt64(0)
	}

	x := constant.BinaryOp(p.ufloat(), token.QUO, p.ufloat())
	if sign < 0 {
		x = constant.UnaryOp(token.SUB, x, 0)
	}
	return x
}
Пример #5
0
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
}
Пример #6
0
func complexBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
	if len(args) != 2 {
		return nil, fmt.Errorf("wrong number of arguments to complex: %d", len(args))
	}

	realev := args[0]
	imagev := args[1]

	realev.loadValue()
	imagev.loadValue()

	if realev.Unreadable != nil {
		return nil, realev.Unreadable
	}

	if imagev.Unreadable != nil {
		return nil, imagev.Unreadable
	}

	if realev.Value == nil || ((realev.Value.Kind() != constant.Int) && (realev.Value.Kind() != constant.Float)) {
		return nil, fmt.Errorf("invalid argument 1 %s (type %s) to complex", exprToString(nodeargs[0]), realev.TypeString())
	}

	if imagev.Value == nil || ((imagev.Value.Kind() != constant.Int) && (imagev.Value.Kind() != constant.Float)) {
		return nil, fmt.Errorf("invalid argument 2 %s (type %s) to complex", exprToString(nodeargs[1]), imagev.TypeString())
	}

	sz := int64(0)
	if realev.RealType != nil {
		sz = realev.RealType.(*dwarf.FloatType).Size()
	}
	if imagev.RealType != nil {
		isz := imagev.RealType.(*dwarf.FloatType).Size()
		if isz > sz {
			sz = isz
		}
	}

	if sz == 0 {
		sz = 128
	}

	typ := &dwarf.ComplexType{BasicType: dwarf.BasicType{CommonType: dwarf.CommonType{ByteSize: int64(sz / 8), Name: fmt.Sprintf("complex%d", sz)}, BitSize: sz, BitOffset: 0}}

	r := realev.newVariable("", 0, typ)
	r.Value = constant.BinaryOp(realev.Value, token.ADD, constant.MakeImag(imagev.Value))
	return r, nil
}
Пример #7
0
func (p *importer) float() constant.Value {
	sign := p.int()
	if sign == 0 {
		return constant.MakeInt64(0)
	}

	exp := p.int()
	mant := []byte(p.string()) // big endian

	// remove leading 0's if any
	for len(mant) > 0 && mant[0] == 0 {
		mant = mant[1:]
	}

	// convert to little endian
	// TODO(gri) go/constant should have a more direct conversion function
	//           (e.g., once it supports a big.Float based implementation)
	for i, j := 0, len(mant)-1; i < j; i, j = i+1, j-1 {
		mant[i], mant[j] = mant[j], mant[i]
	}

	// adjust exponent (constant.MakeFromBytes creates an integer value,
	// but mant represents the mantissa bits such that 0.5 <= mant < 1.0)
	exp -= len(mant) << 3
	if len(mant) > 0 {
		for msd := mant[len(mant)-1]; msd&0x80 == 0; msd <<= 1 {
			exp++
		}
	}

	x := constant.MakeFromBytes(mant)
	switch {
	case exp < 0:
		d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
		x = constant.BinaryOp(x, token.QUO, d)
	case exp > 0:
		x = constant.Shift(x, token.SHL, uint(exp))
	}

	if sign < 0 {
		x = constant.UnaryOp(token.SUB, x, 0)
	}
	return x
}
Пример #8
0
// Eval expressions: complex64(<float const>, <float const>) and complex128(<float const>, <float const>)
func (scope *EvalScope) evalComplexCast(typename string, node *ast.CallExpr) (*Variable, error) {
	realev, err := scope.evalAST(node.Args[0])
	if err != nil {
		return nil, err
	}
	imagev, err := scope.evalAST(node.Args[1])
	if err != nil {
		return nil, err
	}

	sz := 128
	ftypename := "float64"
	if typename == "complex64" {
		sz = 64
		ftypename = "float32"
	}

	realev.loadValue()
	imagev.loadValue()

	if realev.Unreadable != nil {
		return nil, realev.Unreadable
	}

	if imagev.Unreadable != nil {
		return nil, imagev.Unreadable
	}

	if realev.Value == nil || ((realev.Value.Kind() != constant.Int) && (realev.Value.Kind() != constant.Float)) {
		return nil, fmt.Errorf("can not convert \"%s\" to %s", exprToString(node.Args[0]), ftypename)
	}

	if imagev.Value == nil || ((imagev.Value.Kind() != constant.Int) && (imagev.Value.Kind() != constant.Float)) {
		return nil, fmt.Errorf("can not convert \"%s\" to %s", exprToString(node.Args[1]), ftypename)
	}

	typ := &dwarf.ComplexType{dwarf.BasicType{dwarf.CommonType{ByteSize: int64(sz / 8), Name: typename}, int64(sz), 0}}

	r := newVariable("", 0, typ, scope.Thread)
	r.Value = constant.BinaryOp(realev.Value, token.ADD, constant.MakeImag(imagev.Value))
	return r, nil
}
Пример #9
0
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))
	}
}
Пример #10
0
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))
	}
}
Пример #11
0
func (v *Variable) readComplex(size int64) {
	var fs int64
	switch size {
	case 8:
		fs = 4
	case 16:
		fs = 8
	default:
		v.Unreadable = fmt.Errorf("invalid size (%d) for complex type", size)
		return
	}

	ftyp := &dwarf.FloatType{BasicType: dwarf.BasicType{CommonType: dwarf.CommonType{ByteSize: fs, Name: fmt.Sprintf("float%d", fs)}, BitSize: fs * 8, BitOffset: 0}}

	realvar := v.newVariable("real", v.Addr, ftyp)
	imagvar := v.newVariable("imaginary", v.Addr+uintptr(fs), ftyp)
	realvar.loadValue(loadSingleValue)
	imagvar.loadValue(loadSingleValue)
	v.Value = constant.BinaryOp(realvar.Value, token.ADD, constant.MakeImag(imagvar.Value))
}
Пример #12
0
// 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
}
Пример #13
0
// ConstDecl   = "const" ExportedName [ Type ] "=" Literal .
// Literal     = bool_lit | int_lit | float_lit | complex_lit | rune_lit | string_lit .
// bool_lit    = "true" | "false" .
// complex_lit = "(" float_lit "+" float_lit "i" ")" .
// rune_lit    = "(" int_lit "+" int_lit ")" .
// string_lit  = `"` { unicode_char } `"` .
//
func (p *parser) parseConstDecl() {
	p.expectKeyword("const")
	pkg, name := p.parseExportedName()

	var typ0 types.Type
	if p.tok != '=' {
		// constant types are never structured - no need for parent type
		typ0 = p.parseType(nil)
	}

	p.expect('=')
	var typ types.Type
	var val exact.Value
	switch p.tok {
	case scanner.Ident:
		// bool_lit
		if p.lit != "true" && p.lit != "false" {
			p.error("expected true or false")
		}
		typ = types.Typ[types.UntypedBool]
		val = exact.MakeBool(p.lit == "true")
		p.next()

	case '-', scanner.Int:
		// int_lit
		typ, val = p.parseNumber()

	case '(':
		// complex_lit or rune_lit
		p.next()
		if p.tok == scanner.Char {
			p.next()
			p.expect('+')
			typ = types.Typ[types.UntypedRune]
			_, val = p.parseNumber()
			p.expect(')')
			break
		}
		_, re := p.parseNumber()
		p.expect('+')
		_, im := p.parseNumber()
		p.expectKeyword("i")
		p.expect(')')
		typ = types.Typ[types.UntypedComplex]
		val = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))

	case scanner.Char:
		// rune_lit
		typ = types.Typ[types.UntypedRune]
		val = exact.MakeFromLiteral(p.lit, token.CHAR, 0)
		p.next()

	case scanner.String:
		// string_lit
		typ = types.Typ[types.UntypedString]
		val = exact.MakeFromLiteral(p.lit, token.STRING, 0)
		p.next()

	default:
		p.errorf("expected literal got %s", scanner.TokenString(p.tok))
	}

	if typ0 == nil {
		typ0 = typ
	}

	pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, typ0, val))
}
Пример #14
0
// builtin type-checks a call to the built-in specified by id and
// returns true if the call is valid, with *x holding the result;
// but x.expr is not set. If the call is invalid, the result is
// false, and *x is undefined.
//
func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ bool) {
	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if call.Ellipsis.IsValid() && id != _Append {
		check.invalidOp(call.Ellipsis, "invalid use of ... with built-in %s", bin.name)
		check.use(call.Args...)
		return
	}

	// For len(x) and cap(x) we need to know if x contains any function calls or
	// receive operations. Save/restore current setting and set hasCallOrRecv to
	// false for the evaluation of x so that we can check it afterwards.
	// Note: We must do this _before_ calling unpack because unpack evaluates the
	//       first argument before we even call arg(x, 0)!
	if id == _Len || id == _Cap {
		defer func(b bool) {
			check.hasCallOrRecv = b
		}(check.hasCallOrRecv)
		check.hasCallOrRecv = false
	}

	// determine actual arguments
	var arg getter
	nargs := len(call.Args)
	switch id {
	default:
		// make argument getter
		arg, nargs, _ = unpack(func(x *operand, i int) { check.multiExpr(x, call.Args[i]) }, nargs, false)
		if arg == nil {
			return
		}
		// evaluate first argument, if present
		if nargs > 0 {
			arg(x, 0)
			if x.mode == invalid {
				return
			}
		}
	case _Make, _New, _Offsetof, _Trace:
		// arguments require special handling
	}

	// check argument count
	{
		msg := ""
		if nargs < bin.nargs {
			msg = "not enough"
		} else if !bin.variadic && nargs > bin.nargs {
			msg = "too many"
		}
		if msg != "" {
			check.invalidOp(call.Rparen, "%s arguments for %s (expected %d, found %d)", msg, call, bin.nargs, nargs)
			return
		}
	}

	switch id {
	case _Append:
		// append(s S, x ...T) S, where T is the element type of S
		// spec: "The variadic function append appends zero or more values x to s of type
		// S, which must be a slice type, and returns the resulting slice, also of type S.
		// The values x are passed to a parameter of type ...T where T is the element type
		// of S and the respective parameter passing rules apply."
		S := x.typ
		var T Type
		if s, _ := S.Underlying().(*Slice); s != nil {
			T = s.elem
		} else {
			check.invalidArg(x.pos(), "%s is not a slice", x)
			return
		}

		// remember arguments that have been evaluated already
		alist := []operand{*x}

		// spec: "As a special case, append also accepts a first argument assignable
		// to type []byte with a second argument of string type followed by ... .
		// This form appends the bytes of the string.
		if nargs == 2 && call.Ellipsis.IsValid() && x.assignableTo(check.conf, NewSlice(universeByte), nil) {
			arg(x, 1)
			if x.mode == invalid {
				return
			}
			if isString(x.typ) {
				if check.Types != nil {
					sig := makeSig(S, S, x.typ)
					sig.variadic = true
					check.recordBuiltinType(call.Fun, sig)
				}
				x.mode = value
				x.typ = S
				break
			}
			alist = append(alist, *x)
			// fallthrough
		}

		// check general case by creating custom signature
		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
		sig.variadic = true
		check.arguments(x, call, sig, func(x *operand, i int) {
			// only evaluate arguments that have not been evaluated before
			if i < len(alist) {
				*x = alist[i]
				return
			}
			arg(x, i)
		}, nargs)
		// ok to continue even if check.arguments reported errors

		x.mode = value
		x.typ = S
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, sig)
		}

	case _Cap, _Len:
		// cap(x)
		// len(x)
		mode := invalid
		var typ Type
		var val constant.Value
		switch typ = implicitArrayDeref(x.typ.Underlying()); t := typ.(type) {
		case *Basic:
			if isString(t) && id == _Len {
				if x.mode == constant_ {
					mode = constant_
					val = constant.MakeInt64(int64(len(constant.StringVal(x.val))))
				} else {
					mode = value
				}
			}

		case *Array:
			mode = value
			// spec: "The expressions len(s) and cap(s) are constants
			// if the type of s is an array or pointer to an array and
			// the expression s does not contain channel receives or
			// function calls; in this case s is not evaluated."
			if !check.hasCallOrRecv {
				mode = constant_
				val = constant.MakeInt64(t.len)
			}

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}
		}

		if mode == invalid {
			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
			return
		}

		x.mode = mode
		x.typ = Typ[Int]
		x.val = val
		if check.Types != nil && mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, typ))
		}

	case _Close:
		// close(c)
		c, _ := x.typ.Underlying().(*Chan)
		if c == nil {
			check.invalidArg(x.pos(), "%s is not a channel", x)
			return
		}
		if c.dir == RecvOnly {
			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, c))
		}

	case _Complex:
		// complex(x, y floatT) complexT
		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}

		// convert or check untyped arguments
		d := 0
		if isUntyped(x.typ) {
			d |= 1
		}
		if isUntyped(y.typ) {
			d |= 2
		}
		switch d {
		case 0:
			// x and y are typed => nothing to do
		case 1:
			// only x is untyped => convert to type of y
			check.convertUntyped(x, y.typ)
		case 2:
			// only y is untyped => convert to type of x
			check.convertUntyped(&y, x.typ)
		case 3:
			// x and y are untyped =>
			// 1) if both are constants, convert them to untyped
			//    floating-point numbers if possible,
			// 2) if one of them is not constant (possible because
			//    it contains a shift that is yet untyped), convert
			//    both of them to float64 since they must have the
			//    same type to succeed (this will result in an error
			//    because shifts of floats are not permitted)
			if x.mode == constant_ && y.mode == constant_ {
				toFloat := func(x *operand) {
					if isNumeric(x.typ) && constant.Sign(constant.Imag(x.val)) == 0 {
						x.typ = Typ[UntypedFloat]
					}
				}
				toFloat(x)
				toFloat(&y)
			} else {
				check.convertUntyped(x, Typ[Float64])
				check.convertUntyped(&y, Typ[Float64])
				// x and y should be invalid now, but be conservative
				// and check below
			}
		}
		if x.mode == invalid || y.mode == invalid {
			return
		}

		// both argument types must be identical
		if !Identical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			return
		}

		// the argument types must be of floating-point type
		if !isFloat(x.typ) {
			check.invalidArg(x.pos(), "arguments have type %s, expected floating-point", x.typ)
			return
		}

		// if both arguments are constants, the result is a constant
		if x.mode == constant_ && y.mode == constant_ {
			x.val = constant.BinaryOp(constant.ToFloat(x.val), token.ADD, constant.MakeImag(constant.ToFloat(y.val)))
		} else {
			x.mode = value
		}

		// determine result type
		var res BasicKind
		switch x.typ.Underlying().(*Basic).kind {
		case Float32:
			res = Complex64
		case Float64:
			res = Complex128
		case UntypedFloat:
			res = UntypedComplex
		default:
			unreachable()
		}
		resTyp := Typ[res]

		if check.Types != nil && x.mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ, x.typ))
		}

		x.typ = resTyp

	case _Copy:
		// copy(x, y []T) int
		var dst Type
		if t, _ := x.typ.Underlying().(*Slice); t != nil {
			dst = t.elem
		}

		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}
		var src Type
		switch t := y.typ.Underlying().(type) {
		case *Basic:
			if isString(y.typ) {
				src = universeByte
			}
		case *Slice:
			src = t.elem
		}

		if dst == nil || src == nil {
			check.invalidArg(x.pos(), "copy expects slice arguments; found %s and %s", x, &y)
			return
		}

		if !Identical(dst, src) {
			check.invalidArg(x.pos(), "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
			return
		}

		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(Typ[Int], x.typ, y.typ))
		}
		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		// delete(m, k)
		m, _ := x.typ.Underlying().(*Map)
		if m == nil {
			check.invalidArg(x.pos(), "%s is not a map", x)
			return
		}
		arg(x, 1) // k
		if x.mode == invalid {
			return
		}

		if !x.assignableTo(check.conf, m.key, nil) {
			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.key)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
		}

	case _Imag, _Real:
		// imag(complexT) floatT
		// real(complexT) floatT

		// convert or check untyped argument
		if isUntyped(x.typ) {
			if x.mode == constant_ {
				// an untyped constant number can alway be considered
				// as a complex constant
				if isNumeric(x.typ) {
					x.typ = Typ[UntypedComplex]
				}
			} else {
				// an untyped non-constant argument may appear if
				// it contains a (yet untyped non-constant) shift
				// expression: convert it to complex128 which will
				// result in an error (shift of complex value)
				check.convertUntyped(x, Typ[Complex128])
				// x should be invalid now, but be conservative and check
				if x.mode == invalid {
					return
				}
			}
		}

		// the argument must be of complex type
		if !isComplex(x.typ) {
			check.invalidArg(x.pos(), "argument has type %s, expected complex type", x.typ)
			return
		}

		// if the argument is a constant, the result is a constant
		if x.mode == constant_ {
			if id == _Real {
				x.val = constant.Real(x.val)
			} else {
				x.val = constant.Imag(x.val)
			}
		} else {
			x.mode = value
		}

		// determine result type
		var res BasicKind
		switch x.typ.Underlying().(*Basic).kind {
		case Complex64:
			res = Float32
		case Complex128:
			res = Float64
		case UntypedComplex:
			res = UntypedFloat
		default:
			unreachable()
		}
		resTyp := Typ[res]

		if check.Types != nil && x.mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ))
		}

		x.typ = resTyp

	case _Make:
		// make(T, n)
		// make(T, n, m)
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		T := check.typ(arg0)
		if T == Typ[Invalid] {
			return
		}

		var min int // minimum number of arguments
		switch T.Underlying().(type) {
		case *Slice:
			min = 2
		case *Map, *Chan:
			min = 1
		default:
			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
			return
		}
		if nargs < min || min+1 < nargs {
			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, nargs)
			return
		}
		var sizes []int64 // constant integer arguments, if any
		for _, arg := range call.Args[1:] {
			if s, ok := check.index(arg, -1); ok && s >= 0 {
				sizes = append(sizes, s)
			}
		}
		if len(sizes) == 2 && sizes[0] > sizes[1] {
			check.invalidArg(call.Args[1].Pos(), "length and capacity swapped")
			// safe to continue
		}
		x.mode = value
		x.typ = T
		if check.Types != nil {
			params := [...]Type{T, Typ[Int], Typ[Int]}
			check.recordBuiltinType(call.Fun, makeSig(x.typ, params[:1+len(sizes)]...))
		}

	case _New:
		// new(T)
		// (no argument evaluated yet)
		T := check.typ(call.Args[0])
		if T == Typ[Invalid] {
			return
		}

		x.mode = value
		x.typ = &Pointer{base: T}
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, T))
		}

	case _Panic:
		// panic(x)
		T := new(Interface)
		check.assignment(x, T, "argument to panic")
		if x.mode == invalid {
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, T))
		}

	case _Print, _Println:
		// print(x, y, ...)
		// println(x, y, ...)
		var params []Type
		if nargs > 0 {
			params = make([]Type, nargs)
			for i := 0; i < nargs; i++ {
				if i > 0 {
					arg(x, i) // first argument already evaluated
				}
				check.assignment(x, nil, "argument to "+predeclaredFuncs[id].name)
				if x.mode == invalid {
					// TODO(gri) "use" all arguments?
					return
				}
				params[i] = x.typ
			}
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, params...))
		}

	case _Recover:
		// recover() interface{}
		x.mode = value
		x.typ = new(Interface)
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ))
		}

	case _Alignof:
		// unsafe.Alignof(x T) uintptr
		check.assignment(x, nil, "argument to unsafe.Alignof")
		if x.mode == invalid {
			return
		}

		x.mode = constant_
		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Offsetof:
		// unsafe.Offsetof(x T) uintptr, where x must be a selector
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		selx, _ := unparen(arg0).(*ast.SelectorExpr)
		if selx == nil {
			check.invalidArg(arg0.Pos(), "%s is not a selector expression", arg0)
			check.use(arg0)
			return
		}

		check.expr(x, selx.X)
		if x.mode == invalid {
			return
		}

		base := derefStructPtr(x.typ)
		sel := selx.Sel.Name
		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
		switch obj.(type) {
		case nil:
			check.invalidArg(x.pos(), "%s has no single field %s", base, sel)
			return
		case *Func:
			// TODO(gri) Using derefStructPtr may result in methods being found
			// that don't actually exist. An error either way, but the error
			// message is confusing. See: https://play.golang.org/p/al75v23kUy ,
			// but go/types reports: "invalid argument: x.m is a method value".
			check.invalidArg(arg0.Pos(), "%s is a method value", arg0)
			return
		}
		if indirect {
			check.invalidArg(x.pos(), "field %s is embedded via a pointer in %s", sel, base)
			return
		}

		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
		check.recordSelection(selx, FieldVal, base, obj, index, false)

		offs := check.conf.offsetof(base, index)
		x.mode = constant_
		x.val = constant.MakeInt64(offs)
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Sizeof:
		// unsafe.Sizeof(x T) uintptr
		check.assignment(x, nil, "argument to unsafe.Sizeof")
		if x.mode == invalid {
			return
		}

		x.mode = constant_
		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Assert:
		// assert(pred) causes a typechecker error if pred is false.
		// The result of assert is the value of pred if there is no error.
		// Note: assert is only available in self-test mode.
		if x.mode != constant_ || !isBoolean(x.typ) {
			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
			return
		}
		if x.val.Kind() != constant.Bool {
			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
			return
		}
		if !constant.BoolVal(x.val) {
			check.errorf(call.Pos(), "%s failed", call)
			// compile-time assertion failure - safe to continue
		}
		// result is constant - no need to record signature

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		// (no argument evaluated yet)
		if nargs == 0 {
			check.dump("%s: trace() without arguments", call.Pos())
			x.mode = novalue
			break
		}
		var t operand
		x1 := x
		for _, arg := range call.Args {
			check.rawExpr(x1, arg, nil) // permit trace for types, e.g.: new(trace(T))
			check.dump("%s: %s", x1.pos(), x1)
			x1 = &t // use incoming x only for first argument
		}
		// trace is only available in test mode - no need to record signature

	default:
		unreachable()
	}

	return true
}
Пример #15
0
Файл: expr.go Проект: 2thetop/go
// The binary expression e may be nil. It's passed in for better error messages only.
func (check *Checker) binary(x *operand, e *ast.BinaryExpr, lhs, rhs ast.Expr, op token.Token) {
	var y operand

	check.expr(x, lhs)
	check.expr(&y, rhs)

	if x.mode == invalid {
		return
	}
	if y.mode == invalid {
		x.mode = invalid
		x.expr = y.expr
		return
	}

	if isShift(op) {
		check.shift(x, &y, e, op)
		return
	}

	check.convertUntyped(x, y.typ)
	if x.mode == invalid {
		return
	}
	check.convertUntyped(&y, x.typ)
	if y.mode == invalid {
		x.mode = invalid
		return
	}

	if isComparison(op) {
		check.comparison(x, &y, op)
		return
	}

	if !Identical(x.typ, y.typ) {
		// only report an error if we have valid types
		// (otherwise we had an error reported elsewhere already)
		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
			check.invalidOp(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
		}
		x.mode = invalid
		return
	}

	if !check.op(binaryOpPredicates, x, op) {
		x.mode = invalid
		return
	}

	if (op == token.QUO || op == token.REM) && (x.mode == constant_ || isInteger(x.typ)) && y.mode == constant_ && constant.Sign(y.val) == 0 {
		check.invalidOp(y.pos(), "division by zero")
		x.mode = invalid
		return
	}

	if x.mode == constant_ && y.mode == constant_ {
		xval := x.val
		yval := y.val
		typ := x.typ.Underlying().(*Basic)
		// force integer division of integer operands
		if op == token.QUO && isInteger(typ) {
			op = token.QUO_ASSIGN
		}
		x.val = constant.BinaryOp(xval, op, yval)
		// Typed constants must be representable in
		// their type after each constant operation.
		if isTyped(typ) {
			if e != nil {
				x.expr = e // for better error message
			}
			check.representable(x, typ)
		}
		return
	}

	x.mode = value
	// x.typ is unchanged
}
Пример #16
0
Файл: expr.go Проект: 2thetop/go
// representableConst reports whether x can be represented as
// value of the given basic type and for the configuration
// provided (only needed for int/uint sizes).
//
// If rounded != nil, *rounded is set to the rounded value of x for
// representable floating-point and complex values, and to an Int
// value for integer values; it is left alone otherwise.
// It is ok to provide the addressof the first argument for rounded.
func representableConst(x constant.Value, conf *Config, typ *Basic, rounded *constant.Value) bool {
	if x.Kind() == constant.Unknown {
		return true // avoid follow-up errors
	}

	switch {
	case isInteger(typ):
		x := constant.ToInt(x)
		if x.Kind() != constant.Int {
			return false
		}
		if rounded != nil {
			*rounded = x
		}
		if x, ok := constant.Int64Val(x); ok {
			switch typ.kind {
			case Int:
				var s = uint(conf.sizeof(typ)) * 8
				return int64(-1)<<(s-1) <= x && x <= int64(1)<<(s-1)-1
			case Int8:
				const s = 8
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int16:
				const s = 16
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int32:
				const s = 32
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int64, UntypedInt:
				return true
			case Uint, Uintptr:
				if s := uint(conf.sizeof(typ)) * 8; s < 64 {
					return 0 <= x && x <= int64(1)<<s-1
				}
				return 0 <= x
			case Uint8:
				const s = 8
				return 0 <= x && x <= 1<<s-1
			case Uint16:
				const s = 16
				return 0 <= x && x <= 1<<s-1
			case Uint32:
				const s = 32
				return 0 <= x && x <= 1<<s-1
			case Uint64:
				return 0 <= x
			default:
				unreachable()
			}
		}
		// x does not fit into int64
		switch n := constant.BitLen(x); typ.kind {
		case Uint, Uintptr:
			var s = uint(conf.sizeof(typ)) * 8
			return constant.Sign(x) >= 0 && n <= int(s)
		case Uint64:
			return constant.Sign(x) >= 0 && n <= 64
		case UntypedInt:
			return true
		}

	case isFloat(typ):
		x := constant.ToFloat(x)
		if x.Kind() != constant.Float {
			return false
		}
		switch typ.kind {
		case Float32:
			if rounded == nil {
				return fitsFloat32(x)
			}
			r := roundFloat32(x)
			if r != nil {
				*rounded = r
				return true
			}
		case Float64:
			if rounded == nil {
				return fitsFloat64(x)
			}
			r := roundFloat64(x)
			if r != nil {
				*rounded = r
				return true
			}
		case UntypedFloat:
			return true
		default:
			unreachable()
		}

	case isComplex(typ):
		x := constant.ToComplex(x)
		if x.Kind() != constant.Complex {
			return false
		}
		switch typ.kind {
		case Complex64:
			if rounded == nil {
				return fitsFloat32(constant.Real(x)) && fitsFloat32(constant.Imag(x))
			}
			re := roundFloat32(constant.Real(x))
			im := roundFloat32(constant.Imag(x))
			if re != nil && im != nil {
				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case Complex128:
			if rounded == nil {
				return fitsFloat64(constant.Real(x)) && fitsFloat64(constant.Imag(x))
			}
			re := roundFloat64(constant.Real(x))
			im := roundFloat64(constant.Imag(x))
			if re != nil && im != nil {
				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case UntypedComplex:
			return true
		default:
			unreachable()
		}

	case isString(typ):
		return x.Kind() == constant.String

	case isBoolean(typ):
		return x.Kind() == constant.Bool
	}

	return false
}
Пример #17
0
func (constantFolderVisitor) VisitPost(expr Expr) (retExpr Expr) {
	defer func() {
		// go/constant operations can panic for a number of reasons (like division
		// by zero), but it's difficult to preemptively detect when they will. It's
		// safest to just recover here without folding the expression and let
		// normalization or evaluation deal with error handling.
		if r := recover(); r != nil {
			retExpr = expr
		}
	}()
	switch t := expr.(type) {
	case *ParenExpr:
		switch cv := t.Expr.(type) {
		case *NumVal, *StrVal:
			return cv
		}
	case *UnaryExpr:
		switch cv := t.Expr.(type) {
		case *NumVal:
			if token, ok := unaryOpToToken[t.Operator]; ok {
				return &NumVal{Value: constant.UnaryOp(token, cv.Value, 0)}
			}
			if token, ok := unaryOpToTokenIntOnly[t.Operator]; ok {
				if intVal, ok := cv.asConstantInt(); ok {
					return &NumVal{Value: constant.UnaryOp(token, intVal, 0)}
				}
			}
		}
	case *BinaryExpr:
		switch l := t.Left.(type) {
		case *NumVal:
			if r, ok := t.Right.(*NumVal); ok {
				if token, ok := binaryOpToToken[t.Operator]; ok {
					return &NumVal{Value: constant.BinaryOp(l.Value, token, r.Value)}
				}
				if token, ok := binaryOpToTokenIntOnly[t.Operator]; ok {
					if lInt, ok := l.asConstantInt(); ok {
						if rInt, ok := r.asConstantInt(); ok {
							return &NumVal{Value: constant.BinaryOp(lInt, token, rInt)}
						}
					}
				}
				if token, ok := binaryShiftOpToToken[t.Operator]; ok {
					if lInt, ok := l.asConstantInt(); ok {
						if rInt64, err := r.asInt64(); err == nil && rInt64 >= 0 {
							return &NumVal{Value: constant.Shift(lInt, token, uint(rInt64))}
						}
					}
				}
			}
		case *StrVal:
			if r, ok := t.Right.(*StrVal); ok {
				switch t.Operator {
				case Concat:
					// When folding string-like constants, if either was byte-escaped,
					// the result is also considered byte escaped.
					return &StrVal{s: l.s + r.s, bytesEsc: l.bytesEsc || r.bytesEsc}
				}
			}
		}
	case *ComparisonExpr:
		switch l := t.Left.(type) {
		case *NumVal:
			if r, ok := t.Right.(*NumVal); ok {
				if token, ok := comparisonOpToToken[t.Operator]; ok {
					return MakeDBool(DBool(constant.Compare(l.Value, token, r.Value)))
				}
			}
		case *StrVal:
			// ComparisonExpr folding for String-like constants is not significantly different
			// from constant evalutation during normalization (because both should be exact,
			// unlike numeric comparisons). Still, folding these comparisons when possible here
			// can reduce the amount of work performed during type checking, can reduce necessary
			// allocations, and maintains symmetry with numeric constants.
			if r, ok := t.Right.(*StrVal); ok {
				switch t.Operator {
				case EQ:
					return MakeDBool(DBool(l.s == r.s))
				case NE:
					return MakeDBool(DBool(l.s != r.s))
				case LT:
					return MakeDBool(DBool(l.s < r.s))
				case LE:
					return MakeDBool(DBool(l.s <= r.s))
				case GT:
					return MakeDBool(DBool(l.s > r.s))
				case GE:
					return MakeDBool(DBool(l.s >= r.s))
				}
			}
		}
	}
	return expr
}
Пример #18
0
Файл: expr.go Проект: gmwu/go
// representableConst reports whether x can be represented as
// value of the given basic type kind and for the configuration
// provided (only needed for int/uint sizes).
//
// If rounded != nil, *rounded is set to the rounded value of x for
// representable floating-point values; it is left alone otherwise.
// It is ok to provide the addressof the first argument for rounded.
func representableConst(x constant.Value, conf *Config, as BasicKind, rounded *constant.Value) bool {
	switch x.Kind() {
	case constant.Unknown:
		return true

	case constant.Bool:
		return as == Bool || as == UntypedBool

	case constant.Int:
		if x, ok := constant.Int64Val(x); ok {
			switch as {
			case Int:
				var s = uint(conf.sizeof(Typ[as])) * 8
				return int64(-1)<<(s-1) <= x && x <= int64(1)<<(s-1)-1
			case Int8:
				const s = 8
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int16:
				const s = 16
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int32:
				const s = 32
				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
			case Int64:
				return true
			case Uint, Uintptr:
				if s := uint(conf.sizeof(Typ[as])) * 8; s < 64 {
					return 0 <= x && x <= int64(1)<<s-1
				}
				return 0 <= x
			case Uint8:
				const s = 8
				return 0 <= x && x <= 1<<s-1
			case Uint16:
				const s = 16
				return 0 <= x && x <= 1<<s-1
			case Uint32:
				const s = 32
				return 0 <= x && x <= 1<<s-1
			case Uint64:
				return 0 <= x
			case Float32, Float64, Complex64, Complex128,
				UntypedInt, UntypedFloat, UntypedComplex:
				return true
			}
		}

		n := constant.BitLen(x)
		switch as {
		case Uint, Uintptr:
			var s = uint(conf.sizeof(Typ[as])) * 8
			return constant.Sign(x) >= 0 && n <= int(s)
		case Uint64:
			return constant.Sign(x) >= 0 && n <= 64
		case Float32, Complex64:
			if rounded == nil {
				return fitsFloat32(x)
			}
			r := roundFloat32(x)
			if r != nil {
				*rounded = r
				return true
			}
		case Float64, Complex128:
			if rounded == nil {
				return fitsFloat64(x)
			}
			r := roundFloat64(x)
			if r != nil {
				*rounded = r
				return true
			}
		case UntypedInt, UntypedFloat, UntypedComplex:
			return true
		}

	case constant.Float:
		switch as {
		case Float32, Complex64:
			if rounded == nil {
				return fitsFloat32(x)
			}
			r := roundFloat32(x)
			if r != nil {
				*rounded = r
				return true
			}
		case Float64, Complex128:
			if rounded == nil {
				return fitsFloat64(x)
			}
			r := roundFloat64(x)
			if r != nil {
				*rounded = r
				return true
			}
		case UntypedFloat, UntypedComplex:
			return true
		}

	case constant.Complex:
		switch as {
		case Complex64:
			if rounded == nil {
				return fitsFloat32(constant.Real(x)) && fitsFloat32(constant.Imag(x))
			}
			re := roundFloat32(constant.Real(x))
			im := roundFloat32(constant.Imag(x))
			if re != nil && im != nil {
				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case Complex128:
			if rounded == nil {
				return fitsFloat64(constant.Real(x)) && fitsFloat64(constant.Imag(x))
			}
			re := roundFloat64(constant.Real(x))
			im := roundFloat64(constant.Imag(x))
			if re != nil && im != nil {
				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case UntypedComplex:
			return true
		}

	case constant.String:
		return as == String || as == UntypedString

	default:
		unreachable()
	}

	return false
}