}
		ir.Visit(n, c.findExtraCalls)
	}
	c.curfn = nil
	return c
}

func (c *nowritebarrierrecChecker) findExtraCalls(nn ir.Node) {
	if nn.Op() != ir.OCALLFUNC {
		return
	}
	n := nn.(*ir.CallExpr)
	if n.Fun == nil || n.Fun.Op() != ir.ONAME {
		return
	}
	fn := n.Fun.(*ir.Name)
	if fn.Class != ir.PFUNC || fn.Defn == nil {
		return
	}
	if types.RuntimeSymName(fn.Sym()) != "systemstack" {
		return
	}

		types := make(map[syntax.Expr]TypeAndValue)
		mustTypecheck(src, nil, &Info{Types: types})

		var n int
		for x, tv := range types {
			if x, _ := x.(*syntax.CallExpr); x != nil {
				// there must be exactly one CallExpr which is the P(val) conversion
				n++
				tpar, _ := tv.Type.(*TypeParam)
				if tpar == nil {
					t.Fatalf("%s: got type %s, want type parameter", ExprString(x), tv.Type)
				}

		types := make(map[ast.Expr]TypeAndValue)
		mustTypecheck(src, nil, &Info{Types: types})

		var n int
		for x, tv := range types {
			if x, _ := x.(*ast.CallExpr); x != nil {
				// there must be exactly one CallExpr which is the P(val) conversion
				n++
				tpar, _ := tv.Type.(*TypeParam)
				if tpar == nil {
					t.Fatalf("%s: got type %s, want type parameter", ExprString(x), tv.Type)
				}

	//     24  .  .  .  Body: *ast.BlockStmt {
	//     25  .  .  .  .  Lbrace: 3:13
	//     26  .  .  .  .  List: []ast.Stmt (len = 1) {
	//     27  .  .  .  .  .  0: *ast.ExprStmt {
	//     28  .  .  .  .  .  .  X: *ast.CallExpr {
	//     29  .  .  .  .  .  .  .  Fun: *ast.Ident {
	//     30  .  .  .  .  .  .  .  .  NamePos: 4:2
	//     31  .  .  .  .  .  .  .  .  Name: "println"
	//     32  .  .  .  .  .  .  .  }

		if n.High != nil {
			Walk(v, n.High)
		}
		if n.Max != nil {
			Walk(v, n.Max)
		}

	case *TypeAssertExpr:
		Walk(v, n.X)
		if n.Type != nil {
			Walk(v, n.Type)
		}

	case *CallExpr:
		Walk(v, n.Fun)
		walkList(v, n.Args)

	case *StarExpr:
		Walk(v, n.X)

	case *UnaryExpr:
		Walk(v, n.X)

	case *BinaryExpr:
		Walk(v, n.X)
		Walk(v, n.Y)

		} else {
			check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
		}
	}).describef(pos, "verify instantiation")

	return inst
}

func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
	var inst *syntax.IndexExpr // function instantiation, if any
	if iexpr, _ := call.Fun.(*syntax.IndexExpr); iexpr != nil {
		if check.indexExpr(x, iexpr) {

		} else {
			check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
		}
	}).describef(atPos(pos), "verify instantiation")

	return inst
}

func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
	ix := typeparams.UnpackIndexExpr(call.Fun)
	if ix != nil {
		if check.indexExpr(x, ix) {
			// Delay function instantiation to argument checking,

			for _, r := range f.Ref {
				if r.Expr == px {
					*px = p.rewriteName(f, r, addPosition)
					r.Done = true
					break
				}
			}

			return
		}

		call, ok := (*px).(*ast.CallExpr)
		if !ok {
			return
		}

		for _, c := range f.Calls {
			if !c.Done && c.Call.Lparen == call.Lparen {
				cstr, nu := p.rewriteCall(f, c)
				if cstr != "" {

// reports whether 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) {
	argList := call.Args

	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if hasDots(call) && id != _Append {

func (r *rewriter) editDefer(x *syntax.CallStmt) syntax.Stmt {
	if r.defers == nil {
		// Declare and initialize the #defers token.
		init := &syntax.CallExpr{
			Fun: runtimeSym(r.info, "deferrangefunc"),
		}
		tv := syntax.TypeAndValue{Type: r.any.Type()}
		tv.SetIsValue()
		init.SetTypeInfo(tv)
		r.defers = r.declVar("#defers", r.any.Type(), init)
	}