var (
		arch   *asmArch
		fn     *asmFunc
		offset int
	)

	// addParams adds asmVars for each of the parameters in list.
	// isret indicates whether the list are the arguments or the return values.
	// TODO(adonovan): simplify by passing (*types.Signature).{Params,Results}
	// instead of list.
	addParams := func(list []*ast.Field, isret bool) {
		argnum := 0
		for _, fld := range list {