That depends on the context of the book. What sort of book is it? Are the child torture/rape parts small partd of the plot, like, a book about a group of devil worshippers, with a sidetrack on thier activities, or what?
Id need to know the entire context of the book. If it was simply a bunch of short stories of graphic sex with kids, then yes, it would be childporn,
but of the book was simply a large novel with these things as smaller parts of the plot, then no, its not kiddie porn.
but they do not give us this information.