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Re: how to ensure loop unrolling with template programming


On 9 July 2010 02:29, Frank Winter <frank.winter@desy.de> wrote:
>
> How can I make sure the compiler unrolls the loop and inlines all function
> calls? Do I have to use the preprocessor in my case?
>

if you're *really* sure you know so much better than the heuristics, then:
- __attribute__((__force_inline__)) or something like that will inline the calls
- And change the loop to one at compile time using template specialization

template <unsigned I>
struct repeat {
    template <typename F>
    repeat(F f) { f(); repeat<I-1>(f); }
};
template <>
struct repeat<0> {
    template <typename F>
    repeat(F) {}
};

void bar();
void foo() {
    repeat<4>(bar);
}

HTH,
~ Scott


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