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Re: [PATCH] Add zero-overhead looping for xtensa backend


On Thu, Oct 23, 2014 at 11:40 PM, Yangfei (Felix) <felix.yang@huawei.com> wrote:
> 1. The original xtensa port never generates "loop" instruction at all.
> 2. A port doesn't need to implement hwloop_pattern_reg hook if it has no zero-cost loop instruction.
>
> Is that clear?

We are talking in circles. I understand very well what goes on here.

My point is:

1. Right now, today, GCC generates loops with branch instructions even
when the trip count is spilled.
2. Branch instructions and loop instructions have identical register
requirements.

Therefore:

3. loop instructions should be generatable when the trip count is spilled.


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