search for: letp

...separate the decrementing of the loop counter with the instruction that branches back, which should help us recover if LR gets spilt between these two pseudo ops. For Armv8.1-M, the while.setup intrinsic is used to generate the wls and wlstp instructions, while loop.end generates the le and letp instructions. The active.mask can just be removed because the lane predication is handled implicitly. I'm not sure of the vectorizers limitations of generating vector instructions that operate across lanes, such as reductions, when generating a predicated loop but this needs to be considered....