[PATCH] D90591: [ARM] Introduce t2DoLoopStartTP

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

In D90591#2375686 <https://reviews.llvm.org/D90591#2375686>, @samparker wrote:

> With the MVE instructions taking LR, maybe you wouldn't need to make the terminator change, have you tried it yet? I guess I'm naively assuming that the register allocator will be much less likely to spill something that is used by most / all of the MVE instructions within the loop.

"Much less likely" isn't a fantastic answer for something that we should really never be reverting, unfortunately. You can always have a number of MVE instructions at the start of the loop followed by a load of scalar instructions. I think when I had it that way in experimental patches there were still some reverts happening.

That's all about different patches though! Any comments on this one? If we can get this in, I can commit a few others without breaking performance on some important machine learning matrix multiply kernels, which would be good.


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