[PATCH] D146199: [LoopVectorize] Don't tail-fold for scalable VFs when there is no scalar tail

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

> Hi @dmgreen, so I don't have a strong objection to doing this as a new vscale_power_of_2 attribute, but I am trying to avoid changing the LangRef again if we don't have a compelling case to do so yet. This is what we did originally with the vscale max, i.e. we first added a TTI interface, then as time went on we saw more and more convincing arguments for moving this to be a vscale_range attribute instead. There is nothing to stop us doing something similar in future I think, right? Of course, there is already a TLI hook of the same name that would need removing too.

Yeah sounds good. I was thinking as a followup, something to keep in mind. It could even go like @reames suggested where we only support power-of-2 vscales - I heard that GCC always took that route for SVE and has only ever supported power-of-2 vscales.


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https://reviews.llvm.org/D146199