[PATCH] D113209: [LV] Use VScaleForTuning to fine-tune the cost per lane.

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck added a comment.

In D113209#3111194 <https://reviews.llvm.org/D113209#3111194>, @sdesmalen wrote:

> In D113209#3111176 <https://reviews.llvm.org/D113209#3111176>, @frasercrmck wrote:
>
>> How does this interact with `vscale_range`? Could it perhaps automatically infer `getVScaleForTuning` using that? Or is the idea the target ultimately chooses?
>
> The two are actually quite different; `vscale_range` specifies the range of vscale that the compiled binary is compatible with. LLVM guarantees that the compiled binary is correct for that vscale_range. `VScaleForTuning` can be set separately by `mcpu/mtune` and will purely tune the cost-model without changing the requirements on vscale. This means it doesn't change the compatibility of the binary, it just helps choose a better VF for the CPU it compiles for.

Fair enough, thanks for the explanation!


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https://reviews.llvm.org/D113209