[PATCH] D124457: [AArch64][SVE] Only fold frame indexes referencing SVE objects into SVE loads/stores

[Bradley Smith via Phabricator via llvm-commits]

bsmith added a comment.

In D124457#3474976 <https://reviews.llvm.org/D124457#3474976>, @efriedma wrote:

> Is FrameIndex 0 actually reliably located in a position that doesn't have an offset?  That seems unlikely to me, especially if variable-size allocation becomes involved.

Hm, you might be right. It seems a shame to regress cases where the index would be zero, but I'm not sure there is way to tell at this point if the offset will resolve to zero?

> Alternatively, we could fix the code that decides whether we need an emergency spill slot. But I guess there's not really much point to attempting to fold the frame indexes in the first place.

I considered that, the issue though is finding the correct condition to do this in without being far too conservative, I think you'd have to do it by traversing the function finding all SVE load/stores and checking what they access, which doesn't seem very nice for an issue we are creating for ourselves.


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https://reviews.llvm.org/D124457