[PATCH] D123473: [LICM] Only create load in pre-header when promoting load.

Mon Apr 11 07:38:02 PDT 2022

fhahn added a comment.

In D123473#3442753 <https://reviews.llvm.org/D123473#3442753>, @nlopes wrote:

> I think the patch is not the full fix, as far as I understand. It's a good improvement, perf & correctness wise, though, but doesn't fix #51248.
>
> There's one missing case: the load is needed and the function can't load memory (writeonly, readnone, etc?). In that case the optimization should bail out.

I think at the moment, the load will only be generated if the source already had a load that is guaranteed to execute. So hoisting that in a write only function should be fine, as it is already UB.

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https://reviews.llvm.org/D123473