[PATCH] D65360: [AArch64][GlobalISel] Eliminate redundant G_ZEXT when the source is implicitly zext-loaded

[Amara Emerson via Phabricator via llvm-commits]

aemerson added a comment.

In D65360#1604646 <https://reviews.llvm.org/D65360#1604646>, @paquette wrote:

> I am a little concerned that continuing down this route is going to result in a bunch of work that every target will have to duplicate. I think it makes sense to come up with a plan to prevent that if possible.
>
> For now, though, I feel like we don't //really// know how many things like this show up/how they show up. So, I don't know if it makes sense to run the combiner twice at -O0/add another more minimal pass/etc. yet.
>
> (Do we know what the compile time/code size tradeoff of running the combiner twice is for -O0?)


It seems the issue here is that we have a minor but noticeable codegen issue at -O0, which IMO is not alone worth adding an entire new pass to the -O0 pipeline for. However, if we decide to add another combiner run in future then we can revisit this,


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https://reviews.llvm.org/D65360