[PATCH] D155688: [PATCH] [llvm] [InstCombine] Canonicalise ADD+GEP

Tue Oct 10 08:35:04 PDT 2023

nikic added a comment.

In D155688#4653520 <https://reviews.llvm.org/D155688#4653520>, @fiigii wrote:

>> The reverse transform is only done if A + B simplifies.
>
> Looks like`simplifyAddInst` may give add expressions, so I guess this patch may make IC run into infinite loops.

simplifyAddInst can return an add instruction, but it will be an existing one. It will never introduce a new one. So I'm not sure how this would result in infinite loops?

In D155688#4653629 <https://reviews.llvm.org/D155688#4653629>, @d-smirnov wrote:

> We have some improvements with the patch, most notable: 549.fotonik_3d improves about 6%. 
> @nikic Should we revert the patch and try another location for it (in LICM pass, as you previously suggested)?

I don't think we have cause to revert just yet, as we're not aware of any //specific// issues.

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