[PATCH] D131356: [InstCombine] reassociate bitwise logic chains based on uses

Tue Aug 16 23:03:16 PDT 2022

bcl5980 added a comment.

In D131356#3727022 <https://reviews.llvm.org/D131356#3727022>, @fhahn wrote:

> In D131356#3727010 <https://reviews.llvm.org/D131356#3727010>, @spatel wrote:
>
>> In D131356#3726615 <https://reviews.llvm.org/D131356#3726615>, @bcl5980 wrote:
>>
>>> Maybe we can run ipsccp until no changed(Similar to Instcombine) to fix all these tickets. like:
>>
>> I'm not familiar with ipsccp, and I don't know what impact running that pass to fix-point would have on compile-time, but if that works, do you want to make a patch?
>
> IPSCCP/SCCP should iterate until they reach a fixed-point already. If running `runIPSCCP(M, DL, GetTLI, getAnalysis)` multiple times improves the result, then there's likely a dependency missing in the solver.

This is a very simple case that run once `runIPSCCP` can't get fix-point result. https://alive2.llvm.org/ce/z/o6rkTy

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https://reviews.llvm.org/D131356