[Mlir-commits] [mlir] [mlir][presburger] Preserve relative ordering of symbols and non-symbol vars when setting up SymbolicLexSimplex (PR #119036)

[Christopher Bate]

christopherbate wrote:

> Hi, thanks for the patch! This looks great. I left some comments. Once these are addressed, we should be good to go.
> 
> It does seem concerning if the Simplex becomes slow after reordering some variables. Do I understand correctly that you can reproduce the slowness by using the modified variable ordering in the initial test case? If not, I don't understand why it should be slow if the reordering occurs internally but not externally. Either way, as you say, your patch makes sense regardless. I will look into the Simplex issue further later. Thanks for reporting it!
> 
> (Sorry about the delay, I was on vacation. As a heads up, I may not have great availability for the coming week either, but hopefully all I'll need to do is approve it! :))


Yes, the test I added will demonstrate the slowness without the additional changes added here. 

https://github.com/llvm/llvm-project/pull/119036