Albert Cohen from Google gave a really good lecture on polyhedral compilation in the real world at PLISS [1] this year: slides [2], lecture videos [3, 4].
A core problem of the polyhedral approach, is that the thing that makes it so appealing (it being expressive enough to enable the many interesting program transformations), is costly for large programs making, the overall optimisation process and hence the compiler hard to scale. Naturally, this difficulty makes for interesting research problems.
[2] https://pliss2019.github.io/albert_cohen_slides.pdf
Polyhedral development in LLVM stagnated a while ago, maybe we find the people and time to actually land the PolyhedralValueInfo (see for example this talk: https://www.youtube.com/watch?v=xSA0XLYJ-G0).