Thanks for the work on this, after thinking about it for a while I believe the proposed hooks runs counter to goals of the TECompiler and "unified lowering" refactor that we've been working on in pieces. Our design goal is to not allow arbitrary customization of "lowering" but instead seal it behind a stable interface. The lowering process should be a straight forward mapping from TE -> TIR, and then any necessary customization should be possible in resulting passes which are allowed to view the entire program including both the Relay code and TIR code.
The goal is to remove the need for many slightly different code paths through the central parts of the compiler and instead provide standard interfaces that allow targets, and users to customize the compiler without having to touch any of the flows or modify the data structures. The proliferation of customizations in the old compile engine for example makes it nearly impossible to refactor the compiler in its current state, and has lead to the world where we need lots of per-flow customization because the compiler is insufficiently factored into a common prefix of code. I plan on providing a longer form document on this hopefully this week that argues this more in depth but I believe the tenants should be customization of the compiler happens via passes, passes only can produce IRModules, and all data is stored in the IRModule. Today's compiler requires a little more work to get to this world, but I think we should push in this direction. Now that doesn't mean the desire to have per target behavior is necessarily bad, but I think instead of overriding the lowering code with arbitrary functions we could provide hooks that allow the insertion of target specific passes at the "correct" time in the compiler flow. In this world the proposed hooks should return a `Pass` object which can be inserted after the appropriate phases. Happy to discuss more, and have others such as @electriclilies @csullivan @mbs-octoml -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/apache/tvm-rfcs/pull/10#issuecomment-891293282
