The major constraint is that the compiler needs to guarantee that transformations produce semantically identical results to the unoptimized code, with the exception of undefined behavior or specific opt-outs (eg. `-ffast-math` rules).
An ML model can fit into existing compiler pipelines anywhere that heuristics are used though, as an alternative to PGO.
An ML model can fit into existing compiler pipelines anywhere that heuristics are used though, as an alternative to PGO.