Tiberium is absolutely correct, but I do admit I'd love a TRYD-like project. Thanks for giving me some useful search terms!

(to be clear, what I had in mind: not just merging trace heads to form a tree, but merging their tails as well [à la NFA minimisation] to form a cyclic graph; after which one could use region-based techniques on the identified cycles.

Rpython's metatracing does a reasonable job for multiple interlacing warm paths, but there's still room for improvement)