[kannanvijayan]

I'd disagree. Classical compiler work is very mature, yes - and new progress in things like register allocation and backend IR-based optimization stuff is well trod ground.

But in the context of JIT compilers for dynamically typed languages, in particular the space involving runtime inferred hidden type models, there is a TON of work left on the table.

It hasn't been paid much attention to in academia, IMHO largley because of a historical perspective on optimizing dynamic languages as "not classy" work among language theorists. I hope that perspective changes over time.