Comment by the-alchemist

I believe the term for this is "partial escape analysis" (PEA).

GraalVM is the SOTA in the JVM world for this.

Here's an oldish blog on this: https://chrisseaton.com/truffleruby/seeing-escape-analysis/

I'm sure PEA is better now, but it's not sure if it's moved beyond scalars (int, float, etc.)