I assume it's a reference to tracing JIT (https://en.wikipedia.org/wiki/Tracing_just-in-time_compilation https://en.wikipedia.org/wiki/Tracing_just-in-time_comp

I assume it's a reference to tracing JIT (https://en.wikipedia.org/wiki/Tracing_just-in-time_compilation https://en.wikipedia.org/wiki/Tracing_just-in-time_compilati...). It's a JIT that traces runtime execution, rather than looking at whole method or function bodies. In particular it eliminates control flow, which simplifies optimisation.