[kazinator]

It is a seemingly outlandish claim.

Even in just the C world, for instance, profiling tools are able to trace all the function calls to determine how many times they are called, how much time is spent, and to recover the call graph information.

The --ftrace option in cosmpolitan shares a name with a Linux kernel function tracing mechanism.

What Justine may mean is that it's done in some new, unusual way; e.g. other than patching the initial instructions of functions to branch somewhere.