The profiling runcore allows users and HLL developers to profile their programs at the PIR level. Rakudo needs this desperately.

* Make runloops pluggable (pluggable_runcore branch)

• factor out the common runcore operations
• define a struct to represent these operations
• refactor existing runcores to use this struct
• define a mechanism to load and register a new runcore
• beware of runcore switching; probably need a better way to switch than compile-time constants

* Create a new profiling dyncore

• figure out the extra data and this runcore needs for profiling
  • open output file
  • store profiling information
  • close output file

* Explore callgrind output format (NYTProf format a good second strategy)

• How do you represent non-local jumps?
• How do you detect non-local jumps and other CPS-style control flow changes?
• How do you get current line number and source file from the active Context?
• (stretch goal) How do you retrieve and record current HLL location?
• How do you report different runcores (exceptions) and threads (interpreters)
• Probably need to avoid PIO to avoid that overhead
• Can you add timing to include what's expensive in C terms?

possible problem: can callgrind represent all the ways PIR can do control flow

• parrot_op_info table gets populated based on what kind of flow
• function attrs in ops files will probably help too

- if callgrind supports it, find what happens between ops (i.e. how much time between starting ops)