Yeah computing backtraces in a crashreporter is extremely similar to a debugger in that you need a lot of fudge-factor heuristics and fallback modes for known toolchain bugs or common corruptions.

You're probably remembering https://pernos.co/blog/tzcnt-portability/

Speaking of the rr folk, they also had the fascinating point that you can reliably generate a "stack trace" by figuring out which `call` instructions were executed with what values (also other jump instructions I suppose), instead of walking the stack. Thereby skipping the whole "parsing the stack is insanely difficult and unreliable" issue.

FWIW, that's from pernosco, not rr.

I think it's the same people?

It is. rr records the trace and the Pernosco converts it into a database that can be queried.