[llvm-dev] Get Source Code Location of a Loop

[Michael Kruse via llvm-dev]

Loop::getStartLoc() looks up the DebugLoc in the metadata attached to
the loop. It is up to the language frontend (classic flang? f18 flang?
Dragonegg?). Therefore, it is up to the frontend to correctly set that
information.

However, getStartLoc() also has a fallback strategy to look for debug
info of the pre-header. After loop-rotation of the outer loop, the
inner loop's pre-header would might have been merged with the exit
condition of the outer loop.

> How to get the proper beginning line in the source?

This is the responsibility of your Fortran front-end.

Michael