[llvm] [DebugInfo] Preserve line and column number when merging debug info. (PR #129960)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse commented:

My understanding of this is that with this flag on, a consistent but essentially arbitrary source location will be kept for merged instructions -- potentially misleading for debugging (hence it's an option), but good for PGO, yes?

I wonder how effective this is in the general case, but you've got numbers for a workload, so SGTM.

https://github.com/llvm/llvm-project/pull/129960