[clang] [llvm] [IR] Don't use TrackingMDNodeRef for DebugLoc (PR #200649)

[Alexis Engelke via cfe-commits]

aengelke wrote:

>  We do rely on DebugLoc being able to store MDNode and not specifically tied to DILocation.

This was also not supported previously -- only for parsing textual IR files, as explicitly stated in the corresponding DebugLoc constructor.

If you feel that this should be long-term-reverted, include this in your RFC and discuss the different value propositions. Note that using metadata for debug locations is going against the current development direction.

A short-term-revert might be doable (but then again, why not temporarily revert downstream?), but I'm not yet convinced that this patch broke anything hard enough to do so...

https://github.com/llvm/llvm-project/pull/200649