[llvm] [DebugInfo][InstCombine] Do not overwrite prior DILocation for new Insts (PR #108565)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

> so the same location as before, so there's no regression?

That's correct - there's no regression from this patch, I'm simply noting that it's not a perfect solution. A more perfect solution would be one where we could state explicitly in this case, "Do not copy the original instruction's DebugLoc to the replacement instruction", but that would require making more intrusive changes to InstCombine with probably a large diff footprint, hence I'm considering this a worthwhile partial solution.

https://github.com/llvm/llvm-project/pull/108565