[llvm] [ThinLTO] Add metedata 'thinlto_src_module' and 'thinlto_src_file' (PR #83110)

[Teresa Johnson via llvm-commits]

teresajohnson wrote:

There are some uses of this metadata in llvm/lib/Analysis/ImportedFunctionsInliningStatistics.cpp, do they or their tests need changing?

https://github.com/llvm/llvm-project/pull/83110