[clang] [llvm] [ThinLTO][Split] Split module for parallel compilation in backend (1/N) (PR #198702)

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mmjjpp wrote:

In SplitModuleCG, we do not perform the actual renaming immediately. We only record the required renaming information and apply the rename after the opt pipeline has completed.

This is intentional: deferring the rename minimizes the impact of renaming on subsequent optimizations while still allowing us to handle name collisions consistently.

https://github.com/llvm/llvm-project/pull/198702