[clang] Patch series to reapply #118734 and substantially improve it (PR #120534)

[Chandler Carruth via cfe-commits]

chandlerc wrote:

@dyung -- Could you try out https://github.com/chandlerc/llvm-project/tree/shard-loongarch and see if that works?

Notably, it includes one additional patch on top of this series: https://github.com/chandlerc/llvm-project/commit/2d593288dc18c55307779ae82a18d024761356ad

This won't be enough to fully resolve the issue, but if the LoongArch errors go away with this patch, then it gives me a strong theory about what is still going wrong and I can likely find a workaround for the rest as well.

https://github.com/llvm/llvm-project/pull/120534