[llvm-branch-commits] [llvm] release/21.x: MC: Better handle backslash-escaped symbols (PR #159420)

[Nikita Popov via llvm-branch-commits]

nikic wrote:

The diff here is fairly large, but also very mechanical. This fixes a regression for the Rust defmt crate with LLVM 21.

https://github.com/llvm/llvm-project/pull/159420