[clang] [llvm] [libunwind] [compiler-rt] [libc] [flang] [lld] [libcxx] [lldb] [libclc] [clang-tools-extra] [libcxxabi] [RISCV] Support Global Dynamic TLSDESC in the RISC-V backend (PR #66915)

[Fangrui Song via cfe-commits]

MaskRay wrote:

This PR needs a rebase.. There are quite a few merge commits. Hmm, I don't know how to squash the changes to rebase them to latest main branch. `git rebase --keep-base -i main` has quite a few merge conflicts.

(My lld change (https://github.com/maskray/llvm-project/tree/rv-tlsdesc) is almost complete. I want to rebase it onto the latest revision of this LLVM PR.)

https://github.com/llvm/llvm-project/pull/66915