[clang] [compiler-rt] [flang] [libc] [libcxx] [lldb] [llvm] [mlir] [X86] Fast AVX-512-VNNI vpdpwssd tuning (PR #85033)

[Simon Pilgrim via cfe-commits]

https://github.com/RKSimon requested changes to this pull request.

This patch needs to be cleanly rebased on trunk (force push is OK in PR branchs)

https://github.com/llvm/llvm-project/pull/85033