[llvm] Perform bitreverse using AVX512 GFNI for i32 and i64. (PR #81764)

[via llvm-commits]

shamithoke wrote:

> @shamithoke reverse-ping?

Hello @RKSimon, Sorry somehow I misunderstood that your restructured code will also take care of i32/i64 support. So I did not pay attention to this PR. I just realized that the changes for i32/i64 are still required (which I've added). 

https://github.com/llvm/llvm-project/pull/81764