[llvm] X86: Add pattern for optimized BLSIC IR form (PR #209814)

[via llvm-commits]

Logans-olo wrote:

> @Logans-olo when we talk about the update script - we're asking you to manually run llvm-project\llvm\utils\update_llc_test_checks.py on the test file to regenerate all the CHECK lines.
> 
> One of your earlier comments suggested you thought it had something to with github updating the patch against trunk latest - sorry if there was any confusion.

Also sorry, that's completely on me. Should know to be running (build/update) scripts after every change. I think its good now though?

https://github.com/llvm/llvm-project/pull/209814