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

[Nikita Popov via llvm-commits]

nikic wrote:

You can also use `build/bin/llvm-lit --update-tests llvm/test/CodeGen/X86/tbm_patterns.ll` so you don't have to mess with paths.

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