[llvm] [Codegen, X86] Add prefetch insertion based on Propeller profile (PR #166324)

[Robert Imschweiler via llvm-commits]

ro-i wrote:

@rlavaee This PR seems to have introduced a sometimes-occurring test failure in https://lab.llvm.org/buildbot/#/builders/187.
`LLVM::basic-block-sections-code-prefetch.ll`



https://github.com/llvm/llvm-project/pull/166324