[llvm] [PGO]add bitcode-use-sample-profile (PR #66178)

[via llvm-commits]

lifengxiang1025 wrote:

> -fprofile-sample-use should also be specified in step 1, otherwise it's too late because IR are not being annotated

Could you explain why it's too late?
I tried this patch and I can see some new inline behavior and hotness information.
Do you mean step 1 have do inline pass before step 4's ProfileSampleLoader pass? Normally, IR do inline and PSI,BFI update in ProfileSampleLoader pass which head of IPO pass. How about step 1 use -O0 or -fno-inline?

https://github.com/llvm/llvm-project/pull/66178