[llvm] [BOLT] Add an option to remove pseudo probe sections (PR #218662)

[Rafael Auler via llvm-commits]

rafaelauler wrote:

If you are deploying a custom binary to a dedicated small tier, do you still need to deliver good perf to that small tier? Potentially you could completely disable BOLT and BAT and collect perfect pre-BOLT profile there, then deploy the perfect profile to the rest of prod.

And the same for FDO I guess, except that FDO is more complicated and you might have some wins you're getting from inlining decisions made in the past that are replayed in the future version of the binary when you do continuous profile (as opposed to on-demand profile). It appears that you're doing on-demand, profile in a canary or small tier.

The problem of doing the ondemand/collect-profile-in-a-canary pipeline is a potential ~7hr delay to deploy the fully optimized version, since you need to wait for the intermediary builds to collect their profile. But if you do it right, it should reap maximum benefits.

https://github.com/llvm/llvm-project/pull/218662