[llvm] [InlineCost] Disable cost-benefit when sample based PGO is used (PR #86626)

[Haohai Wen via llvm-commits]

HaohaiWen wrote:

> @HaohaiWen Thanks for working on profile maintenance. I don't think the patches you mentioned are going to change the results meaningfully. Is there a particular reason you want this to be default on? As others mentioned, you can just turn it on as needed.

We'd like to turn it on since we have see gains on our internal workloads. We hope it can be always beneficial for all workloads. Unfortunately it caused regression in your workloads. I agree to disable it for SPGO currently to workaround your regression. In long term, I hope we can try to tune and turn it on after fixing real root cause of this regression.

> 
> I'd also like to share some general feedbacks: 1) landing default changes like the original patch generally has a high bar. 2) the way it was done, without perf numbers, and without stakeholder review before landing is not how things are usually done.

Thanks for feedbacks.



https://github.com/llvm/llvm-project/pull/86626