[llvm] [CSSPGO] Error out if the checksum mismatch is high (PR #84097)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

> The current version looks good. For testing, have you tried to build with some workloads to make sure we don't have false positives?

Update the flag tuning:   looks it's quite distinguishable. On one ads service, when using a super bad profile(applying both #79919 + #75092), surprisedly even using a 300000(30%) as hot-cut-off, it can still throw the error, 20% doesn't work... on the other side, when using a regular profile(1~2 week old), using 99.9% doesn't trigger the false positives.. so pretty large room for those upgrade error.. Now I set to 80%, leaning towards a low bar to avoid false negative. 


https://github.com/llvm/llvm-project/pull/84097