[llvm] [llvm-profdata] Emit error when counter value is greater than 2^56. (PR #69513)

[Zequan Wu via llvm-commits]

ZequanWu wrote:

> still needs to be put under a flag that's on by default

I found that llvm-profdata usually print the warning for the first time: https://github.com/llvm/llvm-project/blob/main/llvm/tools/llvm-profdata/llvm-profdata.cpp#L343-L355. So, there won't be too much noise to the user.

https://github.com/llvm/llvm-project/pull/69513