[llvm] [BOLT] CDSplit Main Logic Part 2/3 (PR #73083)

[via llvm-commits]

ShatianWang wrote:

Note: this PR is 7/8 for upstreaming a new 3-way (hot-warm-cold) function splitting algorithm CDSplit.
It is one commit ahead of #73082 

https://github.com/llvm/llvm-project/pull/73083