[clang] [IRPGO][ValueProfile] Instrument virtual table address that could be used to do virtual table address comparision for indirect-call-promotion. (PR #66825)

[Hongtao Yu via cfe-commits]

htyu wrote:


> The performance win depends a lot on value distribution. For large copies, using SIMD with nontemporal hint is the way to go.

Right, and the dominating single-range distribution is also important for our approach, similar to how speculative indirect call promotion works.

Recently we have also found out that rep mov started outperforming nontemporal SIMD for very large copies, e.g above 1KB.

https://github.com/llvm/llvm-project/pull/66825