[llvm] [BOLT][AArch64] Expand cmpbr when reversing would overflow (PR #202998)

[Rafael Auler via llvm-commits]

https://github.com/rafaelauler commented:

Thanks @labrinea ! New code is already addressing a lot, a few more comments below on the overall design, let me know what you think.

Absolutely agree on register scavenger being low return on investment sometimes. If you think about it, if the compiler did a good job and really pushed the limits of inlining, it should absolutely be well utilizing the register bank almost to the limit, leaving little choices for BOLT, even if we run an analysis pass to try to spot opportunities.

https://github.com/llvm/llvm-project/pull/202998