Let me add my modest +1 to the idea of upstreaming Bolt. It goes to
the road less travelled (static binary optimizers), its usefulness
proved in the wild and confirmed by a third party (Google), so BOLT
would be a great addition to the set of LLVM-based tools!
When we tried to use BOLT on our AArch64-based platform, we faced with
a few hiccups, some of them due to BOLT being based on an outdated
LLVM lacking support for some of the latest AArch64 instructions. Such
kind of problems should disappear after upstreaming, which would be
great for all. Also, it would be easier for us to contribute our
patches (one CLA less to sign).
Thank you for working on BOLT and creating such a useful tool!