cmd/compile: feedback-guided optimization #28262
This is an umbrella issue for supporting feedback-guided optimization. This has been discussed offhand in a few other contexts (inlining decisions: #17566, code layout decisions: #20356, language changes: #24204, stack growth: #18138).
It is not clear what the design for FGO/PGO support might look like. In particular, what do the feedback/profile files look like?
@aclements observed during conversation at GopherCon 2018 that in order to preserve reproducible builds and efficiency, the feedback file needs to be hashed by cmd/go along with all other inputs, which suggests that it ought to be committed to version control.