[hyperpape]

I think you're discussing two different phases of optimization. PGO and Java's JIT use branch information to emit different machine code. Hardware branch prediction takes machine code and determines which branches in the machine code are taken, and speculates based on that information. There's an underlying pattern that both follow, but they're very different.

[bluGill]

PGO and JIT both use their information to change the machine code to suggest which branch is more likely.

PGO and JIT also do a lot of other things that are unrelated to this discussion. Some of those things can have a much larger gain than branch prediction.