AFAIK there isn't any notion of likely/unlikely in object code on most CPU architectures. I'm only really familiar with x86 and ARM though.
__builtin_expect() in GCC (the "likely()" and "unlikely()" macros in the Linux kernel use this) can do a lot of things to optimize branches, like prefetch instructions and decide whether or not the jump should be the usually taken or usually not taken side, but it can't actually emit instructions that directly tell the CPU "always predict this" AFAIK.
That's a fair point, although I think using a single function for all your checked addition like the one above would go a long way towards mitigating the resource waste you mention.
Maybe that's a naive assumption on my part: I suppose you could construct a branch predictor that maintains state based on the function call chain as opposed simply using the address of the branch... but that seems like it would be prohibitively complex.