PGO guides inlining and branch prediction IIRC. You can give static hints about each of these. But the hints aren't on a continuum like they are with PGO. So fi

PGO guides inlining and branch prediction IIRC. You can give static hints about each of these. But the hints aren't on a continuum like they are with PGO. So finding an optimal balance for these will be harder. Also you have to maintain these hints. So if you were somehow giving hints with a hotness ratio in the source it would be impossible to maintain and keep it accurate.