Depending on your use-case, a worst case execution time (WCET) analysis can yield these numbers. These are usually deployed for analysis of safety critical syst

Depending on your use-case, a worst case execution time (WCET) analysis can yield these numbers. These are usually deployed for analysis of safety critical systems (e.g. for ECU in cars or industrial controllers), but it could be (ab-)used for that case as well. Of course the analysis needs to support both your ISA (RISC-V) and the exact core implementing it, plus adjusting the parameters; this isn't exactly cheap, since it requires a lot of very specific know-how, and I wouldn't suspect SiFive will produce something like this (Disclaimer: I work in the field).