The conditional moves convert into a NOP when the condition is false. The idea here is that a branch results in a pipeline flush which takes a couple of cycles

The conditional moves convert into a NOP when the condition is false. The idea here is that a branch results in a pipeline flush which takes a couple of cycles to refill. In practice, most CPUs have very good branch predictors these days and conditional moves aren’t all that useful anymore. That’s probably the reason why they don’t exist for later ISAs such as RISC-V.