There are lots of JIT compilers out there, I don't know if any that would detect the divisor is a constant at runtime and specialize code for that. I think it's

There are lots of JIT compilers out there, I don't know if any that would detect the divisor is a constant at runtime and specialize code for that. I think it's almost never done. In real life JIT compilation can't take long so the JIT compiler leaves a lot of possible optimizations on the table, just covering the low hanging fruit.