How does Experimental.@force_compile work?

So I was playing around with @edit:

@edit @time exp(1)

In the definition of the time macro, timing.jl, line 216:

while false; end # compiler heuristic: compile this block (alter this if the heuristic changes)

I followed this through timing.jl, to experimental.jl all the way to this discussion in a GitHub issue. That being said, can someone explain how Experimental.@force_compile works?