In order to peak into hardware speculation/BTB, having a look atswitch lowering seems a good way. Big switches will go into serious convolution to please that hardware since by definition this is a source of a lot of branch mispredicitions.
It is still possible that a later pass arranges jump targets to avoid false sharing of their entries (addresses) in prediction mechanisms and such.
Obvsiously engaging in pleasing as much as it can speculative/BTB hardware (to the cost of memory tables!)