This code drops the old edge and weight on it:

If we have blocks A -> B -> C, with an empty B, then we should end up with the same result whether we compact B into C or whether we just remove B. However, currently we drop the A -> B weight if we remove B:

BB02 [0085]  2       BB01,BB36             1    211  0 [???..???)-> BB13 ( cond )                     IBC internal Loop loopheader 
BB03 [0087]  1       BB02                  0.42  88  0 [01D..???)-> BB04 (always)                     IBC internal LoopPH q
BB04 [0002]  2       BB03,BB12             0.55 117  1 [01D..02D)-> BB41 ( cond )                     i IBC Loop bwd bwd-target loopheader 
...
Setting edge weights for BB02 -> BB03 to [88.48387 .. 88.48387]
...
fgRemoveBlock BB03, unreachable=false
Removing empty BB03
Setting edge weights for BB02 -> BB04 to [0 .. 117] // not the right weight

When removing B, should the weight on A -> C be inherited from A -> B?

There's probably a ton of these in the JIT, but I figured I would open an issue since I saw it be the cause of diffs. (Also, maybe the fact that B -> C is not already the same as A -> B is a problem in maintenance in and of itself, so maybe the issue exists elsewhere.)

out_base.txt (jitdump with fgRemoveBlock)
out.txt (jitdump with compaction)