Xavier Bouchoux f10b9e8fd7 update Liveness to detect that safety checks do not modify memory
followup to [25d3713b07a100d8fdb349317db97fd9d0c1e366]
Resolves #12215

Previous code didn't account for the extra unreach() that now exists in the air:

```
 %29!= block(void, {
    %30!= cond_br(%22!, {
      %31!= br(%29, @Air.Inst.Ref.void_value)
    }, {
      %2! %15!
      %27!= call(%26, [%19!, %21])
      %28!= unreach()
    })
  } %22!)
```
2023-06-24 12:57:46 -07:00
..
2023-06-20 14:02:09 -04:00
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2023-06-20 12:55:38 -04:00
2022-11-04 00:09:27 +03:30
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