# HDLBits Dead-Branch Notes

These notes are meant to separate "CGA failed to find a reachable path" from
"the remaining branch is mostly an illegal-state/default guard."

## Likely dead-branch ceiling

- `ece241_2013_q8`
  - `default: next = 'x;`
  - `default: z = 'x;`
  - Under legal reset-driven execution, these branches are not expected to fire.

- `m2014_q6`
  - `default: next = 'x;`
  - Remaining uncovered logic is likely dominated by the illegal-state guard.

- `review2015_fsm`
  - `default: next = States'(4'bx);`
  - `if (|state === 1'bx)` output guard
  - These are defensive X-state branches rather than normal protocol behavior.

## Likely reachable but hard

- `2014_q3fsm`
  - Coverage is below 100%, but the named FSM states are all part of the legal
    state graph.
  - Treat this as a "reachable but not hit consistently" task, not a pure
    dead-branch ceiling case.

## Use in the paper

- For aggregate structural coverage analysis, keep these tasks in the dataset.
- In discussion, explicitly label the first group as `dead_branch ceiling`.
- Do not claim that failure on these tasks implies CGA cannot explore normal
  protocol logic.