36 lines
1.1 KiB
Markdown
36 lines
1.1 KiB
Markdown
# HDLBits Dead-Branch Notes
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These notes are meant to separate "CGA failed to find a reachable path" from
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"the remaining branch is mostly an illegal-state/default guard."
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## Likely dead-branch ceiling
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- `ece241_2013_q8`
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- `default: next = 'x;`
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- `default: z = 'x;`
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- Under legal reset-driven execution, these branches are not expected to fire.
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- `m2014_q6`
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- `default: next = 'x;`
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- Remaining uncovered logic is likely dominated by the illegal-state guard.
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- `review2015_fsm`
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- `default: next = States'(4'bx);`
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- `if (|state === 1'bx)` output guard
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- These are defensive X-state branches rather than normal protocol behavior.
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## Likely reachable but hard
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- `2014_q3fsm`
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- Coverage is below 100%, but the named FSM states are all part of the legal
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state graph.
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- Treat this as a "reachable but not hit consistently" task, not a pure
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dead-branch ceiling case.
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## Use in the paper
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- For aggregate structural coverage analysis, keep these tasks in the dataset.
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- In discussion, explicitly label the first group as `dead_branch ceiling`.
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- Do not claim that failure on these tasks implies CGA cannot explore normal
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protocol logic.
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