[LifetimeSafety] Add loan expiry analysis #148712
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This was referenced Jul 17, 2025
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|
Added unit tests for loan expiry! |
This was referenced Jul 18, 2025
ymand
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Jul 21, 2025
| @@ -832,6 +833,65 @@ class LoanPropagationAnalysis | |||
| } | |||
| }; | |||
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| // ========================================================================= // | |||
| // Expired Loans Analysis | |||
| // ========================================================================= // | |||
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Can you please add a suggestion? I don't quite get the location where you are referring.
| } | ||
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| Lattice transfer(Lattice In, const IssueFact &F) { | ||
| return Lattice(Factory.remove(In.Expired, F.getLoanID())); |
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Might be worth explaining why this is necessary. Specifically, now its possible that the loan would appear in In.Expired at all to be worth removing. I assume this arises because of backedges.
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Done. There is a subtle false negative due to this as well. Mentioned that.
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This PR adds the `ExpiredLoansAnalysis` class to track which loans have expired. The analysis uses a dataflow lattice (`ExpiredLattice`) to maintain the set of expired loans at each program point. This is a very light weight dataflow analysis and is expected to reach fixed point in ~2 iterations. In principle, this does not need a dataflow analysis but is used for convenience in favour of lean code.
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This PR adds the
ExpiredLoansAnalysisclass to track which loans have expired. The analysis uses a dataflow lattice (ExpiredLattice) to maintain the set of expired loans at each program point.This is a very light weight dataflow analysis and is expected to reach fixed point in ~2 iterations.
In principle, this does not need a dataflow analysis but is used for convenience in favour of lean code.