perf: simplifier performance issues on match and if-then-else terms
#3118
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The new test exposes a performance problem found in software verification applications.
See new test for example that takes exponential time without new simp theorems. TODO: replace auxiliary theorems with simprocs as soon as we implement them.
leodemoura
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match and if-then-else termsmatch and if-then-else terms
leodemoura
changed the title
match and if-then-else termsmatch and if-then-else terms
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!bench |
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Here are the benchmark results for commit 6110405. |
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The example was looping with the new `simp` reduction strategy. Here is the looping trace. ``` List.reverseAux (List.reverseAux as []) bs ==> rewrite using reverseAux_reverseAux List.reverseAux [] (List.reverseAux (List.reverseAux as []) bs) ==> unfold reverseAux List.reverseAux (List.reverseAux as []) bs ==> rewrite using reverseAux_reverseAux List.reverseAux [] (List.reverseAux (List.reverseAux as []) bs) ==> ... ```
leodemoura
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Dec 27, 2023
Using `simp [forIn]` may cause nontermination with different `simp` reduction strategies. We have the following theorem ``` @[simp] theorem forIn_eq_forIn [Monad m] : @List.forIn α β m _ = forIn := rfl ``` Then, executing `simp [forIn]` in a term containing `forIn` iterating over a `List` may cause nontermination since the theorem above will fold it again. Remark: the reduction strategy implemented leanprover/lean4#3118 triggers nontermination.
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!bench |
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Here are the benchmark results for commit 308942c. |
joehendrix
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Dec 28, 2023
Using `simp [forIn]` may cause nontermination with different `simp` reduction strategies. We have the following theorem ``` @[simp] theorem forIn_eq_forIn [Monad m] : @List.forIn α β m _ = forIn := rfl ``` Then, executing `simp [forIn]` in a term containing `forIn` iterating over a `List` may cause nontermination since the theorem above will fold it again. Remark: the reduction strategy implemented leanprover/lean4#3118 triggers nontermination. Co-authored-by: Joe Hendrix <joe@lean-fro.org>
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Subsumed by #3124 |
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