fix: tail-recursive BitVec.ofBoolListLE/ofBoolListBE to avoid stack overflow#13576
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kim-em wants to merge 3 commits intoleanprover:masterfrom
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fix: tail-recursive BitVec.ofBoolListLE/ofBoolListBE to avoid stack overflow#13576kim-em wants to merge 3 commits intoleanprover:masterfrom
BitVec.ofBoolListLE/ofBoolListBE to avoid stack overflow#13576kim-em wants to merge 3 commits intoleanprover:masterfrom
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…ck overflow This PR adds tail-recursive replacements for `BitVec.ofBoolListLE` and `BitVec.ofBoolListBE`, registered via `@[csimp]`, to avoid stack overflow on lists with ~1M elements. The reference definitions in `Init.Data.BitVec.Basic` recurse via `concat`, which is clean for proofs but allocates O(n) stack frames. The new implementations in `Init.Data.BitVec.Impl` pack bits in 64-bit chunks (`packChunk`, `collectChunks`) and combine them via a balanced tree merge (`mergePass`, `treeMerge`), giving O(n log n) work and O(1) stack usage. Correctness is established via a list-level spec function `flattenList` giving the intended Nat semantics of `(value, width)` pairs, with `flattenList_append`, `flattenList_mergePassList` (key bit-packing identity), and a chunk-local `testBit_flattenList_collectChunks_aux`. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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….Internal` Codex review feedback applied: - Mark `packChunk`, `collectChunks`, `mergePass`, `treeMerge` as `private` — these have unreachable-fuel branches that make them bad public contracts. - Mark proof-only scaffolding (`flattenList`, `totalWidth`, `WellFormedList`, `mergePassList`) as `private` to avoid exposing them as API. - Extract `half_le_pow_of_le_double` (the `arr.size ≤ 2^(k+1) → (arr.size+1)/2 ≤ 2^k` bound used in the `treeMerge` halving step) into a standalone lemma. This isolates the omega/`Int.pow_succ` workaround to one place and turns `treeMerge_go_eq_flattenList`'s arithmetic step into a one-liner. Public surface is now just `ofBoolListLEImpl`, `ofBoolListBEImpl`, and the two `@[csimp]` theorems. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Replace the file-wide `public section` with `public` modifiers on just the two `ofBoolListLEImpl`/`ofBoolListBEImpl` defs and the two `@[csimp]` theorems. Everything else (the chunked-encoding helpers `packChunk`, `collectChunks`, `mergePass`, `treeMerge`, the proof-only `flattenList`/`totalWidth`/ `WellFormedList`/`mergePassList`, and all auxiliary lemmas) is now file-local. Also drop redundant imports `Init.Data.Nat.Lemmas` (transitive via `Init.Data.Array.Lemmas`) and `Init.Data.List.Lemmas` (transitive via `Init.Data.List.Nat.TakeDrop`). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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This PR adds tail-recursive replacements for
BitVec.ofBoolListLEandBitVec.ofBoolListBE, registered via@[csimp], to avoid stack overflow on lists with ~1M elements.The reference definitions in
Init.Data.BitVec.Basicrecurse viaconcat, which is clean for proofs but allocates O(n) stack frames. The new implementations inInit.Data.BitVec.Implpack bits in 64-bit chunks (packChunk,collectChunks) and combine them via a balanced tree merge (mergePass,treeMerge), giving O(n log n) work and O(1) stack usage.Correctness is established via a list-level spec function
flattenListgiving the intended Nat semantics of(value, width)pairs, withflattenList_append,flattenList_mergePassList(key bit-packing identity), and a chunk-localtestBit_flattenList_collectChunks_aux. The two@[csimp]theorems chain throughBitVec.eq_of_getLsbD_eqand the existinggetLsbD_ofBoolListLE/getLsbD_ofBoolListBEcharacterizations.🤖 Prepared with Claude Code