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cda4cac27f
The per-language verification swarm reproduced, AT PRODUCTION DEFAULTS, a reaching-defs blow-up: a machine-generated ~2000-line all-loops function (under DEFAULT_PDG_MAX_FUNCTION_LINES) reaches ~10k basic blocks because loops emit ~5 blocks/line, and the dataflow fixpoint is O(blocks^2.3) on deep loop nests — measured 62s (C/C++) and 2.05s + 810MB (Go) for ONE function. maxFacts does not help: the fact count stays LINEAR, so it never fires. Iterative reaching-defs on a reducible CFG converges in O(loop-nesting-depth) passes, so a worklist re-visits each block a small multiple of times for real code. Add a maxBlockVisits ceiling (emit passes blocks.length × 64 — far beyond any hand-written nesting depth, ~15) that bails when the fixpoint has not converged. An unconverged fixpoint's in/out sets are not sound, so it returns NO facts (status 'truncated', like the existing 'overflow' guard) — a per- function coverage gap, never wrong facts. Real code is byte-identical: full cfg suites 725 passed, bench --check fingerprints unchanged. NOTE: computeControlDependence's O(N²) up-walk on deep post-dom chains is the sibling concern but stays ~13ms in production (bounded by the line cap + the CDG materialization cap); a CDG work-budget is a documented follow-up. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> |
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