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txgraph: check that DoWork finds optimal if given high budget (tests)

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This commit is contained in:
Pieter Wuille
2025-07-13 13:32:35 -04:00
parent f3c2fc867f
commit 62ed1f92ef
3 changed files with 55 additions and 24 deletions
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17
src/test/fuzz/cluster_linearize.cpp
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@@ -1167,24 +1167,9 @@ FUZZ_TARGET(clusterlin_linearize)
}
// If the iteration count is sufficiently high, an optimal linearization must be found.
// Each linearization step can use up to 2^(k-1) iterations, with steps k=1..n. That sum is
// 2^n - 1.
const uint64_t n = depgraph.TxCount();
if (n <= 19 && iter_count > (uint64_t{1} << n)) {
if (iter_count >= MaxOptimalLinearizationIters(depgraph.TxCount())) {
assert(optimal);
}
// Additionally, if the assumption of sqrt(2^k)+1 iterations per step holds, plus ceil(k/4)
// start-up cost per step, plus ceil(n^2/64) start-up cost overall, we can compute the upper
// bound for a whole linearization (summing for k=1..n) using the Python expression
// [sum((k+3)//4 + int(math.sqrt(2**k)) + 1 for k in range(1, n + 1)) + (n**2 + 63) // 64 for n in range(0, 35)]:
static constexpr uint64_t MAX_OPTIMAL_ITERS[] = {
0, 4, 8, 12, 18, 26, 37, 51, 70, 97, 133, 182, 251, 346, 480, 666, 927, 1296, 1815, 2545,
3576, 5031, 7087, 9991, 14094, 19895, 28096, 39690, 56083, 79263, 112041, 158391, 223936,
316629, 447712
};
if (n < std::size(MAX_OPTIMAL_ITERS) && iter_count >= MAX_OPTIMAL_ITERS[n]) {
Assume(optimal);
}
// If Linearize claims optimal result, run quality tests.
if (optimal) {