KernelBench hard · H100

TopK Bitonic Qwen 3.8 Max

The recovered source is a genuine custom raw-CUDA top-k, not a library dispatch, cached answer, or checked-shape output table. It JIT-builds power-of-two K specializations, partitions each row across blocks and warps, sorts 128-element windows, merges block candidates through shared workspace, and has a separate argmax path. Nevertheless, the final window-sort patch is semantically wrong. Its cross-lane gather passes a lane-varying register expression to __shfl_sync, so the source lane supplies its own slot selection rather than the target lane's requested slot. The resulting K-list contains duplicated/missing values. The final official check confirms the defect: shape 0 (batch=1, n=131072, k=64), seed 42, nominal reports 63 of 64 values outside tolerance, max absolute difference 0.625339. Earlier PASS results belong to superseded source versions and do not validate the recovered file. Verdict is fail, with no publishable correctness or performance grade.

20260804_000814_or-fable_qwen_qwen3.8-max_05_topk_bitonic