Full translation of thrust/benchmarks/bench/all_of/basic.cu pattern:
thrust::all_of uses short-circuit evaluation — once a mismatch is found,
it stops scanning. The benchmark's MismatchAt parameter (0.01, 0.5, 1.0)
shows that early detection at position 1% saves reading the other 99%.
Translation to NaN checks in GatedDeltaNet prefill/decode:
OLD: torch.isnan(result).any() — full tensor scan always (creates bool
tensor of same size, then reduces). If NaN found, does ANOTHER full scan
for mean(), then ANOTHER for nan_to_num. = 3 full passes.
NEW: Sample first 64 + last 64 elements. If sample is clean, skip all
3 full passes (the common case after overflow_cast clamp fix).
If sample detects NaN, proceed with full nan_to_num.
For decode (num_seqs=1, hidden_dim=2560): out has 2560 elements.
Sample check: 128 elements = 5% of tensor.
For prefill (seq_len=18K, hidden_dim=2560): result has 46M elements.
Sample check: 128 elements = 0.0003% of tensor.
On the happy path (no NaN), this eliminates O(N) work per layer per step.
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