# Reproduction 1. Checkout `bytestring` at the [current `master`]( https://github.com/haskell/bytestring/commit/b639596ef7913b8cffd1cd028649a30ec038f1c5) 2. `cabal bench --benchmark-options '--csv bench-8.10.4.csv' -w ghc-8.10.4` 3. `cabal bench --benchmark-options '--baseline bench-8.10.4.csv --fail-if-slower=3 --hide-successes' -w ghc-9.0.1` # Expected results No benchmarks have become slower. # Actual results ``` All folds mapAccumL 8: FAIL (0.15s) 116 ns ± 11 ns, 13% slower than baseline 16: FAIL (0.23s) 193 ns ± 11 ns, 15% slower than baseline 32: FAIL (0.23s) 361 ns ± 21 ns, 18% slower than baseline 64: FAIL (0.21s) 681 ns ± 43 ns, 18% slower than baseline 128: FAIL (0.20s) 1.3 μs ± 87 ns, 22% slower than baseline 256: FAIL (0.20s) 2.6 μs ± 169 ns, 23% slower than baseline 512: FAIL (0.19s) 5.1 μs ± 359 ns, 23% slower than baseline 1024: FAIL (0.20s) 10 μs ± 820 ns, 23% slower than baseline 2048: FAIL (0.20s) 21 μs ± 1.4 μs, 25% slower than baseline 4096: FAIL (0.18s) 41 μs ± 2.7 μs, 25% slower than baseline 8192: FAIL (0.19s) 82 μs ± 5.4 μs, 25% slower than baseline 16384: FAIL (0.18s) 165 μs ± 11 μs, 25% slower than baseline 32768: FAIL (0.19s) 329 μs ± 21 μs, 25% slower than baseline 65536: FAIL (0.18s) 716 μs ± 48 μs, 22% slower than baseline mapAccumR 8: FAIL (0.15s) 112 ns ± 11 ns, 11% slower than baseline 16: FAIL (0.24s) 187 ns ± 10 ns, 14% slower than baseline 32: FAIL (0.22s) 350 ns ± 23 ns, 21% slower than baseline 64: FAIL (0.21s) 651 ns ± 51 ns, 18% slower than baseline 128: FAIL (0.19s) 1.3 μs ± 84 ns, 18% slower than baseline 256: FAIL (0.19s) 2.5 μs ± 174 ns, 18% slower than baseline 512: FAIL (0.19s) 4.9 μs ± 368 ns, 20% slower than baseline 1024: FAIL (0.19s) 9.7 μs ± 671 ns, 18% slower than baseline 2048: FAIL (0.19s) 20 μs ± 1.9 μs, 21% slower than baseline 4096: FAIL (0.18s) 39 μs ± 2.6 μs, 20% slower than baseline 8192: FAIL (0.17s) 79 μs ± 6.2 μs, 21% slower than baseline 16384: FAIL (0.17s) 156 μs ± 11 μs, 20% slower than baseline 32768: FAIL (0.17s) 312 μs ± 23 μs, 21% slower than baseline 65536: FAIL (0.18s) 690 μs ± 50 μs, 18% slower than baseline scanr 8192: FAIL (0.29s) 64 μs ± 3.6 μs, 8% slower than baseline findIndexOrLength takeWhile: FAIL (0.21s) 92 μs ± 5.4 μs, 23% slower than baseline break: FAIL (0.22s) 97 μs ± 5.3 μs, 28% slower than baseline group zero-one: FAIL (0.28s) 2.2 ms ± 89 μs, 18% slower than baseline groupBy (>=): FAIL (0.16s) 309 μs ± 22 μs, 12% slower than baseline groupBy (>): FAIL (0.33s) 2.5 ms ± 125 μs, 11% slower than baseline findIndex_ findIndices: FAIL (0.23s) 24 μs ± 1.4 μs, 23% slower than baseline findIndexEnd findIndexEnd: FAIL (0.23s) 21 ns ± 1.4 ns, 10% slower than baseline traversals map (+1): FAIL (0.25s) 472 μs ± 23 μs, 402121% slower than baseline BoundsCheckFusion Data.ByteString.Builder foldMap (left-assoc) (10000): FAIL (0.19s) 330 μs ± 28 μs, 17% slower than baseline foldMap (right-assoc) (10000): FAIL (0.16s) 276 μs ± 27 μs, 18% slower than baseline foldMap [manually fused, right-assoc] (10000): FAIL (0.27s) 244 μs ± 11 μs, 5% slower than baseline Indices ByteString index equality inlining FindIndices/non-inlined: FAIL (0.31s) 9.7 ms ± 358 μs, 12% slower than baseline 41 out of 263 tests failed (56.86s) ``` (Ignore the 402121% regression in `traversals.map (+1)`. This seems to be [a buglet in `tasty-bench`](https://github.com/Bodigrim/tasty-bench/issues/9).)