Hi all, I'd like to submit this patch introducing an Arm MTE compatible strchr implementation. Follows a performance comparison of the strchr benchmark run on Cortex-A72, Cortex-A53, Neoverse N1. | length | alignment | perf-uplift A72 | perf-uplift A53 | perf-uplift N1 | |--------+-----------+-----------------+-----------------+----------------| | 32 | 0 | 1.91x | 1.10x | 1.33x | | 32 | 1 | 2.06x | 1.22x | 1.41x | | 64 | 0 | 1.61x | 1.00x | 1.18x | | 64 | 2 | 1.69x | 1.08x | 1.15x | | 128 | 0 | 1.51x | 0.85x | 1.06x | | 128 | 3 | 1.57x | 0.90x | 1.15x | | 256 | 0 | 1.37x | 0.84x | 1.09x | | 256 | 4 | 1.41x | 0.83x | 1.15x | | 512 | 0 | 1.18x | 0.80x | 1.09x | | 512 | 5 | 1.19x | 0.82x | 1.14x | | 1024 | 0 | 1.15x | 0.78x | 1.09x | | 1024 | 6 | 1.05x | 0.79x | 1.09x | | 2048 | 0 | 1.15x | 0.76x | 1.08x | | 2048 | 7 | 1.13x | 0.77x | 1.08x | | 64 | 1 | 1.28x | 1.08x | 1.33x | | 64 | 1 | 1.28x | 1.08x | 1.31x | | 64 | 2 | 1.28x | 1.08x | 1.31x | | 64 | 2 | 1.28x | 1.08x | 1.15x | | 64 | 3 | 1.28x | 1.08x | 1.15x | | 64 | 3 | 1.28x | 1.08x | 1.31x | | 64 | 4 | 1.28x | 1.08x | 1.31x | | 64 | 4 | 1.28x | 1.08x | 1.31x | | 64 | 5 | 1.28x | 1.08x | 1.31x | | 64 | 5 | 1.28x | 1.08x | 1.31x | | 64 | 6 | 1.28x | 1.08x | 1.31x | | 64 | 6 | 1.28x | 1.08x | 1.31x | | 64 | 7 | 1.28x | 1.08x | 1.31x | | 64 | 7 | 1.28x | 1.08x | 1.31x | | 0 | 0 | 1.32x | 1.63x | 1.53x | | 0 | 0 | 1.32x | 1.63x | 1.53x | | 1 | 0 | 1.31x | 1.64x | 1.53x | | 1 | 0 | 1.32x | 1.67x | 1.53x | | 2 | 0 | 1.32x | 1.63x | 1.52x | | 2 | 0 | 1.32x | 1.69x | 1.52x | | 3 | 0 | 1.32x | 1.67x | 1.51x | | 3 | 0 | 1.32x | 1.66x | 1.52x | | 4 | 0 | 1.32x | 1.69x | 1.52x | | 4 | 0 | 1.32x | 1.69x | 1.52x | | 5 | 0 | 1.32x | 1.69x | 1.26x | | 5 | 0 | 1.32x | 1.69x | 1.26x | | 6 | 0 | 1.32x | 1.69x | 1.26x | | 6 | 0 | 1.32x | 1.68x | 1.51x | | 7 | 0 | 1.32x | 1.63x | 1.54x | | 7 | 0 | 1.32x | 1.63x | 1.52x | | 8 | 0 | 1.32x | 1.69x | 1.53x | | 8 | 0 | 1.32x | 1.65x | 1.53x | | 9 | 0 | 1.32x | 1.63x | 1.54x | | 9 | 0 | 1.32x | 1.68x | 1.52x | | 10 | 0 | 1.32x | 1.63x | 1.52x | | 10 | 0 | 1.32x | 1.69x | 1.51x | | 11 | 0 | 1.32x | 1.64x | 1.52x | | 11 | 0 | 1.32x | 1.63x | 1.52x | | 12 | 0 | 1.32x | 1.64x | 1.52x | | 12 | 0 | 1.32x | 1.68x | 1.54x | | 13 | 0 | 1.32x | 1.63x | 1.53x | | 13 | 0 | 1.32x | 1.67x | 1.52x | | 14 | 0 | 1.32x | 1.65x | 1.53x | | 14 | 0 | 1.32x | 1.63x | 1.52x | | 15 | 0 | 1.32x | 1.67x | 1.52x | | 15 | 0 | 1.32x | 1.65x | 1.26x | | 16 | 0 | 1.08x | 1.00x | 1.03x | | 16 | 0 | 1.08x | 1.00x | 1.03x | | 17 | 0 | 1.09x | 1.00x | 1.03x | | 17 | 0 | 1.09x | 1.00x | 1.03x | | 18 | 0 | 1.09x | 1.00x | 1.03x | | 18 | 0 | 1.08x | 1.00x | 1.03x | | 19 | 0 | 1.08x | 1.00x | 1.03x | | 19 | 0 | 1.08x | 1.00x | 1.03x | | 20 | 0 | 1.08x | 1.00x | 1.03x | | 20 | 0 | 1.09x | 1.00x | 1.03x | | 21 | 0 | 1.08x | 1.00x | 1.03x | | 21 | 0 | 1.08x | 1.00x | 1.08x | | 22 | 0 | 1.09x | 1.00x | 1.09x | | 22 | 0 | 1.08x | 1.00x | 1.09x | | 23 | 0 | 1.08x | 1.00x | 1.08x | | 23 | 0 | 1.08x | 1.00x | 1.08x | | 24 | 0 | 1.08x | 1.00x | 1.08x | | 24 | 0 | 1.08x | 1.00x | 1.09x | | 25 | 0 | 1.08x | 1.00x | 1.10x | | 25 | 0 | 1.08x | 1.00x | 1.09x | | 26 | 0 | 1.08x | 1.00x | 1.08x | | 26 | 0 | 1.08x | 1.00x | 1.08x | | 27 | 0 | 1.09x | 1.00x | 1.08x | | 27 | 0 | 1.08x | 1.00x | 1.08x | | 28 | 0 | 1.08x | 1.00x | 1.08x | | 28 | 0 | 1.08x | 1.00x | 1.08x | | 29 | 0 | 1.08x | 1.00x | 1.09x | | 29 | 0 | 1.08x | 1.00x | 1.08x | | 30 | 0 | 1.08x | 1.00x | 1.08x | | 30 | 0 | 1.08x | 1.00x | 1.08x | | 31 | 0 | 1.09x | 1.00x | 1.08x | | 31 | 0 | 1.08x | 1.00x | 1.08x | | 32 | 0 | 1.27x | 1.10x | 1.25x | | 32 | 1 | 1.38x | 1.21x | 1.38x | | 64 | 0 | 1.17x | 1.00x | 1.20x | | 64 | 2 | 1.28x | 1.08x | 1.33x | | 128 | 0 | 1.17x | 0.85x | 1.17x | | 128 | 3 | 1.23x | 0.90x | 1.29x | | 256 | 0 | 1.17x | 0.84x | 1.15x | | 256 | 4 | 1.21x | 0.83x | 1.21x | | 512 | 0 | 1.16x | 0.80x | 1.08x | | 512 | 5 | 1.19x | 0.82x | 1.14x | | 1024 | 0 | 1.15x | 0.78x | 1.09x | | 1024 | 6 | 1.05x | 0.79x | 1.09x | | 2048 | 0 | 1.15x | 0.76x | 1.08x | | 2048 | 7 | 1.14x | 0.77x | 1.08x | | 64 | 1 | 1.20x | 1.08x | 1.33x | | 64 | 1 | 1.28x | 1.08x | 1.33x | | 64 | 2 | 1.28x | 1.08x | 1.35x | | 64 | 2 | 1.28x | 1.08x | 1.35x | | 64 | 3 | 1.28x | 1.08x | 1.15x | | 64 | 3 | 1.28x | 1.08x | 1.15x | | 64 | 4 | 1.28x | 1.08x | 1.35x | | 64 | 4 | 1.28x | 1.08x | 1.31x | | 64 | 5 | 1.28x | 1.08x | 1.35x | | 64 | 5 | 1.28x | 1.08x | 1.35x | | 64 | 6 | 1.28x | 1.08x | 1.31x | | 64 | 6 | 1.28x | 1.08x | 1.31x | | 64 | 7 | 1.28x | 1.08x | 1.35x | | 64 | 7 | 1.28x | 1.08x | 1.35x | | 0 | 0 | 1.32x | 1.68x | 1.52x | | 0 | 0 | 1.32x | 1.63x | 1.53x | | 1 | 0 | 1.32x | 1.69x | 1.52x | | 1 | 0 | 1.32x | 1.68x | 1.52x | | 2 | 0 | 1.32x | 1.69x | 1.51x | | 2 | 0 | 1.32x | 1.69x | 1.52x | | 3 | 0 | 1.32x | 1.67x | 1.51x | | 3 | 0 | 1.32x | 1.69x | 1.52x | | 4 | 0 | 1.32x | 1.67x | 1.52x | | 4 | 0 | 1.32x | 1.69x | 1.56x | | 5 | 0 | 1.32x | 1.69x | 1.52x | | 5 | 0 | 1.32x | 1.69x | 1.52x | | 6 | 0 | 1.32x | 1.69x | 1.51x | | 6 | 0 | 1.32x | 1.69x | 1.52x | | 7 | 0 | 1.32x | 1.63x | 1.52x | | 7 | 0 | 1.32x | 1.63x | 1.53x | | 8 | 0 | 1.32x | 1.65x | 1.52x | | 8 | 0 | 1.32x | 1.63x | 1.52x | | 9 | 0 | 1.32x | 1.63x | 1.51x | | 9 | 0 | 1.32x | 1.64x | 1.52x | | 10 | 0 | 1.32x | 1.63x | 1.52x | | 10 | 0 | 1.32x | 1.65x | 1.52x | | 11 | 0 | 1.32x | 1.63x | 1.52x | | 11 | 0 | 1.32x | 1.63x | 1.51x | | 12 | 0 | 1.32x | 1.63x | 1.53x | | 12 | 0 | 1.32x | 1.63x | 1.51x | | 13 | 0 | 1.32x | 1.63x | 1.52x | | 13 | 0 | 1.32x | 1.65x | 1.52x | | 14 | 0 | 1.32x | 1.66x | 1.53x | | 14 | 0 | 1.32x | 1.64x | 1.26x | | 15 | 0 | 1.32x | 1.68x | 1.26x | | 15 | 0 | 1.32x | 1.69x | 1.26x | | 16 | 0 | 1.08x | 1.00x | 1.03x | | 16 | 0 | 1.08x | 1.00x | 1.05x | | 17 | 0 | 1.08x | 1.00x | 1.08x | | 17 | 0 | 1.09x | 1.00x | 1.03x | | 18 | 0 | 1.09x | 1.00x | 1.08x | | 18 | 0 | 1.08x | 1.00x | 1.08x | | 19 | 0 | 1.08x | 1.00x | 1.08x | | 19 | 0 | 1.08x | 1.00x | 1.09x | | 20 | 0 | 1.09x | 1.00x | 1.08x | | 20 | 0 | 1.08x | 1.00x | 1.08x | | 21 | 0 | 1.08x | 1.00x | 1.09x | | 21 | 0 | 1.08x | 1.00x | 1.08x | | 22 | 0 | 1.09x | 1.00x | 1.08x | | 22 | 0 | 1.08x | 1.00x | 1.09x | | 23 | 0 | 1.08x | 1.00x | 1.08x | | 23 | 0 | 1.08x | 1.00x | 1.08x | | 24 | 0 | 1.08x | 1.00x | 1.08x | | 24 | 0 | 1.08x | 1.00x | 1.08x | | 25 | 0 | 1.08x | 1.00x | 1.08x | | 25 | 0 | 1.08x | 1.00x | 1.09x | | 26 | 0 | 1.08x | 1.00x | 1.08x | | 26 | 0 | 1.08x | 1.00x | 1.09x | | 27 | 0 | 1.09x | 1.00x | 1.08x | | 27 | 0 | 1.08x | 1.00x | 1.08x | | 28 | 0 | 1.08x | 1.00x | 1.08x | | 28 | 0 | 1.09x | 1.00x | 1.03x | | 29 | 0 | 1.08x | 1.00x | 1.03x | | 29 | 0 | 1.08x | 1.00x | 1.03x | | 30 | 0 | 1.08x | 1.00x | 1.08x | | 30 | 0 | 1.08x | 1.00x | 1.08x | | 31 | 0 | 1.09x | 1.00x | 1.08x | | 31 | 0 | 1.08x | 1.00x | 1.08x | This patch is passing GLIBC tests. Regards Andrea 8< --- 8< --- 8< Introduce an Arm MTE compatible strchr implementation. Benchmarked on Cortex-A72, Cortex-A53, Neoverse N1 does not show performance regressions. Co-authored-by: Wilco Dijkstra