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f44eee8f1b
The mutually misaligned inputs on aarch64 are compared with a simple byte copy, which is not very efficient. Enhance the comparison similar to strcmp by loading a double-word at a time. The peak performance improvement (i.e. 4k maxlen comparisons) due to this on the strncmp microbenchmark in glibc is as follows: falkor: 3.5x (up to 72% time reduction) cortex-a73: 3.5x (up to 71% time reduction) cortex-a53: 3.5x (up to 71% time reduction) All mutually misaligned inputs from 16 bytes maxlen onwards show upwards of 15% improvement and there is no measurable effect on the performance of aligned/mutually aligned inputs.