[AArch64] Optimize GHASH
This patch optimizes GHASH on AArch64 architecture. The patch check for little-endian mode to enable the optimized GHASH core, Optimizing GHASH on little-endian mode using PMULL instruction is a little bit tricky because the 64-bit operations on SIMD registers are byte-reversed in little-endian mode so in order to get a correct result the input must be 64-bit byte-reversed and in this case the output of PMULL instruction will be 128-bit byte-reversed.
GCM Benchmark result:
| Version | Mbyte/s |
|---|---|
| C | 208 |
| Optimized GHASH | 3255 |