cbb7229457
The AArch64 support was a bit broken and was using Armv7 style barriers, which aren't required with Armv8 acquire-release load/stores. The fallback CAS loops and RMW, for AArch64, have also been updated to use acquire-release, exclusive, instructions which, again, remove the need for barriers. The CAS loop has also been further optimised by using the extending form of the cmp instruction. Copyright (c) 2021, Arm Limited.