Glibc Lands HWCAPs Support For LoongArch

When it comes to Glibc HWCAPs for allowing the C library to load optimized libraries based upon the CPU features at run-time, it's mostly been focused on the x86_64 world for targeting higher x86-64 levels or being able to load optimized libraries for systems with AVX support. Loongson though has now contributed initial LoongArch HWCAPs support.

Complementing the x86_64 Glibc HWCAPs support is now having these hardware capabilities infrastructure for LoongArch processors. The LoongArch HWCAP support is focused currently on the presence of the LASX, LSX, and UAL processor ISA extensions. LSX (Loongson SIMD eXtension) and LASX (Loongson Advanced SIMD eXtension) are the LoongArch vector extensions akin to AVX. UAL is the LoongArch extension around handling of non-aligned memory accesses.

Thus with this code now merged to Glibc is the HWCAPs support on LoongArch for allowing optimized library handling based on the presence of LSX / LASX / UAL processor ISA capabilities. As x86_64 HWCAPs support still isn't too widely used yet (unfortunately), we'll see how much uptake there is to LoongArch HWCAPs use.