Comment by Findecanor

The chip uses LoongSon's own "LoongArch" ISA. They moved away from MIPS supposedly because of fears of licensing issues.

It is very much like the last revision of MIPS but modernised a bit: No more branch delay slot. No HI/LO registers. The arithmetic ops that trapped on overflow are also gone.

There are published docs only for the scalar ISA subset: https://loongson.github.io/LoongArch-Documentation/README-EN...

Chips and Cheese has an analysis of the "LSX" and "LASX" SIMD sets. LSX is very much like MIPS's MSA. LASX is extended to 256 bits: https://chipsandcheese.com/2023/02/26/loongsons-lsx-and-lasx...