The LoongArch architecture is an Instruction Set Architecture (ISA) that has Reduced Instruction Set Computer (RISC) style. The LoongArch Reference Manual is used to explain the LoongArch specification.

LoongArch has the typical characteristics of RISC. LoongArch instructions are of fixed size and have regular instruction formats. Most of the instructions have two source operands and one destination operand. LoongArch is a load-store architecture; this means only the load/store instructions can access memory the operands of the other instructions are within the processor core or the immediate number in the instruction opcode.

LoongArch is divided into two versions, the 32-bit version (LA32) and the 64-bit version (LA64). LA64 applications are “application-level backward binary compatibility” with LA32 applications. That means LA32 applications can run directly on the machine compatible with LA64, but the behavior of system softwares (such as the kernel) on the machine compatible with LA32 is not guaranteed to be the same as on the machine compatible with LA64.

LoongArch is composed of a basic part (Loongson Base) and an expanded part, as shown in the figure. The expansion part includes Loongson Binary Translation (LBT), Loongson VirtualiZation (LVZ), Loongson SIMD EXtension (LSX), and Loongson Advanced SIMD EXtension(LASX).

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