GCC Optimization for LoongArch Memory Accessing Instructions with Bound-Checking

LoongArch ISA (instruction set architecture) introduces new memory accessing instructions with bound-checking to decrease the overhead of memory security check. However, as a new type of memory accessing instruction, the existing GCC (GNU compiler collection) compiler tools cannot support it and thus LoongArch based hardware remains underutilized. Therefore, in this paper, we revise the GCC compiler with the LoongArch memory accessing instructions to optimize the memory security check. Specifically, our work is divided into three parts: 1) designing built-in functions for the memory accessing instructions; 2) improving the RTL (register transfer language) optimizer of GCC to recognize two kinds of semantic patterns of memory accessing instructions with bound-checking, which are non-exception handling and exception handling; 3) implementing a new exception signal SIGBCE for the bound check exception BCE that is raised by CPU in Linux kernel, and implementing the corresponding signal handling function in glibc (GNU C library) to deal with the bound check exception. The experiments on GCC 12.2.0 and Loongson 3C5000L server show that the revised compiler is able to correctly employ the new memory accessing instructions and bring an acceleration of approximately 20% in some security routines. Our work improves the ecosystem of LoongArch and boosts the development of LoongArch ISA. It will also be referential to GCC optimization for the specialized instructions.