Generated Peephole Optimizations in LLVM Compiler

One of the important feature of application specific processors is performance. To maximize it, the compiler must adapt to needs of processor that it is going to compile for and it must generate the most efficient code. One of the ways to do that is to search for appropriate instructions that can be implemented as one instruction with multiple outputs. Afterwards the generated code can be parsed through peephole optimizations that search for instruction patterns and replace them with other instructions to make code more effective. This paper describes the problem of finding and selecting suitable candidates for multiple output instructions. It also provides a brief overview of the few best known algorithms that solve this problem. Eventually it examines possibilities of incorporating this optimizations to LLVM compiler