Adding a new instruction to RISC-V back end in LLVM
3 days ago
- #RISC-V
- #LLVM
- #compiler
- A compiler is described as a complex but understandable piece of software that transforms high-level code into optimized machine code.
- The article demonstrates adding a new dummy instruction called 'foo' to the RISC-V target in LLVM, showcasing the process as straightforward.
- The 'foo' instruction is an R-type instruction in RISC-V, taking two operands and storing the result in a register, with specific encoding details provided.
- TableGen, a domain-specific language in LLVM, is introduced as a tool for declaring records and templates, simplifying the instruction definition process.
- The implementation involves defining the 'foo' instruction in TableGen, specifying its properties, operands, and encoding without writing C++ code directly.
- A new feature flag 'dummy' is created to gate the 'foo' instruction, following RISC-V's modular extension model, requiring explicit enabling during compilation.
- The article concludes by encouraging readers to explore compiler development, highlighting the accessibility of such tasks with the right knowledge.