How many place you need to modify when implementing a new extension for RISC-V?
At least 7 places as I know:
- Add new SubtargetFeature at RISCV.td
- -march parser in RISCV.cpp
- RISCVTargetInfo::initFeatureMap@RISCV.cpp for handling feature vector.
- RISCVTargetInfo::getTargetDefines@RISCV.cpp for pre-define marco.
- Arch string parser for ELF attribute in RISCVAsmParser.cpp
- ELF attribute emittion in RISCVAsmParser.cpp, and make sure it's in canonical order...
- ELF attribute emittion in RISCVTargetStreamer.cpp, and again, must in canonical order...
And now, this patch provide an unified infrastructure for handling (almost)
everything of RISC-V arch string.
After this patch, you only need to update 2 places for implement an extension
- Add new SubtargetFeature at RISCV.td, hmmm, it's hard to avoid.
- Add new entry to SupportedExtensionInfos@RISCVISAInfo.cpp.
Most codes are come from existing -march parser, but with few new feature/bug
- Accept version for -march, e.g. -march=rv32i2p0.
- Reject version info with p but without minor version number like rv32i2p.