This repository contains the compiler infrastructure for the Radiance project. It is derived from Vortex's LLVM compiler stack, with some notable changes:
Encoding:
- Instruction words are now 64-bit;
- Each instruction can contain up to 4 source registers and 1 destination register;
- Two more bits for opcode;
- Reserved instruction space for predicates;
- Much larger immediates - up to 32-bit for I-type instructions.
Registers:
- Register encoding is now 8-bits, which means up to 256 architectural registers;
- Currently, the compiler defines 128 GPRs;
- Floating point numbers are stored in GPRs through the
zfinxextension, for which some support is backported from LLVM 20.
Extended ISA:
- There are new instruction formats that exploit the extra operands and larger immediates;
- New instructions will be added to support Radiance components such as Neutrino instructions;
- Tentative ISA is documented here.
You might find the guide at ucb-bar/radiance-kernels to be easier for setting up the toolchain along with some tests to run.
Compiling clang is similar to the normal LLVM compilation process. To use clang
after compiling it, you must have a functional rv32 GNU toolchain. There should
not be a rv64 toolchain existing in the same place as the rv32 toolchain.
To compile hello.c to an object file, for example:
./bin/clang --target=riscv32-unknown-elf -march=rv32im_zfinx --sysroot=$RV32_TOOLCHAIN/riscv32-unknown-elf --gcc-toolchain=$RV32_TOOLCHAIN ../hello.c -v -c -o hello.o(The LLVM project README follows below)
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