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Compiler toolchains

Vanadis has been tested with two compiler toolchains: musl and llvm/riscv-gnu-toolchain. musl works for MIPS and RV64 while clang works for RV64 only. All binaries must be statically linked.

Threading and GPU support:

  • CUDA: use the llvm-based toolchain (see balar)
  • OpenMP: use the musl OpenMP library
  • pthreads: works under both toolchains

MUSL Toolchain​

Refer to the musl project for installation and download instructions.

LLVM/RISCV-gnu-toolchain​

To install this toolchain, download llvm and the riscv-gnu-toolchain.

Follow the instructions below. Refer to llvm and the riscv-gnu-toolchain instructions for any dependencies you may need to acquire. For riscv-gnu-toolchain, build the linux (not newlib) version.

# Create installation dirs
mkdir llvm-install
mkdir riscv-gnu-install

# Set up environment vars to LLVM and RISCV gnu installation folders
export LLVM_INSTALL_PATH=$(pwd)/llvm-install
export RISCV_TOOLCHAIN_INSTALL_PATH=$(pwd)/riscv-gnu-install

# Build LLVM with desired support
# -DLLVM_TARGETS_TO_BUILD="RISCV" : RISCV only for vanadis
# -DLLVM_TARGETS_TO_BUILD="RISCV;NVPTX" : Add cuda support for balar/vanadis
git clone https://github.com/llvm/llvm-project.git

cd llvm-project
mkdir build && cd build
cmake -DLLVM_TARGETS_TO_BUILD="RISCV" -DLLVM_DEFAULT_TARGET_TRIPLE=riscv64-unknown-linux-gnu \
      -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;lld" -DCMAKE_INSTALL_PREFIX=$LLVM_INSTALL_PATH ../llvm
cmake --build . -j
cmake --build . --target install
cd ..

# Build RISC-V GCC toolchain
git clone https://github.com/riscv-collab/riscv-gnu-toolchain.git

cd riscv-gnu-toolchain
./configure --prefix=$RISCV_INSTALL_PATH
make linux -j
cd ..

Compiling for Vanadis​

To compile for vanadis, set CC and/or CXX to point to the cross-compiler you built above. Ensure linking is done statically. There are a number of Makefiles in the vanadis tests/small/ directory that can be used as examples for musl. Below are Makefiles that can be used to build vanadis/tests/small/basic-io/hello-world-cpp/hello-world-cpp.cc.

This makefile uses the musl compiler and requires that ARCH be set to either mipsel to build a mips binary or riscv64 for RISCV. The musl compiler must be in your PATH.

Building hello-world-cpp using the musl compiler
CXX=$(ARCH)-linux-musl-g++

CFLAGS=-O3
CXXFLAGS=-O3
LDFLAGS=-static

PROG=hello-world-cpp

$(PROG) : $(PROG).cc
        $(CXX) $(CFLAGS) $(LDFLAGS) -o $(ARCH)/$@ $<

clean:
        rm -r $(ARCH)/$(PROG)

This makefile uses the llvm toolchain and requires that RISCV_TOOLCHAIN_INSTALL_PATH and LLVM_INSTALL_PATH be set, as described in the installation instructions. This makefile does not require llvm to be in your PATH.

Building hello-world-cpp using clang compiler
RISCV_SYSROOT := $(RISCV_TOOLCHAIN_INSTALL_PATH)/sysroot

CXXFLAGS := --unwindlib=libgcc --gcc-toolchain=$(RISCV_TOOLCHAIN_INSTALL_PATH)
CXXFLAGS += --sysroot=$(RISCV_SYSROOT) -I$(RISCV_SYSROOT)/usr/include 
CXXFLAGS += --target=riscv64-unknown-linux-gnu -march=rv64gc -mabi=lp64d

CXX := $(LLVM_INSTALL_PATH)/bin/clang++

LDFLAGS := -static -static-libstdc++ -static-libgcc
LDFLAGS += -Wl,-rpath,$(RISCV_SYSROOT)/lib64:$(RISCV_SYSROOT)/usr/lib64

PROG=hello-world-cpp

$(PROG) : $(PROG).cc
        $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $<

clean:
        rm -r $(PROG)