### build LLVM/gnu toolchain/spike/pk
1. clone LLVM

版本選用 17.0.2

git clone --depth 1 --branch llvmorg-17.0.2 https://github.com/llvm/llvm-project.git

2.

cd llvm-project
mkdir build && cd build

* 生成build files

* RISC-V only

cmake -S ../llvm -B . -G Ninja \
  -DCMAKE_INSTALL_PREFIX=../install \
  -DLLVM_ENABLE_PROJECTS="clang" \
  -DLLVM_TARGETS_TO_BUILD="RISCV" \
  -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
  -DCMAKE_BUILD_TYPE="Debug" \
  -DBUILD_SHARED_LIBS=True \
  -DLLVM_USE_SPLIT_DWARF=True \
  -DLLVM_OPTIMIZED_TABLEGEN=True \
  -DLLVM_CCACHE_BUILD=OFF \
  -DLLVM_INSTALL_UTILS=ON \
  -DLLVM_USE_LINKER=gold

cmake -S ../llvm -B . -G Ninja \
  -DCMAKE_INSTALL_PREFIX=../install \
  -DLLVM_ENABLE_PROJECTS="clang" \
  -DLLVM_TARGETS_TO_BUILD="RISCV" \
  -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
  -DCMAKE_BUILD_TYPE="Debug" \
  -DBUILD_SHARED_LIBS=True \
  -DLLVM_USE_SPLIT_DWARF=True \
  -DLLVM_OPTIMIZED_TABLEGEN=True \
  -DLLVM_CCACHE_BUILD=OFF \
  -DLLVM_INSTALL_UTILS=ON \
  -DLLVM_USE_LINKER=lld

* RISC-V && ARM

cmake -S ../llvm -B . -G Ninja \
  -DCMAKE_INSTALL_PREFIX=../install \
  -DLLVM_ENABLE_PROJECTS="clang" \
  -DLLVM_TARGETS_TO_BUILD="RISCV;AArch64" \
  -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
  -DCMAKE_BUILD_TYPE="Debug" \
  -DBUILD_SHARED_LIBS=True \
  -DLLVM_USE_SPLIT_DWARF=True \
  -DLLVM_OPTIMIZED_TABLEGEN=True \
  -DLLVM_CCACHE_BUILD=OFF \
  -DLLVM_INSTALL_UTILS=ON \
  -DLLVM_USE_LINKER=gold

* build

ninja -j N         # N: number of jobs
ninja install

3.
此時clang已經被安裝到 llvm-project/install/bin 資料夾。
我們要測試看看是否安裝成功

cd llvm-project/install/bin
./clang --help

### build risc-v tool chain
linker, loader...

git clone https://github.com/riscv/riscv-gnu-toolchain.git
export RISCV=/where/you/wanna/install

mkdir build && cd build
../configure \
  --prefix=$RISCV \
  --with-arch=rv64imafdcv \
  --with-abi=lp64d

make -j`nproc`

### build spike and pk
* spike: simulator

git clone https://github.com/riscv/riscv-isa-sim.git
cd riscv-isa-sim

apt-get install device-tree-compiler
# execute "echo $RISCV" to check if $RISCV is set well
# if not, go back to build "risc-v tool chain"
mkdir build && cd build
../configure \
  --prefix=$RISCV \
  --with-isa=RV64IMAFDCV \
  --with-varch=vlen:1024,elen:64

make -j`nproc` install

* pk: proxy kernel

git clone https://github.com/riscv/riscv-pk.git
cd riscv-pk

mkdir build && cd build
# requires riscv64-unknown-elf-gcc in PATH
export PATH=$RISCV/bin:$PATH

../configure \
  --prefix=$RISCV \
  --with-arch=rv64gcv \
  --with-abi=lp64d \
  --host=riscv64-unknown-elf

make -j`nproc` install

### test our environment
[rvv_saxpy](https://github.com/riscv-non-isa/rvv-intrinsic-doc/blob/main/examples/rvv_saxpy.c)

clang \
  --target=riscv64-unknown-elf \
  --sysroot=$RISCV/riscv64-unknown-elf \
  --gcc-toolchain=$RISCV \
  -march=rv64gcv1p0 \
  rvv_saxpy.c -o rvv_saxpy
# spike is installed in $RISCV/bin
# pk is installed in $RISCV/riscv64-unknown-elf/bin
# you can add those paths to PATH
spike --isa=RV64GCV_zfh_zvfh --varch=vlen:128,elen:64 pk rvv_saxpy

### instruction count measurement

// use this function to get current cycles
// "rdcycle" need zicntr extension
//ex:
// t1 = Read_cycles();
// ...
// t2 = Read_cycles();
// t2 - t1 = cycle counts
unsigned long Read_cycles(void)
{
        unsigned long a;
        asm volatile ("rdcycle %0" : "=r" (a));
        return a;
}

spike --isa=RV64GCV_zicntr_zfh_zvfh --varch=vlen:128,elen:64 pk foo