LLVM | LLVM Installation On Ubuntu

Prerequest

Git, to download source code and related materials.
LLVM source code, from its github mirror.
cmake, tool to compile and install LLVM.
Clang, compiler created with LLVM. We can have this source code for clang from its github mirror.

Download source code for LLVM realated projects

Download source code from github.

 git clone https://github.com/llvm/llvm-project.git

Add Clang to LLVM tools
```
 cp -rf clang ./llvm/tools
```

Compile and install LLVM, need to be attention that LLVM cannot be compiled in root of program, so we need to create a directory build.

-G: generator
DCMAKE_INSTALL_PREFIX: final path
DCMAKE_BUILD_TYPE: could be debug or Release etc.
Options for compiling LLVM

 mkdir build
 cd build
 cmake -G "Unix Makefiles" -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_INSTALL_PREFIX=/usr/local/llvm -DCMAKE_BUILD_TYPE=MinSizeRel -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_TESTS=OFF -DCLANG_INCLUDE_TESTS=OFF ..
 make -j10 # modify accourding to your cpu lcore number.
 make install

Add ENVIRONMENT to bash file. e.g export CPLUS_INCLUDE_PATH=/usr/local/llvm/include

My Installation Script, run in administrator

# !/bin/bash
# This is a bash file to install LLVM on unbuntu. Run in administrator mode(root).

echo --------------------------------------------------------------------------
echo STEP 1: Preparation. Update apt and install Cmake and git
echo --------------------------------------------------------------------------
apt update
apt install cmake
apt install git
echo --------------------------------------------------------------------------
echo STEP 2: Download source code of LLVM.
echo --------------------------------------------------------------------------
# Please change to your desired directory from root.
LLVM_ROOT='/home/xiaob6/test'
if [ ! -d '$LLVM_ROOT' ];then
    mkdir $LLVM_ROOT
else
	echo [$LLVM_ROOT] has already existed.
	exit 1
fi
cd $LLVM_ROOT
git clone https://github.com/llvm/llvm-project.git
cd llvm-project
cp -rf clang ./llvm/tools
echo --------------------------------------------------------------------------
echo STEP 3: Compile and install LLVM
echo --------------------------------------------------------------------------
cd ./llvm
mkdir build
cd build
cmake -G "Unix Makefiles" -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_INSTALL_PREFIX=/usr/local/llvm -DCMAKE_BUILD_TYPE=MinSizeRel -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_TESTS=OFF -DCLANG_INCLUDE_TESTS=OFF ..
make -j10 # modify accourding to your cpu lcore number.
make install