Build LLVM From Source

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Quickly had LLVM 17.0.3 built from source again. Just follow the official website:

1. Git clone

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

2. CMake Configure

There is a very serious pitfall here, please refer to LLVM CMake documentation

For LLVM-related variable LLVM_ENABLE_PROJECTS, if you want to build ALL projects by specifying -DLLVM_ENABLE_PROJECTS=all, all the following projects clang;clang-tools-extra;cross-project-tests;libc;libclc;lld;lldb;openmp;polly;pstl are to be built. Particularly, libc is also to be built, which will bring me the following error:

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....../llvm-project/libc/src/string/strcpy.cpp:17:28: error: ‘char*__llvm_libc_18_0_0_git::strcpy(char*, const char*)’ aliased to external symbol ‘strcpy’
   17 | LLVM_LIBC_FUNCTION(char*, strcpy,

Therefore, it’s better to avoid building libc.

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cmake -S llvm-project/llvm -B llvm-project/build \
        -DCMAKE_BUILD_TYPE=Release \
        -DLLVM_ENABLE_PROJECTS="clang;lld;lldb" \
        -DCMAKE_CXX_COMPILER=clang++ \
        -DCMAKE_C_COMPILER=clang \
        -DBUILD_SHARED_LIBS=Onhexo

3. Build

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cmake --build llvm-project/build -j16

4. Installation

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sudo cmake --install llvm-project/build --prefix /usr/local