*** will not compile in 4gb ***
*** requires 8gb swapfile ***

tce-load -i compiletc cmake libxml2-dev libffi-dev ninja zstd-dev perl5 python3.9

wget https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/llvm-19.1.0.src.tar.xz
wget https://anduin.linuxfromscratch.org/BLFS/llvm/llvm-cmake-19.src.tar.xz
wget https://anduin.linuxfromscratch.org/BLFS/llvm/llvm-third-party-19.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/clang-19.1.0.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/compiler-rt-19.1.0.src.tar.xz

cd llvm-19.1.0.src

tar -xf ../llvm-cmake-19.src.tar.xz
tar -xf ../llvm-third-party-19.src.tar.xz
sed '/LLVM_COMMON_CMAKE_UTILS/s@../cmake@llvm-cmake-19.src@' -i CMakeLists.txt
sed '/LLVM_THIRD_PARTY_DIR/s@../third-party@llvm-third-party-19.src@' -i cmake/modules/HandleLLVMOptions.cmake

tar -xf ../clang-19.1.0.src.tar.xz -C tools
mv tools/clang-19.1.0.src tools/clang

tar -xf ../compiler-rt-19.1.0.src.tar.xz -C projects
mv projects/compiler-rt-19.1.0.src projects/compiler-rt

grep -rl '#!.*python' | xargs sed -i '1s/python$/python3/'

sed 's/utility/tool/' -i utils/FileCheck/CMakeLists.txt

mkdir build
cd build

export CC=gcc CXX=g++
LD_PRELOAD="/mnt/sdc1/usr/src/uname_hack.so /usr/local/lib/libatomic.so" cmake -LAH -DCMAKE_C_FLAGS_RELEASE="-march=i486 -mtune=i686 -Os -pipe" -DCMAKE_CXX_FLAGS_RELEASE="-march=i486 -mtune=i686 -Os -pipe -atomic" -DCMAKE_INSTALL_PREFIX=/usr/local -DCMAKE_SKIP_INSTALL_RPATH=ON -DLLVM_ENABLE_FFI=ON -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_ENABLE_RTTI=ON -DLLVM_TARGETS_TO_BUILD="host;AMDGPU;BPF;WebAssembly" -DLLVM_BINUTILS_INCDIR=/usr/local/include -DLLVM_INCLUDE_BENCHMARKS=OFF -DCLANG_DEFAULT_PIE_ON_LINUX=ON -DCLANG_CONFIG_FILE_SYSTEM_DIR=/usr/local/etc/clang -DCMAKE_VERBOSE_MAKEFILE=TRUE -DCMAKE_INSTALL_LIBDIR=lib -DCMAKE_INSTALL_LIBEXECDIR=lib/clang -DLLVM_DEFAULT_TARGET_TRIPLE="i486-pc-linux-gnu" -Wno-dev -G Ninja ../

[static libs huge with -flto]

find . -name flags.make -type f -exec sed -i 's/ -O3 -g//g' {} \;
find . -name flags.make -type f -exec sed -i 's/ -O3//g' {} \;
find . -name link.txt -type f -exec sed -i 's/-Wl,-O3/-Wl -Os/g' {} \;
find . -name AddLLVM.cmake -type f -exec sed -i 's/-Wl,-O3/-Wl,-Os/g' {} \;
find . -name compile_commands.json -type f -exec sed -i 's/ -O3 -g//g' {} \;
find . -name build.make -type f -exec sed -i 's/ -O3 -g//g' {} \;

LD_PRELOAD="/mnt/sdc1/usr/src/uname_hack.so /usr/local/lib/libatomic.so" ninja [3h 2m 53s]

[..fixes]
undefined reference to `__atomic_load_8'
collect2: error: ld returned 1 exit status

sudo ninja install

sudo mkdir /usr/local/lib/bfd-plugins
cd /usr/local/lib/bfd-plugins
sudo ln -s ../LLVMgold.so ./

[links against ncursesw without ncursesw-dev]