*** compiled in 8gb with 8gb swap ***

tce-load -i compiletc cmake libxml2-dev ninja zstd-dev python3.8

wget https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/llvm-15.0.7.src.tar.xz
wget https://anduin.linuxfromscratch.org/BLFS/llvm/llvm-cmake-15.0.7.src.tar.xz
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/clang-15.0.7.src.tar.xz
wget https://www.linuxfromscratch.org/patches/blfs/svn/clang-15.0.7-enable_default_ssp-1.patch
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/compiler-rt-15.0.7.src.tar.xz

SRCDIR="../../../sources"

tar xf $SRCDIR/llvm-15.0.7.src.tar.xz

cd llvm-15.0.7.src

tar -xf ../$SRCDIR/llvm-cmake-15.0.7.src.tar.xz
sed '/LLVM_COMMON_CMAKE_UTILS/s@../cmake@cmake-15.0.7.src@' -i CMakeLists.txt

tar -xf ../$SRCDIR/clang-15.0.7.src.tar.xz -C tools
mv tools/clang-15.0.7.src tools/clang

tar -xf ../$SRCDIR/compiler-rt-15.0.7.src.tar.xz -C projects
mv projects/compiler-rt-15.0.7.src projects/compiler-rt

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

patch -Np2 -d tools/clang <../$SRCDIR/clang-15.0.7-enable_default_ssp-1.patch

mkdir build
cd build

case $(uname -m) in
    armv*)
       CMPFLAGS="-Os -pipe -march=armv6zk -mtune=arm1176jzf-s -mfpu=vfp"
    ;;
    aarch64)
       CMPFLAGS="-Os -pipe -march=armv8-a+crc -mtune=cortex-a72"
    ;;
esac

cmake -LAH -DCMAKE_C_FLAGS_RELEASE="$CMPFLAGS" \
CC="gcc" CXX="g++" -DCMAKE_CXX_FLAGS_RELEASE="$CMPFLAGS" \
-DCMAKE_INSTALL_PREFIX=/usr/local -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" \
-DLLVM_BINUTILS_INCDIR=/usr/local/include -DLLVM_INCLUDE_BENCHMARKS=OFF -DCLANG_DEFAULT_PIE_ON_LINUX=ON \
-DCMAKE_VERBOSE_MAKEFILE=TRUE -DCMAKE_INSTALL_LIBDIR=lib -DCMAKE_INSTALL_LIBEXECDIR=lib/clang -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' {} \;

ninja [7h 14m 41s]
sudo ninja install

sudo cp bin/FileCheck /usr/local/bin

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

[links against ncursesw without ncursesw-dev]