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Merged
morrisonlevi merged 3 commits into from
Sep 30, 2026
Merged

Build a smaller CentOS 7 LLVM toolchain with compiler-rt #4249

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8e8bc34
Build a smaller CentOS 7 LLVM toolchain with compiler-rt
morrisonlevi Sep 30, 2026
b3d1484
Merge branch 'master' into levi/centos7-llvm-toolchain
morrisonlevi Sep 30, 2026
d7827aa
Merge branch 'master' into levi/centos7-llvm-toolchain
morrisonlevi Sep 30, 2026
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20 changes: 16 additions & 4 deletions dockerfiles/ci/centos/7/base.Dockerfile
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Expand Up @@ -196,9 +196,9 @@ ENV PKG_CONFIG_PATH="${PKG_CONFIG_PATH}:/usr/local/lib/pkgconfig:/usr/local/lib6
# Caution, takes a very long time! Since we have to build one from source,
# I picked LLVM 21, which matches Rust 1.91.
# Ordinarily we leave sources, but LLVM is 2GiB just for the sources...
# Minimum: libclang. Nice-to-have: full toolchain including linker to play
# with cross-language link-time optimization. Needs to match rustc -Vv's llvm
# version.
# Share LLVM and Clang code between the clang driver, LLD and libclang instead
# of embedding static LLVM libraries in each executable (saves a lot of size).
# compiler-rt builtins remain static; libgcc_s still supplies the C++ unwinder.
RUN yum install -y --nogpgcheck devtoolset-9 \
&& source scl_source enable devtoolset-9 \
&& yum install -y python3 \
Expand All @@ -214,8 +214,20 @@ RUN yum install -y --nogpgcheck devtoolset-9 \
&& git clone --depth 1 -b release/21.x https://github.com/llvm/llvm-project.git \
&& mkdir -vp llvm-project/build \
&& cd llvm-project/build \
&& cmake -G Ninja -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/local -DLLVM_INCLUDE_TESTS=OFF -DLLVM_ENABLE_BINDINGS=OFF -DLLVM_INSTALL_TOOLCHAIN_ONLY=ON ../llvm \
&& cmake -G Ninja -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_ENABLE_RUNTIMES=compiler-rt -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON -DCLANG_BUILD_CLANG_DYLIB=ON -DCLANG_LINK_CLANG_DYLIB=ON -DLLVM_TARGETS_TO_BUILD=host -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON -DCOMPILER_RT_ENABLE_PER_TARGET_RUNTIME_DIR=ON -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON -DCOMPILER_RT_BUILD_SANITIZERS=OFF -DCOMPILER_RT_BUILD_PROFILE=OFF -DCOMPILER_RT_BUILD_LIBFUZZER=OFF -DCOMPILER_RT_BUILD_XRAY=OFF -DCMAKE_BUILD_TYPE=MinSizeRel -DCMAKE_INSTALL_PREFIX=/usr/local -DLLVM_INCLUDE_TESTS=OFF -DLLVM_ENABLE_BINDINGS=OFF -DLLVM_INSTALL_TOOLCHAIN_ONLY=ON ../llvm \
&& cmake --build . --parallel $(nproc) --target "install/strip" \
&& ldconfig \
&& cmake --build . --parallel $(nproc) --target install-runtimes \
&& resource_dir="$(/usr/local/bin/clang --print-resource-dir)/lib" \
&& target="$(/usr/local/bin/clang -dumpmachine)" \
&& if [ ! -s "$resource_dir/$target/libclang_rt.builtins.a" ]; then \
test -s "$resource_dir/linux/libclang_rt.builtins-$(uname -m).a"; \
mkdir -p "$resource_dir/$target"; \
ln -s "../linux/libclang_rt.builtins-$(uname -m).a" "$resource_dir/$target/libclang_rt.builtins.a"; \
fi \
&& test -s "$resource_dir/$target/libclang_rt.builtins.a" \
&& printf 'int main(void) { return 0; }\n' | /usr/local/bin/clang -x c - -rtlib=compiler-rt -fuse-ld=lld -o /tmp/compiler-rt-smoke \
&& /tmp/compiler-rt-smoke && rm /tmp/compiler-rt-smoke \
&& rm -f /usr/local/lib/libclang*.a /usr/local/lib/libLLVM*.a \
&& rm -rf /usr/local/include/llvm /usr/local/include/clang \
&& rm -rf /usr/local/lib/cmake/llvm /usr/local/lib/cmake/clang /usr/local/lib/cmake/lld \
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