I am trying to build release/16.x of llvm-project; but hitting a snafu:
First things first, the system I am on is as follows
Inside my Oracle VirtualBox 7.0, I have
RAM: 5 GiB
CPU: 3 x Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
OS: Ubuntu 22.04.2 LTS
Clang: Ubuntu clang version 14.0.0-1ubuntu1
CMake: cmake version 3.22.1
Ninja: 1.10.1
Gold: GNU gold (GNU Binutils for Ubuntu 2.38) 1.16
Python: Python 3.10
After cloning the release/16.x branch, I am using the following configuration:
mkdir -p build; mkdir -p installed; cd build; \
cmake -G "Ninja" \
-DCMAKE_C_COMPILER=$(which clang) \
-DCMAKE_CXX_COMPILER=$(which clang++) \
-DLLVM_ENABLE_PROJECTS="clang;lld" \
-DLLVM_TARGETS_TO_BUILD="X86;RISCV" \
-DCMAKE_BUILD_TYPE="Debug" \
-DLLVM_ENABLE_ASSERTIONS=ON \
-DLLVM_PARALLEL_COMPILE_JOBS=2 \
-DCMAKE_INSTALL_PREFIX=$(pwd)/../installed \
-DLLVM_PARALLEL_LINK_JOBS=2 \
-DLLVM_BUILD_LLVM_DYLIB=ON \
-DLLVM_LINK_LLVM_DYLIB=ON \
-DBUILD_SHARED_LIBS=OFF \
-DLLVM_USE_SPLIT_DWARF=ON \
-DLLVM_USE_LINKER=gold \
-DLLVM_OPTIMIZED_TABLEGEN=ON \
-DCMAKE_EXE_LINKER_FLAGS='-Wl,-no-keep-memory,-fuse-ld=gold' \
../llvm
The cmake configuration completes successfully, and build files are written:
...
...
-- Configuring done
-- Generating done
-- Build files have been written to: /media/sf_shared_folder/myProject/llvm-project/build
Subsequently, when I am trying to build the project using ninja, I am facing the following problem:
ninja -j2 all
[243/3771] Building native llvm-tblgen...
[236/236] Linking CXX executable bin/llvm-tblgen
[326/3771] Building Attributes.inc...
FAILED: include/llvm/IR/Attributes.inc /media/sf_shared_folder/myProject/llvm-project/build/include/llvm/IR/Attributes.inc
cd /media/sf_shared_folder/myProject/llvm-project/build && /media/sf_shared_folder/myProject/llvm-project/build/NATIVE/bin/llvm-tblgen -gen-attrs -I /media/sf_shared_folder/myProject/llvm-project/llvm/include/llvm/IR -I/media/sf_shared_folder/myProject/llvm-project/build/include -I/media/sf_shared_folder/myProject/llvm-project/llvm/include /media/sf_shared_folder/myProject/llvm-project/llvm/include/llvm/IR/Attributes.td --write-if-changed -o include/llvm/IR/Attributes.inc -d include/llvm/IR/Attributes.inc.d
/bin/sh: 1: /media/sf_shared_folder/myProject/llvm-project/build/NATIVE/bin/llvm-tblgen: Exec format error
[327/3771] Building CXX object tools/clang/utils/TableGen/CMakeFiles/clang-tblgen.dir/ClangAttrEmitter.cpp.o
ninja: build stopped: subcommand failed.
Now, what is this llvm-tblgen: Exec format error and how do I fix this for a successful build?
I have also raised the issue over at the github repo for llvm-project, issue 62429
So the fix was not even related to LLVM. The real problem was that I had cloned the LLVM project to a shared_folder (a directory shared between guest OS and host OS, under VirtualBox). Now, with Windows 10 host, the symbolic link creation is messed up for the guest OS.
Since LLVM was not throwing an error specific to this, I was unable to detect this. So I tried to use the following command:
cmake -G "Ninja" \
-DCMAKE_C_COMPILER=$(which clang) \
-DCMAKE_CXX_COMPILER=$(which clang++) \
-DLLVM_ENABLE_PROJECTS="clang;lld" \
-DLLVM_TARGETS_TO_BUILD="X86;RISCV" \
-DCMAKE_BUILD_TYPE="Debug" \
-DLLVM_ENABLE_ASSERTIONS=ON \
-DLLVM_PARALLEL_COMPILE_JOBS=2 \
-DCMAKE_INSTALL_PREFIX=$(pwd)/../installed \
-DLLVM_PARALLEL_LINK_JOBS=2 \
-DLLVM_BUILD_LLVM_DYLIB=OFF \
-DLLVM_LINK_LLVM_DYLIB=OFF \
-DBUILD_SHARED_LIBS=ON \
-DLLVM_USE_SPLIT_DWARF=ON \
-DLLVM_USE_LINKER=gold \
-DLLVM_OPTIMIZED_TABLEGEN=ON \
-DCMAKE_EXE_LINKER_FLAGS='-Wl,-no-keep-memory,-fuse-ld=gold' \
../llvm
with BUILD_SHARED_LIBS=ON, during ninja -j2 the build system immediately complained that it is not able to create symbolic links. Armed with this information I then cloned the project on a path internal to the guest OS and ran the original command (as in the question above). This resulted in a successful build.