Linker issue with libclang_rt.builtins.a

[ritikanair03]

Running into this error while using the latest version of compiler with hip backend:
/opt/compiler/llvm/clang/test/Driver/Inputs/debian_per_target_tree/usr/lib/llvm-14/lib/clang/14.0.0/lib/x86_64-linux-gnu/libclang_rt.builtins.a: file not recognized: File truncated
Please provide a solution.

[bader]

Something is wrong with your environment.
Remove /opt/compiler/llvm/clang/test/Driver/Inputs/debian_per_target_tree path from your environment variables or better start with clean environment if possible.

[ritikanair03]

We need libclang_rt.builtins.a file from the compiler to build a library.
While that file was present in the compiler but it is empty and didn't get created.

[bader]

Are we talking about DPC++ compiler? AFAIK, DPC++ compiler doesn't use this library. I think it uses libgcc_s instead.
I'm not that familiar with HIP back-end, but I don't expect it to use different compiler built-in library.

[ritikanair03]

we're using Intel LLVM compiler built for HIP backend with the following configuration:

export CC=gcc
export CXX=g++

export DPCPPCOMPROOT=/opt/compiler/llvm
python3 $DPCPPCOMPROOT/buildbot/configure.py -s $DPCPPCOMPROOT -o $DPCPPCOMPROOT/build --cmake-opt="-DLLVM_ENABLE_RUNTIMES=compiler-rt" -t release --shared-libs --hip
python3 $DPCPPCOMPROOT/buildbot/compile.py -s $DPCPPCOMPROOT/llvm -o $DPCPPCOMPROOT/build

And we're expecting the compiler to build libclang_rt.builtins.a file which we need to link with a library

[bader]

We don't test this configuration, so I'm not sure if we can provide much help.

1. I've found -print-libgcc-file-name option in clang's documentation, which might be useful. It "prints the library path for the currently used compiler runtime library ("libgcc.a" or "libclang_rt.builtins.*.a")."
2. "You can instruct Clang to use compiler-rt with the --rtlib=compiler-rt flag. This is not supported on every platform." from https://clang.llvm.org/docs/Toolchain.html#compiler-rt-llvm. I'm not sure if this is set by default when compiler-rt runtime library build is ON.

Building libclang_rt.builtins.a is not related to DPC++ project, so you might want to contact compiler-rt developers via Discourse - https://discourse.llvm.org/c/runtimes/64.

One more note: don't use --shared-libs. According to LLVM documentation, it's intended for compiler developer's convenience (to speed-up incremental builds specifically) and not intended for building a production compiler.

[npmiller]

And we're expecting the compiler to build libclang_rt.builtins.a file which we need to link with a library

The default target of compile.py is deploy-sycl-toolchain which I don't think includes compiler-rt, try to compile it manually afterwards:

python3 $DPCPPCOMPROOT/buildbot/compile.py -s $DPCPPCOMPROOT/llvm -o $DPCPPCOMPROOT/build
cd $DPCPPCOMPROOT/build
ninja install-compiler-rt

This should hopefully build libclang_rt.builtins.a and install it alongside the compiler.

[abagusetty]

If this is associated with oneMKL related for HIP backend, please refer to the following threads (for workaround) in addition to the above:
oneapi-src/oneMKL#336