Can't seem to build libclang_rt.profile

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1

Hello,

I’m trying to build LLVM from scratch as I need 32 bit library support. I am using certain flags ( -fprofile-arc) that require libclang_rt.profile, specifically libclang_rt.profile-i386.a.

This is the error I encounter:
ld.lld: error: cannot open

/llvm_32/lib/clang/10.0.1/lib/linux/libclang_rt.profile-i386.a: No such file or directory
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)

If you look at the directory of which it complains, there is nothing in there
/nfs/proj/fast/user/efatehi/llvm_32/lib/clang/10.0.1/

Only file is directory to include, no lib directory whatsoever, meaning nothing is being built here…

I’m trying with llvm-project-10.0.1

llvm-project-10.0.1.tar.xz

Using:

cmake -DCMAKE_BUILD_TYPE=Release -DBENCHMARK_BUILD_32_BITS:BOOL=1 -DLLVM_BUILD_INSTRUMENTED=IR -DLLVM_ENABLE_PROJECTS=lld,clang,compiler-rt,clang-tools-extra,libclc -DLLVM_ENABLE_ZLIB:bool=0 -DLLVM_ENABLE_EH=ON -DLLVM_ENABLE_PIC=ON -DLLVM_ENABLE_RTTI=ON -DCOMPILER_RT_BUILD_BUILTINS=On -DCOMPILER_RT_USE_BUILTINS_LIBRARY=On -DCMAKE_INSTALL_PREFIX=…/…//llvm_32 …/

Any idea what I am doing wrong here?

Thanks

2

ninja clang does not build some needed runtime libraries.
For -fprofile-arcs, `ninja profile`. To install it, `ninja install-profile`.

3

Hello Fangrui,

I’m still not following, if you could help me a bit more. I added ninja but seems to not have fixed anything.
This is what I did:

cmake -DCMAKE_BUILD_TYPE=Release -DBENCHMARK_BUILD_32_BITS:BOOL=1 -DLLVM_BUILD_INSTRUMENTED=IR -DLLVM_ENABLE_PROJECTS=lld,clang,compiler-rt,clang-tools-extra,libclc -DLLVM_ENABLE_ZLIB:bool=0 -G Ninja -DCMAKE_INSTALL_PREFIX=…/…/llvm_32 …/

ninja all
ninja install

It made no difference. I could not find ninja profile and ninja install-profile.

Thank you so much for your help!

Still no library files such as libclang_rt.profile

4

The -DLLVM_ENABLE_PROJECTS list needs to be `;` separated.
If the list has `compiler-rt`, you should get a build target called
`profile` which builds libclang_rt.profile-$arch.a

5

Thank you! I was totally building it wrong. I need to build llvm and clang first then feed the llvm-config into compiler-rt
-DLLVM_CONFIG_PATH=/path/to/llvm-config

As explained here: https://compiler-rt.llvm.org/

The initial errors I got led me astray to building this completely wrong. Thanks again!