[flang] fatal Fortran runtime error

[dnoan]

Hello,
I am encountering a runtime error while running MUMPS compiled with LLVM Flang 20.1.0:

fatal Fortran runtime error(/Users/qe_jenkins/tmp/open-source-llvm/488/.conan/data/open-source-llvm_Flang-New_Mac/24.10.0.488/infra/stable/build/b7b9f539de0226c6f51a52f11baaa5d1d9c3e56f/llvm-project/flang/runtime/descriptor.cpp:71): not yet implemented: type category(6)

This issue appears to be new in LLVM 20, as version 19 did not have this problem.

The source code for MUMPS can be found here: http://deb.debian.org/debian/pool/main/m/mumps/mumps_5.7.3.orig.tar.gz

[dnoan]

This is the stack trace which I obtained from LLDB:

    frame #3: 0x000000038d539e40 libmumps.dylib`Fortran::runtime::Terminator::CrashFooter() const + 48
    frame #4: 0x000000038d2df8b0 libmumps.dylib`char const* Fortran::runtime::Terminator::Crash<int>(char const*, int) const + 72
    frame #5: 0x000000038d315088 libmumps.dylib`Fortran::runtime::Descriptor::BytesFor(Fortran::common::TypeCategory, int) + 376
    frame #6: 0x000000038d315108 libmumps.dylib`Fortran::runtime::Descriptor::Establish(Fortran::common::TypeCategory, int, void*, int, long const*, unsigned char, bool) + 80
    frame #7: 0x000000038d53c7e4 libmumps.dylib`Fortran::runtime::typeInfo::Component::EstablishDescriptor(Fortran::runtime::Descriptor&, Fortran::runtime::Descriptor const&, Fortran::runtime::Terminator&) const + 196
    frame #8: 0x000000038d31168c libmumps.dylib`Fortran::runtime::Initialize(Fortran::runtime::Descriptor const&, Fortran::runtime::typeInfo::DerivedType const&, Fortran::runtime::Terminator&, bool, Fortran::runtime::Descriptor const*) + 2480
    frame #9: 0x000000038d537ee0 libmumps.dylib`_FortranAPointerAllocate + 200
    frame #10: 0x000000038d1d1cc4 libmumps.dylib`dmumps_f77_ + 360
    frame #11: 0x000000038d2d4c08 libmumps.dylib`dmumps_c + 3048
    frame #12: 0x000000038cf798f0 libmumps.dylib`init + 288

[llvmbot]

@llvm/issue-subscribers-flang-runtime

Author: Noan (dnoan)

Hello, I am encountering a runtime error while running MUMPS compiled with LLVM Flang 20.1.0:

fatal Fortran runtime error(/Users/qe_jenkins/tmp/open-source-llvm/488/.conan/data/open-source-llvm_Flang-New_Mac/24.10.0.488/infra/stable/build/b7b9f539de0226c6f51a52f11baaa5d1d9c3e56f/llvm-project/flang/runtime/descriptor.cpp:71): not yet implemented: type category(6)

This issue appears to be new in LLVM 20, as version 19 did not have this problem.

The source code for MUMPS can be found here: http://deb.debian.org/debian/pool/main/m/mumps/mumps_5.7.3.orig.tar.gz

[jeanPerier]

Thanks for the bug report.

Can you double check you ran the application against the correct flang runtime (the one from llvm 20 if you compiled with llvm 20)?

The line number of the assert suggests the runtime version was older than this commit from august 1st 2024 that modified the assert line position.
The runtime of version 20 would crash pointing to the runtime line descriptor.cpp:74, not 71.

So it looks like the application was compiled with version 20, but ran using the runtime of llvm 19, which is not expected to work.
Version 20 introduced a new type code for the unsigned extension that shifted the existing codes, so the runtime of llvm 19 expects 5 as the code for derived type while it is now set to 6 in the binaries compiled with llvm 20.

[dnoan]

I don't link to the runtime directly. It seems that the compiler links it automatically. My link command:

/usr/local/llvm-20.1.0/bin/flang -shared -L/Users/builduser/mumps/lib -L/usr/local/llvm-20.1.0/lib -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -fopenmp -pthread -g -o /Users/builduser/mumps/lib/libmumps.dylib /Users/builduser/mumps/obj/mumpswrap.o -lmumps -lmetis -larmpl_mp

I have exactly the same problem on WoA.

[klausler]

The type category value 6 suggests to me that this is a case of a newer compiler (with UNSIGNED support) is being used with an old runtime that was still expecting to see derived types arrive with type category 5.

[klausler]

@tstellar this might be a packaging issue with 20.1.0 binaries for MacOS &/or WoA.

[klausler]

@dnoan does this simple sanity check work in your environment?

type t
  character(5) :: s = "works"
end type
type(t), pointer :: x
allocate(x)
print *, x%s
end

[dnoan]

I pasted the code in a file called foo.f90:

/usr/local/llvm-20.1.0/bin/flang -o foo foo.f90 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk

The result:

% ./foo
 works

Note that I have built LLVM from source code both on macOS and Windows. This is my build command for macOS:

curl -LO https://github.com/llvm/llvm-project/archive/refs/tags/llvmorg-20.1.0.tar.gz
tar xzf llvmorg-20.1.0.tar.gz
mkdir -p llvm-project-llvmorg-20.1.0/build
cd llvm-project-llvmorg-20.1.0/build
cmake -G Ninja \
      -DCMAKE_INSTALL_PREFIX=/usr/local/llvm-20.1.0 \
      -DCMAKE_BUILD_TYPE=Release \
      -DLLVM_TARGETS_TO_BUILD=AArch64 \
      -DLLVM_ENABLE_PROJECTS="clang;openmp;flang" \
      -DLLVM_ENABLE_RUNTIMES="compiler-rt" \
      -DCOMPILER_RT_EXCLUDE_ATOMIC_BUILTIN=OFF \
      -DCOMPILER_RT_BUILD_STANDALONE_LIBATOMIC=OFF \
      -DCOMPILER_RT_USE_ATOMIC_LIBRARY=ON \
      -DCOMPILER_RT_BUILD_BUILTINS=ON \
      -DCOMPILER_RT_USE_BUILTINS_LIBRARY=ON \
      ../llvm
ninja
ninja install

[jeanPerier]

I do not think the way you built the application is the problem, I suspect the issue is with the flang runtime version found by ld when running the program.

Could you use ldd on your application to see which runtime version it is resolving to?

This could also be related to this issue #129688 if you have an older flang version installed on your system.

[eugeneepshteyn]

Maybe also check LD_LIBRARY_PATH for any directories pointing to the old runtime?