[INSTALL]: LLVM Flang compiler

[DusanJovic-NOAA]

Package name

LLVM Flang

Package version/tag

latest (22.1.8)

Build options

none

Installation timeframe

Please install on Ursa preferably before the next release. We need to test building the libraries required by the ufs-weather-model. We also need a MPI library built with this compiler.

Other information

No response

[DusanJovic-NOAA]

@AlexanderRichert-NOAA @rickgrubin-noaa

[AlexanderRichert-NOAA]

If we install with Spack, I think llvm@22.1.8 +clang +flang ~offload ~polly targets=aarch64,x86 should do the trick

[AlexanderRichert-NOAA]

Please try /contrib/spack-stack/spack-extra/opt/spack/linux-zen4/llvm-22.1.8-6qcfu74fzptc6nynjfxlqgraack5ouxf (or /contrib/spack-stack/spack-extra/var/spack/environments/llvm-22/.spack-env/view).

[DusanJovic-NOAA]

I tried building a simple library (bacio) that depends on C and Fortran. CMake correctly identified both C and Fortran compilers
and successfully compiled the code. Tests pass.

$ export PATH=/contrib/spack-stack/spack-extra/opt/spack/linux-zen4/llvm-22.1.8-6qcfu74fzptc6nynjfxlqgraack5ouxf/bin:$PATH

$ CC=clang FC=flang cmake ..
-- The C compiler identification is Clang 22.1.8
-- The Fortran compiler identification is LLVMFlang 22.1.8
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /contrib/spack-stack/spack-extra/opt/spack/linux-zen4/llvm-22.1.8-6qcfu74fzptc6nynjfxlqgraack5ouxf/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting Fortran compiler ABI info
-- Detecting Fortran compiler ABI info - done
-- Check for working Fortran compiler: /contrib/spack-stack/spack-extra/opt/spack/linux-zen4/llvm-22.1.8-6qcfu74fzptc6nynjfxlqgraack5ouxf/bin/flang - skipped
-- Setting build type to 'Release' as none was specified.
-- Configuring done (1.4s)
-- Generating done (0.4s)
-- Build files have been written to: /scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/build

$ make
[  6%] Building Fortran object src/CMakeFiles/bacio_f.dir/baciof.F90.o
[ 12%] Building Fortran object src/CMakeFiles/bacio_f.dir/bafrio.F90.o
/scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/src/bafrio.F90:188:6: warning: Reference to the procedure 'bareadl' has an implicit interface that is distinct from another reference: incompatible dummy argument #5: incompatible dummy data object shapes [-Wincompatible-implicit-interfaces]
       CALL BAREADL(LU,IB+LBCW,NB,KR,A)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/src/bafrio.F90:97:6: previous reference to 'bareadl'
       CALL BAREADL(LU,IB,LBCW,KR,BCW1)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/src/bafrio.F90:280:6: warning: Reference to the procedure 'bawritel' has an implicit interface that is distinct from another reference: incompatible dummy argument #5: incompatible dummy data object shapes [-Wincompatible-implicit-interfaces]
       CALL BAWRITEL(LU,IB+LBCW,NB,KR,A)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/src/bafrio.F90:276:3: previous reference to 'bawritel'
    CALL BAWRITEL(LU,IB,LBCW,KR,BCW)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[ 18%] Building Fortran object src/CMakeFiles/bacio_f.dir/chk_endianc.F90.o
[ 18%] Built target bacio_f
[ 25%] Building C object src/CMakeFiles/bacio_c.dir/bacio.c.o
[ 31%] Building C object src/CMakeFiles/bacio_c.dir/byteswap.c.o
[ 31%] Built target bacio_c
[ 37%] Linking Fortran static library libbacio.a
[ 37%] Built target bacio
[ 43%] Building Fortran object tests/CMakeFiles/test_bacio.dir/test_bacio.F90.o
[ 50%] Linking Fortran executable test_bacio
[ 50%] Built target test_bacio
[ 56%] Building Fortran object tests/CMakeFiles/test_bacio2.dir/test_bacio2.F90.o
[ 62%] Linking Fortran executable test_bacio2
[ 62%] Built target test_bacio2
[ 68%] Building Fortran object tests/CMakeFiles/test_bafrio.dir/test_bafrio.F90.o
[ 75%] Linking Fortran executable test_bafrio
[ 75%] Built target test_bafrio
[ 81%] Building C object tests/CMakeFiles/test_bacio_c.dir/test_bacio_c.c.o
[ 87%] Linking C executable test_bacio_c
[ 87%] Built target test_bacio_c
[ 93%] Building C object tests/CMakeFiles/test_byteswap.dir/test_byteswap.c.o
[100%] Linking C executable test_byteswap
[100%] Built target test_byteswap

$ ctest
Test project /scratch3/NCEPDEV/stmp/Dusan.Jovic/test_llvmflang/NCEPLIBS-bacio-2.6.0/build
    Start 1: test_bacio
1/5 Test #1: test_bacio .......................   Passed    0.97 sec
    Start 2: test_bacio2
2/5 Test #2: test_bacio2 ......................   Passed    0.01 sec
    Start 3: test_bafrio
3/5 Test #3: test_bafrio ......................   Passed    0.00 sec
    Start 4: test_bacio_c
4/5 Test #4: test_bacio_c .....................   Passed    1.26 sec
    Start 5: test_byteswap
5/5 Test #5: test_byteswap ....................   Passed    0.00 sec

100% tests passed, 0 tests failed out of 5

Total Test time (real) =   2.26 sec

Could you add MPI library to this environment.

[climbfuji]

I tend to pair (build) the same MPI library I use with GNU on any given machine to LLVM. Mostly OpenMPI 4.1.8 or cray-mpich in my case.