Fortran Tests in the LLVM Test Suite

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The LLVM Test Suite is a separate git repo from the main LLVM project. We recommend that first-time users read through LLVM Test Suite Guide which describes the organizational structure of the test suite and how to run it.

Although the Flang driver is unable to generate code at this time, we are neverthelesss incrementally adding Fortran tests into the LLVM Test Suite. We are currently testing against GFortran while we make progress towards completing the new Flang driver with full code-generation capabilities.

Running the LLVM test-suite with Fortran

Fortran support can be enabled by setting the following CMake variables:

cmake -G "Ninja" -DCMAKE_C_COMPILER=<path to C compiler> \
    -DCMAKE_CXX_COMPILER=<path to C++ compiler> \
    -DCMAKE_Fortran_COMPILER=<path to Fortran compiler> \

This will configure the test-suite to run only the Fortran tests which are found in the Fortran subdirectory. To run the C/C++ tests alongside the Fortran tests omit the -DTEST_SUITE_SUBDIRS CMake variable.

Running the SPEC CPU 2017

We recently added CMake hooks into the LLVM Test Suite to support Fortran tests from SPEC CPU 2017. We strongly encourage the use of the CMake Ninja (1.10 or later) generator due to better support for Fortran module dependency detection. Some of the SPEC CPU 2017 Fortran tests, those that are derived from climate codes, require support for little-endian/big-endian byte swapping capabilities which we automatically detect at CMake configuration time. Note that a copy of SPEC CPU 2017 must be purchased by your home institution and is not provided by LLVM.

Here is an example of how to build SPEC CPU 2017 with GCC

    -DCMAKE_Fortran_COMPILER=gfortran \
    -DTEST_SUITE_SPEC2017_ROOT=<path to SPEC directory>  ..