Report on Maturity of LLVM's Fortran Support

This report summarises our findings on the maturity of Flang, the Fortran compiler of the LLVM project.

We have analysed two important aspects for the DARE project: the current OpenMP support, and then the general compliance and correctness of the implementation based on existing Fortran testsuites.

We can conclude that Flang delivers a reasonable level of compliance in the language but the OpenMP support is still a bit lacking, specially for features that go beyond OpenMP 2.5. However the support is slightly scattered and is influenced by how difficult it is to implement OpenMP functionalities in the existing LLVM infrastructure.

This work has received funding from the DARE SGA1 Project, from the European High-Performance Computing Joint Undertaking (JU) under Grant Agreement No 101202459 and from PCI2024-161687-3 Project funded by MICIU/AEI/10.13039/501100011033 and European´s Unión “NextGenerationEU”/PRTR”.