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Add support for non-allocatable module-level CUDA managed variables using pointer indirection through a companion global in __nv_managed_data__. The CUDA runtime populates this pointer with the unified memory address via __cudaRegisterManagedVar and __cudaInitModule. 1. Create a .managed.ptr companion global in the __nv_managed_data__ section and register it with _FortranACUFRegisterManagedVariable (CUFAddConstructor.cpp) 2. Call __cudaInitModule after registration to populate the managed pointer (registration.cpp) 3. Annotate managed globals in gpu.module with nvvm.managed for PTX .attribute(.managed) generation (cuda-code-gen.mlir) 4. Suppress cuf.data_transfer for assignments to/from non-allocatable module managed variables, since cudaMemcpy would target the shadow address rather than the actual unified memory (tools.h) 5. Preserve cuf.data_transfer for device_var = managed_var assignments where explicit transfer is still required
Flang
Flang is a ground-up implementation of a Fortran front end written in modern C++. It started off as the f18 project (https://github.com/flang-compiler/f18) with an aim to replace the previous flang project (https://github.com/flang-compiler/flang) and address its various deficiencies. F18 was subsequently accepted into the LLVM project and rechristened as Flang.
Please note that flang is not ready yet for production usage.
Getting Started
Read more about flang in the docs directory. Start with the compiler overview.
To better understand Fortran as a language and the specific grammar accepted by flang, read Fortran For C Programmers and flang's specifications of the Fortran grammar and the OpenMP grammar.
Treatment of language extensions is covered in this document.
To understand the compilers handling of intrinsics, see the discussion of intrinsics.
To understand how a flang program communicates with libraries at runtime, see the discussion of runtime descriptors.
If you're interested in contributing to the compiler, read the style guide and also review how flang uses modern C++ features.
If you are interested in writing new documentation, follow LLVM's Markdown style guide.
Consult the Getting Started with Flang for information on building and running flang.