aac1f85393
Before this change, OmpShared was not always set in shared symbols. Instead, absence of private flags was interpreted as shared DSA. The problem was that symbols with no flags, with only a host association, could also mean "has same DSA as in the enclosing context". Now shared symbols behave the same as private and can be treated the same way. Because of the host association symbols with no flags mentioned above, it was also incorrect to simply test the flags of a given symbol to find out if it was private or shared. The function GetSymbolDSA() was added to fix this. It would be better to avoid the need of these special symbols, but this would require changes to how symbols are collected in lowering. Besides that, some semantic checks need to know if a DSA clause was used or not. To avoid confusing implicit symbols with DSA clauses a new flag was added: OmpExplicit. It is now set for all symbols with explicitly determined data-sharing attributes. With the changes above, AddToContextObjectWithDSA() and the symbol to DSA map could probably be removed and the DSA could be obtained directly from the symbol, but this was not attempted. Some debug messages were also added, with the "omp" DEBUG_TYPE, to make it easier to debug the creation of implicit symbols and to visualize all associations of a given symbol. Fixes #130533 Fixes #140882
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.