edc2fb0733
Re-land commit 3787fd942f3927345320cc97a479f13e44355805 This patch adds support for storing OpenMP REQUIRES information in the semantics symbols for programs/subprograms and modules/submodules, and populates them during directive resolution. A pass is added to name resolution that makes sure this information is also propagated across top-level programs, functions and subprograms. Storing REQUIRES information inside of semantics symbols will also allow supporting the propagation of this information across Fortran modules. This will come as a separate patch. The `bool DirectiveAttributeVisitor::Pre(const parser::SpecificationPart &x)` method is removed since it resulted in specification parts being visited twice. This is patch 3/5 of a series splitting D149337 to simplify review. Differential Revision: https://reviews.llvm.org/D157983
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.