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Use hlfir::loadTrivialScalars to dereference pointer, allocatables, and load numerical and logical scalars. This has a small fallout on tests: - load is done on the HLFIR entity (#0 of hlfir.declare) and not the FIR one (#1). This makes no difference at the FIR level (#1 and #0 only differs to account for assumed and explicit shape lower bounds). - loadTrivialScalars get rids of allocatable fir.box for monomoprhic scalars (it is not needed). This exposed a bug in lowering of MERGE with a polymorphic and a monomorphic argument: when the monomorphic is not a fir.box, the polymorphic fir.class should not be reboxed but its address should be read. Reviewed By: tblah Differential Revision: https://reviews.llvm.org/D153252
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.