898df4b8ed
Memory effects on the volatile memory resource may not be attached to a particular source, in which case the value of an effect will be null. This caused this test case to crash in the optimized bufferization pass's safety analysis because it assumes it can get the SSA value modified by the memory effect. This is because memory effects on the volatile resource indicate that the operation must not be reordered with respect to other volatile operations, but there is not a material ssa value that can be pointed to. This patch changes the safety checks such that memory effects which do not have associated values are not safe for optimized bufferization.
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.