abeb6c9f58
This is a slightly more slimmed down and up-to-date version of the older PR from here: https://reviews.llvm.org/D144203, written by @jsjodin, which has already under gone some review. This PR places allocas in the alloca address space specified by the provided data layout (default is 0 for all address spaces, unless explicitly specified by the layout), and then will cast these alloca's to the program address space if this address space is different from the allocation address space. For most architectures data layouts, this will be a no-op, as they have a flat address space. But in the case of AMDGPU it will result in allocas being placed in the correct address space (5, private), and then casted into the correct program address space (0, generic). This results in correct (partially, a follow up PR will be forthcoming soon) generation of allocations inside of device code. This PR is in addition to the work by @skatrak in this PR: https://github.com/llvm/llvm-project/pull/69599 and adds seperate and neccesary functionality of casting alloca's from their address space to the program address space, both are independent PRs, although there is some minor overlap e.g. this PR incorporates some of the useful helper functions from 69599, so whichever lands first will need a minor rebase. Co-author: jsjodin
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.