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## Purpose This patch is one in a series of code-mods that annotate LLVM’s public interface for export. This patch ensures a few `cl::opt` declarations are properly annotated with `LLVM_ABI`. The annotations currently have no meaningful impact on the LLVM build; however, they are a prerequisite to support an LLVM Windows DLL (shared library) build. ## Background This effort is tracked in #109483. Additional context is provided in [this discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307), and documentation for `LLVM_ABI` and related annotations is found in the LLVM repo [here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst). ## Overview - Remove local `extern` declarations of `llvm::PrintPipelinePasses` because it is already correctly declared with an `LLVM_ABI` annotation in `llvm\Passes\PassBuilder.h`. Leaving these declarations results in a gcc compile warning unless they are also annotated with `LLVM_ABI`. - Similarly, remove local `extern` declarations of `ProfileSummaryCutoffHot` and `UseContextLessSummary` from `llvm/tools/llvm-profgen/ProfileGenerator.cpp` since they are declared with `LLVM_ABI` in `llvm\ProfileData\ProfileCommon.h`. - Explicitly annotate the extern declaration of `ProfileCorrelate` in `clang/lib/CodeGen/BackendUtil.cpp` since it is not declared in a header. The definition of `ProfileCorrelate` in `llvm\lib\Transforms\Instrumentation\InstrProfiling.cpp` is already annotated with `LLVM_ABI`. ## Validation Local builds and tests to validate cross-platform compatibility. This included llvm, clang, and lldb on the following configurations: - Windows with MSVC - Windows with Clang - Linux with GCC - Linux with Clang - Darwin with Clang
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.