| commit | c2b7c00d2a08029009216cdfde4e437176e4d838 | [log] [tgz] |
|---|---|---|
| author | Peter Klausler <35819229+klausler@users.noreply.github.com> | Fri Mar 01 13:58:36 2024 -0800 |
| committer | Copybara-Service <copybara-worker@google.com> | Fri Mar 01 14:05:15 2024 -0800 |
| tree | dc17a992c9c4970048d7dc89183620c4fb01323f | |
| parent | 89b4fa8dcf987472db1d87c41e042cd90cb42e0f [diff] |
[flang] Use module file hashes for more checking and disambiguation (#80354) f18's module files are Fortran with a leading header comment containing the module file format version and a hash of the following contents. This hash is currently used only to protect module files against corruption and truncation. Extend the use of these hashes to catch or avoid some error cases. When one module file depends upon another, note its hash in additional module file header comments. This allows the compiler to detect when the module dependency is on a module file that has been updated. Further, it allows the compiler to find the right module file dependency when the same module file name appears in multiple directories on the module search path. The order in which module files are written, when multiple modules appear in a source file, is such that every dependency is written before the module(s) that depend upon it, so that their hashes are known. A warning is emitted when a module file is not the first hit on the module file search path. Further work is needed to add a compiler option that emits (larger) stand-alone module files that incorporate copies of their dependencies rather than relying on search paths. This will be desirable for application libraries that want to ship only "top-level" module files without needing to include their dependencies. Another future work item would be to admit multiple modules in the same compilation with the same name if they have distinct hashes. GitOrigin-RevId: f7a15e0021697e2346d3aa335dedf2bb3cf468f9
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.
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.