-<!--===- README.md
+# Flang
- Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
- See https://llvm.org/LICENSE.txt for license information.
- SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
--->
-
-# F18
-
-F18 is a ground-up implementation of a Fortran front end written in modern C++.
-F18, when combined with LLVM, is intended to replace the Flang compiler.
-
-Flang is a Fortran compiler targeting LLVM.
-Visit the [Flang wiki](https://github.com/flang-compiler/flang/wiki)
-for more information about 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.
## Getting Started
-Read more about f18 in the [documentation directory](documentation).
+Read more about flang in the [documentation directory](documentation).
Start with the [compiler overview](documentation/Overview.md).
To better understand Fortran as a language
-and the specific grammar accepted by f18,
+and the specific grammar accepted by flang,
read [Fortran For C Programmers](documentation/FortranForCProgrammers.md)
and
-f18's specifications of the [Fortran grammar](documentation/f2018-grammar.txt)
+flang's specifications of the [Fortran grammar](documentation/f2018-grammar.txt)
and
the [OpenMP grammar](documentation/OpenMP-4.5-grammar.txt).
To understand the compilers handling of intrinsics,
see the [discussion of intrinsics](documentation/Intrinsics.md).
-To understand how an f18 program communicates with libraries at runtime,
+To understand how a flang program communicates with libraries at runtime,
see the discussion of [runtime descriptors](documentation/RuntimeDescriptor.md).
If you're interested in contributing to the compiler,
read the [style guide](documentation/C++style.md)
and
-also review [how f18 uses modern C++ features](documentation/C++17.md).
+also review [how flang uses modern C++ features](documentation/C++17.md).
-## Building F18
-
-### Get the Source Code
-
-```
-cd where/you/want/the/source
-git clone https://github.com/flang-compiler/f18.git
-```
+## Supported C++ compilers
-### Supported C++ compilers
-
-F18 is written in C++17.
+Flang is written in C++17.
The code has been compiled and tested with
-GCC versions 7.2.0, 7.3.0, 8.1.0, and 8.2.0.
+GCC versions from 7.2.0 to 9.3.0.
The code has been compiled and tested with
-clang version 7.0 and 8.0
+clang version 7.0, 8.0, 9.0 and 10.0
using either GNU's libstdc++ or LLVM's libc++.
-### LLVM dependency
+The code has been compiled on
+AArch64, x86\_64 and ppc64le servers
+with CentOS7, Ubuntu18.04, Rhel, MacOs, Mojave, XCode and
+Apple Clang version 10.0.1.
-F18 uses components from LLVM.
+The code does not compile with Windows and a compiler that does not have
+support for C++17.
+
+## Building Flang out of tree
+These instructions are for building Flang separately from LLVM; if you are
+building Flang alongside LLVM then follow the standard LLVM build instructions
+and add flang to `LLVM_ENABLE_PROJECTS` instead, as detailed there.
+
+### LLVM dependency
The instructions to build LLVM can be found at
-https://llvm.org/docs/GettingStarted.html.
+https://llvm.org/docs/GettingStarted.html. If you are building flang as part
+of LLVM, follow those instructions and add flang to `LLVM_ENABLE_PROJECTS`.
-We highly recommend using the same compiler to compile both llvm and f18.
+We highly recommend using the same compiler to compile both llvm and flang.
-The f18 CMakeList.txt file uses
+The flang CMakeList.txt file uses
the variable `LLVM_DIR` to find the installed LLVM components
and
the variable `MLIR_DIR` to find the installed MLIR components.
-To get the correct LLVM and MLIR libraries included in your f18 build,
+To get the correct LLVM and MLIR libraries included in your flang build,
define LLVM_DIR and MLIR_DIR on the cmake command line.
```
LLVM=<LLVM_BUILD_DIR>/lib/cmake/llvm \
where `LLVM_BUILD_DIR` is
the top-level directory where LLVM was built.
-### LLVM dependency when building f18 with Fortran IR
-
-If you do not want to build Fortran IR, add `-DLINK_WITH_FIR=Off` to f18 cmake
-command and ignore the rest of this section.
-
-If you intend to build f18 with Fortran IR (`-DLINK_WITH_FIR` On by default),
-you must:
-- build LLVM with the same compiler and options as the one you are using
-to build F18.
-- pass `-DCMAKE_CXX_STANDARD=17 -DLLVM_ENABLE_PROJECTS="mlir"`
-to LLVM cmake command.
-- install LLVM somewhere with `make install` in order to get the required
-AddMLIR cmake file (it is not generated in LLVM build directory).
-
-Installing LLVM from packages is most likely not an option as it will not include
-MLIR and not be built following C++17 standard.
-
-MLIR is under active development and the most recent development version
-may be incompatible. A branch named `f18` is available inside LLVM fork in
-https://github.com/flang-compiler/f18-llvm-project. It contains a version of LLVM
-that is known be compatible to build f18 with FIR.
-
-The fastest way to get set up is to do:
-
-```
-cd where/you/want/to/build/llvm
-git clone --depth=1 -b f18 https://github.com/flang-compiler/f18-llvm-project.git
-mkdir build
-mkdir install
-cd build
-cmake ../f18-llvm-project/llvm -DCMAKE_BUILD_TYPE=Release \
- -DLLVM_ENABLE_PROJECTS=mlir -DCMAKE_CXX_STANDARD=17 \
- -DLLVM_INSTALL_UTILS=On \
- -DCMAKE_INSTALL_PREFIX=../install
-make
-make install
-```
-
-Then, `-DLLVM_DIR` would have to be set to
- `<where/you/want/to/build/llvm>/install/lib/cmake/llvm`
-and, `-DMLIR_DIR` would have to be set to
- `<where/you/want/to/build/llvm>/install/lib/cmake/mlir`
-
-in f18 cmake command.
-
-To run lit tests,
-`-DLLVM_EXTERNAL_LIT=<where/you/want/to/build/llvm>/build/bin/llvm-lit` must be
-added to f18 cmake command. This is because `llvm-lit` is not part of
-LLVM installation.
-
-Note that when using some advanced options from f18 cmake file it may be
-necessary to reproduce their effects in LLVM cmake command.
-
-### Building f18 with GCC
+### Building flang with GCC
By default,
cmake will search for g++ on your PATH.
The g++ version must be one of the supported versions
-in order to build f18.
+in order to build flang.
+
+Or, cmake will use the variable CXX to find the C++ compiler. CXX should include
+the full path to the compiler or a name that will be found on your PATH, e.g.
+g++-8.3, assuming g++-8.3 is on your PATH.
-Or,
-cmake will use the variable CXX to find the C++ compiler.
-CXX should include the full path to the compiler
-or a name that will be found on your PATH,
-e.g. g++-8.3, assuming g++-8.3 is on your PATH.
```
export CXX=g++-8.3
```
CXX=/opt/gcc-8.3/bin/g++-8.3 cmake ...
```
-### Building f18 with clang
+### Building flang with clang
-To build f18 with clang,
+To build flang with clang,
cmake needs to know how to find clang++
and the GCC library and tools that were used to build clang++.
`-DCMAKE_INSTALL_PREFIX=<INSTALL_PREFIX>`
to the cmake command
where `<INSTALL_PREFIX>`
-is the path where f18 should be installed.
+is the path where flang should be installed.
### Build Types
to the cmake command.
Release builds execute quickly.
-### Build F18
+### Build Flang out of tree
```
-cd ~/f18/build
-cmake -DLLVM_DIR=$LLVM -DMLIR_DIR=$MLIR ~/f18/src
+cd ~/flang/build
+cmake -DLLVM_DIR=$LLVM -DMLIR_DIR=$MLIR ~/flang/src
make
```
-
### How to Run the Regression Tests
To run all tests:
```
-cd ~/f18/build
-cmake -DLLVM_DIR=$LLVM -DMLIR_DIR=$MLIR ~/f18/src
+cd ~/flang/build
+cmake -DLLVM_DIR=$LLVM -DMLIR_DIR=$MLIR ~/flang/src
make test check-all
```
To run individual regression tests llvm-lit needs to know the lit
-configuration for f18. The parameters in charge of this are:
+configuration for flang. The parameters in charge of this are:
flang_site_config and flang_config. And they can be set as shown bellow:
```
<path-to-llvm-lit>/llvm-lit \
- --param flang_site_config=<path-to-f18-build>/test-lit/lit.site.cfg.py \
- --param flang_config=<path-to-f18-build>/test-lit/lit.cfg.py \
+ --param flang_site_config=<path-to-flang-build>/test-lit/lit.site.cfg.py \
+ --param flang_config=<path-to-flang-build>/test-lit/lit.cfg.py \
<path-to-fortran-test>
```
projects / platform / upstream / llvm.git / commitdiff