llvm/flang/README.md

f18

Selection of the C/C++ compiler

F18 requires a C++17 compiler. As of today, the code was only tested with g++ 7.2.0, g++ 7.3.0 and clang 6.0.

For a proper installation, we assume that the PATH and LD_LIBRARY_PATH environment variables are properly set to use gcc, g++ and the associated libraries.

cmake will require that the environement variables CC and CXX are properly set (else it will search for use the 'cc' and 'c++' program which are likely /usr/bin/cc and /usr/bin/c++) that can be done now or while calling cmake

export CC=gcc
export CXX=g++

Installation of LLVM & CLANG 6.0

F18 depends of the LLVM & CLANG libraries even when clang is not used as C++ compiler.

If those libraries are not provided by your system then you may want to follow the build instructions at https://clang.llvm.org/get_started.html

Installation of F18

######## Choose the installation directory

F18_PREFIX=...   

######## Get Flang sources in $ROOT/f18
cd $ROOT
git clone https://github.com/ThePortlandGroup/f18.git

######## And build it in a dedicated directory
######## Reminder: If LLVM & Clang where not installed in a standard 
########           location then you may also have to specify it via the
########           CMAKE_MODULE_PATH or CMAKE_PREFIX_PATH variables. 
mkdir $ROOT/f18-build
cd $ROOT/f18-build   
CC=gcc CXX=g++ cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$F18_PREFIX $ROOT/f18
make -j 4
make install