Compiling

Compilers

Language	Developer	Command	MPI	OpenMP
Fortran 77	GNU	gfortran	mpif77	gfortran -fopenmp
Fortran 90/95/03	GNU	gfortran	mpif90	gfortran -fopenmp
C	GNU	gcc (cc)	mpicc	gcc -fopenmp
C++	GNU	g++ (c++)	mpicxx (mpic++, mpiCC)	g++ -fopenmp
Fortran 77	PGI	pgfortran (pgf77)	mpif77	pgfortran -mp
Fortran 90/95/03	PGI	pgfortran (pgf90, pgf95)	mpif90	pgfortran -mp
C	PGI	pgcc	mpicc	pgcc -mp
C++	PGI	pgc++	mpicxx (mpic++, mpiCC)	pgc++ -mp
Fortran 77/90/95/03	Intel	ifort	mpifort (mpif90, mpif77)	ifort -openmp
C	Intel	icc	mpicc	icc -openmp
C++	Intel	icpc	mpicxx (mpic++, mpiCC)	icpc -openmp

General compiler flags (GCC/Clang)

• -g - turn on debugging (so GDB gives more friendly output)
• -Wall - turns on most warnings
• -std=c++11 - specify C++ version 11
• -fPIC - Position Independent Code to avoid error when building shared libraries for dynamic linking
• -O0 - no optimization, faster compilation, better for debugging builds
• -O1 - turn on optimizations - minimize code size
• -O2 - turn on optimizations - maximize speed
• -O3 - turn on higher level of optimizations, slow compiling-time, better for production builds
• -OFast - higher level of optimizations than -O3
• -o <name> - name of the output file
• -c - output an object file (.o)
• -D_GLIBCXX_USE_CXX11_ABI=0 - if you use GCC 5 or higher
• -I<include path> - specify an include directory
• -L<library path> - specify a lib directory
• -l<library> - link with library lib.a

Tricks for C++ compilation

1. Parallelism: -J N, where N is number of jobs
2. Build on local disk instead of a network file system like NFS. SSD is better than HDD.
3. Upgrade to a newer version of gcc
4. The more RAM your machine has, the faster compilation
5. Guard condition for header

#ifndef SOME_NAME_h
#define SOME_NAME_h

...

#endif

6. Forward declaration

int sum(int, int);

int sum(int a, int b)
{
    return a+b;
}

7. unnamed or anonymous namespaces

namespace {
...
}