Dozens of “free” compilers exist for C, C++ and Fortran. However, only five compiler families available at no charge support the modern features of these popular compiled languages.
GCC has broad support of modern standards on a very wide range of computing platforms. GCC’s downside in some cases can be slower runtime performance than compilers having less broad language and platform support.
LLVM Clang and Flang have significant industry support, including from Nvidia, and are known for high performance, but somewhat less language feature support and less broad platform support than GCC.
clangC17 support. Since Clang 6, defaults to C11.
flangFortran 2008 support includes
Intel compilers are a paid product in general. For non-commercial purposes, including:
- open-source projects
IBM XL compilers are currently for POWER CPUs only e.g. ppc64le. IBM XL compilers do not work with a typical x86-based computer. If you have a $2000 Raptor IBM POWER9 desktop, then IBM XL may be for you.
The IBM XL compilers are high-performance compilers that have a free community edition. IBM XL Fortran has wide support for Fortran 2008.