Compilation Phases

The compiler processes Fortran language source and generates object files. You decide the input and output by setting options when you run the compiler.

When invoked, the compiler determines which compilation phases to perform based on the extension of the source filename and on the compilation options specified in the command line.

The compilation phases and the software that controls each phase are shown below:

Compilation phase

Controlling software

IA-32 or Itanium®-based applications?

Preprocess (optional)






Assemble (optional)

as or ias

as for IA-32 applications; ias for Itanium-based applications




By default, the compiler generates an object file directly without calling the assembler. However, if you need to use specific assembly input files and then link them with the rest of your project, you can use an assembler for these files.

The compiler passes object files and any unrecognized filename to the linker. The linker then determines whether the file is an object file (.o) or a library (.a) or shared library (.so).The compiler handles all types of input files correctly. Thus, you can use it to invoke any phase of compilation.