Compiler

A Compiler is a computer program translating code from one language to another.

General

When people write applications, they usually employ a text editor and a high level language like C/C++ or Fortran to produce code that looks somewhat like this:

Schematic of the compile process

#include <stdio.h>

int main()
{
   printf("Hello, World!\n");
   return 0;
}

This is easy to write, understand and maintain for humans. However, since a computer only understands 0s and 1s, this can not be executed directly. A Compiler tranlates this code into a binary file, which can be executed.

With the emergence of higher level programming languages, the entry barrier into programming is significantly lowered. This facillitates the creation of more complex programs which cannot (easily) be written just in terms of 0s and 1s by humans.

Basic Usage

You usually use a compiler by calling it from the shell:

$ cc hello_world.c -o hello_world.o

where you feed it the file hello_world.c and let it create the binary output file hello_world.o, which you can then execute by calling

$ ./hello_world.o

producing the desired output

Hello, World!

In most compilers there are optimization flags like -O2 (commonly ranging from 0 to 3), where the compiler tries to figure out, what your program is doing and whether there is more efficient way of doing that. When the development process is near completion and you begin to use your program productively, optimization should be turned on to ensure that the software runs as fast as possible.

When compiling an application (target) from multiple files, one might need to use another program called linker to bind the different parts together or even employ a build system like Make or CMake to simplify/automate the process of compiling and linking for more complex projects.

Intel Compiler

The Intel Compiler (icc) is a compiler written by Intel and optimized to utilize the features of their microprocessors to their fullest extend, sometimes resulting in a significant performance improvement. It is usually called with (maybe you have to load the corresponding module):

$ icc [files] [options]

Gnu Compiler Collection

The Gnu Compiler Collection (gcc) is a free collection of compilers, originally written for the GNU operating system and now available on all major platforms. It is usually called with (maybe you have to load the corresponding module):