This answer is stolen from the polaris web page at UIUC:
"The Polaris compiler takes a Fortran77 program as input, transforms this program so that it runs efficiently on a parallel computer, and outputs this program version in one of several possible parallel Fortran dialects. The input language includes several directives which allow the user of Polaris to specify parallelism explicitly in the source program. The output language of Polaris is typically in the form of Fortran77 plus parallel directives as well. For example, a generic parallel directive set includes the directives "CSRD$ PARALLEL" and "CSRD$ PRIVATE a,b", specifying that the iterations of the subsequent loop shall be executed concurrently and that the variables a and b shall be declared "private to the current loop", respectively. Another output language that Polaris can generate is the Fortran plus the directive language available on the SGI Challenge machine. (The Purdue version also supports the OpenMP API). Polaris performs its transformations in several "compilation passes". In addition to many commonly known passes, Polaris includes advanced capabilities performing the following tasks: array privatization, data dependence testing, induction variable recognition, interprocedural analysis, and symbolic program analysis. An extensive set of options allow the user and the developer of Polaris to experiment with the tool in a flexible way. An overview of the Polaris transformations is given in the Publication Automatic Detection of Parallelism: A Grand Challenge for High-Performance Computing. The implementation of Polaris consists of 170,000 lines of C++ code. A basic infrastructure provides a hierarchy of C++ classes that the developers of the individual compilation passes can use for manipulating and analyzing the input program. This infrastructure is described in the Publication "The Polaris Internal Representation".