Design of Graphite and the Polyhedral Compilation Package

Graphite is the loop transformation framework that was introduced in GCC 4.4. This paper gives a detailed de-scription of the design and future directions of this in-frastructure. Graphite uses the polyhedral model as the internal representation (GPOLY). The plan is to create a polyhedral compilation package (PCP) that will pro-vide loop optimization and analysis capabilities to GCC. This package will be separated from GIMPLE via an in-terface language that is restricted to express only what GPOLY can represent. The interface language is a set of data structures that encodes the control flow and mem-ory accesses of a code region. A syntax for the language is also defined to facilitate debugging and testing.