Procedure Boundary Elimination for EPIC Compilers

Procedures are the basic units of compilation in traditional optimization frameworks. This presents problems to compilers targeting EPIC architectures, since the limited scope of a single procedure is usually insufficient for extracting ILP and identifying enough optimization opportunities. Although inlining can expand the scope of optimization routines, it is not applicable to all call sites and can cause excessive code growth, which can in turn adversely affect cache performance and compile-time resource usage. In this paper we propose a novel compilation strategy called Procedure Boundary Elimination (PBE). PBE unifies the whole program into a single compilation unit, which is then restructured into units better suited to optimization than the original procedures. A targeted specialization phase exposes further optimization opportunities while limiting code growth only to the cases where it is beneficial. Unlike inlining, PBE can eliminate all procedure calls while avoiding the cost of excessive code growth.