Parallel Static Single Assignment Form and Constant Propagation for Explicitly Parallel Programs

Static Single Assignment (SSA) form has shown its usefulness for powerful code optimization techniques, such as constant propagation, of sequential programs. We introduce a new Parallel Static Single Assignment (PSSA) form and the transformation algorithm for the explicitly parallel programs with interleaving semantics and post-wait synchronization. The parallel construct considered in this paper is cobegin/coend. A new concept ,-assignment, which summarizes the information of interleaving statements among threads, is introduced. Parallel Control Flow Graph, which contains the information of connicting statements in addition to control ow and synchronization information, is used as a intermediate representation for the PSSA transformation. A parallel extension of the Sparse Conditional Constant propagation algorithm based on the PSSA form makes it possible to apply the constant propagation optimization to explicitly parallel programs.