Section: New Results

Parameterized Construction of Program Representations for Sparse Dataflow Analysiss

Participants : André Tavares [UFMG, Belo Horizonte, Brazil] , Benoit Boissinot [Ex-Compsys, Google Zurich] , Fernando Magno Quintão Pereira [UFMG, Belo Horizonte, Brazil] , Fabrice Rastello.

Data-flow analysis usually associates information with control flow regions. Informally, if these regions are too small like a point between two consecutive statements, we call the analysis dense. On the other hand, if these regions include many such points, then we call it sparse. This work presents a systematic method to build program representations that support sparse analyses. To pave the way to this framework, we clarify the literature about well-known intermediate program representations. We show that our approach, subsumes, up to parameter choices, many of these representations, such as the SSA, SSI, and e-SSA forms. In particular, our algorithms are faster, simpler and more frugal than the previous techniques used to construct SSI (static single information) form programs. We produce intermediate representations isomorphic to Choi et al.'s sparse evaluation graphs (SEG) for the family of data-flow problems that can be partitioned by variables. However, contrary to SEGs, we can handle - sparsely - problems that are not in this family. We have tested our ideas in the LLVM compiler, comparing different program representations in terms of size and construction time.

This work is part of the collaboration with UFMG (see Section  8.4 ) and has been accepted for presentation and publication at CC'14 (Compiler Construction Conference) [9] .