Add to ORKGInternational audienceThe polyhedral model is a wonderful but imperfect world. While many advanced and fully automatic program analysis and optimization techniques have been developed thanks to its accuracy and expressiveness, these techniques may fail in producing efficient codes in some circumstances. Recently, this has been identified more clearly through the proposition of a new programming structure called xfor (multifor). This structure eases the manual application of optimizing transformations on loop nests for expert programmers and allows to generate executable codes that may be significantly faster than those generated automatically using well-established polyhedral strategies. In this paper, we highlight five main gaps regarding ...