PhD defense : Beyond the Realm of the Polyhedral Model: Combining Speculative Program Parallelization with Polyhedral Compilation

PhD defense : Aravind SUKUMARAN-RAJAM

Team : ICPS

Title : Beyond the Realm of the Polyhedral Model: Combining Speculative Program Parallelization with Polyhedral Compilation

Abstract : In this thesis, we present our contributions to APOLLO (Automatic speculative POLyhedral Loop Optimizer), which is an automated compiler combining Thread Level Speculation (TLS) and the polyhedral model to optimize codes on the fly. By doing partial instrumentation at runtime, and subjecting it to interpolation, Apollo is able to construct a speculative polyhedral model dynamically. The speculative model is then passed to Pluto -a static polyhedral scheduler-. Apollo then selects one of the statically generated code optimization skeletons and instantiates it. The runtime continuously monitors the code for any dependence violation in a decentralized manner. Another important contribution of this thesis is our extension of the polyhedral model to codes exhibiting a non linear behavior. Thanks to the dynamic and speculative context offered by Apollo, non-linear behaviors are either modeled using linear regression hyperplanes forming tubes, or using ranges of reached values. Our approach enables the application of polyhedral transformations to non-linear codes thanks to an hybrid centralized-decentralized speculation verification system.

The presentation will take place on Thursday 5th November 2015 at 2.00pm in room A302 at the pole API building in Illkirch. This thesis will be supported in english.