Speculative parallelization needs rigor

Software speculative parallelization has shown effectiveness in parallelizing certain applications. Prior techniques have mainly relied on simple exploitation of heuristics for speculation. In this work, we introduce probabilistic analysis into the design of speculation schemes. In particular, by tackling applications that are based on Finite State Machine (FSM) which have the most prevalent dependences among all programs, we show that the obstacles for effective speculation can be much better handled with rigor. We develop a probabilistic model to formulate the relations between speculative executions and the properties of the target computation and inputs. Based on the formulation, we propose two model-based speculation schemes that automatically customize themselves with the best configurations for a given FSM and its inputs. The new technique produces substantial speedup over the state of the art.