Non-uniform program analysis & repeatable execution constraints: exploiting out-of-order processors in real-time systems

The objective of this paper is to enable easy, tight, and safe timing analysis of contemporary complex processors. We exploit the fact that out-of-order processors can be analyzed via simulation in the absence of variable control-flow. In our first technique, Non-Uniform Program Analysis (NUPA), program segments with a single flow of control are analyzed on a complex pipeline via simulation and segments with multiple flows of control are analyzed on a simple pipeline via conventional static analysis. A reconfigurable pipeline with dual complex/simple modes mirrors the hybrid analysis. Our second technique, Repeatable Execution Constraints for out-of-ORDER (RECORDER), defines constraints that guarantee a single input-independent execution time on an out-of-order pipeline for program segments with multiple flows of control. Thus, execution time can be derived via simulation with arbitrary inputs.