Unified control flow and data dependence traces

Abstract

We describe the design, generation, and compression of the extended whole program path (eWPP), representation that not only captures the control flow history of a program execution but also its data dependence history. This representation is motivated by the observation that, typically, a significant fraction of data dependence history can be recovered from the control flow trace. To capture the remainder of the data dependence history, we introduce disambiguation checks in the program whose control flow signatures capture the results of the checks. The resulting extended control flow trace enables the recovery of otherwise irrecoverable data dependences. The code for the checks is designed to minimize the increase in program execution time and the extended control flow trace size when compared to directly collecting control flow and address traces. Our experiments show that compressed eWPPs are only one-quarter of the size of combined compressed control flow and address traces. However, their collection incurs a 5× increase in runtime overhead relative to the overhead required for directly collecting the control flow and address traces, respectively.