Code padding to Improve the WCET Calculability

The Worst-Case Execution Time of tasks with strict deadlines must be predictable: it must be possible to estimate this time both safely and tightly at an acceptable computing cost. Static WCET analysis is facilitated if parts of code can be analyzed more or less independently of one another. This is why it is desirable to prevent timing interferences between blocks. In this paper, we show how it is possible to transform the code to prevent timing effects between distant basic blocks on an execution path. Our approach consists in padding the code to space out basic blocks. Performance results show that the code size is sensibly increased but that the cost in terms of WCET degradation is moderate.