TimeC: A Time Constraint Language for ILP Processor Compilation

Enabled by RISC technologies, low-cost commodity microprocessors are performing at ever increasing levels, significantly via instruction level parallelism (ILP). This in turn increases the opportunities for their use in a variety of day-to-day applications ranging from the simple control of appliances such as microwave ovens, to sophisticated systems for cabin control in modern aircraft. Indeed, “embedded” applications such as these represent segments in the computer industry with great potential for growth. However, this growth is currently impeded by the lack of robust optimizing compiler technologies that support the assured, rapid and inexpensive prototyping of real-time software in the context of microprocessors with ILP. In this paper we describe a novel notation, TimeC, for specifying timing constraints in programs, independent of the base language being used to develop the embedded application; TimeC specifications are language independent and can be instrumented into imperative and object-oriented languages non-intrusively. As we will show, the program synthesis problem that arise out of Time_tract specifications, a subset of TimeC, are always “tractable.” In contrast, a range of specification mechanisms proposed earlier yield substantially intractable synthesis questions, thereby limiting their potential utility. We will compare the tractability and related expressive power issues between TimeC and some of the extant mechanisms for specifying properties of timed programs.