Buffer Sharing in CSP-like Programs

Most compilers focus on optimizing performance, often at the expense of memory, but efficient memory use can be just as important in constrained environments such as embedded systems. In this paper, we present a memory reduction technique for the deterministic concurrent programming language SHIM. We focus on reducing memory consumption by sharing buffers among the tasks, which use them to communicate using CSP-style rendezvous. We determine pairs of buffers that can never be in use simultaneously and use a shared region of memory for each pair. Our technique produces a static abstraction of a SHIM program’s dynamic behavior, which we then analyze to find buffers that can share memory. Experimentally, we find our technique runs quickly on modest-sized programs and often reduces memory requirements by half

Compiling SHIM

Embedded systems demand concurrency for supporting simultaneous actions in their environment and parallel hardware. Although most concurrent programming formalisms are prone to races and non-determinism, some, such as our SHIM (software/hardware integration medium) language, avoid them by design. In particular, the behavior of SHIM programs is scheduling-independent, meaning the I/O behavior of a program is independent of scheduling policies, including the relative execution rates of concurrent processes. The SHIM project demonstrates how a scheduling-independent language simplifies the design, optimization, and verification of concurrent systems. Through examples and discussion, we describe the SHIM language and code generation techniques for both shared-memory and message-passing architectures, along with some verification algorithms