Compiling Real-Time Programs with Timing Constraint Refinement and Structural Code Motion

We present a programming language called TCEL (Time-Constrained Event Language), whose semantics is based on time-constrained relationships between observable events. Such a semantics infers only those timing constraints necessary to achieve real-time correctness, without over-constraining the system. Moreover, an optimizing compiler can exploit this looser semantics to help tune the code, so that its worst-case execution time is consistent with its real-time requirements. In this paper we describe such a transformation system, which works in two phases. First the TCEL source code is translated into an intermediate representation. Then an instructionscheduling algorithm rearranges selected unobservable operations and synthesizes tasks guaranteed to respect the original event-based constraints. Keywords: Real-time, programming languages, compiler optimization, code scheduling, static single assignment, gated single assignment, timing analysis, trace scheduling, code motion. This rese..