Compiling with code-size constraints

Most compilers ignore the problems of limited code space in embedded systems. Designers of embedded software often have no better alternative than to manually reduce the size of the source code or even the compiled code. Besides being tedious and error-prone, such optimization results in obfuscated code which is difficult to maintain and reuse. In this paper, we present a code-size-directed compiler. We phrase register allocation and code generation as an integer linear programming problem where the upper bound on the code size can simply be expressed as an additional constraint. Our experiments show that our compiler, when applied to two commercial microcontroller programs, generates code as compact as carefully crafted code.