The design of an embedded system is often heavily constrained by its performance objective and budget envelope. Software code compression may reduce the instruction memory space and then the overall cost of the system. However, it may also induce performance degradation. Previous studies proposed selective code compression using profile information in order to reduce the performance penalty. In this paper, we go one step further. We propose a software-only compression system, called SCS, that automatically finds trade-offs between code size and performance. Through an iterative approach, SCS automatically determines which functions to be compressed given a performance constraint and/or a code size constraint in order to guarantee a minimal performance and a maximal code size for an application. Experimentations illustrate that even with a non-optimal software decompression approach, SCS achieves a high compression rate with a minimal performance degradation.