Ph.D. dissertation by Jeehoon Kang

Submitted to the Dept. of Computer Science and Engineering, Seoul National University, Korea

Thesis committee


To improve the performance of C programs, mainstream compilers perform aggressive optimizations that may change the behaviors of programs that use low-level features in unidiomatic ways. Unfortunately, despite many years of research and industrial efforts, it has proven very difficult to adequately balance the conflicting criteria for low-level features and compiler optimizations in the design of the C programming language. On the one hand, C should support the common usage patterns of the low-level features in systems programming. On the other hand, C should also support the sophisticated and yet effective optimizations performed by mainstream compilers. None of the existing proposals for C semantics, however, sufficiently support low-level features and compiler optimizations at the same time.

In this dissertation, we resolve the conflict between some of the low-level features crucially used in systems programming and major compiler optimizations. Specifically, we develop the first formal semantics of relaxed-memory concurrency, separate compilation, and cast between integers and pointers that (1) supports their common usage patterns and reasoning principles for programmers, and (2) provably validates major compiler optimizations at the same time. To establish confidence in our formal semantics, we have formalized most of our key results in the Coq theorem prover, which automatically and rigorously checks the validity of the results.