Bounds Check Hoisting for AddressSanitizer

The C programming language is not memory safe, that is to say that the semantics of out-of-bounds memory accesses are undefined. There are tools that make certain guarantees about memory safety for C programs. Amongst these are SAFECode and AddressSanitizer. The latter instruments C programs with runtime checks to guarantee that no invalid memory accesses are allowed to execute. As is to be expected, this incurs in a notable performance decrease in instrumented programs. Our work consists in hoisting these checks out of loops in such a way that we maintain AddressSanitizer’s semantics, but, by providing increased locality of access and by increasing the stride of bounds checks, we make said checks notably cheaper. Unlike previous approaches to bounds check hoisting, we use a parametric interval analysis to bound the index ranges used in array accesses. We evaluated our method on a collection of benchmarks from Polybench and from the domain of scientific computing. The optimization recovers 60.6 % of the overhead introduced by AddressSanitizer on average. Since energy performance is a crucial factor on mobile systems, we have also evaluated our proposed solution on embedded systems in this regard. We observed a 31.7 % reduction in energy consumption in programs instrumented with AddressSanitizer.