Regehr: GCC 4.8 Breaks Broken SPEC 2006 Benchmarks

No, the assumption is how C programs work. It is in general impossible to tell if there is going to be an out-of-bounds access without checking every access. If you want code that checks that, then wrap every array access in the equivalent of vector.at() and let the compiler try to remove redundant checks.

Of course, GCC could do better at static analysis and warning about such cases, but that is a different problem from optimization, and GCC needs new developers that are interested in such things.