actually that story is the opposite of true. John Regher and CSmith fuzzed CompCert and they found no bugs. from the csmith PLDI paper:

"The striking thing about our CompCert results is that the middleend bugs we found in all other compilers are absent. As of early 2011, the under-development version of CompCert is the only compiler we have tested for which Csmith cannot find wrong-code errors. This is not for lack of trying: we have devoted about six CPU-years to the task."