About 9-10 years ago, I worked at a company maintaining an application written in C. There were three other programmers there who had been with the company from

About 9-10 years ago, I worked at a company maintaining an application written in C. There were three other programmers there who had been with the company from the beginning, which at the time was ~15 years. They used the OpenWatcom compiler. A few days in, I discovered that they compiled all their code with all compiler optimizations disabled. They had done so ever since they encountered a bug in the compiler/optimizer where the compiler would somehow think that a boolean expression involving floating point numbers in the head of an if-statement would always evaluate to true or false and thus optimize away either the if-part leaving only the body, or remove the whole if-statement. I did a little bit of research and found what I think was that bug in the release notes to an earlier version, but even so the other programmers were adamant in keeping optimizations disabled. (FWIW, I once did a build with all reasonable optimizations enabled, and the improvement was miniscule. Either our code sucked so hard the optimizer could not do much about it, or it was so good there was nothing left for the compiler to optimize. I doubt it was the latter, though. ;-) )