[andrewchambers]

I don't think this is really true. Generally all optimization passes are run upon the unoptimized version, hence ALL code paths first pass through the -O0 machinery.

Besides, they seem to manually inspect the assembly output themselves for the final production build.

[craftit]

But the code path is first pass + optimisation gives correct code. That doesn't guarantee the first pass generates correct code. I believe there were bugs along those lines at one stage, though I admit they are rare. I've not had to track down a compiler bug in quite a few years.