From my experience most of the bugs were just a 'normal' bugs i.e. human errors when writing and those were fixable by just figuring out what was implemented incorrectly. About 2% on a bts side were cache coherency issues because we had a multicore system without hardware coherency, so imagine, and similarily 2% were hardware issues on a modem side due to race conditions or whatever - harder to fix so workarounds. But miscompilation? x86 host tests are used to separate wheat from the chaff but the only tests anyone cares about, before commit, are on target

On modem side I remember one, maybe two if you push it, issues with miscompilation but it wasn't at all related to bitfields but the compiler was doing some stupid shit with register allocations