Hi Micah, instead of the prefix/suffix logic, why not do this:
...
} else if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
// Print the calling convention being used.
if (CI->getCallingConv() != CallingConv::C) // The default
PrintCallingConv(F->getCallingConv(), Out);
...
?
Ciao, Duncan.