Lionel Debroux (./2) :
There's one significant problem, though: reliability (rather, lack thereof). -fwhole-program --combine are buggy, i.e. you can see more Internal Compiler Errors than the usual with those modes, and invalid generated code happens once in a while.

Is this also true if I only use -fwhole-program and not --combine? I know I have read about people having trouble with --combine, but I thought -fwhole-program just made all functions static (and if optimizing static functions is buggy, then I'm in big trouble, anyway). My program has no name collisions, so I can easily just cat everything together before compiling.