As for proposal to revert the aliasing fixes on the 4.2, IMHO aliasing bugs are pretty nasty it is hard to find a option to work around because alias info is used in many optimizations.
All bugs we are talking about can be worked around by using -fno-strict-aliasing.
FWIW, in Apple distributed GCC 4.0.x, strict-aliasing is disabled by default when -O? is used because it breaks too much existing code (not just Apple internal code). - Devang
