Raymond Sheh wrote: > > Specifying -fsome-optimization without an n >= 0 level of -On is a > > no-op. In other words, optimization must be enabled in order to do any > > optimization. I meant > 0 here, as -O0 means no optimization. > This is all being tested on pretty much a standard Kubuntu 7.10 (Gutsy > Gibbon) install using the distro's GCC packages ... perhaps is there > some way of seeing what the defaults are set to? Is it possible that for > some reason some optimisation level (below -O1, if there is such a > thing) is enabled by default? If you don't specify any -O the default is -O0, which is no optimizations. I don't know why you are able to also trigger a failure without optimizations just by giving -fstrict-aliasing -fschedule-insns, but it's kind of beside the point since combining source that violates the aliasing rules with -fstrict-aliasing is just setting yourself up for failure, regardless of the details. Brian