On Fri, Nov 09, 2018 at 01:03:55PM -0700, Jeff Law wrote: > >> And signed zeroes. Yeah. I think it would have to be > >> flag_unsafe_math_optimizations + some more. > > > > Indeed. > So we need to give Giuliano some clear guidance on guarding. This is > out of my area of expertise, so looking to y'all to help here.
IMO, it needs flag_unsafe_optimizations, as above; and it needs to be investigated which (if any) options like flag_signed_zeros it needs in addition to that. It needs an option like that whenever the new expression can give a zero with a different sign than the original expression, etc. Although it could be said that flag_unsafe_optimizations supercedes all of that. It isn't clear. Segher
