> The HP compiler generates fused multiply and add by default and has several > settings for the +Ofltacc option to control this (and other optimizations > that affect floating point accuracy). > > +Ofltacc=default > > Allows contractions, such as fused multiply-add (FMA), but > disallows any other floating point optimization that can result > in numerical differences. > > +Ofltacc=limited > > Like default, but also allows floating point optimizations which > may affect the generation and propagation of infinities, NaNs, > and the sign of zero. > > +Ofltacc=relaxed > > In addition to the optimizations allowed by limited, permits > optimizations, such as reordering of expressions, even if > parenthesized, that may affect rounding error. This is the same > as +Onofltacc. > > +Ofltacc=strict > > Disallows any floating point optimization that can result in > numerical differences. This is the same as +Ofltacc.
Thanks for the info. > It would be easy enough to add an option that turned off the use of the > fused multiply and add in GCC but I would hate to see its use turned off > by default. If that's the consensus among IA-64 maintainers, it's fine with me. -- Eric Botcazou
