On 02/24/2015 12:14 PM, Richard Biener wrote: > These concerns are correct. Btw, as an answer to Steve - within > -funsafe-math-optimizations FMA_EXPR basically can be either > fused or not fused (but yes, bad as to Josephs concern). > So you could guard the pattern by flag_unsafe_math_optimizations.
The unfused fma is always safe to use: it's the same as a multiply and an add, surely. Andrew.
