On Thu, Feb 16, 2017 at 09:13:31AM +1100, Richard Henderson wrote: > On 02/15/2017 05:37 PM, Bharata B Rao wrote: > > + * > > + * TODO: When float128_muladd() becomes available, switch this > > + * implementation to use that instead of separate float128_mul() > > + * followed by float128_add(). > > Let's just do that, rather than add something that can't pass tests. > > You should be able to copy float64_muladd and, for the most part, s/128/256/ > and s/64/128/. Other of the magic numbers, like the implicit bit and the > exponent bias, you get from float128_mul.
I started like that but got lost somewhere down that path... It needs at least the following new functions to be implemented: propagateFloat128MulAddNaN shortShift256Left shift256RightJamming add256 sub256 It all looked doable, but the magic numbers used around the code that does eventual multiplication looked difficult to understand and I couldn't deduce that from float128_mul. For some reason float128_mul implements multipliction via multiplication and addition (mul128To256 & add128). There is no equivalent to this in float64_muladd. Let me make another attempt at this. Regards, Bharata.
