bigfloat

[bearophile]

Don:
> On Intel machines, in which adc and sbc are ridiculously slow and have 
> an undocumented stall with conditional jumps,

I don't know if a i7 CPU too has such problem.
It may sound silly, but why don't you write that to Intel (giving some demo asm code too, if necessary), asking if they can remove such bug from next generation of CPUs? From several things I have read and seen in the past it seems they are willing to listen to people that know what they are talking about. For example years ago they have listened to the authors of one Doom version, or to the authors of a famous open source video decoder (I think H.264).
A good amount of time ago I have discussed with one of them them regarding a faster integer divisions of small integers (similar to what good C compilers do to divide by small constants).

Bye,
bearophile