On 12/04/12 17:16, Andrew Stubbs wrote: > On 12/04/12 16:48, Richard Earnshaw wrote: >> If negation in Neon needs a scratch register, it seems to me to be >> somewhat odd that we're disparaging the ARM version. > > Good point, I'm really meaning to provide missing functionality in NEON > to prevent unnecessary moves, rather than cause them, so I should remove > the '?'s. > > It probably doesn't need disparaging on A8, etiher?
Possibly not. Which then begs the question as to whether we need an A8 variant at all. > >> Also, wouldn't it be sensible to support a variant that was >> early-clobber on operand 0, but loaded immediate zero into that value first: >> >> vmov Dd, #0 >> vsub Dd, Dd, Dm >> >> That way you'll never need more than two registers, whereas today you >> want three. > > That does seem like a good option. I'll have a go and see what happens. > > Andrew >
