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- Subject: Re: Reproducible floating point arithmetic in LuaJIT 2
- From: Mike Pall <mikelu-0911@...>
- Date: Sat, 14 Nov 2009 23:04:55 +0100
Erik Lindroos wrote:
> [BTW: That still doesn't solve the various issues with the x87
> > transcendental functions or with pow().]
> Yes, I will replace them with fdlibm derivatives.
Be careful about spilled registers when calling C functions. I've
already added generic C call handling for compiled code, so you
may want to wait for the next developer snapshot or the next beta
before adding this.
> Ah, I considered this, but DISPATCH isn't available in lj_vm_foldarith,
> Although, lj_vm_foldarith doesn't need to be very fast anyway.
Yes, it's not available there and yes, performance of this
function is not relevant.
> > But IMHO the better solution is to (optionally) use SSE2 in the
> > interpreter, too. The intersection of the set of people who still
> > have an x87-only box and the set of people who really need
> > reproducible FP arithmetic is probably empty.
> I agree it's almost not worth the bother, but I'd like to keep things as
> portable as possible unless it's a large effort.
Well, I'll need this for the x64 port, anyway. And only a dozen
lines need to be changed (ignoring the transcendental functions).