Re: ANN: LuaJIT 1.1.0 / Re: Lua x DirectX

["Andras Balogh" <andras.balogh@...>]

On Thu, 16 Mar 2006 09:27:41 -0700, Framework Studios: Hugo  
<hugo@framework-studios.com> wrote:

> If it 'only' means the FPU computes things differently internally, why  
> does Lua start crashing as soon as DX sets this flag to  
> single-precision? :-)

I don't know why it crashes, and I don't want to start guessing here..  
Still, floating point bugs can cause FPU exceptions, so it's not  
impossible that this causes a crash. And as far as I know, this flag  
really only changes the FPU control word...

> A performance hit of 3.5% just for having some FPU flag in the correct  
> state without even knowing if it actually really is used (SSE2) sounds  
> like a very good reason not to use double-precision to me.

Don't forget that this 3.5% gain was measured in an ill formed test case.  
In real apps I doubt that you would see this much difference. Anyways,  
this is your call, if there's an easy fix, then good for you, but I would  
rather opt to just avoid all the trouble altogether. You never know when  
it's gonna pop up again in some form of mysterious bug...

jm2c,


andras