Re: [boost] [gsoc] boost.simd news from the front.

Subject: Re: [boost] [gsoc] boost.simd news from the front.
From: Joel falcou (joel.falcou_at_[hidden])
Date: 2011-06-11 14:24:50

On 11/06/11 12:16, David A. Greene wrote:

> You machine intrinsics here, yes?  This is where I think many times
> the compiler might do better.  If the compiler is good.  :)

Well, nothing prevent us to say that if on architecture X with compiler
Y, nothing has to be done, do nothing. Every arch/compiler/os combo is
an extension point in NT2

> It's a little odd that "important" information would be stripped.
> I know this is not a discussion of NT2 but for the curious, can
> you explain this?  Thanks!

not stripped sorry, exploited where it need and potentially removed 
before being passed to the underlying level where they make less sense.

> Oh absolutely.  But I think that such people should be aware that code
> generated by boost.simd may not be the best for their hardware
> implementation IF they have access to a good compiler later.  In those
> cases, though, I suppose replacing, say, pack<float>  with float
> everywhere should get most of the original scalar code back.  There may
> yet be a little more cleanup to do but isn't that the case with _every_
> HPC code?  :) :) :)

The code can be let untouched by sayign that on machine X with compiler 
Y, pack<float> is just w/e it need to be and redirecting pack operators 
and functions to a simple scalar version. We should I think keep the 
pack abstraction, even if for some smart compilers the onyl stuff it 
will do is add w/e mark-up/pragma/infos the compiler want to see.

boost.simd is really for just letting peopel that need to mess with this 
kind of code for w/e reasons (and we evoked a few) to do so in a 
platform independant way with proper abstraction. If you need more, then 
we need to let a higher level tools do it, and that's what nt2 aims to be.