Re: [boost] [GSoC] SIMD proposal

Subject: Re: [boost] [GSoC] SIMD proposal
From: Joel Falcou (joel.falcou_at_[hidden])
Date: 2011-03-23 17:16:36

On 23/03/11 21:45, Mathieu - wrote:
> However I have some questions about the subject in order to do my
> proposal, some of them have already been discussed with Joel Falcou
> and Mathias Gaunard on IRC, but here it is : One of the main concern I
> have is that nt2 relies heavily on cmake to detect various things like
> SSE instruction set support etc. From what I know (I ported nt2 to
> OpenBSD a while ago), depending on the architecture different methods
> are used, in order to be portable, like reading from sysctl in OSX or
> lauching a little executable which collect various informations using
> cpuid. So the question is : is bjam able to do everything we need to
> do, or will we need to do the detection in any other way?

The SIMD capability detection is only needed by the compilation step for 
the unit tests and user code.
It can be delayed there. Maybe bjam can ask for specific stuff like that 
on the user on the command line ?

> Another thing that is a bit blur for me at the moment, is what is the
> scope of boost.simd? I mean, from what I see the simd part is quite
> deep-rooted in nt2, has dependencies on several modules of it, so will
> boost.simd be a subset of nt2 simd module or will we need to rewrite
> part of it to avoid dragging huge dependencies (and well, end up doing
> boost.nt2).

the nt2 part of simd to be leveraged should be the core pack 
abstraction, the simd range adaptors and
first the basic operators + roughly an equivalent of libm or some such. 
We use some other stuff that can
live in boost::details.