[osg-users] Using SSE within OSG

James Killian James_Killian at hotmail.com
Tue Jul 29 08:07:34 PDT 2008


I have to disagree, using VS 7 and up to VS 9.  It has done a terrific job
with the instruction scheduling.  We use to use that technique of asm back
when P3's MMX were around and we had VS 6.  We had one engineer who would
use DOS and MASM.  Times have changed (we had to let him go), intrinsics
have proved to optimize quite well as we use the AMD code analyzer to
confirm that the U and V pipes remain full due to well scheduled placement
of the instructions.

I should add that we avoid using any MMX instructions like the plague now
days.

----- Original Message ----- 
From: "Gordon Tomlinson" <gordon.tomlinson at sensor.com>
To: "'OpenSceneGraph Users'" <osg-users at lists.openscenegraph.org>
Sent: Tuesday, July 29, 2008 8:56 AM
Subject: Re: [osg-users] Using SSE within OSG


> MS does a very poor job,
>
> I know most of our SSE is asm'ed
>
>
>
>   _____
>
> From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of David
> Spilling
> Sent: Tuesday, July 29, 2008 9:11 AM
> To: OpenSceneGraph Users
> Subject: Re: [osg-users] Using SSE within OSG
>
>
> Benjamin,
>
>
>
>
> may I suggest that you check the assembler code that the compilers create
> when
> compiling the OSG code?
>
>
>
> ... g++ with -march=core2 -O3 (see man page for description
> of parameters) the compiler automatically uses SSE
>
>
> I don't have much recent Linux/gcc experience, but can certainly attest
that
> the MS compilers don't do a good job of spotting SSE vectorisation
> possibilities, even when you tell them to optimise with them (and this is
> from reading the generated ssembler). In MS you can insert SSE intrinsics
,
> which still allow the compiler to optimise the execution order and
> memory/register usage e.g. based on cycle counts.
>
> I understand (from other sources) that the Intel vectorising compilers are
> much better at this, naturally.
>
> Perhaps this is then all only aMS/Windows thing?
>
> David
>
>
>
>
>


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