[fpc-devel] Current work

[J. Gareth Moreton]

To show current progress, the .section 
.text.n_system.math.vectors$_$tvector3d_$__$$_$plus$tvector3d$tvector3d$$tvector3d,"ax" 
routine ("class operator TVector3D.+(const aVector1, aVector2: 
TVector3D): TVector3D;") on x86_64-win64 - before (this performs a 
component-wise addition of two 4-component vectors... inputs are pointed 
to by %rdx and %r8, and the result is pointed to by %rcx):

     movss    (%rdx),%xmm0
     addss    (%r8),%xmm0
     movss    %xmm0,(%rcx)
     movss    4(%rdx),%xmm0
     addss    4(%r8),%xmm0
     movss    %xmm0,4(%rcx)
     movss    8(%rdx),%xmm0
     addss    8(%r8),%xmm0
     movss    %xmm0,8(%rcx)
     movss    12(%rdx),%xmm0
     addss    12(%r8),%xmm0
     movss    %xmm0,12(%rcx)
     ret

After:

     movups    (%rdx),%xmm0
     addps    (%r8),%xmm0
     movups    %xmm0,(%rcx)
     ret

(Note that this unit is NOT suitable for 3D graphics because the 
W-coordinate is treated the same as X, Y and Z rather than being kept at 
1, say)

It's not perfect though.  When vectorcall or the System V ABI is 
concerned, it can produce worse code because of constantly needing to 
break up the vector to manipulate individual components, and there may 
be some unnecessary reads and writes between the stack and XMM 
registers, but I'm working on it, bit by it.

My current branch can be found here: 
https://gitlab.com/CuriousKit/optimisations/-/commits/ucomplex-x86-vector

Kit

On 23/08/2024 17:56, J. Gareth Moreton via fpc-devel wrote:
>
> Hi everyone,
>
> So I'm getting ready to showcase my current vector work to others.  I 
> do have a question though...
>
> Currently the feature is locked behind "-Sv", since this is 
> specificially "support vector processing" and the feature is still 
> experimental and inefficient in places, but is this the right 
> approach?  I ask because the -S switches are specifically syntax 
> options, not code generation options (I do wonder exactly what syntax 
> it enables).  Also, at least with the "make" script, it skips whole 
> program optimisation and some of the packages.
>
> Should I use a compiler definition instead like "-dX86_VECTORS"?  That 
> way, the feature can easily be turned off.
>
> Kit
>
> On 21/08/2024 15:59, J. Gareth Moreton via fpc-devel wrote:
>>
>> Hi everyone,
>>
>> Just thought I'd give a heads-up on what's happening with me and the 
>> compiler improvements.  Also, I've been busy with contract work and 
>> have just had some minor surgery, so I'm not running on all cylinders 
>> currently.
>>
>>   * Still waiting on administrator comments and feedback on my
>>     assembly-level CSE feature (a couple of years old now) and the
>>     first part of pure functions.  Both of these should be ready to
>>     merge unless someone found a bug that breaks things (someone did
>>     find some examples with pure functions which have since been fixed).
>>   * Haven't solved the SEH unwinding problem on aarch64-win64 yet. 
>>     This is quite a tough one!
>>   * Also working on vectorisation for x86_64 platforms.  I've got it
>>     working on win64, and can vectorise two-operand commutative
>>     operations like addition and multiplication, although some of the
>>     generated code is less than optimal (unnecessarily copying
>>     vectors to the stack).  Linux (and other OSes that use the System
>>     V ABI) is taking a bit longer since it stores pairs of floats in
>>     single XMM registers even without vectorisation code, and some of
>>     the internal procedures can't properly handle these if the desire
>>     is to combine a pair of these such registers (so 4 singles) into
>>     a single XMM vector, especially where shuffling is involved.
>>
>> I'll let you know the progress.
>>
>> Kit
>>
>>
>> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> 
>> 	Virus-free.www.avast.com 
>> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> 
>>
>>
>> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>>
>> _______________________________________________
>> fpc-devel maillist  -fpc-devel at lists.freepascal.org
>> https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
>
> _______________________________________________
> fpc-devel maillist  -fpc-devel at lists.freepascal.org
> https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

-- 
This email has been checked for viruses by Avast antivirus software.
www.avast.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freepascal.org/pipermail/fpc-devel/attachments/20240823/866826d1/attachment.htm>