Benchmarks - LDC vs GDC

[Bruce Carneal]

On Tuesday, 27 June 2023 at 09:31:50 UTC, Sergey wrote:
> On Monday, 26 June 2023 at 20:22:24 UTC, Cecil Ward wrote:
>>
>> Anyone up for it?
>
> Hi. Every problem from this set of benchmarks has D solution 
> https://programming-language-benchmarks.vercel.app/
> ...
Nice link.

>
> Also GDC and LDC have their special things for vectorizations. 
> And maybe Bruce Carneal could share some examples/benchmarks of 
> them.

The TL;DR from my auto vectorization explorations is that GDC and 
LDC are very close in performance with GDC having a slight edge 
when doing some patterned "gathers" (like pulling elements from 
an RGGB Bayer pattern) and in exploiting the per-lane 
capabilities of later AVX-512 although I expect LDC will match it 
there pretty soon. Anecdotally it appears that they'll both do 
very well on SVE2 and RVV platforms.

Once you get things to unit stride form LDC and GDC are both very 
good. They both handle ternary expression style conditionals 
well, for example.  You may wish to use @restrict pointers to 
signal independence.

Also, if you're serious about programmer friendly data 
parallelism on CPUs definitely take a look at mir.  dcompute (LDC 
only) is worth a hard look for CUDA/OpenCL deployments.

Godbolt is your friend here.  Have fun!