How about implementing SPMD on SIMD for D?

[Guillaume Piolat]

On Friday, 6 July 2018 at 23:08:27 UTC, Random D user wrote:
> [SPMD] works by running multiple iterations/instances of your 
> loop at once on SIMD and the compiler could do that 
> automatically for you and your normal loop & array code.
> It occurred to me that SPMD on SIMD would be really nice 
> addition to D's arsenal.
> Especially, since D doesn't even attempt any auto-vectorization 
> (poor results and difficult to implement) and manual loops are 
> quite tedious to write (even std.simd failed to materialize), 
> so SPMD would be nice alternative.

I think you are mistaken, D code is autovectorized often when 
using LDC.

Sometimes it's not and it's hard to know why.
A pragma we could have is the one in the Intel C++ Compiler that 
says "hey this loop is safe to autovectorize".

> What do you think?

I think that ispc is like OpenCL on the CPU, but can't work on 
the GPU, FPGA or other OpenCL implementation. OpenCL is so fast 
because caching is explicit (several levels of memory are 
exposed).