Michael S (already5chosen.delete@this.yahoo.com) on May 19, 2022 1:14 am wrote:
> E.g. you invested significant effort in manual optimization of AVX path. You organized your arrays
> in 256-bit oriented "hybrid" (==AoSoA) data layout and use of _mm256_xxx() in two inner levels
> of loops. And you achieved good results, say, 65-70% of peak FLOPs of your AVX2 CPU. Then now you
> probably want to achieve similar or slightly lower sustained-to-peak FLOPs ratio with AVX-512.

Why not something like:

#ifdef __AVX512F__

# define _mm(f) _mm512_##f

# define __mfloat __m512



# include "your-code-file.c"



# undef _mm

# undef __mfloat



#else



# define _mm(f) _mm256_##f

# define __mfloat __m256



# include "your-code-file.c"



# undef _mm

# undef __mfloat



#endif

and with a bit of find & replace, the code will magically transform based on a compiler switch. Retains 100% ISA functionality unlike other SIMD abstraction layers.
Obviously won't work if your workload is highly width dependent, but if it isn't, should do a reasonably good job (and you can sprinkle #ifdefs where it's advantageous).