Hello!

I am interested in making a high-performance project which involves a lot of math, which is why I am interested in using SIMD (AVX2) on x86_64 (and for fun as well, if I'm honest). I am coming mainly from the C and C++ world where one has intrinsics (such as `_mm256_add_epi64`, to give an example from the Intel® Intrinsics Guide). I am most familiar with GCC (and to a lesser extent to Clang and ICC), where one can access these intrinsics through headers such as <immintrin.h>. Is there a Free Pascal equivalent for that?

I am well aware I can use asm blocks, but some intrinsics do more than one instruction and over on C it's the compiler's responsibility to find the best instruction for a given intrinsic.

Basically, can I directly implement `_mm256_add_epi64` so they're equivalent to doing the same thing in C? If not, what would be the best course of action to make wrappers for these intrinsics? I tried this:

```
program AVX2Example;
{$mode objfpc}{$H+}{$asmmode intel}
uses
   SysUtils;
type
   __m256i = packed array[0..3] of int64;

function _mm256_loadu_si256(src: __m256i): __m256i; assembler; asm
vmovdqu ymm0, ymmword ptr [src]
vmovdqa [Result], ymm0
end;

function _mm256_add_epi64(a, b: __m256i): __m256i; assembler; asm
vmovdqa ymm0, [a]
vmovdqa ymm1, [b]
vpaddq ymm0, ymm0, ymm1
vmovdqa [Result], ymm0
end;

var
   a: __m256i = (1, 2, 3, 4);
   b: __m256i = (5, 6, 7, 8);
   a1, a2: __m256i;
   res: __m256i;
   e: int64;
begin
   a1 := _mm256_loadu_si256(a);
   a2 := _mm256_loadu_si256(b);
   res := _mm256_add_epi64(a1, a2);
   for e in res do
   begin
     Write(e, ' ');
   end;
   Writeln;
end.
```

but it only works half of the time, so something is wrong.

Kind regards,
Stefan.

I have translated the Intel(R) Integrated Performance Primitives to FreePascal. I can send them if you like.

On MacOS, you can use the Accelerate libraries <https://developer.apple.com/accelerate/> which have headers translated to FreePascal (see the univint pacakage)

Regards,

Adriaan van Os