Using AVX intrinsics with LDC

kinke noone at
Tue May 15 18:23:16 UTC 2018

On Tuesday, 15 May 2018 at 17:21:49 UTC, Jeff wrote:
> Hello,
> I'm a beginner in D (I come from C++/Python), but I'm having 
> great fun learning the language reading Ali's book. I'm using 
> LDC as compiler, and I would like to use intrinsics, but I have 
> difficulties to find the Intel intrinsics equivalent. Here are 
> the functions I'm looking for :
> _mm_cvtsi64x_si128
> _mm256_sll_epi64
> _mm256_movemask_epi8
> Is there a way to call them ? Is there an Intel intrinsics to 
> LDC intrinsics guide somewhere ?
> Thanks for your help !

Hi, you'll want to have a look at LDC's 
`import/ldc/gccbuiltins_x86.di` file (auto-generated from 
corresponding LLVM x86 intrinsics). Make sure to enable extended 
instruction sets via something like `-mattr=+avx2` (or simply 

_mm256_movemask_epi8 => __builtin_ia32_pmovmskb256
_mm256_sll_epi64     => __builtin_ia32_psllqi256

I didn't find the corresponding declaration for 
_mm_cvtsi64x_si128 (__builtin_ia32_vzeroupper strangely takes no 
args). You can always resort to LLVM assembly though (grep for 
`__asm` in import directory to see some examples in 

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