SIMD intrinsics

[via digitalmars-d-ldc]

ldc.gccbuiltins_x86.di does not contain:

__m256 _mm256_add_ps (__m256 a, __m256 b)
#include "immintrin.h"
Instruction: vaddps ymm, ymm, ymm
CPUID Flags: AVX

But it does contain less important instructions such a 256bit 
"addsub".

I am trying to build up a set of standard Intel intrinsics, but 
not sure how to work around this (or did I miss something?)