avx512

There are generally two types of SIMD instructions: A. Ones that work with aligned memory addresses, that will raise general-protection (#GP) exception if the address is not aligned on the operand size boundary: movaps xmm0, xmmword ptr [rax] vmovaps ymm0, ymmword ptr [rax] vmovaps zmm0, zmmword ptr [rax] B. And the ones that work with unaligned memory addresses, that will not raise such exception: movups xmm0, xmmword ptr [rax] vmovups ymm0, ymmword ptr [rax] vmovups zmm0, zmmword ptr [rax] But I'm just curious, why would I want to shoot myself in the foot and use aligned memory instructions

When I do a writemasked AVX-512 store, like so: vmovdqu8 [rsi] {k1}, zmm0 Will the instruction fault if some portion of the memory accessed at [rsi, rsi + 63] is not mapped but the writemask is zero for all those locations (i.e., the data is not actually modified due to the mask). Another way of asking it is if these AVX-512 masked stores have a similar fault suppression ability to vmaskmov introduced in AVX. No fault is raised if masked out elements touch invalid memory. Here's some Windows test code to prove that masking does indeed suppress memory faults. #include <immintrin.h> #include

I was looking through the instruction set in AVX-512 and noticed a set of fixup instructions. Some examples : _mm512_fixupimm_pd, _mm512_mask_fixupimm_pd, _mm512_maskz_fixupimm_pd _mm512_fixupimm_round_pd, _mm512_mask_fixupimm_round_pd, _mm512_maskz_fixupimm_round_pd What is meant here by "fixing up"? That's a great question. Intel's answer (my bold) is here: This instruction is specifically intended for use in fixing up the results of arithmetic calculations involving one source so that they match the spec, although it is generally useful for fixing up the results of multiple-instruction

AVX512CD contains the intrinsic _mm512_conflict_epi32(__m512i a) it returns a vector where for every element in a a bit is set if it has the same value. Is there a way to do something similar in AVX2? I'm not interested in the extact bits I just need to know which elements are duplicates of the elements to their left (or right). I simply need to know if a scatter would conflict. Basically I need an AVX2 equivalent for __mm256i detect_conflict(__mm256i a) { __mm256i cd = _mm256_conflict_epi32(a); return _mm256_cmpgt_epi32(cd, _mm256_set1_epi32(0)); } The only way I could think of is to use