avx

The idea is that I'd like to collect returned values of double into a vector register for processing for machine imm width at a time without storing back into memory first. The particular processing is a vfma with other two operands that are all constexpr , so that they can simply be summoned by _mm256_setr_pd or aligned/unaligned memory load from constexpr array . Is there a way to store double in %ymm at particular position directly from value in %rax for collecting purpose? The target machine is Kaby Lake. More efficient of future vector instructions are welcome also. Inline-assembly is

This question already has an answer here: How to sum __m256 horizontally? 2 answers I have two arrays of floats and I would like to calculate the dot product, using SSE and AVX, in the lowest latency possible. I am aware there is a 256-bit dot product intrinsic for floats but I have read on SO that this is slower than the below technique: ( https://stackoverflow.com/a/4121295/997112 ). I have done most of the work, the vector temp_sums contains all the sums, I just need to sum all the eight 32-bit sums contained within temp_sum at the end. #include "xmmintrin.h" #include "immintrin.h" int main

Is there a convention for displaying/writing large registers, like those available in the Intel AVX instruction set? For example, if you have 1 in the least significant byte, and 20 in the most significant byte, and 0 elsewhere in an xmm register, for a byte-wise display is the following preferred (little-endian): [1, 0, 0, 0, ..., 0, 20] or is this preferred: [20, 0, 0, 0, ..., 0, 1] Similarly, when displaying such registers as made up of larger data items, is the same rule applied? E.g., to display the register as DWORDs, I assume each DWORD is still written in the usual (big-endian) way,

If an SSE/AVX register's value is such that all its bytes are either 0 or 1, is there any way to efficiently get the indices of all non zero elements? For example, if xmm value is | r0=0 | r1=1 | r2=0 | r3=1 | r4=0 | r5=1 | r6=0 |...| r14=0 | r15=1 | the result should be something like (1, 3, 5, ... , 15). The result should be placed in another _m128i variable or char[16] array. If it helps, we can assume that register's value is such that all bytes are either 0 or some constant nonzero value (not necessary 1). I am pretty much wondering if there is an instruction for that or preferably C/C++

I have written and debugged some AVX code with g++ and now I'm trying to get it to work with MSVC, but I keep getting error LNK2019: unresolved external symbol __mm256_setr_epi64x referenced in function "private: union __m256i __thiscall avx_matrix::avx_bit_mask(unsigned int)const " (?avx_bit_mask@avx_matrix@@ABE?AT__m256i@@I@Z) The referenced piece of code is ... #include <immintrin.h> ... /* All zeros except for pos-th position (0..255) */ __m256i avx_matrix::avx_bit_mask(const std::size_t pos) const { int64_t a = (pos >= 0 && pos < 64) ? 1LL << (pos - 0) : 0; int64_t b = (pos >= 64 && pos <

I want to shift SSE/AVX registers multiples of 32 bits left or right while shifting in zeros. Let me be more precise on the shifts I'm interested in. For SSE I want to do the following shifts of four 32bit floats: shift1_SSE: [1, 2, 3, 4] -> [0, 1, 2, 3] shift2_SSE: [1, 2, 3, 4] -> [0, 0, 1, 2] For AVX I want to shift do the following shifts: shift1_AVX: [1, 2, 3, 4, 5, 6, 7, 8] -> [0, 1, 2, 3, 4, 5, 6, 7] shift2_AVX: [1, 2, 3, 4, 5, 6, 7, 8] -> [0, 0, 1, 2, 3, 4, 5, 6] shift3_AVX: [1, 2, 3, 4 ,5 ,6, 7, 8] -> [0, 0, 0, 0, 1, 2, 3, 4] For SSE I have come up with the following code shift1_SSE =

Intel is set to release a new instruction set called AVX , which includes an extension of SSE to 256-bit operation. That is, either 4 double-precision elements or 8 single-precision elements. How would one go about developing code for AVX, considering there's no hardware out there that supports it yet? More generally, how can developers write code for hardware that doesn't exist, for instance if they want to have software ready when the supporting CPU is released? Maybe I'm missing something about your question but it seems the answer is on the website that you linked. Use the Intel Compiler

vextracti128 and vextractf128 have the same functionality, parameters, and return values. In addition one is AVX instruction set while the other is AVX2. What is the difference? vextracti128 and vextractf128 have not only the same functionality, parameters, and return values. They have the same instruction length. And they have the same throughput (according to Agner Fog's optimization manuals). What is not completely clear is their latency values (performance in tight loops with dependency chains). Latency of instructions themselves is 3 cycles. But after reading section 2.1.3 ("Execution

In designing forward looking algorithms for AVX256, AVX512 and one day AVX1024 and considering the potential implementation complexity/cost of fully generic permutes for large SIMD width I wondered if it is better to generally keep to isolated 128bit operations even within AVX512? Especially given that AVX had 128bit units to execute 256bit operations. To that end I wanted to know if there was a performance difference between AVX512 permute type operations across all of the 512bit vector as opposed to permute type operations within each 4x128bit sub-vectors of a 512bit vector? Generally yes,