Extensões Intel® Streaming SIMD

Dynamic Shift


I am trying to achieve a dynamic shift. Well, let me explain the task. I process data with SSE, AVX. Data gets loaded, worked with and later results are stored. To support arbitrary lengths, I need some kind of maskload, but also for SSE.

Suppose my lenght is 9 elements, I work with int32 and SSE. First load, second load is fine. Third load is fine from memory bound, this is no problem. But only element 0 in vector register is valid, others need to be zero. How do I achieve this best?

Why is my AVX slower than SSE?

As the description of "IIR Gaussian Blur Filter Implementation using Intel® Advanced Vector Extensions",

The AVX should be faster than SSE,But, my result of performance measurement as following:

 The computer supports AVX
number CPU in the system = 4

 IIR Gaussian Filter Coefficients are:
a0 = 0.021175, a1 = -0.017807, a2 = 0.021103, a3 = -0.017875, b1 = -1.837578, b2
 = 0.844174, cprev = 0.510583, cnext = 0.489409

image width = 1024, height = 1024

Running multi threaded SSE code

Running multi threaded AVX code

Using the Emscripten* Compiler with the Intel® XDK


Emscripten Compiles C and C++ to Javascript. This allows for running C and C++ programs with HTML5. Intel(R) XDK is an HTML5 Cross-platform Development Tool and provides an easy and fast way to get your apps to market. Emscripten Compiler and Intel XDK now gives you another option to publish apps using C and C++ as part of the application.


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  • Extract non-zero byte from _m128i


    I have 4 _m128i 64byte elements which can contain 0 or non-zero (+ve, -ve) values. I want to extract non-zero values from them.

    I looked at _mm_extract_epi8/_mmextract_epi16 but the syntax is int _mm_extract_epi16 (__m128i a, int imm) where imm is the index, hence I have to loop to get non-zero values.

    Any intrinsics functions that can be used to avoid loop will be helpful. Inputs appreciated.


    Is it ok to create an array of _m256i

    Hi all! I am parallelizing a certain dynamic programming problem using AVX2.
    In the main iteration of my calculation, I calculate column in matrix where each cell is an AVX2 register -> _m256i. I use values from the previous matrix column as input values for calculating the current column. Columns can be big, so what I do is I have an array of _m256i values, like this: _m256i prevColumn [N].

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