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POSSE instruction within nested for loops
 

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    <p>i have several nested for loops in my code and i try to use intel SSE instructions on an intel i7 core to speed up the application. The code structure is as follows (val is set in a higher for loop):</p> <pre><code>_m128 in1,in2,tmp1,tmp2,out; float arr[4] __attribute__ ((aligned(16))); val = ...; ... several higher for loops ... for(f=0; f&lt;=fend; f=f+4){ index2 = ...; for(i=0; i&lt;iend; i++){ for(j=0; j&lt;jend; j++){ inputval = ...; index = ...; if(f&lt;fend-4){ arr[0] = array[index]; arr[1] = array[index+val]; arr[2] = array[index+2*val]; arr[3] = array[index+3*val]; in1 = _mm_load_ps(arr); in2 = _mm_set_ps1(inputval); tmp1 = _mm_mul_ps(in1, in2); tmp2 = _mm_loadu_ps(&amp;array2[index2]); out = _mm_add_ps(tmp1,tmp2); _mm_storeu_ps(&amp;array2[index2], out); } else { //if no 4 values available for SSE instruction execution execute serial code for(int u = 0; u &lt; fend-f; u++ ) array2[index2+u] += array[index+u*val] * inputval; } } } } </code></pre> <p>I think there are two main problems: the buffer used for aligning the values from 'array', and the fact that when no 4 values are left (e.g. when fend = 6, two values are left over which should be executed with the sequential code). Is there any other way of loading the values from in1 and/or executing SSE intructions with 3 or 2 values? </p> <hr> <p>Thanks for the answers so far. The loading is as good as it gets i think, but is there any workaround for the 'leftover' part within the else statement that could be solved using SSE instructions?</p>
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