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середа, 21 жовтня 2009 р.

SSE vector operations in GCC

Thanks to GCC vector types one can do SSE vector operations without having to write any assembly. The below code snippet:
#include <stdio.h>

typedef int v4si __attribute__ ((mode(V4SI)));

int main(int argc, char** argv) {


     v4si a[10], b[10], c[10];

        for(int i = 0; i < 10; i++) {
     c[i] = a[i] + b[i];
}

}

translates into the following assembly:
 movdqa  (%eax), %xmm1
 ...   
 movdqa  (%eax), %xmm0
 paddd   %xmm1, %xmm0

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