How to tell GCC that a pointer argument is always double-word-aligned?

Question

In my program I have a function that does a simple vector addition c[0:15] = a[0:15] + b[0:15]. The function prototype is:

void vecadd(float * r         


        

Answer 1

I never used it, but there is _attribute_((aligned (8)))

If I read the documentation right, then it is used this way:

void vecadd(float * restrict a __attribute__((aligned (8))), 
            float * restrict b __attribute__((aligned (8))), 
            float * restrict c __attribute__((aligned (8))));

see http://ohse.de/uwe/articles/gcc-attributes.html#type-aligned