In some cases, compiler can allocate the same register for operand 'res'
and 'vecoutptr', resulting in segfault at 'stxvd2x 40,0,%[vecoutptr]'
because base register will contain 1, yielding a false-positive.
This is because output 'res' must be marked as an earlyclobber operand so
it may not overlap an input operand ('vecoutptr').