For 32b_1r8x2c under simd16, its data size is 64 bytes in total.
But this function returns int2, which takes 128 bytes.

For this special function, don't change it to 1r16x1c. The result
is valid only for lower 8 lanes.

(cherry picked from commit 8e131ad0bbb0602e2465d553c19ec6c4623f896f)