Add detailed comments explaining why each function should/shouldn't be
unroll-and-jammed based on memory access patterns and dependencies.
Fix loop bounds to ensure array accesses are within array bounds:
* sub_sub_less: j starts from 1 (not 0) to ensure j-1 >= 0
* sub_sub_less_3d: k starts from 1 (not 0) to ensure k-1 >= 0
* sub_sub_outer_scalar: j starts from 1 (not 0) to ensure j-1 >= 0
427c18208f