AArch64 instruction size is 4 bytes. This means instruction addresses are a multiple of 4. So is a difference between addresses. `relocInfo::addr_offset()` is a difference needed to add to the address defined by the previous relocInfo to get a new address. So it is a multiple of 4. Based on this we can set relocInfo::offset_unit to 4. This will increase the range of offsets and reduce a number of filler records.