before a targeted instruction, we place it
after the containing intended instruction, and then follow the sled with an instruction specific check sequence.
Note that this requires the targeted unintended instruction to a) fallthrough (instead of transferring control), and b) have a side effect which can be deterministically detected. It also requires the disassembly and inspection of the misaligned stream for the same conditions. It would be problematic for a unintended instruction to be followed by an unintended branch before the alignment sled.
The length of the alignment sled can be reduced in many cases as we only need to unify the instruction stream containing the targeted unintended instruction and the intended instruction stream. A particularly interesting special case is when the unintended instruction makes up a suffix of the intended one. Such cases can commonly arise when unintended instructions are embedded in immediates or relative displacements.