slop

slop n.  1. A one-sided {fudge factor}, that is, an
   allowance for error but in only one of two directions.  For
   example, if you need a piece of wire 10 feet long and have to guess
   when you cut it, you make very sure to cut it too long, by a large
   amount if necessary, rather than too short by even a little bit,
   because you can always cut off the slop but you can't paste it back
   on again.  When discrete quantities are involved, slop is often
   introduced to avoid the possibility of being on the losing side of
   a {fencepost error}.  2. The percentage of `extra' code
   generated by a compiler over the size of equivalent assembler code
   produced by {hand-hacking}; i.e., the space (or maybe time) you
   lose because you didn't do it yourself.  This number is often used
   as a measure of the goodness of a compiler; slop below 5% is very
   good, and 10% is usually acceptable.  With modern compiler
   technology, esp. on RISC machines, the compiler's slop may
   actually be *negative*; that is, humans may be unable to
   generate code as good.  This is one of the reasons assembler
   programming is no longer common.