slop

jargon 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 assembly 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 quality of a compiler; slop below 5% is very

good, and 10% is usually acceptable. Modern compilers,

especially on RISCs, may actually have *negative* slop; that

is, they may generate better code than humans. This is one of

the reasons assembler programming is becoming less common.

[Jargon File]

(1995-05-28)