silly comment - (nf)

johnl at haddock.UUCP johnl at haddock.UUCP
Sat Apr 21 14:43:14 AEST 1984


#R:sri-arpa:-1210000:haddock:16800011:000:658
haddock!johnl    Apr 20 15:08:00 1984

The "comet sucks" comment in the 4BSD printf routine refers to the
annoying fact that the Vax 750 "movtuc" instruction, which used to be
in printf's inner loop, doesn't work right and sprays crud all over
memory at inconvenient times.

Actually, movtuc turned out to have two bugs in it.  Bill Joy found one,
added the comment, and fiddled the code a little but didn't take out the
movtuc.  I found the other and completely removed the movtuc.

The ramifications were pretty strange.  While fighting that bug, I tried
recompiling the C compiler, and it took three iterations until it converged
to the same object code twice in a row.

John Levine, ima!johnl



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