bad C code or bad object code ?

[Volker Reichelt]

> we noticed that xterm in Gentoo started to produce broken color display when 
> compiled with gcc-4.1 and -Os ... one of our devs ripped apart a small test 
> case to illustrate the issue at hand (Debian shows the same issues)
>
> the trouble centers around a matrix declared as static volatile and is never 
> initialized ... xterm expects the matrix to be zero set already, but when 
> compiled with -Os, this just doesnt work

Ouch. The compiler produces wrong code.
The problem is not the matrix, though, but a bad interaction of
the for-loop and the if-statement.

Filed in Bugzilla as http://gcc.gnu.org/PR28386.

Regards,
Volker