Thomas Lockhart writes:
> Mandrake (as of 7.2) still does a brain-dead mix of "-O3" and
> "-ffast-math", which is a risky and unnecessary combination according to
> the gcc folks (and which kills some of our date/time rounding). From the
> man page for gcc:
>
> -ffast-math
> This option should never be turned on by any `-O' option
> since it can result in incorrect output for programs which
> depend on an exact implementation of IEEE or ANSI
> rules/specifications for math functions.
You're reading this wrong. What this means is:
"If you're working on GCC, do not ever think of enabling -ffast-math
implicitly by any -Ox level [since most other -fxxx options are grouped
under some -Ox], since programs that might want optimization could still
depend on correct IEEE math."
In particular, Mandrake is not wrong to compile with -O3 and -ffast-math.
The consequence would only be slightly incorrect math results, and that is
what indeed happened.
--
Peter Eisentraut peter_e@gmx.net http://yi.org/peter-e/
