Re: [Plib-users] Building Plib on Mac OSX (Darwin)

[Bernie B. <bb...@bi...>]

Steve Baker wrote:
> 
> Reed Hedges wrote:
> 
> >  > The "-O6" stuff was removed recently in CVS.
> >
> >  > Dunno - some attempt to get more speed by increasing the optimisation
> > level
> >  > I guess.
> >
> > Yeah, except gcc 2.95.2 only goes up to -O3, according to the
> > documentation I have...
> > and it fails with -O6 :)
> 
> No it doesn't...
> 
>   /u/steve> gcc -O2 t1.cxx
>   /u/steve> gcc -O6 t1.cxx
>   /u/steve> gcc -O9 t1.cxx
>   /u/steve> gcc --version
>   2.95.2
> 
> Doesn't seem to be a problem.  I don't think you'll get any better optimisation
> after -O3 though.
> 
According to the manual everyything above -O3 is undocumented so YMMV.

Anyways embedding compiler specific options in the autoconf/automake
files is considered bad form.  The approved method is to set CXXFLAGS in
the environment before running configure:

CXX=/usr/intel/ia32/bin/icc CXXFLAGS="-tpp6 -unroll -Kc++eh" ./configure

Cheers,
Bernie