[Development] QTBUG-30440: restricting the SIMD files

[Koehne Kai]

> -----Original Message-----
> From: development-bounces+kai.koehne=digia.com at qt-project.org
> [mailto:development-bounces+kai.koehne=digia.com at qt-project.org] On
> Behalf Of Thiago Macieira
> Sent: Friday, August 16, 2013 5:46 PM
> To: development at qt-project.org
> Subject: Re: [Development] QTBUG-30440: restricting the SIMD files
> 
> On sexta-feira, 16 de agosto de 2013 11:53:45, Koehne Kai wrote:
> > > I recommend:
> > >       CFLAGS (x86) = -march=i686 -mtune=core2 -msse2 -mfpmath=sse
> > >       CFLAGS (x86-64) = -mtune=core2
> > >       LFLAGS = -Wl,-O1 -Wl,--as-needed -Wl,-z,relro
> > >
> > >
> > >
> > > For MSVC, set CFLAGS on x86 to -arch:SSE2.
> >
> > I'm not sure I understand. Do you suggest to update the default
> > mkspec's for e.g. linux-g++ in qtbase? Or do you suggest that we
> > compile our binary installers with CLAGS set?
> 
> I suggest we leave the mkspecs files alone. Don't change them.
> 
> Instead, change the build environment for our binaries only, setting the
> environment variables so that the build picks them up.

I'm not sure whether we should really do this. Deviating too much from a 'stock' self-built has already given us enough issues in the past, and adding yet another difference calls for more ...

I don't know how big the performance gains really are, but if it's noticeable, why not switch the default for everyone using the default mkspec?

Regards

Kai