[Development] QTBUG-30440: restricting the SIMD files

[Thiago Macieira]

On segunda-feira, 19 de agosto de 2013 07:56:43, Koehne Kai wrote:
> > We recommend people set the environment if they want different flags,
> > besides the stock from their compilers. 
> 
> Where do we recommend this? E.g.
> 
> http://qt-project.org/doc/qt-5.0/qtdoc/install-x11.html
> 
> just says to run configure ... Actually it doesn't look like CFLAGS, LFLAGS
> is mentioned anywhere in the Qt documentation.

The Unix configure script behaves like any configure script on Unix. It's 
expected that it honours those variables because every configure script does. I 
don't think we need to document what's the minimum functionality expected from 
any configure script.

> > If we recommend that, why not use
> > that ourselves?
> 
> Well, I just think most people compiling on their own will miss this
> optimization then. If we think it's a useful optimization that helps >95%
> of our customers, it should IMO be the default . If not, I'm not sure we
> should apply it to our binary installers either.

As I said, we don't have to do anything on Windows. Just compile with MSVC 
2012. It generates SSE2 code by default.

As for people compiling Qt from sources, they're getting the same 
optimisations that they're getting in other software. I think it's more 
important to be consistent than to get better code (however better it is).

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
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