On 2013-08-19 05:56, Knoll Lars wrote:
> On 19.08.13 09:56, "Koehne Kai" <[email protected]> wrote: > >>> -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Thiago Macieira Sent: Monday, August 19, 2013 9:42 AM To: [email protected]: Re: [Development] QTBUG-30440: restricting the SIMD files On segunda-feira, 19 de agosto de 2013 07:37:58, Koehne Kai wrote: >>> >>>> 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? >>> Switching the default means making it difficult to unset for those who want it unset. >> Well, it's just copying /editing the mkspec ... Arguably not the most obvious way to do it, but maybe we should just document it a bit better, then :) >> >>> 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 [1]just says to run configure ... Actually it doesn't look like CFLAGS, LFLAGS is mentioned anywhere in the Qt documentation. 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 t >> >>> > > I tend to agree with Kai. Why should we penalize 99% of our users to > support a 15 year old CPU architecture? We don't do this with anything > else. Ie. Qt won't compile on a 15 year old Linux distribution, and we > don't support Win98 anymore neither. > > Cheers, > Lars > > _______________________________________________ > Development mailing list > [email protected] > http://lists.qt-project.org/mailman/listinfo/development [2] >From a long time user's perspective: We still have customers using old test equipment that runs Win NT 4.0. Like it or not, we have to support these customers to stay in business no matter how unreasonable such a thing seems. This support will not end for the foreseeable future. Our app that runs on these systems was built using Qt 2, ported to Qt 3, and we even managed to get it ported to Qt 4 by doing some mental gymnastics. Qt 5 is likely out of the question. So as long as it is remembered that somewhere there are a few of us old folks that still have to create development environments for legacy systems, and those legacy environments are still available to be built, new environments do not need to support "ancient" equipment and it is okay for the "default" settings to support 99. 5% of the users rather than the .5% of users that need legacy support. Karl Links: ------ [1] http://qt-project.org/doc/qt-5.0/qtdoc/install-x11.html [2] http://lists.qt-project.org/mailman/listinfo/development
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