Andreas Enge <andr...@enge.fr> writes: > On Thu, Oct 10, 2013 at 03:09:09PM +0200, Ludovic Courtès wrote: >> Andreas Enge <andr...@enge.fr> skribis: >> > I do not know how much this slows down qt applications. According to >> > wikipedia, >> > sse2 arrived in 2001. So one could argue that adding it would exclude >> > almost >> > no machines. >> Yes, you may be right for SSE2 (especially considering the fact that >> this kind of software is typically used on fairly recent machines.) > > Finally, I disabled everything special.
You can assume SSE2 on x86_64, as _all_ x86_64 processors have it. In fact, the C function calling conventions of SysV x86_64 psABI (used by GNU/Linux) specify that the SSE2 registers are used for passing floating point values as arguments. > As this is not a number crunching library, I would like to be > convinced of the usefulness of SSE. Qt is not a number crunching library, but I suspect it _does_ have image rendering code, where SIMD instruction sets such as SSE2 can make a dramatic difference in performance. Regards, Mark