[Development] Enabling SSE2 by default on x86 builds (32-bit)

[Thiago Macieira]

On terça-feira, 10 de dezembro de 2013 19:52:35, Hausmann Simon wrote:
> Would it be possible to build libQtQml for i686/SSE2, install it into
> lib/sse2 and call it a day? I don't think it's worth shipping a pure i386
> version of that library that's not going to perform on the hardware in
> question - more than 10 years old and no chance for GPU acceleration the
> way Qt needs it.

Options:

1) distro builds Qt once with default flags
[recommended by the Qt Project for specialised distros]
	=> all libs use SSE2 and QtQml generates SSE2 code

2) distro builds Qt once with -no-sse2 flags
[not recommended at all]
	=> all libs compiled without SSE2
	=> QtQml generates SSE2 code and will not work on older machines

3) distro build Qt once with -no-sse2 and then some libs with -config sse2
[recommended by the Qt Project for general distros]
	=> most libs compiled without SSE2, a few with SSE2 code
	=> QtQml generates SSE2 code and will not work on older machines
	=> for that reason, it's pointless to install it and any library that 
	requires it outside of lib/sse2. Do only the sse2 builds.

If we apply the change I mentioned in the other email, we change cases 2 and 
3:

2bis) distro builds Qt once with -no-sse2 flags
	=> all libs compiled without SSE2
	=> QtQml generates interpreted code only

3bis) distro builds Qt once with -no-sse2 and then some libs with -config sse2
	=> most libs compiled without SSE2, a few with SSE2 code
	=> the non-SSE2 QtQml will generate interpreted code, the SSE2 one will
	generate SSE2 code and will be used only in machines less than 14 years 
	old

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 190 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.qt-project.org/pipermail/development/attachments/20131210/50a6e7d0/attachment.sig>