Bug 183632

Summary:	x11-libs/qt ebuild should respect the mmx/3dnow/sse/sse2 USE flags
Product:	Gentoo Linux	Reporter:	Håvard Wall <haavardw>
Component:	New packages	Assignee:	Qt Bug Alias <qt>
Status:	RESOLVED WONTFIX
Severity:	enhancement	CC:	jakub
Priority:	Lowest
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	qt-4.3.0.ebuild.patch

Description Håvard Wall 2007-06-29 09:49:39 UTC

Qt can be configured to omit mmx/3dnow/sse/sse2 optimizations by passing -no-[mmx|3dnow|sse|sse2] to configure. This reduces the library size and makes sense if you don't have any these instruction sets on your CPU anyway.


Reproducible: Always

Steps to Reproduce:

Comment 1 Håvard Wall 2007-06-29 11:26:14 UTC

Created attachment 123383 [details, diff]
qt-4.3.0.ebuild.patch

Comment 2 Jakub Moc (RETIRED) gentoo-dev

2007-06-29 14:40:36 UTC

This is a really bad idea. There's no sane way to enable such flags by default on x86 profiles (the CPUs are not guaranteed to support such feature), so most x86 people with decently recent CPUs will just get sucky QT4 unless they add the flags manually. I disagree with adding such flags to QT, it's pretty pointless.

Comment 3 Caleb Tennis (RETIRED) gentoo-dev

2007-12-19 14:48:07 UTC

note that mmx,3dnow,etc are all tested at configure time and NOT used if they aren't supported by the processor, so I don't think this is necessary.

Comment 4 Håvard Wall 2007-12-19 15:06:37 UTC

No, configure only tests for necessary intrinsics support in the toolchain, not whether the current CPU actually supports the instructions (there's a runtime test for this though).

Anyway, I guess comment #2 have a point. Since none of these flags are enabled by default, it's probably a bad idea to have these optimizations removed by default, so I'm marking the task as a wontfix.