In ebuild variable IUSE has +ssse3. On AMD64 it's ok, but when somebody is using older processor and x86 arch this isn't right. At AMD64 SIMD flags are provided from profile so there is no reason to use +sse3 in IUSE. x86 profiles are designed for older arch, which often can't execute sse3 instructions. I think it's isn't safe idea to forced enabled SSE3. Reproducible: Always
Look at the ebuild first - those flags are treated differently than usual, ebuild doesn't enable anything, it just disables stuff once flags are unset. It's caused by the custom build system of ffmpeg. Standard build automagically detects your processor features and you have only an option to disable them, once detected.
I'm not sure yet. Look at this: # emerge -1 ffmpeg [...] C compiler i686-pc-linux-gnu-gcc .align is power-of-two no ARCH x86 (athlon-4) big-endian no runtime cpu detection no yasm yes MMX enabled yes MMX2 enabled yes 3DNow! enabled yes 3DNow! extended enabled yes SSE enabled yes SSSE3 enabled yes CMOV enabled yes # USE="-ssse3" emerge -v1 ffmpeg [...] >>> Configuring source in /var/tmp/portage/media-video/ffmpeg-0.5_p20373/work/ffmpeg-0.5_p20373 ... true install prefix /usr source path /var/tmp/portage/media-video/ffmpeg-0.5_p20373/work/ffmpeg-0.5_p20373 C compiler i686-pc-linux-gnu-gcc .align is power-of-two no ARCH x86 (athlon-4) big-endian no runtime cpu detection no yasm yes MMX enabled yes MMX2 enabled yes 3DNow! enabled yes 3DNow! extended enabled yes SSE enabled yes SSSE3 enabled no And i have not neither set or unset "ssse3" flag in make.conf . Probably ffmpeg will work correctly with ssse3 enabled, but i'm not sure if sse3 instruction are not used.
# emerge -1 ffmpeg # ls -l /usr/lib/libavcodec.so.52.37.1 -rwxr-xr-x 1 root root 5440804 11-11 21:13 /usr/lib/libavcodec.so.52.37.1 # USE="-ssse3" emerge -1 ffmpeg # ls -l /usr/lib/libavcodec.so.52.37.1 -rwxr-xr-x 1 root root 5465380 11-11 18:33 libavcodec.so.52.37.1 Sizes are diffrent.
(In reply to comment #3) > # emerge -1 ffmpeg > # ls -l /usr/lib/libavcodec.so.52.37.1 > -rwxr-xr-x 1 root root 5440804 11-11 21:13 /usr/lib/libavcodec.so.52.37.1 > # USE="-ssse3" emerge -1 ffmpeg > # ls -l /usr/lib/libavcodec.so.52.37.1 > -rwxr-xr-x 1 root root 5465380 11-11 18:33 libavcodec.so.52.37.1 > > Sizes are diffrent. > As they should be. Read bug 265089.
