Upstream has recently enabled ARM instructions, even on non-ARM platforms.
Steps to Reproduce:
1. emerge pixman
/bin/sh ../libtool --silent --tag=CC --mode=compile x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I/var/tmp/portage/x11-libs/pixman-9999/work/pixman-9999/pixman -I.. -mmmx -Winline -march=nocona -O2 -pipe -Wall -fno-strict-aliasing -fvisibility=hidden -c -o libpixman_mmx_la-pixman-mmx.lo `test -f 'pixman-mmx.c' || echo '/var/tmp/portage/x11-libs/pixman-9999/work/pixman-9999/pixman/'`pixman-mmx.c
/var/tmp/portage/x11-libs/pixman-9999/work/pixman-9999/pixman/pixman-mmx.c:53:1: error: redefinition of '_mm_empty'
/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.1/include/mmintrin.h:47:1: note: previous definition of '_mm_empty' was here
make: *** [libpixman_mmx_la-pixman-mmx.lo] Error 1
If I pass --disable-arm-iwmmxt to ./configure then it compiles fine.
Created attachment 288433 [details]
Created attachment 288435 [details]
Can you attach your config.log?
I see that it's incorrectly detecting iwmmxt:
checking whether to use ARM IWMMXT intrinsics... yes
but I can't reproduce this locally.
The upstream patch in question is mine, and I've been testing it for months and I've never seen this.
Created attachment 288511 [details]
Created attachment 288559 [details, diff]
patch to enable iwmmxt only on ARM
Give this patch a try, and if it works, I'll commit it upstream.
I see exactly why the configure test would succeed on x86/amd64, but for some unknown reason, I'm not able to reproduce it. I really don't know why you're seeing this but I never have.
Anyway, thanks a bunch for testing and for finding this bug. I'm glad it was reported here so that I saw it first. :)
Patch sent to pixman mailing list.
Committed. Thanks for reporting, no thanks for not responding to testing requests. :\