------- Comment #75 from dirtyepic at gentoo dot org 2010-04-29 22:58 ------- if some libraries, (zlib and fontconfig i've had personal experience with, i've also heard libgcrypt) are compiled with -ftree-vectorize (ie. -O3) on x86 systems supporting SSE2, it causes segfaults in certain packages, usually mozilla-based or wine, when SSE2 instructions requiring 16bit alignment are used on unaligned data. nothing is being built with -mpreferred-stack-boundary in these cases. this is PR41156, https://bugzilla.redhat.com/489290, https://bugs.gentoo.org/270120. i'm not convinced this is GCC's problem. it usually gets traced back as far as something in the mozilla codebase misaligning the stack at which point everyone seems to give up. i've yet to see an actual testcase, though I've encountered it several times in the wild.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
