http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> 2012-05-17 15:37:02 UTC --- Following the x86-64 psABI, GCC assumes incoming stack is 16byte aligned and generates 16-byte aligned vector move on stack. If it isn't true, you will get segfault at run-time.
