http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16427
--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-09 14:56:26 UTC --- Related to this is struct X { int i; int j; int k; }; void foo (void) { struct X a, b; __builtin_memcpy (&a, &b, 4); } where we are unable to DCE the memcpy call. Both issues should be tackled at tree DCE level by better handling of aliased (local) variables. Needs the same infrastructure changes as PR41490.