[Bug middle-end/57649] [4.7 Regression] ICE in set_is_used

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57649

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Isn't it going to cause problems if we fold some accesses to the static var
using the expressions in the initializer, we'd end up with not having the vars
referenced?

If backporting anything, my preference would be to actually backport just the
tree-ssa-live.c change and not the tree-dfa.c change.
Or Eric's patch.