[Bug rtl-optimization/66790] Invalid uninitialized register handling in REE

[bernds at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66790

--- Comment #16 from Bernd Schmidt <bernds at gcc dot gnu.org> ---
So I think there's three things to solve
 - which problem should df_live be using, the one it says it's using or the one
it actually does
 - if it's the former, see if passes using the information need fixing
 - if it's the latter and we need the new problem from this patch, ensure that
it actually works correctly (initializing the out bitmaps to all ones,
probably).