https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66790
--- Comment #18 from Bernd Schmidt <bernds at gcc dot gnu.org> --- FWIW I did some googling to refresh my memory, and this may be helpful: www.seas.harvard.edu/courses/cs252/2011sp/slides/Lec02-Dataflow.pdf It looks like you want exactly the available expressions problem from page 26. Maybe that's better terminology than must-initialized? (I'm not sure, but I'd never heard the latter term before.) I think I'm coming to the conclusion that df_live really does want what it currently uses, which is the guarantee that there is _any_ def that reaches a use. The commentary could use updating though, I think it clearly isn't computing a "must" problem. When updating the patch please ensure that all new parameters are documented before the function.
