https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71793
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to DB from comment #2) > Thanks Richard! About this - > > > RTL expansion expands x as register copy for some reason > > - is this person's explanation about this originating in the ABI accurate? > http://stackoverflow.com/a/38248847/2757035 > > If so - again not that I expect anyone really to use this pattern! - but > from a Standard perspective, I'm interested whether it forbids such register > allocation, and whether any workaround is feasible. In practical terms, a > very academic exercise :-) but valuable for its implications wrt the > Standard and ABI Well, if you look at the out-of-line copies of the function then he is correct. But the inline copy in main() does not have this constraint and is still mishandled. Note I didn't yet investigate closer what is going on.
