https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #9 from Matthew Wilcox <matthew at wil dot cx> --- Maybe I'm a little slow, but I don't see what the path is that sets 'nr' to 0. It's 1UL << compound_order. Typically, compound_order is 0, although it may be anything up to log2(number of pages in the machine). Are you saying that nr could be 0 because DOM2 thinks compound_order() could be larger than 64, and thus undefined?
