http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55975
--- Comment #31 from Kostya Serebryany <kcc at gcc dot gnu.org> 2013-01-23 13:32:11 UTC --- I've committed an upstream change http://llvm.org/viewvc/llvm-project?view=rev&revision=173260 that makes kHighMemEnd dynamic. Hopefully, it will simplify further changes. I'd appreciate if someone who has access to a 46-bit AS machine propose a patch that works for both 44 and 46 AS w/ and w/o unlimited stack.