https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65181
--- Comment #5 from Thomas Schwinge <tschwinge at gcc dot gnu.org> --- While reviewing other things, I found that "'alloca' is a preview feature in PTX ISA version 7.3", and "requires 'sm_52' or higher". That got published 2021-05, so it'll be a while until we can reliably use it, but we're getting there... ;-)
