https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64711
--- Comment #7 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > The issue with clearing nothrow is that those pesky builtins have > that "sticky" while the per-stmt flag (gimple_call_nothrow ()) > just amends it. Guess we might want to fix that (in gimple_call_flags) > and then clear the flag always for -fnon-call-exceptions? > > I suppose all/most noexcept specifications in libstdc++ are similarly > questionable. Let's not use too big a hammer though, -fnon-call-exceptions works fine for languages (Ada, Go) that enable it by default and I'm quite wary of C++ folks who try it once in a while, want to pessimize it because it doesn't work on their questionable testcase, and then forget about it. Why not just extend what's done in build_common_builtin_nodes for __builtin_alloca to the family of __builtin_mem* functions?
