[Bug other/59039] Undocumented __builtin_longjmp/__builtin_setjmp

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59039

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I suppose

    // alloca() to force generation of frame pointer.  The argument to alloca
    // is contrived to prevent the compiler from optimizing it away.  This
    // code should never actually be executed.
    int* dummy = (int*) alloca((sizeof(int) + (std::size_t) m_start_proc) &
0x1);
    *dummy = 0xface;

is optimized away.  Try using volatile int *.