[Bug fortran/79929] [7/8 Regression] Bogus Warning: '__builtin_memset': specified size 4294967291 exceeds maximum object size 2147483647

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79929

--- Comment #21 from Martin Sebor <msebor at gcc dot gnu.org> ---
The rtl.c error was discussed in the context of some other bug having to do
with profiledbootstrap failure (I can't find the bug now).  If I recall, it's
due to the same signed <-> unsigned conversion issue as a number of other
warnings of this kind, i.e., rtvec_alloc taking a signed int argument that's
being converted to size_t.  Besides configuring with the --disable-werror
recommended for profiledbootstrap, adding a gcc_assert(n >= 0) fixed it. 
Strangely, though, changing the function's argument to unsigned seemed to
tickle some latent bug somewhere and caused GCC to crash during bootstrap.  I
never investigated why.