[Bug middle-end/108657] csmith: possible wrong checksum with -O3 and -ftrivial-auto-var-init=zero

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108657

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to David Binderman from comment #3)
> (In reply to Andrew Pinski from comment #2)
> > If I initialize __trans_tmp_13 explictly to 0, the issue goes away ....
> 
> $ fgrep trans_tmp_13 bug880.c
>            int64_t __trans_tmp_13;
>                            (g_452) ^= (__trans_tmp_13);
> $ 
> 
> This now looks like a bug in csmith.

It might be both. I have not looked into the IR differences with respect of
initializing and not initializing it and using/not using
-ftrivial-auto-var-init=zero yet. This was mostly to give a hint to the next
person who looks into this issue to see if they understand why there is a
difference happening.
-ftrivial-auto-var-init=zero should produce the similar results to initializing
that variable to 0 but it is not. There has been some bugs (in GCC) recently in
the area of not executed pathes with uninitialized variables changing the
behavior (incorrectly) so it might be related to one of those ...