[Bug rtl-optimization/115877] [15 Regression] wrong code at -Os (missing zero extension)

[xry111 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115877

--- Comment #18 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #15)
> Xi, please file a distinct bug for the loongarch bootstrap failure.  If in
> the end it turns out to be the same failure as this one, when we'll close it
> as a dup.  Please assign that new bug to me.

There's not a bootstrap failure but the miscompilation of libcpp/expr.cc causes
incorrect "integer overflow in preprocessor expression" warning on

#if -0
#endif

And to reproduce the issue one of my local patches is needed.  I'll gather more
info before submitting a new report...