https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103980
--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- If it's specific to s390, I wonder if it's something to do with excess precision being enabled by -std=c89 (see commit a5dd6b69fcbe74c02d4821ac2daf2b8c9f819f6e regarding s390 excess precision, but even if that means it doesn't appear by default with newer GCC on s390, if it's an excess precision issue I'd expect it to appear also with x86 -mfpmath=387).
