https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38960
--- Comment #5 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Since any non-const function can examine floating-point state, I'd expect significant effects on code generation. (Whether this also applies to asms depends on the architecture; some architectures have a register name you can use in asm operands to refer to floating-point state, and in those cases asms reading or writing that state "should" say explicitly that they do so, but I don't think all architectures have such a name supported by GCC in asms.)
