http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60237
--- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to N Schaeffer from comment #6) > Is there somewhere a rationale for not making isnan() find NaN's with > -ffinite-math-only ? finite-math-only is basically a promise that isinf and isnan always return false... I have inline library functions that do: if (isnan(x)) ... When compiled with -ffinite-math-only, I want this eliminated as dead code, that's the reason I made the function inline in the first place. Another way to cheat: int myisnan(double)__asm__("isnan");