https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85661
--- Comment #2 from manuel.serrano at inria dot fr --- Dear Jakub, Thank you very much for your useful answer. I was indeed ignorant of the -fexcess-precision=fast option and as you suggested "-msse2 -mfpmath=sse" solves the problem. I'm still puzzled why inserting a dummy printf changes the behaviour of the double equality test. Is that expected?