According [indirectly] to one of the comments, the issue is that there is no solution which solves all the problems in the context. Reference: https://gcc.gnu

According [indirectly] to one of the comments, the issue is that there is no solution which solves all the problems in the context. Reference: https://gcc.gnu.org/ml/gcc/2003-08/msg01257.html https://gcc.gnu.org/ml/gcc/2003-08/msg01257.html Specifically: There are two things missing. The abililty to turn on the workaround in c (i.e. emit FP rounding instruction after every operation), and a bug fix for the register spills. Even with those things, I think we are still in trouble. In the first case, having explicit rounding instructions eliminates the excess precision problem, but it introduces a double-rounding problem. So we have lost again there. This is probably not fixable without changing the hardware. In the second case, fixing the problem with reload spills eliminates one source of unpredictable rounding, however, we still have the problem that local variables get rounded if they are allocated to the stack and not rounded if they are allocated to an FP reg-stack register. Thus we still have the problem that we get different results at different optimization levels. So we still lose there again also. This might be fixable by promoting all stack locals to long double to avoid unexpected rounding, but that will probably cause other problems in turn. It will break all programs that expect assignments doubles will round to double for instance. If we don't promote stack locals, then we need explicit rounding for them, and then we have double-rounding again. I really see no way to fix this problem other than by fixing the hardware. The hardware has to have explicit float and double operations.