1Regression check for optimizing simplify instruction pass. 2 3A pair (sub, neg) should not be transforemd to (sub) for 4fp calculation because we can lose the sign of zero for 5the following expression: 6 - ( A - B ) != B - A ; if B == A 7 8Addition or subtraction with fp zero should not be eliminated 9because: 10 -0.0 + 0.0 = 0.0 11 -0.0 - -0.0 = 0.0 12