Floating-point subtraction (double precision) (Floating-point Subtract (Double))
This instruction subtracts the double-precision floating-point format contents of the register pair specified by general-purpose register reg1 from the double-precision floating-point format contents of the register pair specified by general-purpose register reg2, and stores the result in the register pair specified by general-purpose register reg3. The operation is executed as if it were of infinite accuracy, and the result is rounded in accordance with the current rounding mode.