-fprecision=<p>

(x86) -fprecision={single, double, extended} Initializes the rounding precision mode bits in the Floating-point Control Word to single (24 bits), double (53 bits), or extended (64 bits), respectively. The default floating-point rounding-precision mode is extended.

Note that on Intel, only the precision, not exponent, range is affected by the setting of floating-point rounding precision mode.