The comment could be more helpful. Explaining what this code does is more important than explaining that it replaces something that no longer exists.
I've found this documentation on the x87 FPU Control Word: http://home.agh.edu.pl/~amrozek/x87.pdf Section 8.1.4. It looks like the value 0x027f changes the Precision Control (PC) field from the default of "Double Extended Precision (64 bits)" (value 3) to "Double Precision (53 bits)" (value 2). https://codereview.appspot.com/577450043/
