#pragma options [no]ignerrno
Allows the compiler to perform optimizations as if system calls would not modify errno.
Some system library functions set errno when an exception occurs. When ignerrno is in effect, the setting and subsequent side effects of errno are ignored. This option allows the compiler to perform optimizations without regard to what happens to errno.
If you require both -O3 or higher and the ability to set errno, you should specify -qnoignerrno after the optimization option on the command line.
__IGNERRNO__ is defined to 1 when ignerrno is in effect; otherwise, it is undefined.