-qignerrno

In IBM® XL C/C++ for AIX® 16.1.0 or earlier releases, the -qignerrno option allows the compiler to perform optimizations as if system calls would not modify errno. The __IGNERRNO__ macro is defined to 1 when the -qignerrno option is in effect.

In IBM Open XL C/C++ for AIX 17.1.3, the -fno-math-errno option provides the same function as -qignerrno. However, the __IGNERRNO__ macro is not supported in IBM Open XL C/C++ for AIX 17.1.3, so -fno-math-errno does not predefine __IGNERRNO__.