#pragma isolated_call
In IBM® XL C/C++ for AIX® 16.1.0 or earlier releases, #pragma isolated_call specifies functions that have no side effects in the source file other than those implied by their parameters.
IBM Open XL C/C++ for AIX 17.1.3
does not support #pragma isolated_call. You are recommended to use the
__attribute__((pure)) function attribute instead.