28.2 Built-In Function Descriptions [DD]
This section describes the programmer interface to the compiler built-in functions.
The functions described in this section are “built in” and do not require a header file;
however, we provide a file <builtins.h> that can be included to provide
readable prototypes of these functions.
Also, there are no command-line switches associated with the built-in functions – they are
always available. The built-in function names are chosen such that they belong to the
compiler’s namespace (they all have the prefix __builtin_), so they will
not conflict with function or variable names in the programmer’s namespace.
Builtin not supported in the current configuration, please see MPLAB XC32
C Compiler User's Guide (section 28.2) for more detail.