#pragma unknown_control_flow (name, [,name] ...)
Use unknown_control_flow to specify a list of routines that violate the usual control flow properties of procedure calls. For example, the statement following a call to setjmp() can be reached from an arbitrary call to any other routine. The statement is reached by a call to longjmp().
Because such routines render standard flowgraph analysis invalid, routines that call them cannot be safely optimized; hence, they are compiled with the optimizer disabled.