MPIR_Breakpoint(3) on Linux
The text e04d03548813, as Debian 2.1 (Slink), Debian 2.0 (Hamm) shipped it. The page shows this text now.
Provide a routine that a debugger can intercept at interesting times. Note that before calling this you should set up MPIR_debug_state, so that the debugger can see what is going on.