There is currently a definition in ujit.h

#define UJIT_CALL_THRESHOLD (1u)

We should make this a command-line argument. That will enable us to set the threshold to 1 when running make check or make btest, so that we can catch as many bugs as possible, but it will also eventually enable us to tune the threshold to maximize performance.

Note: the command line argument parsing code should check that the minimum value is 1.