Exiting on Events

These instructions show how to allow the program to exit when an event is detected.

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FPChecker can exit on the first detected event. To enable this option, the following environment variables can be set:

FPC_TRAP_INFINITY_POS
FPC_TRAP_INFINITY_NEG
FPC_TRAP_NAN
FPC_TRAP_DIVISION_ZERO
FPC_TRAP_CANCELLATION
FPC_TRAP_COMPARISON
FPC_TRAP_UNDERFLOW
FPC_TRAP_LATENT_INF_POS
FPC_TRAP_LATENT_INF_NEG
FPC_TRAP_LATENT_UNDERFLOW

For example, to exit when NaN or positive infinity events are detected, run:

$ FPC_TRAP_NAN=1 FPC_TRAP_INFINITY_POS=1 ./program

If an event is found, the program will print a message and exit:

#FPCHECKER: Interrupting execution...
#FPCHECKER: nan
#FPCHECKER: /path/to/compute.cpp:26

Important: The program must be instrumented to allow the FPChecker runtime to detect events.

Files and Lines

We can also ask FPChecker to only exit on specific files or lines by setting these environment variables:

FPC_TRAP_FILE
FPC_TRAP_LINE

For example, the following will indicate to exit only when a NaN is found in file comp.cpp and line 7

$ FPC_TRAP_NAN=1 FPC_TRAP_LINE=7 FPC_TRAP_FILE=”comp.cpp” ./program

Note: FPChecker will match files that end with the value provided in FPC_TRAP_LINE. For example, ”/path/comp.cpp” and =”file_comp.cpp” will both match.