Timing variables are used to measure elapsed time in various
portions of the compiler. Each measures wall time.
Timing variables are defined using the DEFTIMEVAR macro in
timevar.def. Each has an enumeral identifier, used when referring
to the timing variable in code, and a character string name.
Timing variables can be used in two ways:
- On the timing stack, using timevar_push and timevar_pop.
Timing variables may be pushed onto the stack; elapsed time is
attributed to the topmost timing variable on the stack. When
another variable is pushed on, the previous topmost variable is
`paused' until the pushed variable is popped back off.
- As a standalone timer, using timevar_start and timevar_stop.
All time elapsed between the two calls is attributed to the
variable.
This structure stores the various varieties of time that can be
measured. Times are stored in nanoseconds. The time may be an
absolute time or a time difference; in the former case, the time
base is undefined, except that the difference between two times
produces a valid time difference.
1.13.2