Function cpu_time 

pub fn cpu_time() -> Number

CPU time in seconds. Equivalent to Ipopt::CpuTime.

std offers no portable CPU-time API, so we fall back to wallclock. The bit-equivalence trace strips the timing column before diffing per the plan, so this is acceptable; phase 4 will wire in a libc::clock_gettime(CLOCK_PROCESS_CPUTIME_ID) path where it’s needed by the iteration log.