compile-file execution time driven by `reap-pipes'

[Matt Wette]

I'm wanted to trace down why some of my "compile-file" w/ no optimization
was tasking time.  I was able to turn compile-file under statprof for one
of the moderate sized .scm files, which has about 45,000 lines of code.
It was interesting that the major execution time consumer was reap-pipes.
I'm curious where that fits in.  Does anyone know how compile-file could
be banging on reap-pipes so much?  Below is the top output from statprof.
The results are for a run using guile 3.0.2 on Ubunu 18.04/x86_64.


%     cumulative   self     calls
time   seconds    seconds   procedure
 12.67    190.96    154.99  ice-9/popen.scm:145:0:reap-pipes
 12.30    363.41    150.49  language/cps/intset.scm:270:2:adjoin
 11.23    270.27    137.34  anon #x55befcb4c430
 10.89    186.95    133.18  language/cps/slot-allocation.scm:843:19
 10.58    129.40    129.40  language/cps/intmap.scm:396:0:intmap-ref
  5.31   1279.35     64.90  language/cps/intmap.scm:247:2:adjoin
  3.81    228.54     46.66  language/cps/intset.scm:269:0:intset-add
  3.48   4695.90     42.60  language/cps/intset.scm:470:5:visit-branch
  3.28     40.14     40.14  language/cps/intset.scm:349:0:intset-ref
  2.98    567.14     36.46  language/cps/intmap.scm:246:0:intmap-add