🚀 go-pugleaf

Hi,

We are trying to simulate a large chip (~700,000 transistors) with
irsim.  There are many (almost 7,000) parallel transistors making 
up the clock distribution cell.  When simulating this chip, irsim
gives the following complaint about all of the parallel transistors:

There are too many transistors in parallel (> 300)
Simulation results may be inaccurate, to fix this
you will need to increase this limit in conn_list.c

No problem, just edit conn_list.c, increase MAX_PARALLEL to 7000.
Do the same in globals.h and then recompile.  No problem.  Right?

Now, sure enough, the parallel transistor message is gone, but
now irsim says:

time 100ns; there are pending events (839)
.
.
.
internal error: no events but npending set


What's going on here?  I found where these errors are produced,
but can't figure out whats causing them.  Some things I tried
have left more questions than they answered.  Such as; I set
the MAX_PARALLEL to 600.  Same internal error, but no complaint
about the parallel transistors!  Just what is MAX_PARALLEL?  I 
then removed a large cell from the design and replaced it with 
a dummy cell (just connecting wires) -- but left all 7,000 parallel
transistors in place -- and got no errors.

So it seems that the internal error is not due to the parallel 
transistors, but the number of nodes to keep track of?

If anyone could shed some light on this problem, I'd be happy.



Mike Killoran
killoran@ll.mit.edu