search

nickg / nvc

VHDL compiler and simulator
https://www.nickg.me.uk/nvc/
GNU General Public License v3.0
589 stars 75 forks source link

Coverage refactoring - Tracking Issue #880

Open Blebowski opened 2 months ago

Blebowski commented 2 months ago

Convert all Cover Items to one Bin per item, make each item counter:

  1. [x] Branch coverage - Done only half-way, coverage reporting still uses to mask and flag.
  2. [x] FSM coverage - Each bin single item, but mask is used
  3. [x] Toggle coverage - Not done
  4. [ ] Expression coverage - Not done

Fully encode bin name into the cover item hierarchy:

  1. [x] FSM coverage
  2. [x] Toggle coverage
  3. [x] Branch coverage
  4. [ ] Expression coverage

Other internal refactoring / improvements:

  1. [x] Saturate run-time counters to avoid overflow and therefore rarily marking covered item as uncovered.
  2. [ ] Make index of cover_item (the tag) 64 bit. Large designs can have 2 ^ 32 tags.
  3. [ ] Convert unreachability mask to a single bit flag. Since single cover item is single bin, no "unreachability mask" is needed.
  4. [ ] Convert exclude mask to single bit flag. The same as above

Changes related to the "user":

  1. [ ] Change specification of exclude files not to require bin name separately -> Since bin name will be part of hierarchy, this will simplify exclude file, its loading, checking and handling.
nickg commented 2 months ago

Make run-time counters 64 bit (32 bit toggle can overflow in realistically long simulation)

This will also double the memory usage of the counters and isn't needed in 99% of cases. It would be better to just make the counter saturate at 2^32 - 1 instead.

Blebowski commented 2 months ago

This will also double the memory usage of the counters and isn't needed in 99% of cases. It would be better to just make the counter saturate at 2^32 - 1 instead.

Agreed. Any solution that does not overflow and will cause covered item to be reported as uncovered in works for me.

nickg commented 2 months ago

It would be better to just make the counter saturate at 2^32 - 1 instead.

I did this in 1745c08.

Blebowski commented 2 months ago

Thanks, I have rebased my new branch where I am trying to the the coverage refactoring more gradually. It is still WIP, but I am on a much better track now :) Time wise, I am still busy, but I will try to push it a little.