BROKEN: 12 tests fail (list below). Committed to keep the work resumable,
not because it is ready.
opt_clean stops calling sigNormalize(false) and, for modules carrying an
index, runs a tracing GC against it instead of rebuilding its own view of
the netlist: mark from keep/output/$input_port roots through
wire->driverCell_ (one dereference per input bit, no wire2driver
hashtable, no assign_map), sweep cells, sweep wires on fanout emptiness,
then compact the sigmap over the survivors before the wires are freed.
Per the design decision, it does not rename or rewire: where the old pass
collapsed a public wire and its driver's wire into one, this keeps both
plus the alias in the sigmap, which is fine to traverse.
Kernel support: SigNormIndex::compact() (mfp cannot erase, so the sigmap
only ever grows -- opt_clean is the only pass that knows what is garbage,
hence the only one that can shrink it), an index-aware
Module::remove(pool<Wire*>), and signorm_sigmap() normalizing fully
rather than only flushing, since a caller reading the *index* rather than
just the map has to see it settled.
What this is worth on its own: 4.75s -> 4.54s on a 2000-stage pipeline
(Debug), against main-dbg's 4.56s. The real win needs opt_dff to stop
tearing the index down too -- together they are 3.39s -- but opt_dff
regresses optimization quality under signorm and is left denormalizing.
Neither change pays off without the other, which is the point of keeping
this around. See g/signorm-opt_clean-analysis.md.
Failing: arch/fabulous/fsm, arch/gatemate/fsm,
arch/quicklogic/qlf_k6n10f/t_mem{1,5,6},
asicworld/code_verilog_tutorial_explicit, memories/wide_all, sat/share,
various/{bug3515,bug4909,muxcover,port_sign_extend}.
port_sign_extend is diagnosed and is not this pass's fault: Design::add()
indexes a module while it is still empty, so setup_module_inputs() finds
no ports and the index stays incomplete for wires added afterwards. Same
defect as submod. muxcover is another marker-cell count. sat/share is the
one still worth suspecting the GC over.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MQU5XCqDYY8MbivGkNRrDo
