Currently when `s1` and `s2` are different bits of the same wire,
it is possible for both `compare_signals(s1, s2)` and `compare_signals(s2, s1)` to
return false. This means the calling code will call `assign_map.add()` for
both `s1` and `s2`, which doesn't make much sense --- one of `s1` or `s2`
should be consistently preferred.
So fix that by preferring the `SigBit` with the smaller bit offset.
It's pretty common for `opt_clean` to find no wires to remove. In that case,
there is no point scanning the entire design, which can be significantly
expensive for huge designs.
This commit adds a new run_pass() method to the RTLIL::Design class,
providing a convenient API for executing Yosys passes programmatically.
This is particularly useful for PyYosys users who want to run passes
on a design object without needing to manually construct Pass::call()
invocations. The method wraps Pass::call() with appropriate logging
to maintain consistency with command-line pass execution.
Example usage (from Python):
design = ys.Design()
# ... build or load design ...
design.run_pass("hierarchy")
design.run_pass("proc")
design.run_pass("opt")
Changes:
- kernel/rtlil.h: Add run_pass() method declaration
- kernel/rtlil.cc: Implement run_pass() method
- tests/unit/kernel/test_design_run_pass.cc: Add unit tests
Change from equality check to >= to allow cells where output
is wider than natural width (zero-extended). Only reject cells
with Y_WIDTH < natural width (truncated).
This fixes test failures while still preventing the truncation
issue identified in widlarizer's feedback.
Only allow rebalancing of cells with "natural" output widths (no truncation).
This prevents equivalence failures when moving operands between adders
with different intermediate truncation points.
For each operation type, the natural width is:
- Addition: max(A_WIDTH, B_WIDTH) + 1 (for carry bit)
- Multiplication: A_WIDTH + B_WIDTH
- Logic ops: max(A_WIDTH, B_WIDTH)
Fixes widlarizer's counterexample in YosysHQ/yosys#5605 where an 8-bit
intermediate wire was intentionally truncating adder results, and
rebalancing would change where that truncation occurred.
