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.
Implement iterative queue-based traversal in wreduce pass to propagate
width reductions across dependent cells and wires. Previously, wreduce
would process all cells once, then all wires once. This meant that
reductions couldn't propagate through chains of operations.
The new algorithm maintains work queues for both cells and wires,
processing them iteratively until no more reductions are possible.
When a cell or wire is reduced, dependent cells and wires are added
back to the queues for reprocessing.
Add regression test to verify that width reductions propagate through
a chain of operations: (a + b)[3:0] + c, ensuring the first addition
is reduced from 9 bits to 4 bits.
