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.
This pass converts cascaded chains of arithmetic and logic cells ($add,
$mul, $and, $or, $xor) into balanced binary trees to improve timing
performance in hardware synthesis.
The optimization uses a breadth-first search approach to identify chains
of compatible cells, then recursively constructs balanced trees that
reduce the critical path depth.
Features:
- Supports arithmetic cells: $add, $mul
- Supports logic cells: $and, $or, $xor
- Command-line options: -arith (arithmetic only), -logic (logic only)
- Preserves signed/unsigned semantics
- Comprehensive test suite with 30 test cases
Original implementation by Akash Levy <akash@silimate.com> for Silimate.
Upstreamed from https://github.com/Silimate/yosys
