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opt_clean: move unused_bits analysis to kernel/unused_bits.h

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Emil J. Tywoniak 2026-08-11 17:23:57 +02:00
parent bf86dd7faf
commit 0253911ee2
12 changed files with 86 additions and 104 deletions
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4
docs/source/using_yosys/synthesis/fsm.rst
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@ -108,9 +108,7 @@ FSM optimization
The `fsm_opt` pass performs basic optimizations on `$fsm` cells (not including
state recoding). The following optimizations are performed (in this order):
- Unused control outputs are removed from the `$fsm` cell. The attribute
``unused_bits`` (that is usually set by the `opt_clean` pass) is used to
determine which control outputs are unused.
- Unused control outputs are removed from the `$fsm` cell.
- Control inputs that are connected to the same driver are merged.

2
docs/source/using_yosys/synthesis/opt.rst
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@ -203,8 +203,6 @@ Removing unused cells and wires - `opt_clean` pass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass identifies unused signals and cells and removes them from the design.
It also creates an ``unused_bits`` attribute on wires with unused bits. This
attribute can be used for debugging or by other optimization passes.
When to use `opt` or `clean`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~