Refine GetDeadAfterSynthesisNodes to give more accurate results.#4009
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Refine GetDeadAfterSynthesisNodes to give more accurate results.#4009copybara-service[bot] merged 1 commit intomainfrom
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For procs we would give a rather conservative analysis where we would consider `Next` and `StateRead` nodes always alive even if the `Next` feeds a `StateRead` which is only read by 'dead-after-synthesis' nodes. This extends the analysis to recognize these situations. The SDC scheduler is updated to use ASAP scheduler to actually place dead-after-synthesis nodes. This ensures that any state elements present in this set will respect the II constraints (since that is observable in simulation). This ASAP schedule cannot fail because we can always worst case put everything in exactly one stage at the very end as a valid assignment because by definition since the states are dead after synthesis they cannot be blocked behind any outputs and so the stage is unobservable. PiperOrigin-RevId: 890549884
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Refine GetDeadAfterSynthesisNodes to give more accurate results.
For procs we would give a rather conservative analysis where we would consider
NextandStateReadnodes always alive even if theNextfeeds aStateReadwhich is only read by 'dead-after-synthesis' nodes. This extends the analysis to recognize these situations.The SDC scheduler is updated to use ASAP scheduler to actually place dead-after-synthesis nodes. This ensures that any state elements present in this set will respect the II constraints (since that is observable in simulation). This ASAP schedule cannot fail because we can always worst case put everything in exactly one stage at the very end as a valid assignment because by definition since the states are dead after synthesis they cannot be blocked behind any outputs and so the stage is unobservable.