DeadCodeElimination
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package transforms
Perform the transform, encode renaming with RenameMap, and can delete annotations Called by runTransform.
Perform the transform, encode renaming with RenameMap, and can delete annotations Called by runTransform.
Input Firrtl AST
A transformed Firrtl AST
Extract all References and SubFields from a possibly nested Expression
The firrtl.CircuitForm that this transform requires to operate on
The firrtl.CircuitForm that this transform requires to operate on
A convenience function useful for debugging and error messages
A convenience function useful for debugging and error messages
The firrtl.CircuitForm that this transform outputs
The firrtl.CircuitForm that this transform outputs
Perform the transform and update annotations.
Perform the transform and update annotations.
Input Firrtl AST
A transformed Firrtl AST
Convenience method to get annotations relevant to this Transform
Convenience method to get annotations relevant to this Transform
The CircuitState form which to extract annotations
A collection of annotations
(Since version 1.1) Just collect the actual Annotation types the transform wants
Dead Code Elimination (DCE)
Performs DCE by constructing a global dependency graph starting with top-level outputs, external module ports, and simulation constructs as circuit sinks. External modules can optionally be eligible for DCE via the OptimizableExtModuleAnnotation.
Dead code is eliminated across module boundaries. Wires, ports, registers, and memories are all eligible for removal. Components marked with a DontTouchAnnotation will be treated as a circuit sink and thus anything that drives such a marked component will NOT be removed.
This transform preserves deduplication. All instances of a given firrtl.ir.DefModule are treated as the same individual module. Thus, while certain instances may have dead code due to the circumstances of their instantiation in their parent module, they will still not be removed. To remove such modules, use the NoDedupAnnotation to prevent deduplication.