Packages

c

firrtl.transforms

DeadCodeElimination

class DeadCodeElimination extends Transform with RegisteredTransform with DependencyAPIMigration

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.

Source
DeadCodeElimination.scala
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Inherited
  1. DeadCodeElimination
  2. DependencyAPIMigration
  3. RegisteredTransform
  4. HasShellOptions
  5. Transform
  6. DependencyAPI
  7. TransformLike
  8. LazyLogging
  9. AnyRef
  10. Any
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Visibility
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Instance Constructors

  1. new DeadCodeElimination()

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def addOptions(p: OptionParser[AnnotationSeq]): Unit

    Add all shell (command line) options to an option parser

    Add all shell (command line) options to an option parser

    p

    an option parser

    Definition Classes
    HasShellOptions
  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  7. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  8. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  9. def execute(state: CircuitState): CircuitState

    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.

    state

    Input Firrtl AST

    returns

    A transformed Firrtl AST

    Definition Classes
    DeadCodeEliminationTransform
  10. def extractRefs(expr: Expression): Seq[Expression]

    Extract all References and SubFields from a possibly nested Expression

  11. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  12. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  13. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  14. def invalidates(a: Transform): Boolean

    A function that, given *another* transform (parameter a) will return true if this transform invalidates/undos the effects of the *other* transform (parameter a).

    A function that, given *another* transform (parameter a) will return true if this transform invalidates/undos the effects of the *other* transform (parameter a).

    a

    transform

    Definition Classes
    DeadCodeEliminationDependencyAPIMigrationTransformDependencyAPI
  15. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  16. val logger: Logger
    Attributes
    protected
    Definition Classes
    LazyLogging
  17. def name: String

    A convenience function useful for debugging and error messages

    A convenience function useful for debugging and error messages

    Definition Classes
    TransformTransformLike
  18. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  19. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  20. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  21. def optionalPrerequisiteOf: Seq[Dependency[Transform with DependencyAPIMigration { def optionalPrerequisiteOf: Seq[Nothing] }]]

    A sequence of transforms to add this transform as an optionalPrerequisite.

    A sequence of transforms to add this transform as an optionalPrerequisite. The use of optionalPrerequisiteOf enables the transform declaring them to always run before some other transforms. However, declaring optionalPrerequisiteOf will not result in the sequence of transforms executing.

    This is useful for providing an ordering constraint to guarantee that other transforms (e.g., emitters) will not be scheduled before you.

    Definition Classes
    DeadCodeEliminationDependencyAPIMigrationTransformDependencyAPI
    Note

    This method **will not** result in the listed transforms running. If you want to add multiple transforms at once, you should use a DependencyManager with multiple targets.

  22. def optionalPrerequisites: Seq[Nothing]

    All transforms that, if a prerequisite of *another* transform, will run before this transform.

    All transforms that, if a prerequisite of *another* transform, will run before this transform.

    Definition Classes
    DeadCodeEliminationDependencyAPIMigrationTransformDependencyAPI
    Note

    The use of a Seq here is to preserve input order. Internally, this will be converted to a private, ordered Set.

  23. val options: Seq[ShellOption[Unit]]

    A sequence of options provided

    A sequence of options provided

    Definition Classes
    DeadCodeEliminationHasShellOptions
  24. def prerequisites: Seq[TransformDependency]

    All transform that must run before this transform

    All transform that must run before this transform

    Definition Classes
    DeadCodeEliminationDependencyAPIMigrationTransformDependencyAPI
    Note

    The use of a Seq here is to preserve input order. Internally, this will be converted to a private, ordered Set.

  25. def run(state: CircuitState, dontTouches: Seq[LogicNode], doTouchExtMods: Set[String]): CircuitState
  26. final def runTransform(state: CircuitState): CircuitState

    Perform the transform and update annotations.

    Perform the transform and update annotations.

    state

    Input Firrtl AST

    returns

    A transformed Firrtl AST

    Definition Classes
    Transform
  27. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  28. def toString(): String
    Definition Classes
    AnyRef → Any
  29. def transform(state: CircuitState): CircuitState

    A mathematical transform on some type

    A mathematical transform on some type

    returns

    an output object of the same type

    Definition Classes
    TransformTransformLike
  30. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  31. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  32. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()

Deprecated Value Members

  1. def dependents: Seq[Dependency[Transform]]

    All transforms that must run after this transform

    All transforms that must run after this transform

    This is a means of prerequisite injection into some other transform. Normally a transform will define its own prerequisites. Dependents exist for two main situations:

    First, they improve the composition of optional transforms. If some first transform is optional (e.g., an expensive validation check), you would like to be able to conditionally cause it to run. If it is listed as a prerequisite on some other, second transform then it must always run before that second transform. There's no way to turn it off. However, by listing the second transform as a dependent of the first transform, the first transform will only run (and be treated as a prerequisite of the second transform) if included in a list of target transforms that should be run.

    Second, an external library would like to inject some first transform before a second transform inside FIRRTL. In this situation, the second transform cannot have any knowledge of external libraries. The use of a dependent here allows for prerequisite injection into FIRRTL proper.

    Definition Classes
    DependencyAPI
    Annotations
    @deprecated
    Deprecated

    (Since version FIRRTL 1.3) Due to confusion, 'dependents' is being renamed to 'optionalPrerequisiteOf'. Override the latter instead.

    Note

    The use of a Seq here is to preserve input order. Internally, this will be converted to a private, ordered Set.

    See also

    firrtl.passes.CheckTypes for an example of an optional checking firrtl.Transform

  2. final def inputForm: CircuitForm
    Definition Classes
    DependencyAPIMigration
    Annotations
    @deprecated
    Deprecated

    (Since version FIRRTL 1.3) Use Dependency API methods for equivalent functionality. See: https://bit.ly/2Voppre

  3. final def outputForm: CircuitForm
    Definition Classes
    DependencyAPIMigration
    Annotations
    @deprecated
    Deprecated

    (Since version FIRRTL 1.3) Use Dependency API methods for equivalent functionality. See: https://bit.ly/2Voppre

Inherited from DependencyAPIMigration

Inherited from RegisteredTransform

Inherited from HasShellOptions

Inherited from Transform

Inherited from DependencyAPI[Transform]

Inherited from TransformLike[CircuitState]

Inherited from LazyLogging

Inherited from AnyRef

Inherited from Any

Ungrouped