Packages

c

scala.tools.nsc.transform.TailCalls

TailCallElimination

class TailCallElimination extends Global.Transformer

A Tail Call Transformer

Version

1.1 What it does: Finds method calls in tail-position and replaces them with jumps. A call is in a tail-position if it is the last instruction to be executed in the body of a method. This is done by recursing over the trees that may contain calls in tail-position (trees that can't contain such calls are not transformed). However, they are not that many. Self-recursive calls in tail-position are replaced by jumps to a label at the beginning of the method. As the JVM provides no way to jump from a method to another one, non-recursive calls in tail-position are not optimized. A method call is self-recursive if it calls the current method and the method is final (otherwise, it could be a call to an overridden method in a subclass). Furthermore, if the method has @specialized annotated type parameters, the recursive call must contain these parameters as type arguments. Recursive calls on a different instance are optimized. Since 'this' is not a local variable, a dummy local val is added and used as a label parameter. The backend knows to load the corresponding argument in the 'this' (local at index 0). This dummy local is never used and should be cleaned up by dead code elimination (when enabled). This phase has been moved before pattern matching to catch more of the common cases of tail recursive functions. This means that more cases should be taken into account (like nested function, and pattern cases). If a method contains self-recursive calls, a label is added to at the beginning of its body and the calls are replaced by jumps to that label. Assumes: Uncurry has been run already, and no multiple parameter lists exist.

Linear Supertypes
Global.Transformer, Global.Transformer, AnyRef, Any
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Inherited
  1. TailCallElimination
  2. Transformer
  3. Transformer
  4. AnyRef
  5. Any
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new TailCallElimination(unit: Global.CompilationUnit)

Type Members

  1. class ClonedTailContext extends TailContext
  2. class DefDefTailContext extends TailContext
  3. sealed trait TailContext extends AnyRef

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 asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def atOwner[A](owner: Global.Symbol)(trans: ⇒ A): A
    Definition Classes
    Transformer
  6. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  7. def currentClass: Global.Symbol
    Attributes
    protected
    Definition Classes
    Transformer
  8. def currentMethod: Global.Symbol
    Attributes
    protected
    Definition Classes
    Transformer
  9. var currentOwner: Global.Symbol
    Attributes
    protected[scala]
    Definition Classes
    Transformer
  10. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  11. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  12. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  13. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  14. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  15. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  16. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  17. def noTailTransform(tree: Global.Tree): Global.Tree
  18. def noTailTransforms(trees: List[Global.Tree]): collection.immutable.List[Global.Tree]
  19. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  20. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  21. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  22. def toString(): String
    Definition Classes
    AnyRef → Any
  23. def transform(tree: Global.Tree): Global.Tree
    Definition Classes
    TailCallElimination → Transformer
  24. def transform(tree: Global.Tree, nctx: TailContext): Global.Tree

    Rewrite this tree to contain no tail recursive calls

  25. def transformCaseDefs(trees: List[Global.CaseDef]): List[Global.CaseDef]
    Definition Classes
    Transformer
  26. def transformIdents(trees: List[Global.Ident]): List[Global.Ident]
    Definition Classes
    Transformer
  27. def transformMemberDefs(trees: List[Global.MemberDef]): List[Global.MemberDef]
    Definition Classes
    Transformer
  28. def transformModifiers(mods: Global.Modifiers): Global.Modifiers
    Definition Classes
    Transformer
  29. def transformStats(stats: List[Global.Tree], exprOwner: Global.Symbol): List[Global.Tree]
    Definition Classes
    Transformer
  30. def transformTemplate(tree: Global.Template): Global.Template
    Definition Classes
    Transformer
  31. def transformTrees(trees: List[Global.Tree]): List[Global.Tree]
    Definition Classes
    Transformer
  32. def transformTypeDefs(trees: List[Global.TypeDef]): List[Global.TypeDef]
    Definition Classes
    Transformer
  33. def transformUnit(unit: Global.CompilationUnit): Unit
    Definition Classes
    TailCallEliminationTransformer
  34. def transformValDef(tree: Global.ValDef): Global.ValDef
    Definition Classes
    Transformer
  35. def transformValDefs(trees: List[Global.ValDef]): List[Global.ValDef]
    Definition Classes
    Transformer
  36. def transformValDefss(treess: List[List[Global.ValDef]]): List[List[Global.ValDef]]
    Definition Classes
    Transformer
  37. val treeCopy: Global.TreeCopier
    Definition Classes
    Transformer
  38. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  39. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  40. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  41. def yesTailTransform(tree: Global.Tree): Global.Tree
  42. object EmptyTailContext extends TailContext

Inherited from Global.Transformer

Inherited from Global.Transformer

Inherited from AnyRef

Inherited from Any

Ungrouped